Merge pull request #338 from Gravecat/mingw-fix

Fixes compilation on GCC/MinGW

.bazelrc

@@ -0,0 +1 @@
+build --cxxopt="--std=c++17"

.clang-format

@@ -0,0 +1,4 @@
+BasedOnStyle: LLVM
+SortIncludes: false
+SeparateDefinitionBlocks: Always
+MaxEmptyLinesToKeep: 1

.github/dependabot.yml

@@ -0,0 +1,13 @@
+# Keep GitHub Actions up to date with GitHub's Dependabot...
+# https://docs.github.com/en/code-security/dependabot/working-with-dependabot/keeping-your-actions-up-to-date-with-dependabot
+# https://docs.github.com/en/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file#package-ecosystem
+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: /
+    groups:
+      github-actions:
+        patterns:
+          - "*"  # Group all Actions updates into a single larger pull request
+    schedule:
+      interval: weekly

.github/pull_request_template.md

@@ -0,0 +1,12 @@
+We have benchmarks, please consider running them: [see our README for details](https://github.com/fastfloat/fast_float/blob/main/README.md#benchmarking). We expect you to run our benchmarks if you make claims with respect to the performance.
+
+
+Our CI tests check formatting automating. If such a test fails, please consider running the bash script:
+
+```bash
+bash script/run-clangcldocker.sh
+```
+
+Make sure that you have [docker installed and running](https://docs.docker.com/engine/install/) on your system. Most Linux distributions support docker though some (like RedHat) have the equivalent (Podman). Users of Apple systems may want to [consider OrbStack](https://orbstack.dev). You do not need to familiar with docker, you just need to make sure that you are have it running.
+
+If you are unable to format the code, we may format it for you.

.github/workflows/alpine.yml

@@ -1,27 +1,47 @@
 name: Alpine Linux
-'on':
+on:
   - push
   - pull_request
+
 jobs:
-  ubuntu-build:
+  build:
+    name: Build on Alpine ${{ matrix.arch }}
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        arch:
+          - x86_64
+          - x86
+          - aarch64
+          - armv7
+          - ppc64le
+          - riscv64
     steps:
-      - uses: actions/checkout@v2
-      - name: start docker
+      - name: Checkout repository
+        uses: actions/checkout@v5
+
+      - name: Install latest Alpine Linux for ${{ matrix.arch }}
+        uses: jirutka/setup-alpine@v1
+        with:
+          arch: ${{ matrix.arch }}
+          branch: ${{ matrix.arch == 'riscv64' && 'edge' || 'latest-stable' }}
+          packages: >
+            build-base
+            cmake
+            g++
+            linux-headers
+            git
+            bash
+            build-base
+      - name: Prepare
         run: |
-          docker run -w /src -dit --name alpine -v $PWD:/src alpine:latest
-          echo 'docker exec alpine "$@";' > ./alpine.sh
-          chmod +x ./alpine.sh
-      - name: install packages
+          cmake -DFASTFLOAT_TEST=ON -B build
+        shell: alpine.sh {0}
+      - name: Build
         run: |
-          ./alpine.sh apk update
-          ./alpine.sh apk add build-base cmake g++ linux-headers git bash
-      - name: cmake
+          cmake --build build
+        shell: alpine.sh {0}
+      - name: Test
         run: |
-          ./alpine.sh cmake -DFASTFLOAT_TEST=ON  -B build_for_alpine
-      - name: build
-        run: |
-          ./alpine.sh cmake --build build_for_alpine
-      - name: test
-        run: |
-          ./alpine.sh bash -c "cd build_for_alpine && ctest  -R basictest"
+          ctest --test-dir build -R basictest
+        shell: alpine.sh {0}

.github/workflows/amalgamate-ubuntu20.yml

@@ -1,25 +0,0 @@
-name: Amalgamate Ubuntu 20.04 CI (GCC 9, 8)
-
-on: [push, pull_request]
-
-jobs:
-  ubuntu-build:
-    runs-on: ubuntu-20.04
-    strategy:
-      fail-fast: false
-      matrix:
-        include:
-          # Legacy/x86 compilers cause CI failures.
-          #- {cxx: -DCMAKE_CXX_COMPILER=g++-8, arch:                         }
-          - {cxx:                           , arch:                         } # default=gcc9
-          #- {cxx:                           , arch: -DCMAKE_CXX_FLAGS="-m32"} # default=gcc9
-    steps:
-      - uses: actions/checkout@v2
-      - name: Compile with amalgamation
-        run: |
-          mkdir build &&
-          mkdir build/fast_float &&
-          python3 ./script/amalgamate.py > build/fast_float/fast_float.h &&
-          cp tests/string_test.cpp build/ &&
-          cd build &&
-          g++ string_test.cpp

.github/workflows/amalgamate-ubuntu24.yml

@@ -0,0 +1,17 @@
+name: Amalgamate Ubuntu 24.04 CI
+
+on: [push, pull_request]
+
+jobs:
+  ubuntu-build:
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v5
+      - name: Compile with amalgamation
+        run: |
+          mkdir build &&
+          mkdir build/fast_float &&
+          python3 ./script/amalgamate.py > build/fast_float/fast_float.h &&
+          cp tests/string_test.cpp build/ &&
+          cd build &&
+          g++ string_test.cpp

.github/workflows/cifuzz.yml

@@ -0,0 +1,35 @@
+name: CIFuzz
+on: [pull_request]
+jobs:
+ Fuzzing:
+   runs-on: ubuntu-latest
+   permissions:
+     security-events: write
+   steps:
+   - name: Build Fuzzers
+     id: build
+     uses: google/oss-fuzz/infra/cifuzz/actions/build_fuzzers@master
+     with:
+       oss-fuzz-project-name: 'fast_float'
+       language: c++
+   - name: Run Fuzzers
+     uses: google/oss-fuzz/infra/cifuzz/actions/run_fuzzers@master
+     with:
+       oss-fuzz-project-name: 'fast_float'
+       language: c++
+       fuzz-seconds: 300
+       output-sarif: true
+   - name: Upload Crash
+     uses: actions/upload-artifact@v5
+     if: failure() && steps.build.outcome == 'success'
+     with:
+       name: artifacts
+       path: ./out/artifacts
+   - name: Upload Sarif
+     if: always() && steps.build.outcome == 'success'
+     uses: github/codeql-action/upload-sarif@v4
+     with:
+      # Path to SARIF file relative to the root of the repository
+      sarif_file: cifuzz-sarif/results.sarif
+      checkout_path: cifuzz-sarif
+      category: CIFuzz

.github/workflows/emscripten.yml

@@ -0,0 +1,17 @@
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@ff7abcd0c3c05ccf6adc123a8cd1fd4fb30fb493 # v4.2.2
+      - uses: actions/setup-node@2028fbc5c25fe9cf00d9f06a71cc4710d4507903 # v6.0.0
+      - uses: mymindstorm/setup-emsdk@6ab9eb1bda2574c4ddb79809fc9247783eaf9021 # v14
+      - name: Verify
+        run: emcc -v
+      - name: Checkout
+        uses: actions/checkout@ff7abcd0c3c05ccf6adc123a8cd1fd4fb30fb493 # v3.6.0
+      - name: Configure
+        run: emcmake cmake -B build
+      - name: Build # We build but do not test
+        run: cmake --build build

.github/workflows/lint_and_format_check.yml

@@ -0,0 +1,33 @@
+name: Lint and format
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened, ready_for_review]
+    paths-ignore:
+      - '**.md'
+      - 'docs/**'
+  push:
+    branches:
+      - main
+    paths-ignore:
+      - '**.md'
+      - 'docs/**'
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  lint-and-format:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@ff7abcd0c3c05ccf6adc123a8cd1fd4fb30fb493 # v4.1.7
+
+      - name: Run clang-format
+        uses: jidicula/clang-format-action@4726374d1aa3c6aecf132e5197e498979588ebc8 # v4.15.0
+        with:
+          clang-format-version: '17'
+

.github/workflows/msys2-clang.yml

@@ -23,7 +23,7 @@ jobs:
       CMAKE_GENERATOR: Ninja
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v5
       - uses: msys2/setup-msys2@v2
         with:
           update: true

.github/workflows/msys2.yml

@@ -29,7 +29,7 @@ jobs:
       CMAKE_GENERATOR: Ninja
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v5
       - uses: msys2/setup-msys2@v2
         with:
           update: true

.github/workflows/on-release.yml

@@ -0,0 +1,41 @@
+name: On Release
+
+# By default, a workflow only has read permissions.
+# Add the needed permission to write release assets
+permissions:
+  contents: write
+
+on:
+  release:
+    types:
+      - published
+
+jobs:
+  build:
+    name: Add Release Assets
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v5
+      
+      - name: Amalgamate fast_float.h
+        run: |
+          mkdir build
+          mkdir build/fast_float
+          python3 ./script/amalgamate.py > build/fast_float/fast_float.h
+
+      - name: Test Amalgamation
+        run: |
+          cp tests/string_test.cpp build/
+          cd build
+          g++ string_test.cpp
+
+      - name: Upload Release Asset
+        uses: actions/upload-release-asset@v1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          upload_url: ${{ github.event.release.upload_url }}
+          asset_path: build/fast_float/fast_float.h
+          asset_name: fast_float.h
+          asset_content_type: text/plain

.github/workflows/risc.yml

@@ -0,0 +1,23 @@
+name: Ubuntu RISC-V rvv VLEN=128 (clang 17)
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-24.04
+    steps:
+    - uses: actions/checkout@v5
+    - name: Install packages
+      run: |
+        sudo apt-get update -q -y
+        sudo apt-get install -y cmake make g++-riscv64-linux-gnu qemu-user-static clang-17
+    - name: Build
+      run: |
+        CXX=clang++-17 CXXFLAGS="--target=riscv64-linux-gnu -march=rv64gcv" \
+        cmake --toolchain=cmake/toolchains-ci/riscv64-linux-gnu.cmake -DCMAKE_BUILD_TYPE=Release -B build
+        cmake --build build/ -j$(nproc)
+    - name: Test VLEN=128
+      run: |
+        export QEMU_LD_PREFIX="/usr/riscv64-linux-gnu"
+        export QEMU_CPU="rv64,v=on,vlen=128,rvv_ta_all_1s=on,rvv_ma_all_1s=on"
+        ctest --timeout 1800 --output-on-failure --test-dir build -j $(nproc)

.github/workflows/s390x.yml

@@ -0,0 +1,30 @@
+name: Ubuntu s390x (GCC 11)
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+      - uses: uraimo/run-on-arch-action@v3
+        name: Test
+        id: runcmd
+        with:
+          arch: s390x
+          githubToken: ${{ github.token }}
+          distro: ubuntu_latest
+          install: |
+            apt-get update -q -y
+            apt-get install -y cmake make g++
+          run: |
+            cmake -DCMAKE_BUILD_TYPE=Release -B build
+            cmake --build build -j=2
+            ctest --output-on-failure --test-dir build
+

.github/workflows/ubuntu18.yml

@@ -1,35 +0,0 @@
-name: Ubuntu 18.04 CI (GCC 7, 6, 5)
-
-on: [push, pull_request]
-
-jobs:
-  ubuntu-build:
-    runs-on: ubuntu-18.04
-    strategy:
-      fail-fast: false
-      matrix:
-        include:
-          # Legacy/x86 compilers cause CI failures.
-          #- {cxx: -DCMAKE_CXX_COMPILER=g++-5, arch:                         }
-          #- {cxx: -DCMAKE_CXX_COMPILER=g++-6, arch:                         }
-          - {cxx:                           , arch:                         } # default=gcc7
-          #- {cxx:                           , arch: -DCMAKE_CXX_FLAGS="-m32"} # default=gcc7
-    steps:
-      - uses: actions/checkout@v2
-      - name: Setup cmake
-        uses: jwlawson/actions-setup-cmake@v1.4
-        with:
-          cmake-version: '3.11.x'
-      #- name: Install older compilers
-      #  run: |
-      #    sudo -E dpkg --add-architecture i386
-      #    sudo -E apt-get update
-      #    sudo -E apt-get install -y --force-yes g++-5 g++-6 g++-5-multilib g++-6-multilib g++-multilib linux-libc-dev:i386 libc6:i386 libc6-dev:i386 libc6-dbg:i386
-      - name: Prepare build dir
-        run: mkdir build
-      - name: Configure
-        run: cd build && cmake ${{matrix.cxx}} ${{matrix.arch}} -DFASTFLOAT_TEST=ON ..
-      - name: Build
-        run: cmake --build build
-      - name: Run basic tests
-        run: cd build && ctest --output-on-failure -R basictest

.github/workflows/ubuntu20.yml

@@ -1,29 +0,0 @@
-name: Ubuntu 20.04 CI (GCC 9, 8)
-
-on: [push, pull_request]
-
-jobs:
-  ubuntu-build:
-    runs-on: ubuntu-20.04
-    strategy:
-      fail-fast: false
-      matrix:
-        include:
-          # Legacy/x86 compilers cause CI failures.
-          #- {cxx: -DCMAKE_CXX_COMPILER=g++-8, arch:                         }
-          - {cxx:                           , arch:                         } # default=gcc9
-          #- {cxx:                           , arch: -DCMAKE_CXX_FLAGS="-m32"} # default=gcc9
-    steps:
-      - uses: actions/checkout@v2
-      - name: Use cmake
-        run: |
-          mkdir build &&
-          cd build &&
-          cmake  ${{matrix.cxx}} ${{matrix.arch}} -DFASTFLOAT_TEST=ON -DCMAKE_INSTALL_PREFIX:PATH=destination ..  &&
-          cmake --build .   &&
-          ctest --output-on-failure  &&
-          cmake --install . &&
-          cd ../tests/installation_tests/find &&
-          mkdir build && cd build && cmake -DCMAKE_INSTALL_PREFIX:PATH=../../../build/destination .. &&  cmake --build . &&
-          cd ../../issue72_installation  &&
-          mkdir build && cd build && cmake -DCMAKE_INSTALL_PREFIX:PATH=../../../build/destination .. &&  cmake --build .

.github/workflows/ubuntu22-clang.yml

@@ -0,0 +1,25 @@
+name: Ubuntu 22.04 CI (clang 14)
+
+on: [push, pull_request]
+
+jobs:
+  ubuntu-build:
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v5
+      - name: Install clang++-14
+        run: sudo apt-get install -y clang++-14
+      - name: Use cmake
+        run: |
+          mkdir build &&
+          cd build &&
+          CXX=clang++-14 cmake -DFASTFLOAT_TEST=ON  ..  &&
+          cmake --build .   &&
+          ctest --output-on-failure
+      - name: Use cmake CXX20
+        run: |
+          mkdir build20 &&
+          cd build20 &&
+          CXX=clang++-14 cmake -DFASTFLOAT_CONSTEXPR_TESTS=ON -DFASTFLOAT_CXX_STANDARD=20 -DFASTFLOAT_TEST=ON  ..  &&
+          cmake --build .   &&
+          ctest --output-on-failure

.github/workflows/ubuntu22-gcc12.yml

@@ -0,0 +1,23 @@
+name: Ubuntu 22.04 CI (GCC 12)
+
+on: [push, pull_request]
+
+jobs:
+  ubuntu-build:
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v5
+      - name: Use cmake
+        run: |
+          mkdir build &&
+          cd build &&
+          CXX=g++-12 CXXFLAGS=-Werror cmake -DFASTFLOAT_TEST=ON  ..  &&
+          cmake --build .   &&
+          ctest --output-on-failure
+      - name: Use cmake CXX20
+        run: |
+          mkdir build20 &&
+          cd build20 &&
+          CXX=g++-12 CXXFLAGS=-Werror cmake -DFASTFLOAT_CONSTEXPR_TESTS=ON -DFASTFLOAT_CXX_STANDARD=20 -DFASTFLOAT_TEST=ON  ..  &&
+          cmake --build .   &&
+          ctest --output-on-failure

.github/workflows/ubuntu22-sanitize.yml

@@ -0,0 +1,16 @@
+name: Ubuntu 22.04 CI Sanitized (GCC 11)
+
+on: [push, pull_request]
+
+jobs:
+  ubuntu-build:
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v5
+      - name: Use cmake
+        run: |
+          mkdir build &&
+          cd build &&
+          cmake -DFASTFLOAT_TEST=ON -D FASTFLOAT_SANITIZE=ON  ..  &&
+          cmake --build .   &&
+          ctest --output-on-failure

.github/workflows/ubuntu22.yml

@@ -0,0 +1,16 @@
+name: Ubuntu 22.04 CI (GCC 11)
+
+on: [push, pull_request]
+
+jobs:
+  ubuntu-build:
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v5
+      - name: Use cmake
+        run: |
+          mkdir build &&
+          cd build &&
+          cmake -DFASTFLOAT_TEST=ON  ..  &&
+          cmake --build .   &&
+          ctest --output-on-failure

.github/workflows/ubuntu24-cxx20.yml

@@ -0,0 +1,19 @@
+name: Ubuntu 24.04 CI
+
+on: [push, pull_request]
+
+jobs:
+  ubuntu-build:
+    runs-on: ubuntu-24.04
+    strategy:
+      fail-fast: false
+    steps:
+      - uses: actions/checkout@v5
+      - name: Use cmake
+        run: |
+          mkdir build &&
+          cd build &&
+          cmake -DFASTFLOAT_CXX_STANDARD=20 -DFASTFLOAT_TEST=ON -DCMAKE_INSTALL_PREFIX:PATH=destination ..  &&
+          cmake --build .   &&
+          ctest --output-on-failure  &&
+          cmake --install .

.github/workflows/ubuntu24.yml

@@ -0,0 +1,29 @@
+name: Ubuntu 24.04 CI (GCC 13)
+
+on: [push, pull_request]
+
+jobs:
+  ubuntu-build:
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v5
+      - name: Use cmake
+        run: |
+          set -xe
+          cmake -B build \
+             -DFASTFLOAT_TEST=ON \
+             -DFASTFLOAT_BENCHMARKS=ON \
+             -DCMAKE_CXX_FLAGS=' -Werror -Wundef '
+          cmake --build build --parallel
+          ( cd build ; ctest --output-on-failure )
+      - name: Use cmake CXX23
+        run: |
+          set -xe
+          cmake -B build20 \
+             -DFASTFLOAT_TEST=ON \
+             -DFASTFLOAT_CONSTEXPR_TESTS=ON \
+             -DFASTFLOAT_FIXEDWIDTH_TESTS=ON \
+             -DFASTFLOAT_CXX_STANDARD=23 \
+             -DCMAKE_CXX_FLAGS=' -Werror -Wundef '
+          cmake --build build20 --parallel
+          ( cd build20 ; ctest --output-on-failure )

.github/workflows/vs15-ci.yml

@@ -1,29 +0,0 @@
-name: VS15-CI
-
-on: [push, pull_request]
-
-jobs:
-  ci:
-    if: >-
-      ! contains(toJSON(github.event.commits.*.message), '[skip ci]') &&
-      ! contains(toJSON(github.event.commits.*.message), '[skip github]')
-    name: windows-vs15
-    runs-on: windows-2016
-    strategy:
-      fail-fast: false
-      matrix:
-        include:
-          - {gen: Visual Studio 15 2017, arch: Win32}
-          - {gen: Visual Studio 15 2017, arch: x64}
-    steps:
-    - uses: actions/checkout@v2
-    - name: Configure
-      run: |
-          mkdir build
-          cd build && cmake  -G "${{matrix.gen}}" -A ${{matrix.arch}} -DFASTFLOAT_TEST=ON ..
-    - name: Build
-      run: cmake --build build --verbose --config Release --parallel
-    - name: 'Run CTest'
-      run: |
-          cd build
-          ctest -C Release --output-on-failure -R basictest

.github/workflows/vs16-arm-ci.yml

@@ -1,21 +0,0 @@
-name: VS16-ARM-CI
-
-on: [push, pull_request]
-
-jobs:
-  ci:
-    name: windows-vs16
-    runs-on: windows-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        include:
-          - {arch: ARM}
-          - {arch: ARM64}
-    steps:
-      - name: checkout
-        uses: actions/checkout@v2
-      - name: Use cmake
-        run: |
-          cmake -A ${{ matrix.arch }} -DCMAKE_CROSSCOMPILING=1 -DFASTFLOAT_TEST=ON -B build  &&
-          cmake --build build --verbose

.github/workflows/vs16-ci.yml

@@ -1,29 +0,0 @@
-name: VS16-CI
-
-on: [push, pull_request]
-
-jobs:
-  ci:
-    name: windows-vs16
-    runs-on: windows-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        include:
-          - {gen: Visual Studio 16 2019, arch: Win32}
-          - {gen: Visual Studio 16 2019, arch: x64}
-    steps:
-      - name: checkout
-        uses: actions/checkout@v2
-      - name: Use cmake
-        run: |
-          mkdir build &&
-          cd build &&
-          cmake  ${{matrix.cxx}} ${{matrix.arch}} -DFASTFLOAT_TEST=ON -DCMAKE_INSTALL_PREFIX:PATH=destination ..  &&
-          cmake --build .  --verbose &&
-          ctest --output-on-failure  &&
-          cmake --install . &&
-          cd ../tests/installation_tests/find  &&
-          mkdir build && cd build && cmake -DCMAKE_INSTALL_PREFIX:PATH=../../../build/destination .. &&  cmake --build .   --verbose
-          cd ../../issue72_installation  &&
-          mkdir build && cd build && cmake -DCMAKE_INSTALL_PREFIX:PATH=../../../build/destination .. &&  cmake --build .    --verbose

.github/workflows/vs16-clang-ci.yml

@@ -1,27 +0,0 @@
-name: VS16-CLANG-CI
-
-on: [push, pull_request]
-
-jobs:
-  ci:
-    name: windows-vs16
-    runs-on: windows-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        include:
-          - {gen: Visual Studio 16 2019, arch: Win32}
-          - {gen: Visual Studio 16 2019, arch: x64}
-    steps:
-      - name: checkout
-        uses: actions/checkout@v2
-      - name: Configure
-        run: |
-          mkdir build
-          cd build && cmake -G "${{matrix.gen}}" -A ${{matrix.arch}} -T ClangCL -DFASTFLOAT_TEST=ON ..
-      - name: Build
-        run: cmake --build build --config Release --parallel
-      - name: Run basic tests
-        run: |
-          cd build
-          ctest -C Release --output-on-failure -R basictest

.github/workflows/vs17-arm-ci.yml

@@ -0,0 +1,28 @@
+name: VS17-ARM-CI
+
+on: [push, pull_request]
+
+jobs:
+  ci:
+    name: vs17/${{matrix.arch}}/${{matrix.cfg}}
+    runs-on: windows-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - {gen: Visual Studio 17 2022, arch: ARM64, cfg: Release}
+          - {gen: Visual Studio 17 2022, arch: ARM64, cfg: Debug}
+    steps:
+      - name: checkout
+        uses: actions/checkout@v5
+      - name: configure
+        run: |
+          cmake -S . -B build -G "${{matrix.gen}}" -A ${{matrix.arch}} -DCMAKE_CROSSCOMPILING=1 -DFASTFLOAT_TEST=ON
+      - name: build
+        run: |
+          cmake --build build --verbose --config ${{matrix.cfg}} --parallel
+      # disabled because it requires a toolchain
+      #- name: test
+      #  run: |
+      #    cd build &&
+      #    ctest --output-on-failure -C ${{matrix.cfg}}

.github/workflows/vs17-ci.yml

@@ -0,0 +1,43 @@
+name: VS17-CI
+
+on: [push, pull_request]
+
+jobs:
+  ci:
+    name: vs17/${{matrix.arch}}/${{matrix.cfg}}
+    runs-on: windows-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - {gen: Visual Studio 17 2022, arch: Win32, cfg: Release}
+          #- {gen: Visual Studio 17 2022, arch: Win32, cfg: Debug}
+          - {gen: Visual Studio 17 2022, arch: x64, cfg: Release}
+          - {gen: Visual Studio 17 2022, arch: x64, cfg: Debug}
+    steps:
+      - name: checkout
+        uses: actions/checkout@v5
+      - name: configure
+        run: |
+          cmake -S . -B build -G "${{matrix.gen}}" -A ${{matrix.arch}} -DFASTFLOAT_BENCHMARKS=ON  -DFASTFLOAT_TEST=ON -DCMAKE_INSTALL_PREFIX:PATH=destination
+      - name: build
+        run: |
+          cmake --build build --verbose --config ${{matrix.cfg}} --parallel
+      - name: test
+        run: |
+          cd build &&
+          ctest --output-on-failure -C ${{matrix.cfg}}
+      - name: install
+        run: |
+          cd build &&
+          cmake --install .
+      - name: test install (find)
+        run: |
+          cd tests/installation_tests/find  &&
+          cmake -S . -B build -G "${{matrix.gen}}" -A ${{matrix.arch}} -DCMAKE_INSTALL_PREFIX:PATH=../../../build/destination &&
+          cmake --build build --verbose --config ${{matrix.cfg}} --parallel
+      - name: test install (issue 72)
+        run: |
+          cd tests/installation_tests/issue72_installation  &&
+          cmake -S . -B build -G "${{matrix.gen}}" -A ${{matrix.arch}} -DCMAKE_INSTALL_PREFIX:PATH=../../../build/destination &&
+          cmake --build build --verbose --config ${{matrix.cfg}} --parallel

.github/workflows/vs17-clang-ci.yml

@@ -0,0 +1,28 @@
+name: VS17-CLANG-CI
+
+on: [push, pull_request]
+
+jobs:
+  ci:
+    name: vs17/${{matrix.arch}}/${{matrix.cfg}}
+    runs-on: windows-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - {gen: Visual Studio 17 2022, arch: Win32, cfg: Release}
+          - {gen: Visual Studio 17 2022, arch: Win32, cfg: Debug}
+          - {gen: Visual Studio 17 2022, arch: x64, cfg: Release}
+          - {gen: Visual Studio 17 2022, arch: x64, cfg: Debug}
+    steps:
+      - name: checkout
+        uses: actions/checkout@v5
+      - name: Configure
+        run: |
+          cmake -S . -B build -G "${{matrix.gen}}" -A ${{matrix.arch}} -DFASTFLOAT_BENCHMARKS=ON -T ClangCL -DFASTFLOAT_TEST=ON
+      - name: Build
+        run: cmake --build build --config ${{matrix.cfg}} --parallel --verbose
+      - name: Run basic tests
+        run: |
+          cd build
+          ctest -C ${{matrix.cfg}} --output-on-failure -R basictest

.github/workflows/vs17-cxx20.yml

@@ -0,0 +1,33 @@
+name: VS17-CI C++20
+
+on: [push, pull_request]
+
+jobs:
+  ci:
+    name: vs17/${{matrix.arch}}/${{matrix.cfg}}
+    runs-on: windows-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - {gen: Visual Studio 17 2022, arch: Win32, cfg: Release}
+          - {gen: Visual Studio 17 2022, arch: Win32, cfg: Debug}
+          - {gen: Visual Studio 17 2022, arch: x64, cfg: Release}
+          - {gen: Visual Studio 17 2022, arch: x64, cfg: Debug}
+    steps:
+      - name: checkout
+        uses: actions/checkout@v5
+      - name: configure
+        run: >-
+          cmake -S . -B build -G "${{matrix.gen}}" -A ${{matrix.arch}}
+          -DFASTFLOAT_CXX_STANDARD=20
+          -DFASTFLOAT_TEST=ON
+          -DFASTFLOAT_CONSTEXPR_TESTS=ON
+          -DCMAKE_INSTALL_PREFIX:PATH=destination
+      - name: build
+        run: |
+          cmake --build build --verbose --config ${{matrix.cfg}} --parallel
+      - name: test
+        run: |
+          cd build &&
+          ctest --output-on-failure -C ${{matrix.cfg}}

.gitignore

@@ -2,3 +2,23 @@ build/*
 Testing/*
 .cache/
 compile_commands.json
+bazel-*
+
+# Visual studio
+.vs/
+Debug/
+Release/
+/out/
+*.sln
+*.vcxproj
+*.vcxproj.filters
+*.vcxproj.user
+*.psess
+*.vspx
+*.vsp
+*.diagsession
+*.hint
+
+# VS CMake
+/out/
+/CMakeSettings.json

BUILD.bazel

@@ -0,0 +1,6 @@
+cc_library(
+    name = "fast_float",
+    hdrs = glob(["include/fast_float/*.h"]),
+    strip_include_prefix = "include",
+    visibility = ["//visibility:public"],
+)

CMakeLists.txt

@@ -1,9 +1,11 @@
-cmake_minimum_required(VERSION 3.9)
+cmake_minimum_required(VERSION 3.14)
 
-project(fast_float VERSION 2.0.0 LANGUAGES CXX)
+
+project(fast_float VERSION 8.1.0 LANGUAGES CXX)
+set(FASTFLOAT_CXX_STANDARD 11 CACHE STRING "the C++ standard to use for fastfloat")
+set(CMAKE_CXX_STANDARD ${FASTFLOAT_CXX_STANDARD})
 option(FASTFLOAT_TEST "Enable tests" OFF)
-set(CMAKE_CXX_STANDARD 11)
-set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
 if(FASTFLOAT_TEST)
   enable_testing()
   add_subdirectory(tests)
@@ -22,14 +24,31 @@ if (NOT CMAKE_BUILD_TYPE)
   endif()
 endif()
 
+option(FASTFLOAT_INSTALL "Enable install" ON)
+
+if(FASTFLOAT_INSTALL)
+  include(GNUInstallDirs)
+endif()
 
 add_library(fast_float INTERFACE)
+
+
+option(FASTFLOAT_BENCHMARKS "Enable benchmarks" OFF)
+if(FASTFLOAT_BENCHMARKS)
+  add_subdirectory(benchmarks)
+else(FASTFLOAT_BENCHMARKS)
+  message(STATUS "Benchmarks are disabled. Set FASTFLOAT_BENCHMARKS to ON to build benchmarks (assumes C++17).")
+endif(FASTFLOAT_BENCHMARKS)
+
+
+add_library(FastFloat::fast_float ALIAS fast_float)
 target_include_directories(
   fast_float
   INTERFACE
     $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
-    $<INSTALL_INTERFACE:include>
+    $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>
 )
+target_compile_features(fast_float INTERFACE cxx_std_11)
 if(FASTFLOAT_SANITIZE)
   target_compile_options(fast_float INTERFACE -fsanitize=address -fno-omit-frame-pointer -fsanitize=undefined -fno-sanitize-recover=all)
   target_link_libraries(fast_float INTERFACE -fsanitize=address -fno-omit-frame-pointer -fsanitize=undefined -fno-sanitize-recover=all)
@@ -37,29 +56,39 @@ if(FASTFLOAT_SANITIZE)
     target_link_libraries(fast_float INTERFACE -fuse-ld=gold)
   endif()
 endif()
-if(MSVC_VERSION GREATER 1910)
+
+include(CheckCXXCompilerFlag)
+unset(FASTFLOAT_COMPILER_SUPPORTS_PERMISSIVE)
+CHECK_CXX_COMPILER_FLAG(/permissive- FASTFLOAT_COMPILER_SUPPORTS_PERMISSIVE)
+
+if(FASTFLOAT_COMPILER_SUPPORTS_PERMISSIVE)
   target_compile_options(fast_float INTERFACE /permissive-)
 endif()
 
+if(FASTFLOAT_INSTALL)
+  include(CMakePackageConfigHelpers)
 
-include(CMakePackageConfigHelpers)
+  set(FASTFLOAT_VERSION_CONFIG "${CMAKE_CURRENT_BINARY_DIR}/module/FastFloatConfigVersion.cmake")
+  set(FASTFLOAT_PROJECT_CONFIG "${CMAKE_CURRENT_BINARY_DIR}/module/FastFloatConfig.cmake")
+  set(FASTFLOAT_CONFIG_INSTALL_DIR "${CMAKE_INSTALL_DATAROOTDIR}/cmake/FastFloat")
 
-set(FASTFLOAT_VERSION_CONFIG "${CMAKE_CURRENT_BINARY_DIR}/module/FastFloatConfigVersion.cmake")
-set(FASTFLOAT_PROJECT_CONFIG "${CMAKE_CURRENT_BINARY_DIR}/module/FastFloatConfig.cmake")
-set(FASTFLOAT_INSTALL_DIR "share/FastFloat")
-
-write_basic_package_version_file("${FASTFLOAT_VERSION_CONFIG}" VERSION ${PROJECT_VERSION} COMPATIBILITY SameMajorVersion)
-configure_package_config_file("cmake/config.cmake.in"
+  if(${CMAKE_VERSION} VERSION_LESS "3.14")
+    write_basic_package_version_file("${FASTFLOAT_VERSION_CONFIG}" VERSION ${PROJECT_VERSION} COMPATIBILITY SameMajorVersion)
+  else()
+    write_basic_package_version_file("${FASTFLOAT_VERSION_CONFIG}" VERSION ${PROJECT_VERSION} COMPATIBILITY SameMajorVersion ARCH_INDEPENDENT)
+  endif()
+  configure_package_config_file("cmake/config.cmake.in"
                                 "${FASTFLOAT_PROJECT_CONFIG}"
-                              INSTALL_DESTINATION "${FASTFLOAT_INSTALL_DIR}")
+                                INSTALL_DESTINATION "${FASTFLOAT_CONFIG_INSTALL_DIR}")
 
-install(DIRECTORY "${PROJECT_SOURCE_DIR}/include/fast_float" DESTINATION "include")
-install(FILES "${FASTFLOAT_PROJECT_CONFIG}" "${FASTFLOAT_VERSION_CONFIG}" DESTINATION "${FASTFLOAT_INSTALL_DIR}")
-install(EXPORT ${PROJECT_NAME}-targets NAMESPACE FastFloat:: DESTINATION "${FASTFLOAT_INSTALL_DIR}")
+  install(DIRECTORY "${PROJECT_SOURCE_DIR}/include/fast_float" DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}")
+  install(FILES "${FASTFLOAT_PROJECT_CONFIG}" "${FASTFLOAT_VERSION_CONFIG}" DESTINATION "${FASTFLOAT_CONFIG_INSTALL_DIR}")
+  install(EXPORT ${PROJECT_NAME}-targets NAMESPACE FastFloat:: DESTINATION "${FASTFLOAT_CONFIG_INSTALL_DIR}")
 
-install(TARGETS fast_float 
+  install(TARGETS fast_float
           EXPORT ${PROJECT_NAME}-targets
-        RUNTIME DESTINATION bin
-        ARCHIVE DESTINATION lib
-        LIBRARY DESTINATION lib
-)
+          RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
+          ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
+          LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+  )
+endif()

CONTRIBUTORS

@@ -4,3 +4,8 @@ Marcin Wojdyr
 Neal Richardson
 Tim Paine
 Fabio Pellacini
+Lénárd Szolnoki
+Jan Pharago
+Maya Warrier
+Taha Khokhar
+Anders Dalvander

LICENSE-APACHE

@@ -175,18 +175,7 @@
 
    END OF TERMS AND CONDITIONS
 
-   APPENDIX: How to apply the Apache License to your work.
-
-      To apply the Apache License to your work, attach the following
-      boilerplate notice, with the fields enclosed by brackets "{}"
-      replaced with your own identifying information. (Don't include
-      the brackets!)  The text should be enclosed in the appropriate
-      comment syntax for the file format. We also recommend that a
-      file or class name and description of purpose be included on the
-      same "printed page" as the copyright notice for easier
-      identification within third-party archives.
-
-   Copyright 2020 The fast_float authors 
+   Copyright 2021 The fast_float authors
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.

LICENSE-BOOST

@@ -0,0 +1,23 @@
+Boost Software License - Version 1.0 - August 17th, 2003
+
+Permission is hereby granted, free of charge, to any person or organization
+obtaining a copy of the software and accompanying documentation covered by
+this license (the "Software") to use, reproduce, display, distribute,
+execute, and transmit the Software, and to prepare derivative works of the
+Software, and to permit third-parties to whom the Software is furnished to
+do so, all subject to the following:
+
+The copyright notices in the Software and this entire statement, including
+the above license grant, this restriction and the following disclaimer,
+must be included in all copies of the Software, in whole or in part, and
+all derivative works of the Software, unless such copies or derivative
+works are solely in the form of machine-executable object code generated by
+a source language processor.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.

LICENSE-MIT

@@ -1,3 +1,7 @@
+MIT License
+
+Copyright (c) 2021 The fast_float authors
+
 Permission is hereby granted, free of charge, to any
 person obtaining a copy of this software and associated
 documentation files (the "Software"), to deal in the

MODULE.bazel

@@ -0,0 +1,9 @@
+"""fast_float number parsing library: 4x faster than strtod"""
+
+module(
+    name = "fast_float",
+    version = "6.1.6",
+    compatibility_level = 6,
+)
+
+bazel_dep(name = "doctest", version = "2.4.11", dev_dependency = True)

README.md

@@ -1,127 +1,502 @@
+
 ## fast_float number parsing library: 4x faster than strtod
 
-![Ubuntu 20.04 CI (GCC 9)](https://github.com/lemire/fast_float/workflows/Ubuntu%2020.04%20CI%20(GCC%209)/badge.svg)
-![Ubuntu 18.04 CI (GCC 7)](https://github.com/lemire/fast_float/workflows/Ubuntu%2018.04%20CI%20(GCC%207)/badge.svg)
-![Alpine Linux](https://github.com/lemire/fast_float/workflows/Alpine%20Linux/badge.svg)
-![MSYS2-CI](https://github.com/lemire/fast_float/workflows/MSYS2-CI/badge.svg)
-![VS16-CLANG-CI](https://github.com/lemire/fast_float/workflows/VS16-CLANG-CI/badge.svg)
-[![VS16-CI](https://github.com/fastfloat/fast_float/actions/workflows/vs16-ci.yml/badge.svg)](https://github.com/fastfloat/fast_float/actions/workflows/vs16-ci.yml)
+[![Ubuntu 22.04 CI (GCC 11)](https://github.com/fastfloat/fast_float/actions/workflows/ubuntu22.yml/badge.svg)](https://github.com/fastfloat/fast_float/actions/workflows/ubuntu22.yml)
 
-The fast_float library provides fast header-only implementations for the C++ from_chars
-functions for `float` and `double` types.  These functions convert ASCII strings representing
-decimal values (e.g., `1.3e10`) into binary types. We provide exact rounding (including
-round to even). In our experience, these `fast_float` functions many times faster than comparable number-parsing functions from existing C++ standard libraries.
+The fast_float library provides fast header-only implementations for the C++
+from_chars functions for `float` and `double` types as well as integer types.
+These functions convert ASCII strings representing decimal values (e.g.,
+`1.3e10`) into binary types. We provide exact rounding (including round to
+even). In our experience, these `fast_float` functions many times faster than
+comparable number-parsing functions from existing C++ standard libraries.
 
-Specifically, `fast_float` provides the following two functions with a C++17-like syntax (the library itself only requires C++11):
+Specifically, `fast_float` provides the following two functions to parse
+floating-point numbers with a C++17-like syntax (the library itself only
+requires C++11):
 
 ```C++
-from_chars_result from_chars(const char* first, const char* last, float& value, ...);
-from_chars_result from_chars(const char* first, const char* last, double& value, ...);
+from_chars_result from_chars(char const *first, char const *last, float &value, ...);
+from_chars_result from_chars(char const *first, char const *last, double &value, ...);
+```
+
+You can also parse integer types:
+
+```C++
+from_chars_result from_chars(char const *first, char const *last, int &value, ...);
+from_chars_result from_chars(char const *first, char const *last, unsigned &value, ...);
 ```
 
 The return type (`from_chars_result`) is defined as the struct:
+
 ```C++
 struct from_chars_result {
-    const char* ptr;
+  char const *ptr;
   std::errc ec;
 };
 ```
 
-It parses the character sequence [first,last) for a number. It parses floating-point numbers expecting
-a locale-independent format equivalent to what is used by `std::strtod` in the default ("C") locale. 
-The resulting floating-point value is the closest floating-point values (using either float or double), 
-using the "round to even" convention for values that would otherwise fall right in-between two values.
-That is, we provide exact parsing according to the IEEE standard.
+It parses the character sequence `[first, last)` for a number. It parses
+floating-point numbers expecting a locale-independent format equivalent to the
+C++17 from_chars function. The resulting floating-point value is the closest
+floating-point values (using either `float` or `double`), using the "round to
+even" convention for values that would otherwise fall right in-between two
+values. That is, we provide exact parsing according to the IEEE standard.
 
-Given a successful parse, the pointer (`ptr`) in the returned value is set to point right after the
-parsed number, and the `value` referenced is set to the parsed value. In case of error, the returned
-`ec` contains a representative error, otherwise the default (`std::errc()`) value is stored.
+Given a successful parse, the pointer (`ptr`) in the returned value is set to
+point right after the parsed number, and the `value` referenced is set to the
+parsed value. In case of error, the returned `ec` contains a representative
+error, otherwise the default (`std::errc()`) value is stored.
 
-The implementation does not throw and does not allocate memory (e.g., with `new` or `malloc`).
+The implementation does not throw and does not allocate memory (e.g., with `new`
+or `malloc`).
 
 It will parse infinity and nan values.
 
 Example:
 
-``` C++
+```C++
 #include "fast_float/fast_float.h"
 #include <iostream>
+#include <string>
 
 int main() {
-    const std::string input =  "3.1416 xyz ";
+  std::string input = "3.1416 xyz ";
   double result;
-    auto answer = fast_float::from_chars(input.data(), input.data()+input.size(), result);
-    if(answer.ec != std::errc()) { std::cerr << "parsing failure\n"; return EXIT_FAILURE; }
+  auto answer = fast_float::from_chars(input.data(), input.data() + input.size(), result);
+  if (answer.ec != std::errc()) { std::cerr << "parsing failure\n"; return EXIT_FAILURE; }
   std::cout << "parsed the number " << result << std::endl;
   return EXIT_SUCCESS;
 }
 ```
 
+Though the C++17 standard has you do a comparison with `std::errc()` to check whether the conversion worked, you can avoid it by casting the result to a `bool` like so:
 
-Like the C++17 standard, the `fast_float::from_chars` functions take an optional last argument of
-the type `fast_float::chars_format`. It is a bitset value: we check whether 
-`fmt & fast_float::chars_format::fixed` and `fmt & fast_float::chars_format::scientific` are set
-to determine whether we allow the fixed point and scientific notation respectively.
-The default is  `fast_float::chars_format::general` which allows both `fixed` and `scientific`.
+```cpp
+#include "fast_float/fast_float.h"
+#include <iostream>
+#include <string>
 
-The library seeks to follow the C++17 (see 20.19.3.(7.1))  specification. In particular, it forbids leading spaces and the leading '+' sign.
+int main() {
+  std::string input = "3.1416 xyz ";
+  double result;
+  if(auto answer = fast_float::from_chars(input.data(), input.data() + input.size(), result)) {
+    std::cout << "parsed the number " << result << std::endl;
+    return EXIT_SUCCESS;
+  }
+  std::cerr << "failed to parse " << result << std::endl;
+  return EXIT_FAILURE;
+}
+```
 
-We support Visual Studio, macOS, Linux, freeBSD. We support big and little endian. We support 32-bit and 64-bit systems.
+You can parse delimited numbers:
 
-## Using commas as decimal separator
+```C++
+  std::string input = "234532.3426362,7869234.9823,324562.645";
+  double result;
+  auto answer = fast_float::from_chars(input.data(), input.data() + input.size(), result);
+  if (answer.ec != std::errc()) {
+    // check error
+  }
+  // we have result == 234532.3426362.
+  if (answer.ptr[0] != ',') {
+    // unexpected delimiter
+  }
+  answer = fast_float::from_chars(answer.ptr + 1, input.data() + input.size(), result);
+  if (answer.ec != std::errc()) {
+    // check error
+  }
+  // we have result == 7869234.9823.
+  if (answer.ptr[0] != ',') {
+    // unexpected delimiter
+  }
+  answer = fast_float::from_chars(answer.ptr + 1, input.data() + input.size(), result);
+  if (answer.ec != std::errc()) {
+    // check error
+  }
+  // we have result == 324562.645.
+```
 
+Like the C++17 standard, the `fast_float::from_chars` functions take an optional
+last argument of the type `fast_float::chars_format`. It is a bitset value: we
+check whether `fmt & fast_float::chars_format::fixed` and `fmt &
+fast_float::chars_format::scientific` are set to determine whether we allow the
+fixed point and scientific notation respectively. The default is
+`fast_float::chars_format::general` which allows both `fixed` and `scientific`.
 
-The C++ standard stipulate that `from_chars` has to be locale-independent. In
-particular, the decimal separator has to be the period (`.`). However, 
-some users still want to use the `fast_float` library with in a locale-dependent 
-manner. Using a separate function called `from_chars_advanced`, we allow the users
-to pass a `parse_options` instance which contains a custom decimal separator (e.g., 
-the comma). You may use it as follows.
+The library seeks to follow the C++17 (see
+[28.2.3.(6.1)](https://eel.is/c++draft/charconv.from.chars#6.1)) specification.
+
+* The `from_chars` function does not skip leading white-space characters (unless
+  `fast_float::chars_format::skip_white_space` is set).
+* [A leading `+` sign](https://en.cppreference.com/w/cpp/utility/from_chars) is
+  forbidden (unless `fast_float::chars_format::allow_leading_plus` is set).
+* It is generally impossible to represent a decimal value exactly as binary
+  floating-point number (`float` and `double` types). We seek the nearest value.
+  We round to an even mantissa when we are in-between two binary floating-point
+  numbers.
+
+Furthermore, we have the following restrictions:
+
+* We support `float` and `double`, but not `long double`. We also support
+  fixed-width floating-point types such as `std::float64_t`, `std::float32_t`,
+  `std::float16_t`, and `std::bfloat16_t`.
+* We only support the decimal format: we do not support hexadecimal strings.
+* For values that are either very large or very small (e.g., `1e9999`), we
+  represent it using the infinity or negative infinity value and the returned
+  `ec` is set to `std::errc::result_out_of_range`.
+
+We support Visual Studio, macOS, Linux, freeBSD. We support big and little
+endian. We support 32-bit and 64-bit systems.
+
+We assume that the rounding mode is set to nearest (`std::fegetround() ==
+FE_TONEAREST`).
+
+## Integer types
+
+You can also parse integer types using different bases (e.g., 2, 10, 16). The
+following code will print the number 22250738585072012 three times:
 
 ```C++
 #include "fast_float/fast_float.h"
 #include <iostream>
 
 int main() {
-    const std::string input =  "3,1416 xyz ";
+  uint64_t i;
+  std::string str = "22250738585072012";
+  auto answer = fast_float::from_chars(str.data(), str.data() + str.size(), i);
+  if (answer.ec != std::errc()) {
+    std::cerr << "parsing failure\n";
+    return EXIT_FAILURE;
+  }
+  std::cout << "parsed the number " << i << std::endl;
+
+  std::string binstr = "1001111000011001110110111001001010110100111000110001100";
+
+  answer = fast_float::from_chars(binstr.data(), binstr.data() + binstr.size(), i, 2);
+  if (answer.ec != std::errc()) {
+    std::cerr << "parsing failure\n";
+    return EXIT_FAILURE;
+  }
+  std::cout << "parsed the number " << i << std::endl;
+
+  std::string hexstr = "4f0cedc95a718c";
+
+  answer = fast_float::from_chars(hexstr.data(), hexstr.data() + hexstr.size(), i, 16);
+  if (answer.ec != std::errc()) {
+    std::cerr << "parsing failure\n";
+    return EXIT_FAILURE;
+  }
+  std::cout << "parsed the number " << i << std::endl;
+  return EXIT_SUCCESS;
+}
+```
+
+## Behavior of result_out_of_range
+
+When parsing floating-point values, the numbers can sometimes be too small
+(e.g., `1e-1000`) or too large (e.g., `1e1000`). The C language established the
+precedent that these small values are out of range. In such cases, it is
+customary to parse small values to zero and large values to infinity. That is
+the behaviour of the C language (e.g., `stdtod`). That is the behaviour followed
+by the fast_float library.
+
+Specifically, we follow Jonathan Wakely's interpretation of the standard:
+
+> In any case, the resulting value is one of at most two floating-point values
+> closest to the value of the string matching the pattern.
+
+It is also the approach taken by the [Microsoft C++
+library](https://github.com/microsoft/STL/blob/62205ab155d093e71dd9588a78f02c5396c3c14b/tests/std/tests/P0067R5_charconv/test.cpp#L943-L946).
+
+Hence, we have the following examples:
+
+```cpp
+  double result = -1;
+  std::string str = "3e-1000";
+  auto r = fast_float::from_chars(str.data(), str.data() + str.size(), result);
+  // r.ec == std::errc::result_out_of_range
+  // r.ptr == str.data() + 7
+  // result == 0
+```
+
+```cpp
+  double result = -1;
+  std::string str = "3e1000";
+  auto r = fast_float::from_chars(str.data(), str.data() + str.size(), result);
+  // r.ec == std::errc::result_out_of_range
+  // r.ptr == str.data() + 6
+  // result == std::numeric_limits<double>::infinity()
+```
+
+Users who wish for the value to be left unmodified given
+`std::errc::result_out_of_range` may do so by adding two lines of code:
+
+```cpp
+  double old_result = result; // make copy
+  auto r = fast_float::from_chars(start, end, result);
+  if (r.ec == std::errc::result_out_of_range) { result = old_result; }
+```
+
+## C++20: compile-time evaluation (constexpr)
+
+In C++20, you may use `fast_float::from_chars` to parse strings at compile-time,
+as in the following example:
+
+```C++
+// consteval forces compile-time evaluation of the function in C++20.
+consteval double parse(std::string_view input) {
   double result;
-    fast_float::parse_options options{fast_float::chars_format::general, ','};
-    auto answer = fast_float::from_chars_advanced(input.data(), input.data()+input.size(), result, options);
-    if((answer.ec != std::errc()) || ((result != 3.1416))) { std::cerr << "parsing failure\n"; return EXIT_FAILURE; }
+  auto answer = fast_float::from_chars(input.data(), input.data() + input.size(), result);
+  if (answer.ec != std::errc()) { return -1.0; }
+  return result;
+}
+
+// This function should compile to a function which
+// merely returns 3.1415.
+constexpr double constexptest() {
+  return parse("3.1415 input");
+}
+```
+
+## C++23: Fixed width floating-point types
+
+The library also supports fixed-width floating-point types such as
+`std::float64_t`, `std::float32_t`, `std::float16_t`, and `std::bfloat16_t`.
+E.g., you can write:
+
+```C++
+std::float32_t result;
+auto answer = fast_float::from_chars(f.data(), f.data() + f.size(), result);
+```
+
+## Non-ASCII Inputs
+
+We also support UTF-16 and UTF-32 inputs, as well as ASCII/UTF-8, as in the
+following example:
+
+```C++
+#include "fast_float/fast_float.h"
+#include <iostream>
+
+int main() {
+  std::u16string input = u"3.1416 xyz ";
+  double result;
+  auto answer = fast_float::from_chars(input.data(), input.data() + input.size(), result);
+  if (answer.ec != std::errc()) { std::cerr << "parsing failure\n"; return EXIT_FAILURE; }
   std::cout << "parsed the number " << result << std::endl;
   return EXIT_SUCCESS;
 }
 ```
 
+## Advanced options: using commas as decimal separator, JSON and Fortran
 
-## Reference
+The C++ standard stipulate that `from_chars` has to be locale-independent. In
+particular, the decimal separator has to be the period (`.`). However, some
+users still want to use the `fast_float` library with in a locale-dependent
+manner. Using a separate function called `from_chars_advanced`, we allow the
+users to pass a `parse_options` instance which contains a custom decimal
+separator (e.g., the comma). You may use it as follows.
 
-- Daniel Lemire, [Number Parsing at a Gigabyte per Second](https://arxiv.org/abs/2101.11408), Software: Pratice and Experience 51 (8), 2021.
+```C++
+#include "fast_float/fast_float.h"
+#include <iostream>
+
+int main() {
+  std::string input = "3,1416 xyz ";
+  double result;
+  fast_float::parse_options options{fast_float::chars_format::general, ','};
+  auto answer = fast_float::from_chars_advanced(input.data(), input.data() + input.size(), result, options);
+  if ((answer.ec != std::errc()) || ((result != 3.1416))) { std::cerr << "parsing failure\n"; return EXIT_FAILURE; }
+  std::cout << "parsed the number " << result << std::endl;
+  return EXIT_SUCCESS;
+}
+```
+
+### You can also parse Fortran-like inputs
+
+```C++
+#include "fast_float/fast_float.h"
+#include <iostream>
+
+int main() {
+  std::string input = "1d+4";
+  double result;
+  fast_float::parse_options options{fast_float::chars_format::fortran};
+  auto answer = fast_float::from_chars_advanced(input.data(), input.data() + input.size(), result, options);
+  if ((answer.ec != std::errc()) || ((result != 10000))) { std::cerr << "parsing failure\n"; return EXIT_FAILURE; }
+  std::cout << "parsed the number " << result << std::endl;
+  return EXIT_SUCCESS;
+}
+```
+
+### You may also enforce the JSON format ([RFC 8259](https://datatracker.ietf.org/doc/html/rfc8259#section-6))
+
+```C++
+#include "fast_float/fast_float.h"
+#include <iostream>
+
+int main() {
+  std::string input = "+.1"; // not valid
+  double result;
+  fast_float::parse_options options{fast_float::chars_format::json};
+  auto answer = fast_float::from_chars_advanced(input.data(), input.data() + input.size(), result, options);
+  if (answer.ec == std::errc()) { std::cerr << "should have failed\n"; return EXIT_FAILURE; }
+  return EXIT_SUCCESS;
+}
+```
+
+By default the JSON format does not allow `inf`:
+
+```C++
+#include "fast_float/fast_float.h"
+#include <iostream>
+
+int main() {
+  std::string input = "inf"; // not valid in JSON
+  double result;
+  fast_float::parse_options options{fast_float::chars_format::json};
+  auto answer = fast_float::from_chars_advanced(input.data(), input.data() + input.size(), result, options);
+  if (answer.ec == std::errc()) { std::cerr << "should have failed\n"; return EXIT_FAILURE; }
+  return EXIT_SUCCESS;
+}
+```
+
+You can allow it with a non-standard `json_or_infnan` variant:
+
+```C++
+#include "fast_float/fast_float.h"
+#include <iostream>
+
+int main() {
+  std::string input = "inf"; // not valid in JSON but we allow it with json_or_infnan
+  double result;
+  fast_float::parse_options options{fast_float::chars_format::json_or_infnan};
+  auto answer = fast_float::from_chars_advanced(input.data(), input.data() + input.size(), result, options);
+  if (answer.ec != std::errc() || (!std::isinf(result))) { std::cerr << "should have parsed infinity\n"; return EXIT_FAILURE; }
+  return EXIT_SUCCESS;
+}
+```
+
+## Multiplication of an integer by a power of 10
+An integer `W` can be multiplied by a power of ten `10^Q` and
+converted to `double` with correctly rounded value
+(in "round to nearest, tie to even" fashion) using
+`fast_float::integer_times_pow10()`, e.g.:
+```C++
+const uint64_t W = 12345678901234567;
+const int Q = 23;
+const double result = fast_float::integer_times_pow10(W, Q);
+std::cout.precision(17);
+std::cout << W << " * 10^" << Q << " = " << result << " ("
+  << (result == 12345678901234567e23 ? "==" : "!=") << "expected)\n";
+```
+outputs
+```
+12345678901234567 * 10^23 = 1.2345678901234567e+39 (==expected)
+```
+`fast_float::integer_times_pow10()` gives the same result as
+using `fast_float::from_chars()` when parsing the string `"WeQ"`
+(in this example `"12345678901234567e23"`),
+except `fast_float::integer_times_pow10()` does not report out-of-range errors, and
+underflows to zero or overflows to infinity when the resulting value is
+out of range.
+
+You can use template overloads to get the result converted to different
+supported floating-point types: `float`, `double`, etc.
+For example, to get result as `float` use
+`fast_float::integer_times_pow10<float>()` specialization:
+```C++
+const uint64_t W = 12345678;
+const int Q = 23;
+const float result = fast_float::integer_times_pow10<float>(W, Q);
+std::cout.precision(9);
+std::cout << "float: " << W << " * 10^" << Q << " = " << result << " ("
+          << (result == 12345678e23f ? "==" : "!=") << "expected)\n";
+```
+outputs
+```
+float: 12345678 * 10^23 = 1.23456782e+30 (==expected)
+```
+
+Overloads of `fast_float::integer_times_pow10()` are provided for
+signed and unsigned integer types: `int64_t`, `uint64_t`, etc.
+
+
+## Users and Related Work
+
+The fast_float library is part of:
+
+* GCC (as of version 12): the `from_chars` function in GCC relies on fast_float,
+* [Chromium](https://github.com/Chromium/Chromium), the engine behind Google
+  Chrome, Microsoft Edge, and Opera,
+* Boost JSON, MySQL, etc.
+* Blender
+* [WebKit](https://github.com/WebKit/WebKit), the engine behind Safari (Apple's
+  web browser),
+* [DuckDB](https://duckdb.org),
+* [Redis](https://github.com/redis/redis) and [Valkey](https://github.com/valkey-io/valkey),
+* [Apache Arrow](https://github.com/apache/arrow/pull/8494) where it multiplied
+  the number parsing speed by two or three times,
+* [Google Jsonnet](https://github.com/google/jsonnet),
+* [ClickHouse](https://github.com/ClickHouse/ClickHouse).
+
+The fastfloat algorithm is part of the [LLVM standard
+libraries](https://github.com/llvm/llvm-project/commit/87c016078ad72c46505461e4ff8bfa04819fe7ba).
+There is a [derived implementation part of
+AdaCore](https://github.com/AdaCore/VSS). The [SerenityOS operating
+system](https://github.com/SerenityOS/serenity/commit/53b7f5e6a11e663c83df8030c3171c5945cb75ec)
+has a derived implementation that is inherited by the [Ladybird
+Browser](https://github.com/LadybirdBrowser/ladybird).
+
+The fast_float library provides a performance similar to that of the
+[fast_double_parser](https://github.com/lemire/fast_double_parser) library but
+using an updated algorithm reworked from the ground up, and while offering an
+API more in line with the expectations of C++ programmers. The
+fast_double_parser library is part of the [Microsoft LightGBM machine-learning
+framework](https://github.com/microsoft/LightGBM).
+
+
+
+Packages
+------
+
+[![Packaging status](https://repology.org/badge/vertical-allrepos/fast-float.svg)](https://repology.org/project/fast-float/versions)
+
+
+## References
+
+* Daniel Lemire, [Number Parsing at a Gigabyte per
+  Second](https://arxiv.org/abs/2101.11408), Software: Practice and Experience
+  51 (8), 2021.
+* Noble Mushtak, Daniel Lemire, [Fast Number Parsing Without
+  Fallback](https://arxiv.org/abs/2212.06644), Software: Practice and Experience
+  53 (7), 2023.
 
 ## Other programming languages
 
-- [There is an R binding](https://github.com/eddelbuettel/rcppfastfloat) called `rcppfastfloat`.
-- [There is a Rust port of the fast_float library](https://github.com/aldanor/fast-float-rust/) called `fast-float-rust`.
-- [There is a Java port of the fast_float library](https://github.com/wrandelshofer/FastDoubleParser) called `FastDoubleParser`.
-- [There is a C# port of the fast_float library](https://github.com/CarlVerret/csFastFloat) called `csFastFloat`.
-
-
-## Relation With Other Work
-
-The fast_float library provides a performance similar to that of the [fast_double_parser](https://github.com/lemire/fast_double_parser) library but using an updated algorithm reworked from the ground up, and while offering an API more in line with the expectations of C++ programmers. The fast_double_parser library is part of the [Microsoft LightGBM machine-learning framework](https://github.com/microsoft/LightGBM).
-
-## Users
-
-The fast_float library is used by [Apache Arrow](https://github.com/apache/arrow/pull/8494) where it multiplied the number parsing speed by two or three times. It is also used by [Yandex ClickHouse](https://github.com/ClickHouse/ClickHouse) and by [Google Jsonnet](https://github.com/google/jsonnet).
-
+* [There is an R binding](https://github.com/eddelbuettel/rcppfastfloat) called
+  `rcppfastfloat`.
+* [There is a Rust port of the fast_float
+  library](https://github.com/aldanor/fast-float-rust/) called
+  `fast-float-rust`.
+* [There is a Java port of the fast_float
+  library](https://github.com/wrandelshofer/FastDoubleParser) called
+  `FastDoubleParser`. It used for important systems such as
+  [Jackson](https://github.com/FasterXML/jackson-core).
+* [There is a C# port of the fast_float
+  library](https://github.com/CarlVerret/csFastFloat) called `csFastFloat`.
 
 ## How fast is it?
 
-It can parse random floating-point numbers at a speed of 1 GB/s on some systems. We find that it is often twice as fast as the best available competitor, and many times faster than many standard-library implementations.
+It can parse random floating-point numbers at a speed of 1 GB/s on some systems.
+We find that it is often twice as fast as the best available competitor, and
+many times faster than many standard-library implementations.
 
-<img src="http://lemire.me/blog/wp-content/uploads/2020/11/fastfloat_speed.png" width="400">
+<img src="https://lemire.me/blog/wp-content/uploads/2020/11/fastfloat_speed.png"
+width="400" alt="fast_float is many times faster than many standard-library
+implementations">
 
-```
+```bash
 $ ./build/benchmarks/benchmark
 # parsing random integers in the range [0,1)
 volume = 2.09808 MB
@@ -132,74 +507,131 @@ abseil                                  :   430.45 MB/s (+/- 2.2 %)    20.52 Mfl
 fastfloat                               :  1042.38 MB/s (+/- 9.9 %)    49.68 Mfloat/s
 ```
 
-See https://github.com/lemire/simple_fastfloat_benchmark for our benchmarking code.
-
+See the [Benchmarking](#benchmarking) section for instructions on how to run our benchmarks.
 
 ## Video
 
-[![Go Systems 2020](http://img.youtube.com/vi/AVXgvlMeIm4/0.jpg)](http://www.youtube.com/watch?v=AVXgvlMeIm4)<br />
+[![Go Systems 2020](https://img.youtube.com/vi/AVXgvlMeIm4/0.jpg)](https://www.youtube.com/watch?v=AVXgvlMeIm4)
 
 ## Using as a CMake dependency
 
-This library is header-only by design. The CMake file provides the `fast_float` target
-which is merely a pointer to the `include` directory.
+This library is header-only by design. The CMake file provides the `fast_float`
+target which is merely a pointer to the `include` directory.
 
-If you drop the `fast_float` repository in your CMake project, you should be able to use
-it in this manner:
+If you drop the `fast_float` repository in your CMake project, you should be
+able to use it in this manner:
 
 ```cmake
 add_subdirectory(fast_float)
 target_link_libraries(myprogram PUBLIC fast_float)
 ```
 
-Or you may want to retrieve the dependency automatically if you have a sufficiently recent version of CMake (3.11 or better at least):
+Or you may want to retrieve the dependency automatically if you have a
+sufficiently recent version of CMake (3.11 or better at least):
 
 ```cmake
 FetchContent_Declare(
   fast_float
-  GIT_REPOSITORY https://github.com/lemire/fast_float.git
-  GIT_TAG tags/v1.1.2
+  GIT_REPOSITORY https://github.com/fastfloat/fast_float.git
+  GIT_TAG tags/v8.1.0
   GIT_SHALLOW TRUE)
 
 FetchContent_MakeAvailable(fast_float)
 target_link_libraries(myprogram PUBLIC fast_float)
-
 ```
 
-You should change the `GIT_TAG` line so that you recover the version you wish to use.
+You should change the `GIT_TAG` line so that you recover the version you wish to
+use.
+
+You may also use [CPM](https://github.com/cpm-cmake/CPM.cmake), like so:
+
+```cmake
+CPMAddPackage(
+  NAME fast_float
+  GITHUB_REPOSITORY "fastfloat/fast_float"
+  GIT_TAG v8.1.0)
+```
 
 ## Using as single header
 
 The script `script/amalgamate.py` may be used to generate a single header
-version of the library if so desired.
-Just run the script from the root directory of this repository. 
-You can customize the license type and output file if desired as described in
-the command line help.
+version of the library if so desired. Just run the script from the root
+directory of this repository. You can customize the license type and output file
+if desired as described in the command line help.
 
 You may directly download automatically generated single-header files:
 
-https://github.com/fastfloat/fast_float/releases/download/v1.1.2/fast_float.h
+<https://github.com/fastfloat/fast_float/releases/download/v8.1.0/fast_float.h>
+
+## Benchmarking
+
+The project has its own benchmarks with realistic data inputs. Under Linux or macOS,
+you can use it as follows if your system supports C++17:
+
+```
+cmake -B build -D FASTFLOAT_BENCHMARKS=ON
+cmake --build build
+./build/benchmarks/realbenchmark
+```
+
+Importantly, by default, the benchmark is built in Release mode.
+
+The instructions are similar under Windows.
+
+Under Linux and macOS, it is recommended to run the benchmarks in a privileged manner to get access
+to hardware performance counters. You may be able to do so with the `sudo` command
+in some cases:
+
+```
+sudo ./build/benchmarks/realbenchmark
+```
+
+If you have a text file containing one number per line (`myfile.txt`), you can run a benchmark over it like so:
+```
+cmake -B build -D FASTFLOAT_BENCHMARKS=ON
+cmake --build build
+./build/benchmarks/realbenchmark myfile.txt
+```
+
+
+## Packages
+
+* The fast_float library is part of the [Conan package
+  manager](https://conan.io/center/recipes/fast_float).
+* It is part of the [brew package
+  manager](https://formulae.brew.sh/formula/fast_float).
+* fast_float is available on [xmake](https://xmake.io) repository.
+* Some Linux distribution like Fedora include fast_float (e.g., as
+  `fast_float-devel`).
 
 ## Credit
 
-Though this work is inspired by many different people, this work benefited especially from exchanges with 
-Michael Eisel, who motivated the original research with his key insights, and with Nigel Tao who provided 
-invaluable feedback. Rémy Oudompheng first implemented a fast path we use in the case of long digits.
+Though this work is inspired by many different people, this work benefited
+especially from exchanges with Michael Eisel, who motivated the original
+research with his key insights, and with Nigel Tao who provided invaluable
+feedback. Rémy Oudompheng first implemented a fast path we use in the case of
+long digits.
 
-The library includes code adapted from Google Wuffs (written by Nigel Tao) which was originally published 
-under the Apache 2.0 license.
+The library includes code adapted from Google Wuffs (written by Nigel Tao) which
+was originally published under the Apache 2.0 license.
+
+## Stars
+
+
+[![Star History Chart](https://api.star-history.com/svg?repos=fastfloat/fast_float&type=Date)](https://www.star-history.com/#fastfloat/fast_float&Date)
 
 ## License
 
 <sup>
 Licensed under either of <a href="LICENSE-APACHE">Apache License, Version
-2.0</a> or <a href="LICENSE-MIT">MIT license</a> at your option.
+2.0</a> or <a href="LICENSE-MIT">MIT license</a> or <a
+href="LICENSE-BOOST">BOOST license</a>.
 </sup>
 
-<br>
+<br/>
 
 <sub>
 Unless you explicitly state otherwise, any contribution intentionally submitted
 for inclusion in this repository by you, as defined in the Apache-2.0 license,
-shall be dual licensed as above, without any additional terms or conditions.
+shall be triple licensed as above, without any additional terms or conditions.
 </sub>

SECURITY.md

@@ -0,0 +1,7 @@
+# Security Policy
+
+## Reporting a Vulnerability
+
+Please use the following contact information for reporting a vulnerability:
+
+- [Daniel Lemire](https://github.com/lemire) - daniel@lemire.me

benchmarks/CMakeLists.txt

@@ -0,0 +1,26 @@
+add_executable(realbenchmark benchmark.cpp)
+set_property(
+    TARGET realbenchmark
+    PROPERTY CXX_STANDARD 17)
+
+target_link_libraries(realbenchmark PUBLIC fast_float)
+include(ExternalProject)
+
+# Define the external project
+ExternalProject_Add(simple_fastfloat_benchmark
+    GIT_REPOSITORY https://github.com/lemire/simple_fastfloat_benchmark.git
+    GIT_TAG        master  # or specify a particular commit/tag/branch
+    SOURCE_DIR     ${CMAKE_BINARY_DIR}/simple_fastfloat_benchmark
+    BINARY_DIR     ${CMAKE_BINARY_DIR}/simple_fastfloat_benchmark-build
+    CONFIGURE_COMMAND ""
+    BUILD_COMMAND ""
+    INSTALL_COMMAND ""
+)
+set(DATA_DIR ${CMAKE_BINARY_DIR}/simple_fastfloat_benchmark/data)
+
+add_custom_target(CopyData ALL
+    COMMAND ${CMAKE_COMMAND} -E copy_directory ${DATA_DIR} ${CMAKE_CURRENT_BINARY_DIR}/data
+    DEPENDS simple_fastfloat_benchmark
+)
+add_dependencies(realbenchmark CopyData)
+target_compile_definitions(realbenchmark PUBLIC BENCHMARK_DATA_DIR="${CMAKE_CURRENT_BINARY_DIR}/data")

benchmarks/benchmark.cpp

@@ -0,0 +1,246 @@
+#if defined(__linux__) || (__APPLE__ && __aarch64__)
+#define USING_COUNTERS
+#endif
+#include "event_counter.h"
+#include <algorithm>
+#include "fast_float/fast_float.h"
+#include <chrono>
+#include <climits>
+#include <cmath>
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <ctype.h>
+#include <fstream>
+#include <iomanip>
+#include <iostream>
+#include <random>
+#include <sstream>
+#include <stdio.h>
+#include <string>
+#include <vector>
+#include <locale.h>
+
+template <typename CharT>
+double findmax_fastfloat64(std::vector<std::basic_string<CharT>> &s) {
+  double answer = 0;
+  double x = 0;
+  for (auto &st : s) {
+    auto [p, ec] = fast_float::from_chars(st.data(), st.data() + st.size(), x);
+    if (p == st.data()) {
+      throw std::runtime_error("bug in findmax_fastfloat");
+    }
+    answer = answer > x ? answer : x;
+  }
+  return answer;
+}
+
+template <typename CharT>
+double findmax_fastfloat32(std::vector<std::basic_string<CharT>> &s) {
+  float answer = 0;
+  float x = 0;
+  for (auto &st : s) {
+    auto [p, ec] = fast_float::from_chars(st.data(), st.data() + st.size(), x);
+    if (p == st.data()) {
+      throw std::runtime_error("bug in findmax_fastfloat");
+    }
+    answer = answer > x ? answer : x;
+  }
+  return answer;
+}
+
+event_collector collector{};
+
+#ifdef USING_COUNTERS
+template <class T, class CharT>
+std::vector<event_count>
+time_it_ns(std::vector<std::basic_string<CharT>> &lines, T const &function,
+           size_t repeat) {
+  std::vector<event_count> aggregate;
+  bool printed_bug = false;
+  for (size_t i = 0; i < repeat; i++) {
+    collector.start();
+    double ts = function(lines);
+    if (ts == 0 && !printed_bug) {
+      printf("bug\n");
+      printed_bug = true;
+    }
+    aggregate.push_back(collector.end());
+  }
+  return aggregate;
+}
+
+void pretty_print(double volume, size_t number_of_floats, std::string name,
+                  std::vector<event_count> events) {
+  double volumeMB = volume / (1024. * 1024.);
+  double average_ns{0};
+  double min_ns{DBL_MAX};
+  double cycles_min{DBL_MAX};
+  double instructions_min{DBL_MAX};
+  double cycles_avg{0};
+  double instructions_avg{0};
+  double branches_min{0};
+  double branches_avg{0};
+  double branch_misses_min{0};
+  double branch_misses_avg{0};
+  for (event_count e : events) {
+    double ns = e.elapsed_ns();
+    average_ns += ns;
+    min_ns = min_ns < ns ? min_ns : ns;
+
+    double cycles = e.cycles();
+    cycles_avg += cycles;
+    cycles_min = cycles_min < cycles ? cycles_min : cycles;
+
+    double instructions = e.instructions();
+    instructions_avg += instructions;
+    instructions_min =
+        instructions_min < instructions ? instructions_min : instructions;
+
+    double branches = e.branches();
+    branches_avg += branches;
+    branches_min = branches_min < branches ? branches_min : branches;
+
+    double branch_misses = e.missed_branches();
+    branch_misses_avg += branch_misses;
+    branch_misses_min =
+        branch_misses_min < branch_misses ? branch_misses_min : branch_misses;
+  }
+  cycles_avg /= events.size();
+  instructions_avg /= events.size();
+  average_ns /= events.size();
+  branches_avg /= events.size();
+  printf("%-40s: %8.2f MB/s (+/- %.1f %%) ", name.data(),
+         volumeMB * 1000000000 / min_ns,
+         (average_ns - min_ns) * 100.0 / average_ns);
+  printf("%8.2f Mfloat/s  ", number_of_floats * 1000 / min_ns);
+  if (instructions_min > 0) {
+    printf(" %8.2f i/B %8.2f i/f (+/- %.1f %%) ", instructions_min / volume,
+           instructions_min / number_of_floats,
+           (instructions_avg - instructions_min) * 100.0 / instructions_avg);
+
+    printf(" %8.2f c/B %8.2f c/f (+/- %.1f %%) ", cycles_min / volume,
+           cycles_min / number_of_floats,
+           (cycles_avg - cycles_min) * 100.0 / cycles_avg);
+    printf(" %8.2f i/c ", instructions_min / cycles_min);
+    printf(" %8.2f b/f ", branches_avg / number_of_floats);
+    printf(" %8.2f bm/f ", branch_misses_avg / number_of_floats);
+    printf(" %8.2f GHz ", cycles_min / min_ns);
+  }
+  printf("\n");
+}
+#else
+template <class T, class CharT>
+std::pair<double, double>
+time_it_ns(std::vector<std::basic_string<CharT>> &lines, T const &function,
+           size_t repeat) {
+  std::chrono::high_resolution_clock::time_point t1, t2;
+  double average = 0;
+  double min_value = DBL_MAX;
+  bool printed_bug = false;
+  for (size_t i = 0; i < repeat; i++) {
+    t1 = std::chrono::high_resolution_clock::now();
+    double ts = function(lines);
+    if (ts == 0 && !printed_bug) {
+      printf("bug\n");
+      printed_bug = true;
+    }
+    t2 = std::chrono::high_resolution_clock::now();
+    double dif =
+        std::chrono::duration_cast<std::chrono::nanoseconds>(t2 - t1).count();
+    average += dif;
+    min_value = min_value < dif ? min_value : dif;
+  }
+  average /= repeat;
+  return std::make_pair(min_value, average);
+}
+
+void pretty_print(double volume, size_t number_of_floats, std::string name,
+                  std::pair<double, double> result) {
+  double volumeMB = volume / (1024. * 1024.);
+  printf("%-40s: %8.2f MB/s (+/- %.1f %%) ", name.data(),
+         volumeMB * 1000000000 / result.first,
+         (result.second - result.first) * 100.0 / result.second);
+  printf("%8.2f Mfloat/s  ", number_of_floats * 1000 / result.first);
+  printf(" %8.2f ns/f \n", double(result.first) / number_of_floats);
+}
+#endif
+
+// this is okay, all chars are ASCII
+inline std::u16string widen(std::string line) {
+  std::u16string u16line;
+  u16line.resize(line.size());
+  for (size_t i = 0; i < line.size(); ++i) {
+    u16line[i] = char16_t(line[i]);
+  }
+  return u16line;
+}
+
+std::vector<std::u16string> widen(const std::vector<std::string> &lines) {
+  std::vector<std::u16string> u16lines;
+  u16lines.reserve(lines.size());
+  for (auto const &line : lines) {
+    u16lines.push_back(widen(line));
+  }
+  return u16lines;
+}
+
+void process(std::vector<std::string> &lines, size_t volume) {
+  size_t repeat = 1000;
+  double volumeMB = volume / (1024. * 1024.);
+  std::cout << "ASCII volume = " << volumeMB << " MB " << std::endl;
+  pretty_print(volume, lines.size(), "fastfloat (64)",
+               time_it_ns(lines, findmax_fastfloat64<char>, repeat));
+  pretty_print(volume, lines.size(), "fastfloat (32)",
+               time_it_ns(lines, findmax_fastfloat32<char>, repeat));
+
+  std::vector<std::u16string> lines16 = widen(lines);
+  volume = 2 * volume;
+  volumeMB = volume / (1024. * 1024.);
+  std::cout << "UTF-16 volume = " << volumeMB << " MB " << std::endl;
+  pretty_print(volume, lines.size(), "fastfloat (64)",
+               time_it_ns(lines16, findmax_fastfloat64<char16_t>, repeat));
+  pretty_print(volume, lines.size(), "fastfloat (32)",
+               time_it_ns(lines16, findmax_fastfloat32<char16_t>, repeat));
+}
+
+void fileload(std::string filename) {
+  std::ifstream inputfile(filename);
+  if (!inputfile) {
+    std::cerr << "can't open " << filename << std::endl;
+    return;
+  }
+  std::cout << "#### " << std::endl;
+  std::cout << "# reading " << filename << std::endl;
+  std::cout << "#### " << std::endl;
+  std::string line;
+  std::vector<std::string> lines;
+  lines.reserve(10000); // let us reserve plenty of memory.
+  size_t volume = 0;
+  while (getline(inputfile, line)) {
+    volume += line.size();
+    lines.push_back(line);
+  }
+  std::cout << "# read " << lines.size() << " lines " << std::endl;
+  process(lines, volume);
+}
+
+int main(int argc, char **argv) {
+  if (collector.has_events()) {
+    std::cout << "# Using hardware counters" << std::endl;
+  } else {
+#if defined(__linux__) || (__APPLE__ && __aarch64__)
+    std::cout << "# Hardware counters not available, try to run in privileged "
+                 "mode (e.g., sudo)."
+              << std::endl;
+#endif
+  }
+  if (argc > 1) {
+    fileload(argv[1]);
+    return EXIT_SUCCESS;
+  }
+  fileload(std::string(BENCHMARK_DATA_DIR) + "/canada.txt");
+  fileload(std::string(BENCHMARK_DATA_DIR) + "/mesh.txt");
+  return EXIT_SUCCESS;
+}

benchmarks/event_counter.h

@@ -0,0 +1,181 @@
+#ifndef __EVENT_COUNTER_H
+#define __EVENT_COUNTER_H
+
+#include <cctype>
+#ifndef _MSC_VER
+#include <dirent.h>
+#endif
+#include <cinttypes>
+
+#include <cstring>
+
+#include <chrono>
+#include <vector>
+
+#include "linux-perf-events.h"
+#ifdef __linux__
+#include <libgen.h>
+#endif
+
+#if (defined(__APPLE__) && __APPLE__) && (defined(__aarch64__) && __aarch64__)
+#include "apple_arm_events.h"
+#endif
+
+struct event_count {
+  std::chrono::duration<double> elapsed;
+  std::vector<unsigned long long> event_counts;
+
+  event_count() : elapsed(0), event_counts{0, 0, 0, 0, 0} {}
+
+  event_count(const std::chrono::duration<double> _elapsed,
+              const std::vector<unsigned long long> _event_counts)
+      : elapsed(_elapsed), event_counts(_event_counts) {}
+
+  event_count(const event_count &other)
+      : elapsed(other.elapsed), event_counts(other.event_counts) {}
+
+  // The types of counters (so we can read the getter more easily)
+  enum event_counter_types {
+    CPU_CYCLES = 0,
+    INSTRUCTIONS = 1,
+    BRANCHES = 2,
+    MISSED_BRANCHES = 3
+  };
+
+  double elapsed_sec() const {
+    return std::chrono::duration<double>(elapsed).count();
+  }
+
+  double elapsed_ns() const {
+    return std::chrono::duration<double, std::nano>(elapsed).count();
+  }
+
+  double cycles() const {
+    return static_cast<double>(event_counts[CPU_CYCLES]);
+  }
+
+  double instructions() const {
+    return static_cast<double>(event_counts[INSTRUCTIONS]);
+  }
+
+  double branches() const {
+    return static_cast<double>(event_counts[BRANCHES]);
+  }
+
+  double missed_branches() const {
+    return static_cast<double>(event_counts[MISSED_BRANCHES]);
+  }
+
+  event_count &operator=(const event_count &other) {
+    this->elapsed = other.elapsed;
+    this->event_counts = other.event_counts;
+    return *this;
+  }
+
+  event_count operator+(const event_count &other) const {
+    return event_count(elapsed + other.elapsed,
+                       {
+                           event_counts[0] + other.event_counts[0],
+                           event_counts[1] + other.event_counts[1],
+                           event_counts[2] + other.event_counts[2],
+                           event_counts[3] + other.event_counts[3],
+                           event_counts[4] + other.event_counts[4],
+                       });
+  }
+
+  void operator+=(const event_count &other) { *this = *this + other; }
+};
+
+struct event_aggregate {
+  bool has_events = false;
+  int iterations = 0;
+  event_count total{};
+  event_count best{};
+  event_count worst{};
+
+  event_aggregate() = default;
+
+  void operator<<(const event_count &other) {
+    if (iterations == 0 || other.elapsed < best.elapsed) {
+      best = other;
+    }
+    if (iterations == 0 || other.elapsed > worst.elapsed) {
+      worst = other;
+    }
+    iterations++;
+    total += other;
+  }
+
+  double elapsed_sec() const { return total.elapsed_sec() / iterations; }
+
+  double elapsed_ns() const { return total.elapsed_ns() / iterations; }
+
+  double cycles() const { return total.cycles() / iterations; }
+
+  double instructions() const { return total.instructions() / iterations; }
+
+  double branches() const { return total.branches() / iterations; }
+
+  double missed_branches() const {
+    return total.missed_branches() / iterations;
+  }
+};
+
+struct event_collector {
+  event_count count{};
+  std::chrono::time_point<std::chrono::steady_clock> start_clock{};
+
+#if defined(__linux__)
+  LinuxEvents<PERF_TYPE_HARDWARE> linux_events;
+
+  event_collector()
+      : linux_events(std::vector<int>{
+            PERF_COUNT_HW_CPU_CYCLES, PERF_COUNT_HW_INSTRUCTIONS,
+            PERF_COUNT_HW_BRANCH_INSTRUCTIONS, // Retired branch instructions
+            PERF_COUNT_HW_BRANCH_MISSES}) {}
+
+  bool has_events() { return linux_events.is_working(); }
+#elif __APPLE__ && __aarch64__
+  performance_counters diff;
+
+  event_collector() : diff(0) { setup_performance_counters(); }
+
+  bool has_events() { return setup_performance_counters(); }
+#else
+  event_collector() {}
+
+  bool has_events() { return false; }
+#endif
+
+  inline void start() {
+#if defined(__linux)
+    linux_events.start();
+#elif __APPLE__ && __aarch64__
+    if (has_events()) {
+      diff = get_counters();
+    }
+#endif
+    start_clock = std::chrono::steady_clock::now();
+  }
+
+  inline event_count &end() {
+    const auto end_clock = std::chrono::steady_clock::now();
+#if defined(__linux)
+    linux_events.end(count.event_counts);
+#elif __APPLE__ && __aarch64__
+    if (has_events()) {
+      performance_counters end = get_counters();
+      diff = end - diff;
+    }
+    count.event_counts[0] = diff.cycles;
+    count.event_counts[1] = diff.instructions;
+    count.event_counts[2] = diff.branches;
+    count.event_counts[3] = diff.missed_branches;
+    count.event_counts[4] = 0;
+#endif
+    count.elapsed = end_clock - start_clock;
+    return count;
+  }
+};
+
+#endif

benchmarks/linux-perf-events.h

@@ -0,0 +1,104 @@
+#pragma once
+#ifdef __linux__
+
+#include <asm/unistd.h>       // for __NR_perf_event_open
+#include <linux/perf_event.h> // for perf event constants
+#include <sys/ioctl.h>        // for ioctl
+#include <unistd.h>           // for syscall
+
+#include <cerrno>  // for errno
+#include <cstring> // for memset
+#include <stdexcept>
+
+#include <iostream>
+#include <vector>
+
+template <int TYPE = PERF_TYPE_HARDWARE> class LinuxEvents {
+  int fd;
+  bool working;
+  perf_event_attr attribs{};
+  size_t num_events{};
+  std::vector<uint64_t> temp_result_vec{};
+  std::vector<uint64_t> ids{};
+
+public:
+  explicit LinuxEvents(std::vector<int> config_vec) : fd(0), working(true) {
+    memset(&attribs, 0, sizeof(attribs));
+    attribs.type = TYPE;
+    attribs.size = sizeof(attribs);
+    attribs.disabled = 1;
+    attribs.exclude_kernel = 1;
+    attribs.exclude_hv = 1;
+
+    attribs.sample_period = 0;
+    attribs.read_format = PERF_FORMAT_GROUP | PERF_FORMAT_ID;
+    const int pid = 0;  // the current process
+    const int cpu = -1; // all CPUs
+    const unsigned long flags = 0;
+
+    int group = -1; // no group
+    num_events = config_vec.size();
+    ids.resize(config_vec.size());
+    uint32_t i = 0;
+    for (auto config : config_vec) {
+      attribs.config = config;
+      int _fd = static_cast<int>(
+          syscall(__NR_perf_event_open, &attribs, pid, cpu, group, flags));
+      if (_fd == -1) {
+        report_error("perf_event_open");
+      }
+      ioctl(_fd, PERF_EVENT_IOC_ID, &ids[i++]);
+      if (group == -1) {
+        group = _fd;
+        fd = _fd;
+      }
+    }
+
+    temp_result_vec.resize(num_events * 2 + 1);
+  }
+
+  ~LinuxEvents() {
+    if (fd != -1) {
+      close(fd);
+    }
+  }
+
+  inline void start() {
+    if (fd != -1) {
+      if (ioctl(fd, PERF_EVENT_IOC_RESET, PERF_IOC_FLAG_GROUP) == -1) {
+        report_error("ioctl(PERF_EVENT_IOC_RESET)");
+      }
+
+      if (ioctl(fd, PERF_EVENT_IOC_ENABLE, PERF_IOC_FLAG_GROUP) == -1) {
+        report_error("ioctl(PERF_EVENT_IOC_ENABLE)");
+      }
+    }
+  }
+
+  inline void end(std::vector<unsigned long long> &results) {
+    if (fd != -1) {
+      if (ioctl(fd, PERF_EVENT_IOC_DISABLE, PERF_IOC_FLAG_GROUP) == -1) {
+        report_error("ioctl(PERF_EVENT_IOC_DISABLE)");
+      }
+
+      if (read(fd, temp_result_vec.data(), temp_result_vec.size() * 8) == -1) {
+        report_error("read");
+      }
+    }
+    // our actual results are in slots 1,3,5, ... of this structure
+    for (uint32_t i = 1; i < temp_result_vec.size(); i += 2) {
+      results[i / 2] = temp_result_vec[i];
+    }
+    for (uint32_t i = 2; i < temp_result_vec.size(); i += 2) {
+      if (ids[i / 2 - 1] != temp_result_vec[i]) {
+        report_error("event mismatch");
+      }
+    }
+  }
+
+  bool is_working() { return working; }
+
+private:
+  void report_error(const std::string &) { working = false; }
+};
+#endif

cmake/toolchains-ci/riscv64-linux-gnu.cmake

@@ -0,0 +1,4 @@
+set(CMAKE_SYSTEM_NAME Linux)
+set(CMAKE_SYSTEM_PROCESSOR riscv64)
+
+set(CMAKE_CROSSCOMPILING_EMULATOR "qemu-riscv64-static")

fuzz/build.sh

@@ -0,0 +1,8 @@
+#!/bin/bash
+
+$CXX $CFLAGS $CXXFLAGS \
+     -I $SRC/fast_float/include \
+     -c $SRC/fast_float/fuzz/from_chars.cc -o from_chars.o
+
+$CXX $CFLAGS $CXXFLAGS $LIB_FUZZING_ENGINE from_chars.o \
+     -o $OUT/from_chars

fuzz/from_chars.cc

@@ -0,0 +1,38 @@
+#include "fast_float/fast_float.h"
+#include <fuzzer/FuzzedDataProvider.h>
+#include <string>
+#include <system_error>
+
+fast_float::chars_format arbitrary_format(FuzzedDataProvider &fdp) {
+  using fast_float::chars_format;
+  switch (fdp.ConsumeIntegralInRange<int>(0, 3)) {
+  case 0:
+    return chars_format::scientific;
+    break;
+  case 1:
+    return chars_format::fixed;
+    break;
+  case 2:
+    return chars_format::fixed;
+    break;
+  }
+  return chars_format::general;
+}
+
+extern "C" int LLVMFuzzerTestOneInput(uint8_t const *data, size_t size) {
+  FuzzedDataProvider fdp(data, size);
+  fast_float::chars_format format = arbitrary_format(fdp);
+  double result_d = 0.0;
+  std::string input_d = fdp.ConsumeRandomLengthString(128);
+  auto answer = fast_float::from_chars(
+      input_d.data(), input_d.data() + input_d.size(), result_d, format);
+  std::string input_f = fdp.ConsumeRandomLengthString(128);
+  float result_f = 0.0;
+  answer = fast_float::from_chars(
+      input_f.data(), input_f.data() + input_f.size(), result_f, format);
+  int result_i = 0;
+  std::string input_i = fdp.ConsumeRandomLengthString(128);
+  answer = fast_float::from_chars(input_i.data(),
+                                  input_i.data() + input_i.size(), result_i);
+  return 0;
+}

include/fast_float/ascii_number.h

@@ -1,31 +1,59 @@
 #ifndef FASTFLOAT_ASCII_NUMBER_H
 #define FASTFLOAT_ASCII_NUMBER_H
 
-#include <cstdio>
 #include <cctype>
 #include <cstdint>
 #include <cstring>
+#include <iterator>
+#include <limits>
+#include <type_traits>
 
 #include "float_common.h"
 
+#ifdef FASTFLOAT_SSE2
+#include <emmintrin.h>
+#endif
+
+#ifdef FASTFLOAT_NEON
+#include <arm_neon.h>
+#endif
+
 namespace fast_float {
 
+template <typename UC> fastfloat_really_inline constexpr bool has_simd_opt() {
+#ifdef FASTFLOAT_HAS_SIMD
+  return std::is_same<UC, char16_t>::value;
+#else
+  return false;
+#endif
+}
+
 // Next function can be micro-optimized, but compilers are entirely
 // able to optimize it well.
-fastfloat_really_inline bool is_integer(char c)  noexcept  { return c >= '0' && c <= '9'; }
-
-fastfloat_really_inline uint64_t byteswap(uint64_t val) {
-  return (val & 0xFF00000000000000) >> 56
-    | (val & 0x00FF000000000000) >> 40
-    | (val & 0x0000FF0000000000) >> 24
-    | (val & 0x000000FF00000000) >> 8
-    | (val & 0x00000000FF000000) << 8
-    | (val & 0x0000000000FF0000) << 24
-    | (val & 0x000000000000FF00) << 40
-    | (val & 0x00000000000000FF) << 56;
+template <typename UC>
+fastfloat_really_inline constexpr bool is_integer(UC c) noexcept {
+  return !(c > UC('9') || c < UC('0'));
 }
 
-fastfloat_really_inline uint64_t read_u64(const char *chars) {
+fastfloat_really_inline constexpr uint64_t byteswap(uint64_t val) {
+  return (val & 0xFF00000000000000) >> 56 | (val & 0x00FF000000000000) >> 40 |
+         (val & 0x0000FF0000000000) >> 24 | (val & 0x000000FF00000000) >> 8 |
+         (val & 0x00000000FF000000) << 8 | (val & 0x0000000000FF0000) << 24 |
+         (val & 0x000000000000FF00) << 40 | (val & 0x00000000000000FF) << 56;
+}
+
+// Read 8 UC into a u64. Truncates UC if not char.
+template <typename UC>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 uint64_t
+read8_to_u64(UC const *chars) {
+  if (cpp20_and_in_constexpr() || !std::is_same<UC, char>::value) {
+    uint64_t val = 0;
+    for (int i = 0; i < 8; ++i) {
+      val |= uint64_t(uint8_t(*chars)) << (i * 8);
+      ++chars;
+    }
+    return val;
+  }
   uint64_t val;
   ::memcpy(&val, chars, sizeof(uint64_t));
 #if FASTFLOAT_IS_BIG_ENDIAN == 1
@@ -35,70 +63,258 @@ fastfloat_really_inline uint64_t read_u64(const char *chars) {
   return val;
 }
 
-fastfloat_really_inline void write_u64(uint8_t *chars, uint64_t val) {
-#if FASTFLOAT_IS_BIG_ENDIAN == 1
-  // Need to read as-if the number was in little-endian order.
-  val = byteswap(val);
+#ifdef FASTFLOAT_SSE2
+
+fastfloat_really_inline uint64_t simd_read8_to_u64(__m128i const data) {
+  FASTFLOAT_SIMD_DISABLE_WARNINGS
+  __m128i const packed = _mm_packus_epi16(data, data);
+#ifdef FASTFLOAT_64BIT
+  return uint64_t(_mm_cvtsi128_si64(packed));
+#else
+  uint64_t value;
+  // Visual Studio + older versions of GCC don't support _mm_storeu_si64
+  _mm_storel_epi64(reinterpret_cast<__m128i *>(&value), packed);
+  return value;
 #endif
-  ::memcpy(chars, &val, sizeof(uint64_t));
+  FASTFLOAT_SIMD_RESTORE_WARNINGS
+}
+
+fastfloat_really_inline uint64_t simd_read8_to_u64(char16_t const *chars) {
+  FASTFLOAT_SIMD_DISABLE_WARNINGS
+  return simd_read8_to_u64(
+      _mm_loadu_si128(reinterpret_cast<__m128i const *>(chars)));
+  FASTFLOAT_SIMD_RESTORE_WARNINGS
+}
+
+#elif defined(FASTFLOAT_NEON)
+
+fastfloat_really_inline uint64_t simd_read8_to_u64(uint16x8_t const data) {
+  FASTFLOAT_SIMD_DISABLE_WARNINGS
+  uint8x8_t utf8_packed = vmovn_u16(data);
+  return vget_lane_u64(vreinterpret_u64_u8(utf8_packed), 0);
+  FASTFLOAT_SIMD_RESTORE_WARNINGS
+}
+
+fastfloat_really_inline uint64_t simd_read8_to_u64(char16_t const *chars) {
+  FASTFLOAT_SIMD_DISABLE_WARNINGS
+  return simd_read8_to_u64(
+      vld1q_u16(reinterpret_cast<uint16_t const *>(chars)));
+  FASTFLOAT_SIMD_RESTORE_WARNINGS
+}
+
+#endif // FASTFLOAT_SSE2
+
+// MSVC SFINAE is broken pre-VS2017
+#if defined(_MSC_VER) && _MSC_VER <= 1900
+template <typename UC>
+#else
+template <typename UC, FASTFLOAT_ENABLE_IF(!has_simd_opt<UC>()) = 0>
+#endif
+// dummy for compile
+uint64_t simd_read8_to_u64(UC const *) {
+  return 0;
 }
 
 // credit  @aqrit
-fastfloat_really_inline uint32_t  parse_eight_digits_unrolled(uint64_t val) {
-  const uint64_t mask = 0x000000FF000000FF;
-  const uint64_t mul1 = 0x000F424000000064; // 100 + (1000000ULL << 32)
-  const uint64_t mul2 = 0x0000271000000001; // 1 + (10000ULL << 32)
+fastfloat_really_inline FASTFLOAT_CONSTEXPR14 uint32_t
+parse_eight_digits_unrolled(uint64_t val) {
+  uint64_t const mask = 0x000000FF000000FF;
+  uint64_t const mul1 = 0x000F424000000064; // 100 + (1000000ULL << 32)
+  uint64_t const mul2 = 0x0000271000000001; // 1 + (10000ULL << 32)
   val -= 0x3030303030303030;
   val = (val * 10) + (val >> 8); // val = (val * 2561) >> 8;
   val = (((val & mask) * mul1) + (((val >> 16) & mask) * mul2)) >> 32;
   return uint32_t(val);
 }
 
-fastfloat_really_inline uint32_t parse_eight_digits_unrolled(const char *chars)  noexcept  {
-  return parse_eight_digits_unrolled(read_u64(chars));
+// Call this if chars are definitely 8 digits.
+template <typename UC>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 uint32_t
+parse_eight_digits_unrolled(UC const *chars) noexcept {
+  if (cpp20_and_in_constexpr() || !has_simd_opt<UC>()) {
+    return parse_eight_digits_unrolled(read8_to_u64(chars)); // truncation okay
+  }
+  return parse_eight_digits_unrolled(simd_read8_to_u64(chars));
 }
 
 // credit @aqrit
-fastfloat_really_inline bool is_made_of_eight_digits_fast(uint64_t val)  noexcept  {
+fastfloat_really_inline constexpr bool
+is_made_of_eight_digits_fast(uint64_t val) noexcept {
   return !((((val + 0x4646464646464646) | (val - 0x3030303030303030)) &
             0x8080808080808080));
 }
 
-fastfloat_really_inline bool is_made_of_eight_digits_fast(const char *chars)  noexcept  {
-  return is_made_of_eight_digits_fast(read_u64(chars));
+#ifdef FASTFLOAT_HAS_SIMD
+
+// Call this if chars might not be 8 digits.
+// Using this style (instead of is_made_of_eight_digits_fast() then
+// parse_eight_digits_unrolled()) ensures we don't load SIMD registers twice.
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 bool
+simd_parse_if_eight_digits_unrolled(char16_t const *chars,
+                                    uint64_t &i) noexcept {
+  if (cpp20_and_in_constexpr()) {
+    return false;
+  }
+#ifdef FASTFLOAT_SSE2
+  FASTFLOAT_SIMD_DISABLE_WARNINGS
+  __m128i const data =
+      _mm_loadu_si128(reinterpret_cast<__m128i const *>(chars));
+
+  // (x - '0') <= 9
+  // http://0x80.pl/articles/simd-parsing-int-sequences.html
+  __m128i const t0 = _mm_add_epi16(data, _mm_set1_epi16(32720));
+  __m128i const t1 = _mm_cmpgt_epi16(t0, _mm_set1_epi16(-32759));
+
+  if (_mm_movemask_epi8(t1) == 0) {
+    i = i * 100000000 + parse_eight_digits_unrolled(simd_read8_to_u64(data));
+    return true;
+  } else
+    return false;
+  FASTFLOAT_SIMD_RESTORE_WARNINGS
+#elif defined(FASTFLOAT_NEON)
+  FASTFLOAT_SIMD_DISABLE_WARNINGS
+  uint16x8_t const data = vld1q_u16(reinterpret_cast<uint16_t const *>(chars));
+
+  // (x - '0') <= 9
+  // http://0x80.pl/articles/simd-parsing-int-sequences.html
+  uint16x8_t const t0 = vsubq_u16(data, vmovq_n_u16('0'));
+  uint16x8_t const mask = vcltq_u16(t0, vmovq_n_u16('9' - '0' + 1));
+
+  if (vminvq_u16(mask) == 0xFFFF) {
+    i = i * 100000000 + parse_eight_digits_unrolled(simd_read8_to_u64(data));
+    return true;
+  } else
+    return false;
+  FASTFLOAT_SIMD_RESTORE_WARNINGS
+#else
+  (void)chars;
+  (void)i;
+  return false;
+#endif // FASTFLOAT_SSE2
 }
 
-struct parsed_number_string {
-  int64_t exponent;
-  uint64_t mantissa;
-  const char *lastmatch;
-  bool negative;
-  bool valid;
-  bool too_many_digits;
+#endif // FASTFLOAT_HAS_SIMD
+
+// MSVC SFINAE is broken pre-VS2017
+#if defined(_MSC_VER) && _MSC_VER <= 1900
+template <typename UC>
+#else
+template <typename UC, FASTFLOAT_ENABLE_IF(!has_simd_opt<UC>()) = 0>
+#endif
+// dummy for compile
+bool simd_parse_if_eight_digits_unrolled(UC const *, uint64_t &) {
+  return 0;
+}
+
+template <typename UC, FASTFLOAT_ENABLE_IF(!std::is_same<UC, char>::value) = 0>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 void
+loop_parse_if_eight_digits(UC const *&p, UC const *const pend, uint64_t &i) {
+  if (!has_simd_opt<UC>()) {
+    return;
+  }
+  while ((std::distance(p, pend) >= 8) &&
+         simd_parse_if_eight_digits_unrolled(
+             p, i)) { // in rare cases, this will overflow, but that's ok
+    p += 8;
+  }
+}
+
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 void
+loop_parse_if_eight_digits(char const *&p, char const *const pend,
+                           uint64_t &i) {
+  // optimizes better than parse_if_eight_digits_unrolled() for UC = char.
+  while ((std::distance(p, pend) >= 8) &&
+         is_made_of_eight_digits_fast(read8_to_u64(p))) {
+    i = i * 100000000 +
+        parse_eight_digits_unrolled(read8_to_u64(
+            p)); // in rare cases, this will overflow, but that's ok
+    p += 8;
+  }
+}
+
+enum class parse_error {
+  no_error,
+  // [JSON-only] The minus sign must be followed by an integer.
+  missing_integer_after_sign,
+  // A sign must be followed by an integer or dot.
+  missing_integer_or_dot_after_sign,
+  // [JSON-only] The integer part must not have leading zeros.
+  leading_zeros_in_integer_part,
+  // [JSON-only] The integer part must have at least one digit.
+  no_digits_in_integer_part,
+  // [JSON-only] If there is a decimal point, there must be digits in the
+  // fractional part.
+  no_digits_in_fractional_part,
+  // The mantissa must have at least one digit.
+  no_digits_in_mantissa,
+  // Scientific notation requires an exponential part.
+  missing_exponential_part,
 };
 
+template <typename UC> struct parsed_number_string_t {
+  int64_t exponent{0};
+  uint64_t mantissa{0};
+  UC const *lastmatch{nullptr};
+  bool negative{false};
+  bool valid{false};
+  bool too_many_digits{false};
+  // contains the range of the significant digits
+  span<UC const> integer{};  // non-nullable
+  span<UC const> fraction{}; // nullable
+  parse_error error{parse_error::no_error};
+};
+
+using byte_span = span<char const>;
+using parsed_number_string = parsed_number_string_t<char>;
+
+template <typename UC>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 parsed_number_string_t<UC>
+report_parse_error(UC const *p, parse_error error) {
+  parsed_number_string_t<UC> answer;
+  answer.valid = false;
+  answer.lastmatch = p;
+  answer.error = error;
+  return answer;
+}
 
 // Assuming that you use no more than 19 digits, this will
 // parse an ASCII string.
-fastfloat_really_inline
-parsed_number_string parse_number_string(const char *p, const char *pend, parse_options options) noexcept {
-  const chars_format fmt = options.format;
-  const char decimal_point = options.decimal_point;
+template <bool basic_json_fmt, typename UC>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 parsed_number_string_t<UC>
+parse_number_string(UC const *p, UC const *pend,
+                    parse_options_t<UC> options) noexcept {
+  chars_format const fmt = detail::adjust_for_feature_macros(options.format);
+  UC const decimal_point = options.decimal_point;
 
-  parsed_number_string answer;
+  parsed_number_string_t<UC> answer;
   answer.valid = false;
   answer.too_many_digits = false;
-  answer.negative = (*p == '-');
-  if (*p == '-') { // C++17 20.19.3.(7.1) explicitly forbids '+' sign here
+  // assume p < pend, so dereference without checks;
+  answer.negative = (*p == UC('-'));
+  // C++17 20.19.3.(7.1) explicitly forbids '+' sign here
+  if ((*p == UC('-')) || (uint64_t(fmt & chars_format::allow_leading_plus) &&
+                          !basic_json_fmt && *p == UC('+'))) {
     ++p;
     if (p == pend) {
-      return answer;
+      return report_parse_error<UC>(
+          p, parse_error::missing_integer_or_dot_after_sign);
     }
-    if (!is_integer(*p) && (*p != decimal_point)) { // a sign must be followed by an integer or the dot
-      return answer;
+    FASTFLOAT_IF_CONSTEXPR17(basic_json_fmt) {
+      if (!is_integer(*p)) { // a sign must be followed by an integer
+        return report_parse_error<UC>(p,
+                                      parse_error::missing_integer_after_sign);
       }
     }
-  const char *const start_digits = p;
+    else {
+      if (!is_integer(*p) &&
+          (*p !=
+           decimal_point)) { // a sign must be followed by an integer or the dot
+        return report_parse_error<UC>(
+            p, parse_error::missing_integer_or_dot_after_sign);
+      }
+    }
+  }
+  UC const *const start_digits = p;
 
   uint64_t i = 0; // an unsigned int avoids signed overflows (which are bad)
 
@@ -106,67 +322,100 @@ parsed_number_string parse_number_string(const char *p, const char *pend, parse_
     // a multiplication by 10 is cheaper than an arbitrary integer
     // multiplication
     i = 10 * i +
-        uint64_t(*p - '0'); // might overflow, we will handle the overflow later
+        uint64_t(*p -
+                 UC('0')); // might overflow, we will handle the overflow later
     ++p;
   }
-  const char *const end_of_integer_part = p;
+  UC const *const end_of_integer_part = p;
   int64_t digit_count = int64_t(end_of_integer_part - start_digits);
+  answer.integer = span<UC const>(start_digits, size_t(digit_count));
+  FASTFLOAT_IF_CONSTEXPR17(basic_json_fmt) {
+    // at least 1 digit in integer part, without leading zeros
+    if (digit_count == 0) {
+      return report_parse_error<UC>(p, parse_error::no_digits_in_integer_part);
+    }
+    if ((start_digits[0] == UC('0') && digit_count > 1)) {
+      return report_parse_error<UC>(start_digits,
+                                    parse_error::leading_zeros_in_integer_part);
+    }
+  }
+
   int64_t exponent = 0;
-  if ((p != pend) && (*p == decimal_point)) {
+  bool const has_decimal_point = (p != pend) && (*p == decimal_point);
+  if (has_decimal_point) {
     ++p;
-  // Fast approach only tested under little endian systems
-  if ((p + 8 <= pend) && is_made_of_eight_digits_fast(p)) {
-    i = i * 100000000 + parse_eight_digits_unrolled(p); // in rare cases, this will overflow, but that's ok
-    p += 8;
-    if ((p + 8 <= pend) && is_made_of_eight_digits_fast(p)) {
-      i = i * 100000000 + parse_eight_digits_unrolled(p); // in rare cases, this will overflow, but that's ok
-      p += 8;
-    }
-  }
+    UC const *before = p;
+    // can occur at most twice without overflowing, but let it occur more, since
+    // for integers with many digits, digit parsing is the primary bottleneck.
+    loop_parse_if_eight_digits(p, pend, i);
+
     while ((p != pend) && is_integer(*p)) {
-      uint8_t digit = uint8_t(*p - '0');
+      uint8_t digit = uint8_t(*p - UC('0'));
       ++p;
       i = i * 10 + digit; // in rare cases, this will overflow, but that's ok
     }
-    exponent = end_of_integer_part + 1 - p;
+    exponent = before - p;
+    answer.fraction = span<UC const>(before, size_t(p - before));
     digit_count -= exponent;
   }
-  // we must have encountered at least one integer!
-  if (digit_count == 0) {
-    return answer;
+  FASTFLOAT_IF_CONSTEXPR17(basic_json_fmt) {
+    // at least 1 digit in fractional part
+    if (has_decimal_point && exponent == 0) {
+      return report_parse_error<UC>(p,
+                                    parse_error::no_digits_in_fractional_part);
+    }
+  }
+  else if (digit_count == 0) { // we must have encountered at least one integer!
+    return report_parse_error<UC>(p, parse_error::no_digits_in_mantissa);
   }
   int64_t exp_number = 0; // explicit exponential part
-  if ((fmt & chars_format::scientific) && (p != pend) && (('e' == *p) || ('E' == *p))) {
-    const char * location_of_e = p;
+  if ((uint64_t(fmt & chars_format::scientific) && (p != pend) &&
+       ((UC('e') == *p) || (UC('E') == *p))) ||
+      (uint64_t(fmt & detail::basic_fortran_fmt) && (p != pend) &&
+       ((UC('+') == *p) || (UC('-') == *p) || (UC('d') == *p) ||
+        (UC('D') == *p)))) {
+    UC const *location_of_e = p;
+    if ((UC('e') == *p) || (UC('E') == *p) || (UC('d') == *p) ||
+        (UC('D') == *p)) {
       ++p;
+    }
     bool neg_exp = false;
-    if ((p != pend) && ('-' == *p)) {
+    if ((p != pend) && (UC('-') == *p)) {
       neg_exp = true;
       ++p;
-    } else if ((p != pend) && ('+' == *p)) { // '+' on exponent is allowed by C++17 20.19.3.(7.1)
+    } else if ((p != pend) &&
+               (UC('+') ==
+                *p)) { // '+' on exponent is allowed by C++17 20.19.3.(7.1)
       ++p;
     }
     if ((p == pend) || !is_integer(*p)) {
-      if(!(fmt & chars_format::fixed)) {
-        // We are in error.
-        return answer;
+      if (!uint64_t(fmt & chars_format::fixed)) {
+        // The exponential part is invalid for scientific notation, so it must
+        // be a trailing token for fixed notation. However, fixed notation is
+        // disabled, so report a scientific notation error.
+        return report_parse_error<UC>(p, parse_error::missing_exponential_part);
       }
       // Otherwise, we will be ignoring the 'e'.
       p = location_of_e;
     } else {
       while ((p != pend) && is_integer(*p)) {
-        uint8_t digit = uint8_t(*p - '0');
-        if (exp_number < 0x10000) {
+        uint8_t digit = uint8_t(*p - UC('0'));
+        if (exp_number < 0x10000000) {
           exp_number = 10 * exp_number + digit;
         }
         ++p;
       }
-      if(neg_exp) { exp_number = - exp_number; }
+      if (neg_exp) {
+        exp_number = -exp_number;
+      }
       exponent += exp_number;
     }
   } else {
     // If it scientific and not fixed, we have to bail out.
-    if((fmt & chars_format::scientific) && !(fmt & chars_format::fixed)) { return answer; }
+    if (uint64_t(fmt & chars_format::scientific) &&
+        !uint64_t(fmt & chars_format::fixed)) {
+      return report_parse_error<UC>(p, parse_error::missing_exponential_part);
+    }
   }
   answer.lastmatch = p;
   answer.valid = true;
@@ -181,31 +430,37 @@ parsed_number_string parse_number_string(const char *p, const char *pend, parse_
     // We have to handle the case where we have 0.0000somenumber.
     // We need to be mindful of the case where we only have zeroes...
     // E.g., 0.000000000...000.
-    const char *start = start_digits;
-    while ((start != pend) && (*start == '0' || *start == decimal_point)) {
-      if(*start == '0') { digit_count --; }
+    UC const *start = start_digits;
+    while ((start != pend) && (*start == UC('0') || *start == decimal_point)) {
+      if (*start == UC('0')) {
+        digit_count--;
+      }
       start++;
     }
+
     if (digit_count > 19) {
       answer.too_many_digits = true;
       // Let us start again, this time, avoiding overflows.
+      // We don't need to call if is_integer, since we use the
+      // pre-tokenized spans from above.
       i = 0;
-      p = start_digits;
-      const uint64_t minimal_nineteen_digit_integer{1000000000000000000};
-      while((i < minimal_nineteen_digit_integer) && (p != pend) && is_integer(*p)) {
-        i = i * 10 + uint64_t(*p - '0');
+      p = answer.integer.ptr;
+      UC const *int_end = p + answer.integer.len();
+      uint64_t const minimal_nineteen_digit_integer{1000000000000000000};
+      while ((i < minimal_nineteen_digit_integer) && (p != int_end)) {
+        i = i * 10 + uint64_t(*p - UC('0'));
         ++p;
       }
-      if (i >= minimal_nineteen_digit_integer) { // We have a big integers
+      if (i >= minimal_nineteen_digit_integer) { // We have a big integer
         exponent = end_of_integer_part - p + exp_number;
       } else { // We have a value with a fractional component.
-          p++; // skip the dot
-          const char *first_after_period = p;
-          while((i < minimal_nineteen_digit_integer) && (p != pend) && is_integer(*p)) {
-            i = i * 10 + uint64_t(*p - '0');
+        p = answer.fraction.ptr;
+        UC const *frac_end = p + answer.fraction.len();
+        while ((i < minimal_nineteen_digit_integer) && (p != frac_end)) {
+          i = i * 10 + uint64_t(*p - UC('0'));
           ++p;
         }
-          exponent = first_after_period - p + exp_number;
+        exponent = answer.fraction.ptr - p + exp_number;
       }
       // We have now corrected both exponent and i, to a truncated value
     }
@@ -215,108 +470,119 @@ parsed_number_string parse_number_string(const char *p, const char *pend, parse_
   return answer;
 }
 
+template <typename T, typename UC>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 from_chars_result_t<UC>
+parse_int_string(UC const *p, UC const *pend, T &value,
+                 parse_options_t<UC> options) {
+  chars_format const fmt = detail::adjust_for_feature_macros(options.format);
+  int const base = options.base;
 
-// This should always succeed since it follows a call to parse_number_string
-// This function could be optimized. In particular, we could stop after 19 digits
-// and try to bail out. Furthermore, we should be able to recover the computed
-// exponent from the pass in parse_number_string.
-fastfloat_really_inline decimal parse_decimal(const char *p, const char *pend, parse_options options) noexcept {
-  const char decimal_point = options.decimal_point;
+  from_chars_result_t<UC> answer;
 
-  decimal answer;
-  answer.num_digits = 0;
-  answer.decimal_point = 0;
-  answer.truncated = false;
-  answer.negative = (*p == '-');
-  if (*p == '-') { // C++17 20.19.3.(7.1) explicitly forbids '+' sign here
-    ++p;
-  }
-  // skip leading zeroes
-  while ((p != pend) && (*p == '0')) {
-    ++p;
-  }
-  while ((p != pend) && is_integer(*p)) {
-    if (answer.num_digits < max_digits) {
-      answer.digits[answer.num_digits] = uint8_t(*p - '0');
-    }
-    answer.num_digits++;
-    ++p;
-  }
-  if ((p != pend) && (*p == decimal_point)) {
-    ++p;
-    const char *first_after_period = p;
-    // if we have not yet encountered a zero, we have to skip it as well
-    if(answer.num_digits == 0) {
-      // skip zeros
-      while ((p != pend) && (*p == '0')) {
-       ++p;
-      }
-    }
-    // We expect that this loop will often take the bulk of the running time
-    // because when a value has lots of digits, these digits often
-    while ((p + 8 <= pend) && (answer.num_digits + 8 < max_digits)) {
-      uint64_t val = read_u64(p);
-      if(! is_made_of_eight_digits_fast(val)) { break; }
-      // We have eight digits, process them in one go!
-      val -= 0x3030303030303030;
-      write_u64(answer.digits + answer.num_digits, val);
-      answer.num_digits += 8;
-      p += 8;
-    }
-    while ((p != pend) && is_integer(*p)) {
-      if (answer.num_digits < max_digits) {
-        answer.digits[answer.num_digits] = uint8_t(*p - '0');
-      }
-      answer.num_digits++;
-      ++p;
-    }
-    answer.decimal_point = int32_t(first_after_period - p);
-  }
-  // We want num_digits to be the number of significant digits, excluding
-  // leading *and* trailing zeros! Otherwise the truncated flag later is
-  // going to be misleading.
-  if(answer.num_digits > 0) {
-    // We potentially need the answer.num_digits > 0 guard because we
-    // prune leading zeros. So with answer.num_digits > 0, we know that
-    // we have at least one non-zero digit.
-    const char *preverse = p - 1;
-    int32_t trailing_zeros = 0;
-    while ((*preverse == '0') || (*preverse == decimal_point)) {
-      if(*preverse == '0') { trailing_zeros++; };
-      --preverse;
-    }
-    answer.decimal_point += int32_t(answer.num_digits);
-    answer.num_digits -= uint32_t(trailing_zeros);
-  }
-  if(answer.num_digits > max_digits) {
-    answer.truncated = true;
-    answer.num_digits = max_digits;
-  }
-  if ((p != pend) && (('e' == *p) || ('E' == *p))) {
-    ++p;
-    bool neg_exp = false;
-    if ((p != pend) && ('-' == *p)) {
-      neg_exp = true;
-      ++p;
-    } else if ((p != pend) && ('+' == *p)) { // '+' on exponent is allowed by C++17 20.19.3.(7.1)
-      ++p;
-    }
-    int32_t exp_number = 0; // exponential part
-    while ((p != pend) && is_integer(*p)) {
-      uint8_t digit = uint8_t(*p - '0');
-      if (exp_number < 0x10000) {
-        exp_number = 10 * exp_number + digit;
-      }
-      ++p;
-    }
-    answer.decimal_point += (neg_exp ? -exp_number : exp_number);
-  }
-  // In very rare cases, we may have fewer than 19 digits, we want to be able to reliably
-  // assume that all digits up to max_digit_without_overflow have been initialized.
-  for(uint32_t i = answer.num_digits; i < max_digit_without_overflow; i++) { answer.digits[i] = 0; }
+  UC const *const first = p;
 
+  bool const negative = (*p == UC('-'));
+#ifdef FASTFLOAT_VISUAL_STUDIO
+#pragma warning(push)
+#pragma warning(disable : 4127)
+#endif
+  if (!std::is_signed<T>::value && negative) {
+#ifdef FASTFLOAT_VISUAL_STUDIO
+#pragma warning(pop)
+#endif
+    answer.ec = std::errc::invalid_argument;
+    answer.ptr = first;
+    return answer;
+  }
+  if ((*p == UC('-')) ||
+      (uint64_t(fmt & chars_format::allow_leading_plus) && (*p == UC('+')))) {
+    ++p;
+  }
+
+  UC const *const start_num = p;
+
+  while (p != pend && *p == UC('0')) {
+    ++p;
+  }
+
+  bool const has_leading_zeros = p > start_num;
+
+  UC const *const start_digits = p;
+
+  uint64_t i = 0;
+  if (base == 10) {
+    loop_parse_if_eight_digits(p, pend, i); // use SIMD if possible
+  }
+  while (p != pend) {
+    uint8_t digit = ch_to_digit(*p);
+    if (digit >= base) {
+      break;
+    }
+    i = uint64_t(base) * i + digit; // might overflow, check this later
+    p++;
+  }
+
+  size_t digit_count = size_t(p - start_digits);
+
+  if (digit_count == 0) {
+    if (has_leading_zeros) {
+      value = 0;
+      answer.ec = std::errc();
+      answer.ptr = p;
+    } else {
+      answer.ec = std::errc::invalid_argument;
+      answer.ptr = first;
+    }
+    return answer;
+  }
+
+  answer.ptr = p;
+
+  // check u64 overflow
+  size_t max_digits = max_digits_u64(base);
+  if (digit_count > max_digits) {
+    answer.ec = std::errc::result_out_of_range;
+    return answer;
+  }
+  // this check can be eliminated for all other types, but they will all require
+  // a max_digits(base) equivalent
+  if (digit_count == max_digits && i < min_safe_u64(base)) {
+    answer.ec = std::errc::result_out_of_range;
+    return answer;
+  }
+
+  // check other types overflow
+  if (!std::is_same<T, uint64_t>::value) {
+    if (i > uint64_t(std::numeric_limits<T>::max()) + uint64_t(negative)) {
+      answer.ec = std::errc::result_out_of_range;
+      return answer;
+    }
+  }
+
+  if (negative) {
+#ifdef FASTFLOAT_VISUAL_STUDIO
+#pragma warning(push)
+#pragma warning(disable : 4146)
+#endif
+    // this weird workaround is required because:
+    // - converting unsigned to signed when its value is greater than signed max
+    // is UB pre-C++23.
+    // - reinterpret_casting (~i + 1) would work, but it is not constexpr
+    // this is always optimized into a neg instruction (note: T is an integer
+    // type)
+    value = T(-std::numeric_limits<T>::max() -
+              T(i - uint64_t(std::numeric_limits<T>::max())));
+#ifdef FASTFLOAT_VISUAL_STUDIO
+#pragma warning(pop)
+#endif
+  } else {
+    value = T(i);
+  }
+
+  answer.ec = std::errc();
   return answer;
 }
+
 } // namespace fast_float
 
 #endif

include/fast_float/bigint.h

@@ -0,0 +1,638 @@
+#ifndef FASTFLOAT_BIGINT_H
+#define FASTFLOAT_BIGINT_H
+
+#include <algorithm>
+#include <cstdint>
+#include <climits>
+#include <cstring>
+
+#include "float_common.h"
+
+namespace fast_float {
+
+// the limb width: we want efficient multiplication of double the bits in
+// limb, or for 64-bit limbs, at least 64-bit multiplication where we can
+// extract the high and low parts efficiently. this is every 64-bit
+// architecture except for sparc, which emulates 128-bit multiplication.
+// we might have platforms where `CHAR_BIT` is not 8, so let's avoid
+// doing `8 * sizeof(limb)`.
+#if defined(FASTFLOAT_64BIT) && !defined(__sparc)
+#define FASTFLOAT_64BIT_LIMB 1
+typedef uint64_t limb;
+constexpr size_t limb_bits = 64;
+#else
+#define FASTFLOAT_32BIT_LIMB
+typedef uint32_t limb;
+constexpr size_t limb_bits = 32;
+#endif
+
+typedef span<limb> limb_span;
+
+// number of bits in a bigint. this needs to be at least the number
+// of bits required to store the largest bigint, which is
+// `log2(10**(digits + max_exp))`, or `log2(10**(767 + 342))`, or
+// ~3600 bits, so we round to 4000.
+constexpr size_t bigint_bits = 4000;
+constexpr size_t bigint_limbs = bigint_bits / limb_bits;
+
+// vector-like type that is allocated on the stack. the entire
+// buffer is pre-allocated, and only the length changes.
+template <uint16_t size> struct stackvec {
+  limb data[size];
+  // we never need more than 150 limbs
+  uint16_t length{0};
+
+  stackvec() = default;
+  stackvec(stackvec const &) = delete;
+  stackvec &operator=(stackvec const &) = delete;
+  stackvec(stackvec &&) = delete;
+  stackvec &operator=(stackvec &&other) = delete;
+
+  // create stack vector from existing limb span.
+  FASTFLOAT_CONSTEXPR20 stackvec(limb_span s) {
+    FASTFLOAT_ASSERT(try_extend(s));
+  }
+
+  FASTFLOAT_CONSTEXPR14 limb &operator[](size_t index) noexcept {
+    FASTFLOAT_DEBUG_ASSERT(index < length);
+    return data[index];
+  }
+
+  FASTFLOAT_CONSTEXPR14 const limb &operator[](size_t index) const noexcept {
+    FASTFLOAT_DEBUG_ASSERT(index < length);
+    return data[index];
+  }
+
+  // index from the end of the container
+  FASTFLOAT_CONSTEXPR14 const limb &rindex(size_t index) const noexcept {
+    FASTFLOAT_DEBUG_ASSERT(index < length);
+    size_t rindex = length - index - 1;
+    return data[rindex];
+  }
+
+  // set the length, without bounds checking.
+  FASTFLOAT_CONSTEXPR14 void set_len(size_t len) noexcept {
+    length = uint16_t(len);
+  }
+
+  constexpr size_t len() const noexcept { return length; }
+
+  constexpr bool is_empty() const noexcept { return length == 0; }
+
+  constexpr size_t capacity() const noexcept { return size; }
+
+  // append item to vector, without bounds checking
+  FASTFLOAT_CONSTEXPR14 void push_unchecked(limb value) noexcept {
+    data[length] = value;
+    length++;
+  }
+
+  // append item to vector, returning if item was added
+  FASTFLOAT_CONSTEXPR14 bool try_push(limb value) noexcept {
+    if (len() < capacity()) {
+      push_unchecked(value);
+      return true;
+    } else {
+      return false;
+    }
+  }
+
+  // add items to the vector, from a span, without bounds checking
+  FASTFLOAT_CONSTEXPR20 void extend_unchecked(limb_span s) noexcept {
+    limb *ptr = data + length;
+    std::copy_n(s.ptr, s.len(), ptr);
+    set_len(len() + s.len());
+  }
+
+  // try to add items to the vector, returning if items were added
+  FASTFLOAT_CONSTEXPR20 bool try_extend(limb_span s) noexcept {
+    if (len() + s.len() <= capacity()) {
+      extend_unchecked(s);
+      return true;
+    } else {
+      return false;
+    }
+  }
+
+  // resize the vector, without bounds checking
+  // if the new size is longer than the vector, assign value to each
+  // appended item.
+  FASTFLOAT_CONSTEXPR20
+  void resize_unchecked(size_t new_len, limb value) noexcept {
+    if (new_len > len()) {
+      size_t count = new_len - len();
+      limb *first = data + len();
+      limb *last = first + count;
+      ::std::fill(first, last, value);
+      set_len(new_len);
+    } else {
+      set_len(new_len);
+    }
+  }
+
+  // try to resize the vector, returning if the vector was resized.
+  FASTFLOAT_CONSTEXPR20 bool try_resize(size_t new_len, limb value) noexcept {
+    if (new_len > capacity()) {
+      return false;
+    } else {
+      resize_unchecked(new_len, value);
+      return true;
+    }
+  }
+
+  // check if any limbs are non-zero after the given index.
+  // this needs to be done in reverse order, since the index
+  // is relative to the most significant limbs.
+  FASTFLOAT_CONSTEXPR14 bool nonzero(size_t index) const noexcept {
+    while (index < len()) {
+      if (rindex(index) != 0) {
+        return true;
+      }
+      index++;
+    }
+    return false;
+  }
+
+  // normalize the big integer, so most-significant zero limbs are removed.
+  FASTFLOAT_CONSTEXPR14 void normalize() noexcept {
+    while (len() > 0 && rindex(0) == 0) {
+      length--;
+    }
+  }
+};
+
+fastfloat_really_inline FASTFLOAT_CONSTEXPR14 uint64_t
+empty_hi64(bool &truncated) noexcept {
+  truncated = false;
+  return 0;
+}
+
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 uint64_t
+uint64_hi64(uint64_t r0, bool &truncated) noexcept {
+  truncated = false;
+  int shl = leading_zeroes(r0);
+  return r0 << shl;
+}
+
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 uint64_t
+uint64_hi64(uint64_t r0, uint64_t r1, bool &truncated) noexcept {
+  int shl = leading_zeroes(r0);
+  if (shl == 0) {
+    truncated = r1 != 0;
+    return r0;
+  } else {
+    int shr = 64 - shl;
+    truncated = (r1 << shl) != 0;
+    return (r0 << shl) | (r1 >> shr);
+  }
+}
+
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 uint64_t
+uint32_hi64(uint32_t r0, bool &truncated) noexcept {
+  return uint64_hi64(r0, truncated);
+}
+
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 uint64_t
+uint32_hi64(uint32_t r0, uint32_t r1, bool &truncated) noexcept {
+  uint64_t x0 = r0;
+  uint64_t x1 = r1;
+  return uint64_hi64((x0 << 32) | x1, truncated);
+}
+
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 uint64_t
+uint32_hi64(uint32_t r0, uint32_t r1, uint32_t r2, bool &truncated) noexcept {
+  uint64_t x0 = r0;
+  uint64_t x1 = r1;
+  uint64_t x2 = r2;
+  return uint64_hi64(x0, (x1 << 32) | x2, truncated);
+}
+
+// add two small integers, checking for overflow.
+// we want an efficient operation. for msvc, where
+// we don't have built-in intrinsics, this is still
+// pretty fast.
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 limb
+scalar_add(limb x, limb y, bool &overflow) noexcept {
+  limb z;
+// gcc and clang
+#if defined(__has_builtin)
+#if __has_builtin(__builtin_add_overflow)
+  if (!cpp20_and_in_constexpr()) {
+    overflow = __builtin_add_overflow(x, y, &z);
+    return z;
+  }
+#endif
+#endif
+
+  // generic, this still optimizes correctly on MSVC.
+  z = x + y;
+  overflow = z < x;
+  return z;
+}
+
+// multiply two small integers, getting both the high and low bits.
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 limb
+scalar_mul(limb x, limb y, limb &carry) noexcept {
+#ifdef FASTFLOAT_64BIT_LIMB
+#if defined(__SIZEOF_INT128__)
+  // GCC and clang both define it as an extension.
+  __uint128_t z = __uint128_t(x) * __uint128_t(y) + __uint128_t(carry);
+  carry = limb(z >> limb_bits);
+  return limb(z);
+#else
+  // fallback, no native 128-bit integer multiplication with carry.
+  // on msvc, this optimizes identically, somehow.
+  value128 z = full_multiplication(x, y);
+  bool overflow;
+  z.low = scalar_add(z.low, carry, overflow);
+  z.high += uint64_t(overflow); // cannot overflow
+  carry = z.high;
+  return z.low;
+#endif
+#else
+  uint64_t z = uint64_t(x) * uint64_t(y) + uint64_t(carry);
+  carry = limb(z >> limb_bits);
+  return limb(z);
+#endif
+}
+
+// add scalar value to bigint starting from offset.
+// used in grade school multiplication
+template <uint16_t size>
+inline FASTFLOAT_CONSTEXPR20 bool small_add_from(stackvec<size> &vec, limb y,
+                                                 size_t start) noexcept {
+  size_t index = start;
+  limb carry = y;
+  bool overflow;
+  while (carry != 0 && index < vec.len()) {
+    vec[index] = scalar_add(vec[index], carry, overflow);
+    carry = limb(overflow);
+    index += 1;
+  }
+  if (carry != 0) {
+    FASTFLOAT_TRY(vec.try_push(carry));
+  }
+  return true;
+}
+
+// add scalar value to bigint.
+template <uint16_t size>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 bool
+small_add(stackvec<size> &vec, limb y) noexcept {
+  return small_add_from(vec, y, 0);
+}
+
+// multiply bigint by scalar value.
+template <uint16_t size>
+inline FASTFLOAT_CONSTEXPR20 bool small_mul(stackvec<size> &vec,
+                                            limb y) noexcept {
+  limb carry = 0;
+  for (size_t index = 0; index < vec.len(); index++) {
+    vec[index] = scalar_mul(vec[index], y, carry);
+  }
+  if (carry != 0) {
+    FASTFLOAT_TRY(vec.try_push(carry));
+  }
+  return true;
+}
+
+// add bigint to bigint starting from index.
+// used in grade school multiplication
+template <uint16_t size>
+FASTFLOAT_CONSTEXPR20 bool large_add_from(stackvec<size> &x, limb_span y,
+                                          size_t start) noexcept {
+  // the effective x buffer is from `xstart..x.len()`, so exit early
+  // if we can't get that current range.
+  if (x.len() < start || y.len() > x.len() - start) {
+    FASTFLOAT_TRY(x.try_resize(y.len() + start, 0));
+  }
+
+  bool carry = false;
+  for (size_t index = 0; index < y.len(); index++) {
+    limb xi = x[index + start];
+    limb yi = y[index];
+    bool c1 = false;
+    bool c2 = false;
+    xi = scalar_add(xi, yi, c1);
+    if (carry) {
+      xi = scalar_add(xi, 1, c2);
+    }
+    x[index + start] = xi;
+    carry = c1 | c2;
+  }
+
+  // handle overflow
+  if (carry) {
+    FASTFLOAT_TRY(small_add_from(x, 1, y.len() + start));
+  }
+  return true;
+}
+
+// add bigint to bigint.
+template <uint16_t size>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 bool
+large_add_from(stackvec<size> &x, limb_span y) noexcept {
+  return large_add_from(x, y, 0);
+}
+
+// grade-school multiplication algorithm
+template <uint16_t size>
+FASTFLOAT_CONSTEXPR20 bool long_mul(stackvec<size> &x, limb_span y) noexcept {
+  limb_span xs = limb_span(x.data, x.len());
+  stackvec<size> z(xs);
+  limb_span zs = limb_span(z.data, z.len());
+
+  if (y.len() != 0) {
+    limb y0 = y[0];
+    FASTFLOAT_TRY(small_mul(x, y0));
+    for (size_t index = 1; index < y.len(); index++) {
+      limb yi = y[index];
+      stackvec<size> zi;
+      if (yi != 0) {
+        // re-use the same buffer throughout
+        zi.set_len(0);
+        FASTFLOAT_TRY(zi.try_extend(zs));
+        FASTFLOAT_TRY(small_mul(zi, yi));
+        limb_span zis = limb_span(zi.data, zi.len());
+        FASTFLOAT_TRY(large_add_from(x, zis, index));
+      }
+    }
+  }
+
+  x.normalize();
+  return true;
+}
+
+// grade-school multiplication algorithm
+template <uint16_t size>
+FASTFLOAT_CONSTEXPR20 bool large_mul(stackvec<size> &x, limb_span y) noexcept {
+  if (y.len() == 1) {
+    FASTFLOAT_TRY(small_mul(x, y[0]));
+  } else {
+    FASTFLOAT_TRY(long_mul(x, y));
+  }
+  return true;
+}
+
+template <typename = void> struct pow5_tables {
+  static constexpr uint32_t large_step = 135;
+  static constexpr uint64_t small_power_of_5[] = {
+      1UL,
+      5UL,
+      25UL,
+      125UL,
+      625UL,
+      3125UL,
+      15625UL,
+      78125UL,
+      390625UL,
+      1953125UL,
+      9765625UL,
+      48828125UL,
+      244140625UL,
+      1220703125UL,
+      6103515625UL,
+      30517578125UL,
+      152587890625UL,
+      762939453125UL,
+      3814697265625UL,
+      19073486328125UL,
+      95367431640625UL,
+      476837158203125UL,
+      2384185791015625UL,
+      11920928955078125UL,
+      59604644775390625UL,
+      298023223876953125UL,
+      1490116119384765625UL,
+      7450580596923828125UL,
+  };
+#ifdef FASTFLOAT_64BIT_LIMB
+  constexpr static limb large_power_of_5[] = {
+      1414648277510068013UL, 9180637584431281687UL, 4539964771860779200UL,
+      10482974169319127550UL, 198276706040285095UL};
+#else
+  constexpr static limb large_power_of_5[] = {
+      4279965485U, 329373468U,  4020270615U, 2137533757U, 4287402176U,
+      1057042919U, 1071430142U, 2440757623U, 381945767U,  46164893U};
+#endif
+};
+
+#if FASTFLOAT_DETAIL_MUST_DEFINE_CONSTEXPR_VARIABLE
+
+template <typename T> constexpr uint32_t pow5_tables<T>::large_step;
+
+template <typename T> constexpr uint64_t pow5_tables<T>::small_power_of_5[];
+
+template <typename T> constexpr limb pow5_tables<T>::large_power_of_5[];
+
+#endif
+
+// big integer type. implements a small subset of big integer
+// arithmetic, using simple algorithms since asymptotically
+// faster algorithms are slower for a small number of limbs.
+// all operations assume the big-integer is normalized.
+struct bigint : pow5_tables<> {
+  // storage of the limbs, in little-endian order.
+  stackvec<bigint_limbs> vec;
+
+  FASTFLOAT_CONSTEXPR20 bigint() : vec() {}
+
+  bigint(bigint const &) = delete;
+  bigint &operator=(bigint const &) = delete;
+  bigint(bigint &&) = delete;
+  bigint &operator=(bigint &&other) = delete;
+
+  FASTFLOAT_CONSTEXPR20 bigint(uint64_t value) : vec() {
+#ifdef FASTFLOAT_64BIT_LIMB
+    vec.push_unchecked(value);
+#else
+    vec.push_unchecked(uint32_t(value));
+    vec.push_unchecked(uint32_t(value >> 32));
+#endif
+    vec.normalize();
+  }
+
+  // get the high 64 bits from the vector, and if bits were truncated.
+  // this is to get the significant digits for the float.
+  FASTFLOAT_CONSTEXPR20 uint64_t hi64(bool &truncated) const noexcept {
+#ifdef FASTFLOAT_64BIT_LIMB
+    if (vec.len() == 0) {
+      return empty_hi64(truncated);
+    } else if (vec.len() == 1) {
+      return uint64_hi64(vec.rindex(0), truncated);
+    } else {
+      uint64_t result = uint64_hi64(vec.rindex(0), vec.rindex(1), truncated);
+      truncated |= vec.nonzero(2);
+      return result;
+    }
+#else
+    if (vec.len() == 0) {
+      return empty_hi64(truncated);
+    } else if (vec.len() == 1) {
+      return uint32_hi64(vec.rindex(0), truncated);
+    } else if (vec.len() == 2) {
+      return uint32_hi64(vec.rindex(0), vec.rindex(1), truncated);
+    } else {
+      uint64_t result =
+          uint32_hi64(vec.rindex(0), vec.rindex(1), vec.rindex(2), truncated);
+      truncated |= vec.nonzero(3);
+      return result;
+    }
+#endif
+  }
+
+  // compare two big integers, returning the large value.
+  // assumes both are normalized. if the return value is
+  // negative, other is larger, if the return value is
+  // positive, this is larger, otherwise they are equal.
+  // the limbs are stored in little-endian order, so we
+  // must compare the limbs in ever order.
+  FASTFLOAT_CONSTEXPR20 int compare(bigint const &other) const noexcept {
+    if (vec.len() > other.vec.len()) {
+      return 1;
+    } else if (vec.len() < other.vec.len()) {
+      return -1;
+    } else {
+      for (size_t index = vec.len(); index > 0; index--) {
+        limb xi = vec[index - 1];
+        limb yi = other.vec[index - 1];
+        if (xi > yi) {
+          return 1;
+        } else if (xi < yi) {
+          return -1;
+        }
+      }
+      return 0;
+    }
+  }
+
+  // shift left each limb n bits, carrying over to the new limb
+  // returns true if we were able to shift all the digits.
+  FASTFLOAT_CONSTEXPR20 bool shl_bits(size_t n) noexcept {
+    // Internally, for each item, we shift left by n, and add the previous
+    // right shifted limb-bits.
+    // For example, we transform (for u8) shifted left 2, to:
+    //      b10100100 b01000010
+    //      b10 b10010001 b00001000
+    FASTFLOAT_DEBUG_ASSERT(n != 0);
+    FASTFLOAT_DEBUG_ASSERT(n < sizeof(limb) * 8);
+
+    size_t shl = n;
+    size_t shr = limb_bits - shl;
+    limb prev = 0;
+    for (size_t index = 0; index < vec.len(); index++) {
+      limb xi = vec[index];
+      vec[index] = (xi << shl) | (prev >> shr);
+      prev = xi;
+    }
+
+    limb carry = prev >> shr;
+    if (carry != 0) {
+      return vec.try_push(carry);
+    }
+    return true;
+  }
+
+  // move the limbs left by `n` limbs.
+  FASTFLOAT_CONSTEXPR20 bool shl_limbs(size_t n) noexcept {
+    FASTFLOAT_DEBUG_ASSERT(n != 0);
+    if (n + vec.len() > vec.capacity()) {
+      return false;
+    } else if (!vec.is_empty()) {
+      // move limbs
+      limb *dst = vec.data + n;
+      limb const *src = vec.data;
+      std::copy_backward(src, src + vec.len(), dst + vec.len());
+      // fill in empty limbs
+      limb *first = vec.data;
+      limb *last = first + n;
+      ::std::fill(first, last, 0);
+      vec.set_len(n + vec.len());
+      return true;
+    } else {
+      return true;
+    }
+  }
+
+  // move the limbs left by `n` bits.
+  FASTFLOAT_CONSTEXPR20 bool shl(size_t n) noexcept {
+    size_t rem = n % limb_bits;
+    size_t div = n / limb_bits;
+    if (rem != 0) {
+      FASTFLOAT_TRY(shl_bits(rem));
+    }
+    if (div != 0) {
+      FASTFLOAT_TRY(shl_limbs(div));
+    }
+    return true;
+  }
+
+  // get the number of leading zeros in the bigint.
+  FASTFLOAT_CONSTEXPR20 int ctlz() const noexcept {
+    if (vec.is_empty()) {
+      return 0;
+    } else {
+#ifdef FASTFLOAT_64BIT_LIMB
+      return leading_zeroes(vec.rindex(0));
+#else
+      // no use defining a specialized leading_zeroes for a 32-bit type.
+      uint64_t r0 = vec.rindex(0);
+      return leading_zeroes(r0 << 32);
+#endif
+    }
+  }
+
+  // get the number of bits in the bigint.
+  FASTFLOAT_CONSTEXPR20 int bit_length() const noexcept {
+    int lz = ctlz();
+    return int(limb_bits * vec.len()) - lz;
+  }
+
+  FASTFLOAT_CONSTEXPR20 bool mul(limb y) noexcept { return small_mul(vec, y); }
+
+  FASTFLOAT_CONSTEXPR20 bool add(limb y) noexcept { return small_add(vec, y); }
+
+  // multiply as if by 2 raised to a power.
+  FASTFLOAT_CONSTEXPR20 bool pow2(uint32_t exp) noexcept { return shl(exp); }
+
+  // multiply as if by 5 raised to a power.
+  FASTFLOAT_CONSTEXPR20 bool pow5(uint32_t exp) noexcept {
+    // multiply by a power of 5
+    size_t large_length = sizeof(large_power_of_5) / sizeof(limb);
+    limb_span large = limb_span(large_power_of_5, large_length);
+    while (exp >= large_step) {
+      FASTFLOAT_TRY(large_mul(vec, large));
+      exp -= large_step;
+    }
+#ifdef FASTFLOAT_64BIT_LIMB
+    uint32_t small_step = 27;
+    limb max_native = 7450580596923828125UL;
+#else
+    uint32_t small_step = 13;
+    limb max_native = 1220703125U;
+#endif
+    while (exp >= small_step) {
+      FASTFLOAT_TRY(small_mul(vec, max_native));
+      exp -= small_step;
+    }
+    if (exp != 0) {
+      // Work around clang bug https://godbolt.org/z/zedh7rrhc
+      // This is similar to https://github.com/llvm/llvm-project/issues/47746,
+      // except the workaround described there don't work here
+      FASTFLOAT_TRY(small_mul(
+          vec, limb(((void)small_power_of_5[0], small_power_of_5[exp]))));
+    }
+
+    return true;
+  }
+
+  // multiply as if by 10 raised to a power.
+  FASTFLOAT_CONSTEXPR20 bool pow10(uint32_t exp) noexcept {
+    FASTFLOAT_TRY(pow5(exp));
+    return pow2(exp);
+  }
+};
+
+} // namespace fast_float
+
+#endif

include/fast_float/constexpr_feature_detect.h

@@ -0,0 +1,53 @@
+#ifndef FASTFLOAT_CONSTEXPR_FEATURE_DETECT_H
+#define FASTFLOAT_CONSTEXPR_FEATURE_DETECT_H
+
+#ifdef __has_include
+#if __has_include(<version>)
+#include <version>
+#endif
+#endif
+
+// Testing for https://wg21.link/N3652, adopted in C++14
+#if defined(__cpp_constexpr) && __cpp_constexpr >= 201304
+#define FASTFLOAT_CONSTEXPR14 constexpr
+#else
+#define FASTFLOAT_CONSTEXPR14
+#endif
+
+#if defined(__cpp_lib_bit_cast) && __cpp_lib_bit_cast >= 201806L
+#define FASTFLOAT_HAS_BIT_CAST 1
+#else
+#define FASTFLOAT_HAS_BIT_CAST 0
+#endif
+
+#if defined(__cpp_lib_is_constant_evaluated) &&                                \
+    __cpp_lib_is_constant_evaluated >= 201811L
+#define FASTFLOAT_HAS_IS_CONSTANT_EVALUATED 1
+#else
+#define FASTFLOAT_HAS_IS_CONSTANT_EVALUATED 0
+#endif
+
+#if defined(__cpp_if_constexpr) && __cpp_if_constexpr >= 201606L
+#define FASTFLOAT_IF_CONSTEXPR17(x) if constexpr (x)
+#else
+#define FASTFLOAT_IF_CONSTEXPR17(x) if (x)
+#endif
+
+// Testing for relevant C++20 constexpr library features
+#if FASTFLOAT_HAS_IS_CONSTANT_EVALUATED && FASTFLOAT_HAS_BIT_CAST &&           \
+    defined(__cpp_lib_constexpr_algorithms) &&                                 \
+    __cpp_lib_constexpr_algorithms >= 201806L /*For std::copy and std::fill*/
+#define FASTFLOAT_CONSTEXPR20 constexpr
+#define FASTFLOAT_IS_CONSTEXPR 1
+#else
+#define FASTFLOAT_CONSTEXPR20
+#define FASTFLOAT_IS_CONSTEXPR 0
+#endif
+
+#if __cplusplus >= 201703L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201703L)
+#define FASTFLOAT_DETAIL_MUST_DEFINE_CONSTEXPR_VARIABLE 0
+#else
+#define FASTFLOAT_DETAIL_MUST_DEFINE_CONSTEXPR_VARIABLE 1
+#endif
+
+#endif // FASTFLOAT_CONSTEXPR_FEATURE_DETECT_H

include/fast_float/decimal_to_binary.h

@@ -7,33 +7,39 @@
 #include <cinttypes>
 #include <cmath>
 #include <cstdint>
-#include <cstdio>
 #include <cstdlib>
 #include <cstring>
 
 namespace fast_float {
 
-// This will compute or rather approximate w * 5**q and return a pair of 64-bit words approximating
-// the result, with the "high" part corresponding to the most significant bits and the
-// low part corresponding to the least significant bits.
+// This will compute or rather approximate w * 5**q and return a pair of 64-bit
+// words approximating the result, with the "high" part corresponding to the
+// most significant bits and the low part corresponding to the least significant
+// bits.
 //
 template <int bit_precision>
-fastfloat_really_inline
-value128 compute_product_approximation(int64_t q, uint64_t w) {
-  const int index = 2 * int(q - powers::smallest_power_of_five);
-  // For small values of q, e.g., q in [0,27], the answer is always exact because
-  // The line value128 firstproduct = full_multiplication(w, power_of_five_128[index]);
-  // gives the exact answer.
-  value128 firstproduct = full_multiplication(w, powers::power_of_five_128[index]);
-  static_assert((bit_precision >= 0) && (bit_precision <= 64), " precision should  be in (0,64]");
-  constexpr uint64_t precision_mask = (bit_precision < 64) ?
-               (uint64_t(0xFFFFFFFFFFFFFFFF) >> bit_precision)
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 value128
+compute_product_approximation(int64_t q, uint64_t w) {
+  int const index = 2 * int(q - powers::smallest_power_of_five);
+  // For small values of q, e.g., q in [0,27], the answer is always exact
+  // because The line value128 firstproduct = full_multiplication(w,
+  // power_of_five_128[index]); gives the exact answer.
+  value128 firstproduct =
+      full_multiplication(w, powers::power_of_five_128[index]);
+  static_assert((bit_precision >= 0) && (bit_precision <= 64),
+                " precision should  be in (0,64]");
+  constexpr uint64_t precision_mask =
+      (bit_precision < 64) ? (uint64_t(0xFFFFFFFFFFFFFFFF) >> bit_precision)
                            : uint64_t(0xFFFFFFFFFFFFFFFF);
-  if((firstproduct.high & precision_mask) == precision_mask) { // could further guard with  (lower + w < lower)
-    // regarding the second product, we only need secondproduct.high, but our expectation is that the compiler will optimize this extra work away if needed.
-    value128 secondproduct = full_multiplication(w, powers::power_of_five_128[index + 1]);
+  if ((firstproduct.high & precision_mask) ==
+      precision_mask) { // could further guard with  (lower + w < lower)
+    // regarding the second product, we only need secondproduct.high, but our
+    // expectation is that the compiler will optimize this extra work away if
+    // needed.
+    value128 secondproduct =
+        full_multiplication(w, powers::power_of_five_128[index + 1]);
     firstproduct.low += secondproduct.high;
-    if(secondproduct.high > firstproduct.low) {
+    if (secondproduct.high > firstproduct.low) {
       firstproduct.high++;
     }
   }
@@ -56,20 +62,45 @@ namespace detail {
  * where
  *   p = log(5**-q)/log(2) = -q * log(5)/log(2)
  */
-  fastfloat_really_inline int power(int q)  noexcept  {
+constexpr fastfloat_really_inline int32_t power(int32_t q) noexcept {
   return (((152170 + 65536) * q) >> 16) + 63;
-  }
+}
 } // namespace detail
 
-
-// w * 10 ** q
-// The returned value should be a valid ieee64 number that simply need to be packed.
-// However, in some very rare cases, the computation will fail. In such cases, we
-// return an adjusted_mantissa with a negative power of 2: the caller should recompute
-// in such cases.
+// create an adjusted mantissa, biased by the invalid power2
+// for significant digits already multiplied by 10 ** q.
 template <typename binary>
-fastfloat_really_inline
-adjusted_mantissa compute_float(int64_t q, uint64_t w)  noexcept  {
+fastfloat_really_inline FASTFLOAT_CONSTEXPR14 adjusted_mantissa
+compute_error_scaled(int64_t q, uint64_t w, int lz) noexcept {
+  int hilz = int(w >> 63) ^ 1;
+  adjusted_mantissa answer;
+  answer.mantissa = w << hilz;
+  int bias = binary::mantissa_explicit_bits() - binary::minimum_exponent();
+  answer.power2 = int32_t(detail::power(int32_t(q)) + bias - hilz - lz - 62 +
+                          invalid_am_bias);
+  return answer;
+}
+
+// w * 10 ** q, without rounding the representation up.
+// the power2 in the exponent will be adjusted by invalid_am_bias.
+template <typename binary>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa
+compute_error(int64_t q, uint64_t w) noexcept {
+  int lz = leading_zeroes(w);
+  w <<= lz;
+  value128 product =
+      compute_product_approximation<binary::mantissa_explicit_bits() + 3>(q, w);
+  return compute_error_scaled<binary>(q, product.high, lz);
+}
+
+// Computers w * 10 ** q.
+// The returned value should be a valid number that simply needs to be
+// packed. However, in some very rare cases, the computation will fail. In such
+// cases, we return an adjusted_mantissa with a negative power of 2: the caller
+// should recompute in such cases.
+template <typename binary>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa
+compute_float(int64_t q, uint64_t w) noexcept {
   adjusted_mantissa answer;
   if ((w == 0) || (q < binary::smallest_power_of_ten())) {
     answer.power2 = 0;
@@ -83,7 +114,8 @@ adjusted_mantissa compute_float(int64_t q, uint64_t w)  noexcept  {
     answer.mantissa = 0;
     return answer;
   }
-  // At this point in time q is in [powers::smallest_power_of_five, powers::largest_power_of_five].
+  // At this point in time q is in [powers::smallest_power_of_five,
+  // powers::largest_power_of_five].
 
   // We want the most significant bit of i to be 1. Shift if needed.
   int lz = leading_zeroes(w);
@@ -92,32 +124,32 @@ adjusted_mantissa compute_float(int64_t q, uint64_t w)  noexcept  {
   // The required precision is binary::mantissa_explicit_bits() + 3 because
   // 1. We need the implicit bit
   // 2. We need an extra bit for rounding purposes
-  // 3. We might lose a bit due to the "upperbit" routine (result too small, requiring a shift)
+  // 3. We might lose a bit due to the "upperbit" routine (result too small,
+  // requiring a shift)
 
-  value128 product = compute_product_approximation<binary::mantissa_explicit_bits() + 3>(q, w);
-  if(product.low == 0xFFFFFFFFFFFFFFFF) { //  could guard it further
-    // In some very rare cases, this could happen, in which case we might need a more accurate
-    // computation that what we can provide cheaply. This is very, very unlikely.
-    //
-    const bool inside_safe_exponent = (q >= -27) && (q <= 55); // always good because 5**q <2**128 when q>=0, 
-    // and otherwise, for q<0, we have 5**-q<2**64 and the 128-bit reciprocal allows for exact computation.
-    if(!inside_safe_exponent) {
-      answer.power2 = -1; // This (a negative value) indicates an error condition.
-      return answer;
-    }
-  }
-  // The "compute_product_approximation" function can be slightly slower than a branchless approach:
-  // value128 product = compute_product(q, w);
-  // but in practice, we can win big with the compute_product_approximation if its additional branch
-  // is easily predicted. Which is best is data specific.
+  value128 product =
+      compute_product_approximation<binary::mantissa_explicit_bits() + 3>(q, w);
+  // The computed 'product' is always sufficient.
+  // Mathematical proof:
+  // Noble Mushtak and Daniel Lemire, Fast Number Parsing Without Fallback (to
+  // appear) See script/mushtak_lemire.py
+
+  // The "compute_product_approximation" function can be slightly slower than a
+  // branchless approach: value128 product = compute_product(q, w); but in
+  // practice, we can win big with the compute_product_approximation if its
+  // additional branch is easily predicted. Which is best is data specific.
   int upperbit = int(product.high >> 63);
+  int shift = upperbit + 64 - binary::mantissa_explicit_bits() - 3;
 
-  answer.mantissa = product.high >> (upperbit + 64 - binary::mantissa_explicit_bits() - 3);
+  answer.mantissa = product.high >> shift;
 
-  answer.power2 = int(detail::power(int(q)) + upperbit - lz - binary::minimum_exponent());
+  answer.power2 = int32_t(detail::power(int32_t(q)) + upperbit - lz -
+                          binary::minimum_exponent());
   if (answer.power2 <= 0) { // we have a subnormal?
     // Here have that answer.power2 <= 0 so -answer.power2 >= 0
-    if(-answer.power2 + 1 >= 64) { // if we have more than 64 bits below the minimum exponent, you have a zero for sure.
+    if (-answer.power2 + 1 >=
+        64) { // if we have more than 64 bits below the minimum exponent, you
+              // have a zero for sure.
       answer.power2 = 0;
       answer.mantissa = 0;
       // result should be zero
@@ -126,7 +158,8 @@ adjusted_mantissa compute_float(int64_t q, uint64_t w)  noexcept  {
     // next line is safe because -answer.power2 + 1 < 64
     answer.mantissa >>= -answer.power2 + 1;
     // Thankfully, we can't have both "round-to-even" and subnormals because
-    // "round-to-even" only occurs for powers close to 0.
+    // "round-to-even" only occurs for powers close to 0 in the 32-bit and
+    // and 64-bit case (with no more than 19 digits).
     answer.mantissa += (answer.mantissa & 1); // round up
     answer.mantissa >>= 1;
     // There is a weird scenario where we don't have a subnormal but just.
@@ -136,19 +169,25 @@ adjusted_mantissa compute_float(int64_t q, uint64_t w)  noexcept  {
     // up 0x3fffffffffffff x 2^-1023-53  and once we do, we are no longer
     // subnormal, but we can only know this after rounding.
     // So we only declare a subnormal if we are smaller than the threshold.
-    answer.power2 = (answer.mantissa < (uint64_t(1) << binary::mantissa_explicit_bits())) ? 0 : 1;
+    answer.power2 =
+        (answer.mantissa < (uint64_t(1) << binary::mantissa_explicit_bits()))
+            ? 0
+            : 1;
     return answer;
   }
 
   // usually, we round *up*, but if we fall right in between and and we have an
   // even basis, we need to round down
   // We are only concerned with the cases where 5**q fits in single 64-bit word.
-  if ((product.low <= 1) &&  (q >= binary::min_exponent_round_to_even()) && (q <= binary::max_exponent_round_to_even()) &&
-      ((answer.mantissa & 3) == 1) ) { // we may fall between two floats!
+  if ((product.low <= 1) && (q >= binary::min_exponent_round_to_even()) &&
+      (q <= binary::max_exponent_round_to_even()) &&
+      ((answer.mantissa & 3) == 1)) { // we may fall between two floats!
     // To be in-between two floats we need that in doing
-    //   answer.mantissa = product.high >> (upperbit + 64 - binary::mantissa_explicit_bits() - 3);
-    // ... we dropped out only zeroes. But if this happened, then we can go back!!!
-    if((answer.mantissa  << (upperbit + 64 - binary::mantissa_explicit_bits() - 3)) ==  product.high) {
+    //   answer.mantissa = product.high >> (upperbit + 64 -
+    //   binary::mantissa_explicit_bits() - 3);
+    // ... we dropped out only zeroes. But if this happened, then we can go
+    // back!!!
+    if ((answer.mantissa << shift) == product.high) {
       answer.mantissa &= ~uint64_t(1); // flip it so that we do not round up
     }
   }
@@ -168,7 +207,6 @@ adjusted_mantissa compute_float(int64_t q, uint64_t w)  noexcept  {
   return answer;
 }
 
-
 } // namespace fast_float
 
 #endif

include/fast_float/digit_comparison.h

@@ -0,0 +1,455 @@
+#ifndef FASTFLOAT_DIGIT_COMPARISON_H
+#define FASTFLOAT_DIGIT_COMPARISON_H
+
+#include <algorithm>
+#include <cstdint>
+#include <cstring>
+#include <iterator>
+
+#include "float_common.h"
+#include "bigint.h"
+#include "ascii_number.h"
+
+namespace fast_float {
+
+// 1e0 to 1e19
+constexpr static uint64_t powers_of_ten_uint64[] = {1UL,
+                                                    10UL,
+                                                    100UL,
+                                                    1000UL,
+                                                    10000UL,
+                                                    100000UL,
+                                                    1000000UL,
+                                                    10000000UL,
+                                                    100000000UL,
+                                                    1000000000UL,
+                                                    10000000000UL,
+                                                    100000000000UL,
+                                                    1000000000000UL,
+                                                    10000000000000UL,
+                                                    100000000000000UL,
+                                                    1000000000000000UL,
+                                                    10000000000000000UL,
+                                                    100000000000000000UL,
+                                                    1000000000000000000UL,
+                                                    10000000000000000000UL};
+
+// calculate the exponent, in scientific notation, of the number.
+// this algorithm is not even close to optimized, but it has no practical
+// effect on performance: in order to have a faster algorithm, we'd need
+// to slow down performance for faster algorithms, and this is still fast.
+fastfloat_really_inline FASTFLOAT_CONSTEXPR14 int32_t
+scientific_exponent(uint64_t mantissa, int32_t exponent) noexcept {
+  while (mantissa >= 10000) {
+    mantissa /= 10000;
+    exponent += 4;
+  }
+  while (mantissa >= 100) {
+    mantissa /= 100;
+    exponent += 2;
+  }
+  while (mantissa >= 10) {
+    mantissa /= 10;
+    exponent += 1;
+  }
+  return exponent;
+}
+
+// this converts a native floating-point number to an extended-precision float.
+template <typename T>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa
+to_extended(T value) noexcept {
+  using equiv_uint = equiv_uint_t<T>;
+  constexpr equiv_uint exponent_mask = binary_format<T>::exponent_mask();
+  constexpr equiv_uint mantissa_mask = binary_format<T>::mantissa_mask();
+  constexpr equiv_uint hidden_bit_mask = binary_format<T>::hidden_bit_mask();
+
+  adjusted_mantissa am;
+  int32_t bias = binary_format<T>::mantissa_explicit_bits() -
+                 binary_format<T>::minimum_exponent();
+  equiv_uint bits;
+#if FASTFLOAT_HAS_BIT_CAST
+  bits = std::bit_cast<equiv_uint>(value);
+#else
+  ::memcpy(&bits, &value, sizeof(T));
+#endif
+  if ((bits & exponent_mask) == 0) {
+    // denormal
+    am.power2 = 1 - bias;
+    am.mantissa = bits & mantissa_mask;
+  } else {
+    // normal
+    am.power2 = int32_t((bits & exponent_mask) >>
+                        binary_format<T>::mantissa_explicit_bits());
+    am.power2 -= bias;
+    am.mantissa = (bits & mantissa_mask) | hidden_bit_mask;
+  }
+
+  return am;
+}
+
+// get the extended precision value of the halfway point between b and b+u.
+// we are given a native float that represents b, so we need to adjust it
+// halfway between b and b+u.
+template <typename T>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa
+to_extended_halfway(T value) noexcept {
+  adjusted_mantissa am = to_extended(value);
+  am.mantissa <<= 1;
+  am.mantissa += 1;
+  am.power2 -= 1;
+  return am;
+}
+
+// round an extended-precision float to the nearest machine float.
+template <typename T, typename callback>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR14 void round(adjusted_mantissa &am,
+                                                         callback cb) noexcept {
+  int32_t mantissa_shift = 64 - binary_format<T>::mantissa_explicit_bits() - 1;
+  if (-am.power2 >= mantissa_shift) {
+    // have a denormal float
+    int32_t shift = -am.power2 + 1;
+    cb(am, std::min<int32_t>(shift, 64));
+    // check for round-up: if rounding-nearest carried us to the hidden bit.
+    am.power2 = (am.mantissa <
+                 (uint64_t(1) << binary_format<T>::mantissa_explicit_bits()))
+                    ? 0
+                    : 1;
+    return;
+  }
+
+  // have a normal float, use the default shift.
+  cb(am, mantissa_shift);
+
+  // check for carry
+  if (am.mantissa >=
+      (uint64_t(2) << binary_format<T>::mantissa_explicit_bits())) {
+    am.mantissa = (uint64_t(1) << binary_format<T>::mantissa_explicit_bits());
+    am.power2++;
+  }
+
+  // check for infinite: we could have carried to an infinite power
+  am.mantissa &= ~(uint64_t(1) << binary_format<T>::mantissa_explicit_bits());
+  if (am.power2 >= binary_format<T>::infinite_power()) {
+    am.power2 = binary_format<T>::infinite_power();
+    am.mantissa = 0;
+  }
+}
+
+template <typename callback>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR14 void
+round_nearest_tie_even(adjusted_mantissa &am, int32_t shift,
+                       callback cb) noexcept {
+  uint64_t const mask = (shift == 64) ? UINT64_MAX : (uint64_t(1) << shift) - 1;
+  uint64_t const halfway = (shift == 0) ? 0 : uint64_t(1) << (shift - 1);
+  uint64_t truncated_bits = am.mantissa & mask;
+  bool is_above = truncated_bits > halfway;
+  bool is_halfway = truncated_bits == halfway;
+
+  // shift digits into position
+  if (shift == 64) {
+    am.mantissa = 0;
+  } else {
+    am.mantissa >>= shift;
+  }
+  am.power2 += shift;
+
+  bool is_odd = (am.mantissa & 1) == 1;
+  am.mantissa += uint64_t(cb(is_odd, is_halfway, is_above));
+}
+
+fastfloat_really_inline FASTFLOAT_CONSTEXPR14 void
+round_down(adjusted_mantissa &am, int32_t shift) noexcept {
+  if (shift == 64) {
+    am.mantissa = 0;
+  } else {
+    am.mantissa >>= shift;
+  }
+  am.power2 += shift;
+}
+
+template <typename UC>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 void
+skip_zeros(UC const *&first, UC const *last) noexcept {
+  uint64_t val;
+  while (!cpp20_and_in_constexpr() &&
+         std::distance(first, last) >= int_cmp_len<UC>()) {
+    ::memcpy(&val, first, sizeof(uint64_t));
+    if (val != int_cmp_zeros<UC>()) {
+      break;
+    }
+    first += int_cmp_len<UC>();
+  }
+  while (first != last) {
+    if (*first != UC('0')) {
+      break;
+    }
+    first++;
+  }
+}
+
+// determine if any non-zero digits were truncated.
+// all characters must be valid digits.
+template <typename UC>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 bool
+is_truncated(UC const *first, UC const *last) noexcept {
+  // do 8-bit optimizations, can just compare to 8 literal 0s.
+  uint64_t val;
+  while (!cpp20_and_in_constexpr() &&
+         std::distance(first, last) >= int_cmp_len<UC>()) {
+    ::memcpy(&val, first, sizeof(uint64_t));
+    if (val != int_cmp_zeros<UC>()) {
+      return true;
+    }
+    first += int_cmp_len<UC>();
+  }
+  while (first != last) {
+    if (*first != UC('0')) {
+      return true;
+    }
+    ++first;
+  }
+  return false;
+}
+
+template <typename UC>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 bool
+is_truncated(span<UC const> s) noexcept {
+  return is_truncated(s.ptr, s.ptr + s.len());
+}
+
+template <typename UC>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 void
+parse_eight_digits(UC const *&p, limb &value, size_t &counter,
+                   size_t &count) noexcept {
+  value = value * 100000000 + parse_eight_digits_unrolled(p);
+  p += 8;
+  counter += 8;
+  count += 8;
+}
+
+template <typename UC>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR14 void
+parse_one_digit(UC const *&p, limb &value, size_t &counter,
+                size_t &count) noexcept {
+  value = value * 10 + limb(*p - UC('0'));
+  p++;
+  counter++;
+  count++;
+}
+
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 void
+add_native(bigint &big, limb power, limb value) noexcept {
+  big.mul(power);
+  big.add(value);
+}
+
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 void
+round_up_bigint(bigint &big, size_t &count) noexcept {
+  // need to round-up the digits, but need to avoid rounding
+  // ....9999 to ...10000, which could cause a false halfway point.
+  add_native(big, 10, 1);
+  count++;
+}
+
+// parse the significant digits into a big integer
+template <typename UC>
+inline FASTFLOAT_CONSTEXPR20 void
+parse_mantissa(bigint &result, parsed_number_string_t<UC> &num,
+               size_t max_digits, size_t &digits) noexcept {
+  // try to minimize the number of big integer and scalar multiplication.
+  // therefore, try to parse 8 digits at a time, and multiply by the largest
+  // scalar value (9 or 19 digits) for each step.
+  size_t counter = 0;
+  digits = 0;
+  limb value = 0;
+#ifdef FASTFLOAT_64BIT_LIMB
+  size_t step = 19;
+#else
+  size_t step = 9;
+#endif
+
+  // process all integer digits.
+  UC const *p = num.integer.ptr;
+  UC const *pend = p + num.integer.len();
+  skip_zeros(p, pend);
+  // process all digits, in increments of step per loop
+  while (p != pend) {
+    while ((std::distance(p, pend) >= 8) && (step - counter >= 8) &&
+           (max_digits - digits >= 8)) {
+      parse_eight_digits(p, value, counter, digits);
+    }
+    while (counter < step && p != pend && digits < max_digits) {
+      parse_one_digit(p, value, counter, digits);
+    }
+    if (digits == max_digits) {
+      // add the temporary value, then check if we've truncated any digits
+      add_native(result, limb(powers_of_ten_uint64[counter]), value);
+      bool truncated = is_truncated(p, pend);
+      if (num.fraction.ptr != nullptr) {
+        truncated |= is_truncated(num.fraction);
+      }
+      if (truncated) {
+        round_up_bigint(result, digits);
+      }
+      return;
+    } else {
+      add_native(result, limb(powers_of_ten_uint64[counter]), value);
+      counter = 0;
+      value = 0;
+    }
+  }
+
+  // add our fraction digits, if they're available.
+  if (num.fraction.ptr != nullptr) {
+    p = num.fraction.ptr;
+    pend = p + num.fraction.len();
+    if (digits == 0) {
+      skip_zeros(p, pend);
+    }
+    // process all digits, in increments of step per loop
+    while (p != pend) {
+      while ((std::distance(p, pend) >= 8) && (step - counter >= 8) &&
+             (max_digits - digits >= 8)) {
+        parse_eight_digits(p, value, counter, digits);
+      }
+      while (counter < step && p != pend && digits < max_digits) {
+        parse_one_digit(p, value, counter, digits);
+      }
+      if (digits == max_digits) {
+        // add the temporary value, then check if we've truncated any digits
+        add_native(result, limb(powers_of_ten_uint64[counter]), value);
+        bool truncated = is_truncated(p, pend);
+        if (truncated) {
+          round_up_bigint(result, digits);
+        }
+        return;
+      } else {
+        add_native(result, limb(powers_of_ten_uint64[counter]), value);
+        counter = 0;
+        value = 0;
+      }
+    }
+  }
+
+  if (counter != 0) {
+    add_native(result, limb(powers_of_ten_uint64[counter]), value);
+  }
+}
+
+template <typename T>
+inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa
+positive_digit_comp(bigint &bigmant, int32_t exponent) noexcept {
+  FASTFLOAT_ASSERT(bigmant.pow10(uint32_t(exponent)));
+  adjusted_mantissa answer;
+  bool truncated;
+  answer.mantissa = bigmant.hi64(truncated);
+  int bias = binary_format<T>::mantissa_explicit_bits() -
+             binary_format<T>::minimum_exponent();
+  answer.power2 = bigmant.bit_length() - 64 + bias;
+
+  round<T>(answer, [truncated](adjusted_mantissa &a, int32_t shift) {
+    round_nearest_tie_even(
+        a, shift,
+        [truncated](bool is_odd, bool is_halfway, bool is_above) -> bool {
+          return is_above || (is_halfway && truncated) ||
+                 (is_odd && is_halfway);
+        });
+  });
+
+  return answer;
+}
+
+// the scaling here is quite simple: we have, for the real digits `m * 10^e`,
+// and for the theoretical digits `n * 2^f`. Since `e` is always negative,
+// to scale them identically, we do `n * 2^f * 5^-f`, so we now have `m * 2^e`.
+// we then need to scale by `2^(f- e)`, and then the two significant digits
+// are of the same magnitude.
+template <typename T>
+inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa negative_digit_comp(
+    bigint &bigmant, adjusted_mantissa am, int32_t exponent) noexcept {
+  bigint &real_digits = bigmant;
+  int32_t real_exp = exponent;
+
+  // get the value of `b`, rounded down, and get a bigint representation of b+h
+  adjusted_mantissa am_b = am;
+  // gcc7 buf: use a lambda to remove the noexcept qualifier bug with
+  // -Wnoexcept-type.
+  round<T>(am_b,
+           [](adjusted_mantissa &a, int32_t shift) { round_down(a, shift); });
+  T b;
+  to_float(false, am_b, b);
+  adjusted_mantissa theor = to_extended_halfway(b);
+  bigint theor_digits(theor.mantissa);
+  int32_t theor_exp = theor.power2;
+
+  // scale real digits and theor digits to be same power.
+  int32_t pow2_exp = theor_exp - real_exp;
+  uint32_t pow5_exp = uint32_t(-real_exp);
+  if (pow5_exp != 0) {
+    FASTFLOAT_ASSERT(theor_digits.pow5(pow5_exp));
+  }
+  if (pow2_exp > 0) {
+    FASTFLOAT_ASSERT(theor_digits.pow2(uint32_t(pow2_exp)));
+  } else if (pow2_exp < 0) {
+    FASTFLOAT_ASSERT(real_digits.pow2(uint32_t(-pow2_exp)));
+  }
+
+  // compare digits, and use it to direct rounding
+  int ord = real_digits.compare(theor_digits);
+  adjusted_mantissa answer = am;
+  round<T>(answer, [ord](adjusted_mantissa &a, int32_t shift) {
+    round_nearest_tie_even(
+        a, shift, [ord](bool is_odd, bool _, bool __) -> bool {
+          (void)_;  // not needed, since we've done our comparison
+          (void)__; // not needed, since we've done our comparison
+          if (ord > 0) {
+            return true;
+          } else if (ord < 0) {
+            return false;
+          } else {
+            return is_odd;
+          }
+        });
+  });
+
+  return answer;
+}
+
+// parse the significant digits as a big integer to unambiguously round
+// the significant digits. here, we are trying to determine how to round
+// an extended float representation close to `b+h`, halfway between `b`
+// (the float rounded-down) and `b+u`, the next positive float. this
+// algorithm is always correct, and uses one of two approaches. when
+// the exponent is positive relative to the significant digits (such as
+// 1234), we create a big-integer representation, get the high 64-bits,
+// determine if any lower bits are truncated, and use that to direct
+// rounding. in case of a negative exponent relative to the significant
+// digits (such as 1.2345), we create a theoretical representation of
+// `b` as a big-integer type, scaled to the same binary exponent as
+// the actual digits. we then compare the big integer representations
+// of both, and use that to direct rounding.
+template <typename T, typename UC>
+inline FASTFLOAT_CONSTEXPR20 adjusted_mantissa
+digit_comp(parsed_number_string_t<UC> &num, adjusted_mantissa am) noexcept {
+  // remove the invalid exponent bias
+  am.power2 -= invalid_am_bias;
+
+  int32_t sci_exp =
+      scientific_exponent(num.mantissa, static_cast<int32_t>(num.exponent));
+  size_t max_digits = binary_format<T>::max_digits();
+  size_t digits = 0;
+  bigint bigmant;
+  parse_mantissa(bigmant, num, max_digits, digits);
+  // can't underflow, since digits is at most max_digits.
+  int32_t exponent = sci_exp + 1 - int32_t(digits);
+  if (exponent >= 0) {
+    return positive_digit_comp<T>(bigmant, exponent);
+  } else {
+    return negative_digit_comp<T>(bigmant, am, exponent);
+  }
+}
+
+} // namespace fast_float
+
+#endif

include/fast_float/fast_float.h

@@ -1,63 +1,91 @@
+
 #ifndef FASTFLOAT_FAST_FLOAT_H
 #define FASTFLOAT_FAST_FLOAT_H
 
-#include <system_error>
+#include "float_common.h"
 
 namespace fast_float {
-enum chars_format {
-    scientific = 1<<0,
-    fixed = 1<<2,
-    hex = 1<<3,
-    general = fixed | scientific
-};
-
-
-struct from_chars_result {
-  const char *ptr;
-  std::errc ec;
-};
-
-struct parse_options {
-  explicit parse_options(chars_format fmt = chars_format::general,
-                         char dot = '.')
-    : format(fmt), decimal_point(dot) {}
-
-  /** Which number formats are accepted */
-  chars_format format;
-  /** The character used as decimal point */
-  char decimal_point;
-};
-
 /**
- * This function parses the character sequence [first,last) for a number. It parses floating-point numbers expecting
- * a locale-indepent format equivalent to what is used by std::strtod in the default ("C") locale.
- * The resulting floating-point value is the closest floating-point values (using either float or double),
- * using the "round to even" convention for values that would otherwise fall right in-between two values.
- * That is, we provide exact parsing according to the IEEE standard.
+ * This function parses the character sequence [first,last) for a number. It
+ * parses floating-point numbers expecting a locale-indepent format equivalent
+ * to what is used by std::strtod in the default ("C") locale. The resulting
+ * floating-point value is the closest floating-point values (using either float
+ * or double), using the "round to even" convention for values that would
+ * otherwise fall right in-between two values. That is, we provide exact parsing
+ * according to the IEEE standard.
  *
- * Given a successful parse, the pointer (`ptr`) in the returned value is set to point right after the
- * parsed number, and the `value` referenced is set to the parsed value. In case of error, the returned
- * `ec` contains a representative error, otherwise the default (`std::errc()`) value is stored.
+ * Given a successful parse, the pointer (`ptr`) in the returned value is set to
+ * point right after the parsed number, and the `value` referenced is set to the
+ * parsed value. In case of error, the returned `ec` contains a representative
+ * error, otherwise the default (`std::errc()`) value is stored.
  *
- * The implementation does not throw and does not allocate memory (e.g., with `new` or `malloc`).
+ * The implementation does not throw and does not allocate memory (e.g., with
+ * `new` or `malloc`).
  *
- * Like the C++17 standard, the `fast_float::from_chars` functions take an optional last argument of
- * the type `fast_float::chars_format`. It is a bitset value: we check whether
- * `fmt & fast_float::chars_format::fixed` and `fmt & fast_float::chars_format::scientific` are set
- * to determine whether we allowe the fixed point and scientific notation respectively.
- * The default is  `fast_float::chars_format::general` which allows both `fixed` and `scientific`.
+ * Like the C++17 standard, the `fast_float::from_chars` functions take an
+ * optional last argument of the type `fast_float::chars_format`. It is a bitset
+ * value: we check whether `fmt & fast_float::chars_format::fixed` and `fmt &
+ * fast_float::chars_format::scientific` are set to determine whether we allow
+ * the fixed point and scientific notation respectively. The default is
+ * `fast_float::chars_format::general` which allows both `fixed` and
+ * `scientific`.
  */
-template<typename T>
-from_chars_result from_chars(const char *first, const char *last,
-                             T &value, chars_format fmt = chars_format::general)  noexcept;
+template <typename T, typename UC = char,
+          typename = FASTFLOAT_ENABLE_IF(is_supported_float_type<T>::value)>
+FASTFLOAT_CONSTEXPR20 from_chars_result_t<UC>
+from_chars(UC const *first, UC const *last, T &value,
+           chars_format fmt = chars_format::general) noexcept;
 
 /**
  * Like from_chars, but accepts an `options` argument to govern number parsing.
+ * Both for floating-point types and integer types.
  */
-template<typename T>
-from_chars_result from_chars_advanced(const char *first, const char *last,
-                                      T &value, parse_options options)  noexcept;
+template <typename T, typename UC = char>
+FASTFLOAT_CONSTEXPR20 from_chars_result_t<UC>
+from_chars_advanced(UC const *first, UC const *last, T &value,
+                    parse_options_t<UC> options) noexcept;
+
+/**
+ * This function multiplies an integer number by a power of 10 and returns
+ * the result as a double precision floating-point value that is correctly
+ * rounded. The resulting floating-point value is the closest floating-point
+ * value, using the "round to nearest, tie to even" convention for values that
+ * would otherwise fall right in-between two values. That is, we provide exact
+ * conversion according to the IEEE standard.
+ *
+ * On overflow infinity is returned, on underflow 0 is returned.
+ *
+ * The implementation does not throw and does not allocate memory (e.g., with
+ * `new` or `malloc`).
+ */
+FASTFLOAT_CONSTEXPR20 inline double
+integer_times_pow10(uint64_t mantissa, int decimal_exponent) noexcept;
+FASTFLOAT_CONSTEXPR20 inline double
+integer_times_pow10(int64_t mantissa, int decimal_exponent) noexcept;
+
+/**
+ * This function is a template overload of `integer_times_pow10()`
+ * that returns a floating-point value of type `T` that is one of
+ * supported floating-point types (e.g. `double`, `float`).
+ */
+template <typename T>
+FASTFLOAT_CONSTEXPR20
+    typename std::enable_if<is_supported_float_type<T>::value, T>::type
+    integer_times_pow10(uint64_t mantissa, int decimal_exponent) noexcept;
+template <typename T>
+FASTFLOAT_CONSTEXPR20
+    typename std::enable_if<is_supported_float_type<T>::value, T>::type
+    integer_times_pow10(int64_t mantissa, int decimal_exponent) noexcept;
+
+/**
+ * from_chars for integer types.
+ */
+template <typename T, typename UC = char,
+          typename = FASTFLOAT_ENABLE_IF(is_supported_integer_type<T>::value)>
+FASTFLOAT_CONSTEXPR20 from_chars_result_t<UC>
+from_chars(UC const *first, UC const *last, T &value, int base = 10) noexcept;
+
+} // namespace fast_float
 
-}
 #include "parse_number.h"
 #endif // FASTFLOAT_FAST_FLOAT_H

include/fast_float/parse_number.h

@@ -1,10 +1,11 @@
 #ifndef FASTFLOAT_PARSE_NUMBER_H
 #define FASTFLOAT_PARSE_NUMBER_H
+
 #include "ascii_number.h"
 #include "decimal_to_binary.h"
-#include "simple_decimal_conversion.h"
+#include "digit_comparison.h"
+#include "float_common.h"
 
-#include <cassert>
 #include <cmath>
 #include <cstring>
 #include <limits>
@@ -12,47 +13,56 @@
 
 namespace fast_float {
 
-
 namespace detail {
 /**
  * Special case +inf, -inf, nan, infinity, -infinity.
  * The case comparisons could be made much faster given that we know that the
  * strings a null-free and fixed.
  **/
-template <typename T>
-from_chars_result parse_infnan(const char *first, const char *last, T &value)  noexcept  {
-  from_chars_result answer;
+template <typename T, typename UC>
+from_chars_result_t<UC>
+    FASTFLOAT_CONSTEXPR14 parse_infnan(UC const *first, UC const *last,
+                                       T &value, chars_format fmt) noexcept {
+  from_chars_result_t<UC> answer{};
   answer.ptr = first;
   answer.ec = std::errc(); // be optimistic
-  bool minusSign = false;
-  if (*first == '-') { // assume first < last, so dereference without checks; C++17 20.19.3.(7.1) explicitly forbids '+' here
-      minusSign = true;
+  // assume first < last, so dereference without checks;
+  bool const minusSign = (*first == UC('-'));
+  // C++17 20.19.3.(7.1) explicitly forbids '+' sign here
+  if ((*first == UC('-')) ||
+      (uint64_t(fmt & chars_format::allow_leading_plus) &&
+       (*first == UC('+')))) {
     ++first;
   }
   if (last - first >= 3) {
-    if (fastfloat_strncasecmp(first, "nan", 3)) {
+    if (fastfloat_strncasecmp(first, str_const_nan<UC>(), 3)) {
       answer.ptr = (first += 3);
-      value = minusSign ? -std::numeric_limits<T>::quiet_NaN() : std::numeric_limits<T>::quiet_NaN();
-      // Check for possible nan(n-char-seq-opt), C++17 20.19.3.7, C11 7.20.1.3.3. At least MSVC produces nan(ind) and nan(snan).
-      if(first != last && *first == '(') {
-        for(const char* ptr = first + 1; ptr != last; ++ptr) {
-          if (*ptr == ')') {
+      value = minusSign ? -std::numeric_limits<T>::quiet_NaN()
+                        : std::numeric_limits<T>::quiet_NaN();
+      // Check for possible nan(n-char-seq-opt), C++17 20.19.3.7,
+      // C11 7.20.1.3.3. At least MSVC produces nan(ind) and nan(snan).
+      if (first != last && *first == UC('(')) {
+        for (UC const *ptr = first + 1; ptr != last; ++ptr) {
+          if (*ptr == UC(')')) {
             answer.ptr = ptr + 1; // valid nan(n-char-seq-opt)
             break;
-          }
-          else if(!(('a' <= *ptr && *ptr <= 'z') || ('A' <= *ptr && *ptr <= 'Z') || ('0' <= *ptr && *ptr <= '9') || *ptr == '_'))
+          } else if (!((UC('a') <= *ptr && *ptr <= UC('z')) ||
+                       (UC('A') <= *ptr && *ptr <= UC('Z')) ||
+                       (UC('0') <= *ptr && *ptr <= UC('9')) || *ptr == UC('_')))
             break; // forbidden char, not nan(n-char-seq-opt)
         }
       }
       return answer;
     }
-    if (fastfloat_strncasecmp(first, "inf", 3)) {
-      if ((last - first >= 8) && fastfloat_strncasecmp(first + 3, "inity", 5)) {
+    if (fastfloat_strncasecmp(first, str_const_inf<UC>(), 3)) {
+      if ((last - first >= 8) &&
+          fastfloat_strncasecmp(first + 3, str_const_inf<UC>() + 3, 5)) {
         answer.ptr = first + 8;
       } else {
         answer.ptr = first + 3;
       }
-      value = minusSign ? -std::numeric_limits<T>::infinity() : std::numeric_limits<T>::infinity();
+      value = minusSign ? -std::numeric_limits<T>::infinity()
+                        : std::numeric_limits<T>::infinity();
       return answer;
     }
   }
@@ -60,72 +70,416 @@ from_chars_result parse_infnan(const char *first, const char *last, T &value)  n
   return answer;
 }
 
-template<typename T>
-fastfloat_really_inline void to_float(bool negative, adjusted_mantissa am, T &value) {
-  uint64_t word = am.mantissa;
-  word |= uint64_t(am.power2) << binary_format<T>::mantissa_explicit_bits();
-  word = negative
-  ? word | (uint64_t(1) << binary_format<T>::sign_index()) : word;
-#if FASTFLOAT_IS_BIG_ENDIAN == 1
-   if (std::is_same<T, float>::value) {
-     ::memcpy(&value, (char *)&word + 4, sizeof(T)); // extract value at offset 4-7 if float on big-endian
-   } else {
-     ::memcpy(&value, &word, sizeof(T));
-   }
-#else
-   // For little-endian systems:
-   ::memcpy(&value, &word, sizeof(T));
+/**
+ * Returns true if the floating-pointing rounding mode is to 'nearest'.
+ * It is the default on most system. This function is meant to be inexpensive.
+ * Credit : @mwalcott3
+ */
+fastfloat_really_inline bool rounds_to_nearest() noexcept {
+  // https://lemire.me/blog/2020/06/26/gcc-not-nearest/
+#if (FLT_EVAL_METHOD != 1) && (FLT_EVAL_METHOD != 0)
+  return false;
+#endif
+  // See
+  // A fast function to check your floating-point rounding mode
+  // https://lemire.me/blog/2022/11/16/a-fast-function-to-check-your-floating-point-rounding-mode/
+  //
+  // This function is meant to be equivalent to :
+  // prior: #include <cfenv>
+  //  return fegetround() == FE_TONEAREST;
+  // However, it is expected to be much faster than the fegetround()
+  // function call.
+  //
+  // The volatile keyword prevents the compiler from computing the function
+  // at compile-time.
+  // There might be other ways to prevent compile-time optimizations (e.g.,
+  // asm). The value does not need to be std::numeric_limits<float>::min(), any
+  // small value so that 1 + x should round to 1 would do (after accounting for
+  // excess precision, as in 387 instructions).
+  static float volatile fmin = std::numeric_limits<float>::min();
+  float fmini = fmin; // we copy it so that it gets loaded at most once.
+//
+// Explanation:
+// Only when fegetround() == FE_TONEAREST do we have that
+// fmin + 1.0f == 1.0f - fmin.
+//
+// FE_UPWARD:
+//  fmin + 1.0f > 1
+//  1.0f - fmin == 1
+//
+// FE_DOWNWARD or  FE_TOWARDZERO:
+//  fmin + 1.0f == 1
+//  1.0f - fmin < 1
+//
+// Note: This may fail to be accurate if fast-math has been
+// enabled, as rounding conventions may not apply.
+#ifdef FASTFLOAT_VISUAL_STUDIO
+#pragma warning(push)
+//  todo: is there a VS warning?
+//  see
+//  https://stackoverflow.com/questions/46079446/is-there-a-warning-for-floating-point-equality-checking-in-visual-studio-2013
+#elif defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wfloat-equal"
+#elif defined(__GNUC__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wfloat-equal"
+#endif
+  return (fmini + 1.0f == 1.0f - fmini);
+#ifdef FASTFLOAT_VISUAL_STUDIO
+#pragma warning(pop)
+#elif defined(__clang__)
+#pragma clang diagnostic pop
+#elif defined(__GNUC__)
+#pragma GCC diagnostic pop
 #endif
 }
 
 } // namespace detail
 
+template <typename T> struct from_chars_caller {
+  template <typename UC>
+  FASTFLOAT_CONSTEXPR20 static from_chars_result_t<UC>
+  call(UC const *first, UC const *last, T &value,
+       parse_options_t<UC> options) noexcept {
+    return from_chars_advanced(first, last, value, options);
+  }
+};
 
+#ifdef __STDCPP_FLOAT32_T__
+template <> struct from_chars_caller<std::float32_t> {
+  template <typename UC>
+  FASTFLOAT_CONSTEXPR20 static from_chars_result_t<UC>
+  call(UC const *first, UC const *last, std::float32_t &value,
+       parse_options_t<UC> options) noexcept {
+    // if std::float32_t is defined, and we are in C++23 mode; macro set for
+    // float32; set value to float due to equivalence between float and
+    // float32_t
+    float val;
+    auto ret = from_chars_advanced(first, last, val, options);
+    value = val;
+    return ret;
+  }
+};
+#endif
 
-template<typename T>
-from_chars_result from_chars(const char *first, const char *last,
-                             T &value, chars_format fmt /*= chars_format::general*/)  noexcept  {
-  return from_chars_advanced(first, last, value, parse_options{fmt});
+#ifdef __STDCPP_FLOAT64_T__
+template <> struct from_chars_caller<std::float64_t> {
+  template <typename UC>
+  FASTFLOAT_CONSTEXPR20 static from_chars_result_t<UC>
+  call(UC const *first, UC const *last, std::float64_t &value,
+       parse_options_t<UC> options) noexcept {
+    // if std::float64_t is defined, and we are in C++23 mode; macro set for
+    // float64; set value as double due to equivalence between double and
+    // float64_t
+    double val;
+    auto ret = from_chars_advanced(first, last, val, options);
+    value = val;
+    return ret;
+  }
+};
+#endif
+
+template <typename T, typename UC, typename>
+FASTFLOAT_CONSTEXPR20 from_chars_result_t<UC>
+from_chars(UC const *first, UC const *last, T &value,
+           chars_format fmt /*= chars_format::general*/) noexcept {
+  return from_chars_caller<T>::call(first, last, value,
+                                    parse_options_t<UC>(fmt));
 }
 
-template<typename T>
-from_chars_result from_chars_advanced(const char *first, const char *last,
-                                      T &value, parse_options options)  noexcept  {
+template <typename T>
+fastfloat_really_inline FASTFLOAT_CONSTEXPR20 bool
+clinger_fast_path_impl(uint64_t mantissa, int64_t exponent, bool is_negative,
+                       T &value) noexcept {
+  // The implementation of the Clinger's fast path is convoluted because
+  // we want round-to-nearest in all cases, irrespective of the rounding mode
+  // selected on the thread.
+  // We proceed optimistically, assuming that detail::rounds_to_nearest()
+  // returns true.
+  if (binary_format<T>::min_exponent_fast_path() <= exponent &&
+      exponent <= binary_format<T>::max_exponent_fast_path()) {
+    // Unfortunately, the conventional Clinger's fast path is only possible
+    // when the system rounds to the nearest float.
+    //
+    // We expect the next branch to almost always be selected.
+    // We could check it first (before the previous branch), but
+    // there might be performance advantages at having the check
+    // be last.
+    if (!cpp20_and_in_constexpr() && detail::rounds_to_nearest()) {
+      // We have that fegetround() == FE_TONEAREST.
+      // Next is Clinger's fast path.
+      if (mantissa <= binary_format<T>::max_mantissa_fast_path()) {
+        value = T(mantissa);
+        if (exponent < 0) {
+          value = value / binary_format<T>::exact_power_of_ten(-exponent);
+        } else {
+          value = value * binary_format<T>::exact_power_of_ten(exponent);
+        }
+        if (is_negative) {
+          value = -value;
+        }
+        return true;
+      }
+    } else {
+      // We do not have that fegetround() == FE_TONEAREST.
+      // Next is a modified Clinger's fast path, inspired by Jakub Jelínek's
+      // proposal
+      if (exponent >= 0 &&
+          mantissa <= binary_format<T>::max_mantissa_fast_path(exponent)) {
+#if defined(__clang__) || defined(FASTFLOAT_32BIT)
+        // Clang may map 0 to -0.0 when fegetround() == FE_DOWNWARD
+        if (mantissa == 0) {
+          value = is_negative ? T(-0.) : T(0.);
+          return true;
+        }
+#endif
+        value = T(mantissa) * binary_format<T>::exact_power_of_ten(exponent);
+        if (is_negative) {
+          value = -value;
+        }
+        return true;
+      }
+    }
+  }
+  return false;
+}
 
-  static_assert (std::is_same<T, double>::value || std::is_same<T, float>::value, "only float and double are supported");
+/**
+ * This function overload takes parsed_number_string_t structure that is created
+ * and populated either by from_chars_advanced function taking chars range and
+ * parsing options or other parsing custom function implemented by user.
+ */
+template <typename T, typename UC>
+FASTFLOAT_CONSTEXPR20 from_chars_result_t<UC>
+from_chars_advanced(parsed_number_string_t<UC> &pns, T &value) noexcept {
+  static_assert(is_supported_float_type<T>::value,
+                "only some floating-point types are supported");
+  static_assert(is_supported_char_type<UC>::value,
+                "only char, wchar_t, char16_t and char32_t are supported");
 
+  from_chars_result_t<UC> answer;
 
-  from_chars_result answer;
+  answer.ec = std::errc(); // be optimistic
+  answer.ptr = pns.lastmatch;
+
+  if (!pns.too_many_digits &&
+      clinger_fast_path_impl(pns.mantissa, pns.exponent, pns.negative, value))
+    return answer;
+
+  adjusted_mantissa am =
+      compute_float<binary_format<T>>(pns.exponent, pns.mantissa);
+  if (pns.too_many_digits && am.power2 >= 0) {
+    if (am != compute_float<binary_format<T>>(pns.exponent, pns.mantissa + 1)) {
+      am = compute_error<binary_format<T>>(pns.exponent, pns.mantissa);
+    }
+  }
+  // If we called compute_float<binary_format<T>>(pns.exponent, pns.mantissa)
+  // and we have an invalid power (am.power2 < 0), then we need to go the long
+  // way around again. This is very uncommon.
+  if (am.power2 < 0) {
+    am = digit_comp<T>(pns, am);
+  }
+  to_float(pns.negative, am, value);
+  // Test for over/underflow.
+  if ((pns.mantissa != 0 && am.mantissa == 0 && am.power2 == 0) ||
+      am.power2 == binary_format<T>::infinite_power()) {
+    answer.ec = std::errc::result_out_of_range;
+  }
+  return answer;
+}
+
+template <typename T, typename UC>
+FASTFLOAT_CONSTEXPR20 from_chars_result_t<UC>
+from_chars_float_advanced(UC const *first, UC const *last, T &value,
+                          parse_options_t<UC> options) noexcept {
+
+  static_assert(is_supported_float_type<T>::value,
+                "only some floating-point types are supported");
+  static_assert(is_supported_char_type<UC>::value,
+                "only char, wchar_t, char16_t and char32_t are supported");
+
+  chars_format const fmt = detail::adjust_for_feature_macros(options.format);
+
+  from_chars_result_t<UC> answer;
+  if (uint64_t(fmt & chars_format::skip_white_space)) {
+    while ((first != last) && fast_float::is_space(*first)) {
+      first++;
+    }
+  }
   if (first == last) {
     answer.ec = std::errc::invalid_argument;
     answer.ptr = first;
     return answer;
   }
-  parsed_number_string pns = parse_number_string(first, last, options);
+  parsed_number_string_t<UC> pns =
+      uint64_t(fmt & detail::basic_json_fmt)
+          ? parse_number_string<true, UC>(first, last, options)
+          : parse_number_string<false, UC>(first, last, options);
   if (!pns.valid) {
-    return detail::parse_infnan(first, last, value);
+    if (uint64_t(fmt & chars_format::no_infnan)) {
+      answer.ec = std::errc::invalid_argument;
+      answer.ptr = first;
+      return answer;
+    } else {
+      return detail::parse_infnan(first, last, value, fmt);
     }
-  answer.ec = std::errc(); // be optimistic
-  answer.ptr = pns.lastmatch;
-  // Next is Clinger's fast path.
-  if (binary_format<T>::min_exponent_fast_path() <= pns.exponent && pns.exponent <= binary_format<T>::max_exponent_fast_path() && pns.mantissa <=binary_format<T>::max_mantissa_fast_path() && !pns.too_many_digits) {
-    value = T(pns.mantissa);
-    if (pns.exponent < 0) { value = value / binary_format<T>::exact_power_of_ten(-pns.exponent); }
-    else { value = value * binary_format<T>::exact_power_of_ten(pns.exponent); }
-    if (pns.negative) { value = -value; }
+  }
+
+  // call overload that takes parsed_number_string_t directly.
+  return from_chars_advanced(pns, value);
+}
+
+template <typename T, typename UC, typename>
+FASTFLOAT_CONSTEXPR20 from_chars_result_t<UC>
+from_chars(UC const *first, UC const *last, T &value, int base) noexcept {
+
+  static_assert(is_supported_integer_type<T>::value,
+                "only integer types are supported");
+  static_assert(is_supported_char_type<UC>::value,
+                "only char, wchar_t, char16_t and char32_t are supported");
+
+  parse_options_t<UC> options;
+  options.base = base;
+  return from_chars_advanced(first, last, value, options);
+}
+
+template <typename T>
+FASTFLOAT_CONSTEXPR20
+    typename std::enable_if<is_supported_float_type<T>::value, T>::type
+    integer_times_pow10(uint64_t mantissa, int decimal_exponent) noexcept {
+  T value;
+  if (clinger_fast_path_impl(mantissa, decimal_exponent, false, value))
+    return value;
+
+  adjusted_mantissa am =
+      compute_float<binary_format<T>>(decimal_exponent, mantissa);
+  to_float(false, am, value);
+  return value;
+}
+
+template <typename T>
+FASTFLOAT_CONSTEXPR20
+    typename std::enable_if<is_supported_float_type<T>::value, T>::type
+    integer_times_pow10(int64_t mantissa, int decimal_exponent) noexcept {
+  const bool is_negative = mantissa < 0;
+  const uint64_t m = static_cast<uint64_t>(is_negative ? -mantissa : mantissa);
+
+  T value;
+  if (clinger_fast_path_impl(m, decimal_exponent, is_negative, value))
+    return value;
+
+  adjusted_mantissa am = compute_float<binary_format<T>>(decimal_exponent, m);
+  to_float(is_negative, am, value);
+  return value;
+}
+
+FASTFLOAT_CONSTEXPR20 inline double
+integer_times_pow10(uint64_t mantissa, int decimal_exponent) noexcept {
+  return integer_times_pow10<double>(mantissa, decimal_exponent);
+}
+
+FASTFLOAT_CONSTEXPR20 inline double
+integer_times_pow10(int64_t mantissa, int decimal_exponent) noexcept {
+  return integer_times_pow10<double>(mantissa, decimal_exponent);
+}
+
+// the following overloads are here to avoid surprising ambiguity for int,
+// unsigned, etc.
+template <typename T, typename Int>
+FASTFLOAT_CONSTEXPR20
+    typename std::enable_if<is_supported_float_type<T>::value &&
+                                std::is_integral<Int>::value &&
+                                !std::is_signed<Int>::value,
+                            T>::type
+    integer_times_pow10(Int mantissa, int decimal_exponent) noexcept {
+  return integer_times_pow10<T>(static_cast<uint64_t>(mantissa),
+                                decimal_exponent);
+}
+
+template <typename T, typename Int>
+FASTFLOAT_CONSTEXPR20
+    typename std::enable_if<is_supported_float_type<T>::value &&
+                                std::is_integral<Int>::value &&
+                                std::is_signed<Int>::value,
+                            T>::type
+    integer_times_pow10(Int mantissa, int decimal_exponent) noexcept {
+  return integer_times_pow10<T>(static_cast<int64_t>(mantissa),
+                                decimal_exponent);
+}
+
+template <typename Int>
+FASTFLOAT_CONSTEXPR20 typename std::enable_if<
+    std::is_integral<Int>::value && !std::is_signed<Int>::value, double>::type
+integer_times_pow10(Int mantissa, int decimal_exponent) noexcept {
+  return integer_times_pow10(static_cast<uint64_t>(mantissa), decimal_exponent);
+}
+
+template <typename Int>
+FASTFLOAT_CONSTEXPR20 typename std::enable_if<
+    std::is_integral<Int>::value && std::is_signed<Int>::value, double>::type
+integer_times_pow10(Int mantissa, int decimal_exponent) noexcept {
+  return integer_times_pow10(static_cast<int64_t>(mantissa), decimal_exponent);
+}
+
+template <typename T, typename UC>
+FASTFLOAT_CONSTEXPR20 from_chars_result_t<UC>
+from_chars_int_advanced(UC const *first, UC const *last, T &value,
+                        parse_options_t<UC> options) noexcept {
+
+  static_assert(is_supported_integer_type<T>::value,
+                "only integer types are supported");
+  static_assert(is_supported_char_type<UC>::value,
+                "only char, wchar_t, char16_t and char32_t are supported");
+
+  chars_format const fmt = detail::adjust_for_feature_macros(options.format);
+  int const base = options.base;
+
+  from_chars_result_t<UC> answer;
+  if (uint64_t(fmt & chars_format::skip_white_space)) {
+    while ((first != last) && fast_float::is_space(*first)) {
+      first++;
+    }
+  }
+  if (first == last || base < 2 || base > 36) {
+    answer.ec = std::errc::invalid_argument;
+    answer.ptr = first;
     return answer;
   }
-  adjusted_mantissa am = compute_float<binary_format<T>>(pns.exponent, pns.mantissa);
-  if(pns.too_many_digits) {
-    if(am != compute_float<binary_format<T>>(pns.exponent, pns.mantissa + 1)) {
-      am.power2 = -1; // value is invalid.
+
+  return parse_int_string(first, last, value, options);
+}
+
+template <size_t TypeIx> struct from_chars_advanced_caller {
+  static_assert(TypeIx > 0, "unsupported type");
+};
+
+template <> struct from_chars_advanced_caller<1> {
+  template <typename T, typename UC>
+  FASTFLOAT_CONSTEXPR20 static from_chars_result_t<UC>
+  call(UC const *first, UC const *last, T &value,
+       parse_options_t<UC> options) noexcept {
+    return from_chars_float_advanced(first, last, value, options);
   }
+};
+
+template <> struct from_chars_advanced_caller<2> {
+  template <typename T, typename UC>
+  FASTFLOAT_CONSTEXPR20 static from_chars_result_t<UC>
+  call(UC const *first, UC const *last, T &value,
+       parse_options_t<UC> options) noexcept {
+    return from_chars_int_advanced(first, last, value, options);
   }
-  // If we called compute_float<binary_format<T>>(pns.exponent, pns.mantissa) and we have an invalid power (am.power2 < 0),
-  // then we need to go the long way around again. This is very uncommon.
-  if(am.power2 < 0) { am = parse_long_mantissa<binary_format<T>>(first, last, options); }
-  detail::to_float(pns.negative, am, value);
-  return answer;
+};
+
+template <typename T, typename UC>
+FASTFLOAT_CONSTEXPR20 from_chars_result_t<UC>
+from_chars_advanced(UC const *first, UC const *last, T &value,
+                    parse_options_t<UC> options) noexcept {
+  return from_chars_advanced_caller<
+      size_t(is_supported_float_type<T>::value) +
+      2 * size_t(is_supported_integer_type<T>::value)>::call(first, last, value,
+                                                             options);
 }
 
 } // namespace fast_float

include/fast_float/simple_decimal_conversion.h

@@ -1,360 +0,0 @@
-#ifndef FASTFLOAT_GENERIC_DECIMAL_TO_BINARY_H
-#define FASTFLOAT_GENERIC_DECIMAL_TO_BINARY_H
-
-/**
- * This code is meant to handle the case where we have more than 19 digits.
- *
- * It is based on work by Nigel Tao (at https://github.com/google/wuffs/)
- * who credits Ken Thompson for the design (via a reference to the Go source
- * code).
- *
- * Rob Pike suggested that this algorithm be called "Simple Decimal Conversion".
- *
- * It is probably not very fast but it is a fallback that should almost never
- * be used in real life. Though it is not fast, it is "easily" understood and debugged.
- **/
-#include "ascii_number.h"
-#include "decimal_to_binary.h"
-#include <cstdint>
-
-namespace fast_float {
-
-namespace detail {
-
-// remove all final zeroes
-inline void trim(decimal &h) {
-  while ((h.num_digits > 0) && (h.digits[h.num_digits - 1] == 0)) {
-    h.num_digits--;
-  }
-}
-
-
-
-inline uint32_t number_of_digits_decimal_left_shift(const decimal &h, uint32_t shift) {
-  shift &= 63;
-  const static uint16_t number_of_digits_decimal_left_shift_table[65] = {
-    0x0000, 0x0800, 0x0801, 0x0803, 0x1006, 0x1009, 0x100D, 0x1812, 0x1817,
-    0x181D, 0x2024, 0x202B, 0x2033, 0x203C, 0x2846, 0x2850, 0x285B, 0x3067,
-    0x3073, 0x3080, 0x388E, 0x389C, 0x38AB, 0x38BB, 0x40CC, 0x40DD, 0x40EF,
-    0x4902, 0x4915, 0x4929, 0x513E, 0x5153, 0x5169, 0x5180, 0x5998, 0x59B0,
-    0x59C9, 0x61E3, 0x61FD, 0x6218, 0x6A34, 0x6A50, 0x6A6D, 0x6A8B, 0x72AA,
-    0x72C9, 0x72E9, 0x7B0A, 0x7B2B, 0x7B4D, 0x8370, 0x8393, 0x83B7, 0x83DC,
-    0x8C02, 0x8C28, 0x8C4F, 0x9477, 0x949F, 0x94C8, 0x9CF2, 0x051C, 0x051C,
-    0x051C, 0x051C,
-  };
-  uint32_t x_a = number_of_digits_decimal_left_shift_table[shift];
-  uint32_t x_b = number_of_digits_decimal_left_shift_table[shift + 1];
-  uint32_t num_new_digits = x_a >> 11;
-  uint32_t pow5_a = 0x7FF & x_a;
-  uint32_t pow5_b = 0x7FF & x_b;
-  const static uint8_t
-    number_of_digits_decimal_left_shift_table_powers_of_5[0x051C] = {
-        5, 2, 5, 1, 2, 5, 6, 2, 5, 3, 1, 2, 5, 1, 5, 6, 2, 5, 7, 8, 1, 2, 5, 3,
-        9, 0, 6, 2, 5, 1, 9, 5, 3, 1, 2, 5, 9, 7, 6, 5, 6, 2, 5, 4, 8, 8, 2, 8,
-        1, 2, 5, 2, 4, 4, 1, 4, 0, 6, 2, 5, 1, 2, 2, 0, 7, 0, 3, 1, 2, 5, 6, 1,
-        0, 3, 5, 1, 5, 6, 2, 5, 3, 0, 5, 1, 7, 5, 7, 8, 1, 2, 5, 1, 5, 2, 5, 8,
-        7, 8, 9, 0, 6, 2, 5, 7, 6, 2, 9, 3, 9, 4, 5, 3, 1, 2, 5, 3, 8, 1, 4, 6,
-        9, 7, 2, 6, 5, 6, 2, 5, 1, 9, 0, 7, 3, 4, 8, 6, 3, 2, 8, 1, 2, 5, 9, 5,
-        3, 6, 7, 4, 3, 1, 6, 4, 0, 6, 2, 5, 4, 7, 6, 8, 3, 7, 1, 5, 8, 2, 0, 3,
-        1, 2, 5, 2, 3, 8, 4, 1, 8, 5, 7, 9, 1, 0, 1, 5, 6, 2, 5, 1, 1, 9, 2, 0,
-        9, 2, 8, 9, 5, 5, 0, 7, 8, 1, 2, 5, 5, 9, 6, 0, 4, 6, 4, 4, 7, 7, 5, 3,
-        9, 0, 6, 2, 5, 2, 9, 8, 0, 2, 3, 2, 2, 3, 8, 7, 6, 9, 5, 3, 1, 2, 5, 1,
-        4, 9, 0, 1, 1, 6, 1, 1, 9, 3, 8, 4, 7, 6, 5, 6, 2, 5, 7, 4, 5, 0, 5, 8,
-        0, 5, 9, 6, 9, 2, 3, 8, 2, 8, 1, 2, 5, 3, 7, 2, 5, 2, 9, 0, 2, 9, 8, 4,
-        6, 1, 9, 1, 4, 0, 6, 2, 5, 1, 8, 6, 2, 6, 4, 5, 1, 4, 9, 2, 3, 0, 9, 5,
-        7, 0, 3, 1, 2, 5, 9, 3, 1, 3, 2, 2, 5, 7, 4, 6, 1, 5, 4, 7, 8, 5, 1, 5,
-        6, 2, 5, 4, 6, 5, 6, 6, 1, 2, 8, 7, 3, 0, 7, 7, 3, 9, 2, 5, 7, 8, 1, 2,
-        5, 2, 3, 2, 8, 3, 0, 6, 4, 3, 6, 5, 3, 8, 6, 9, 6, 2, 8, 9, 0, 6, 2, 5,
-        1, 1, 6, 4, 1, 5, 3, 2, 1, 8, 2, 6, 9, 3, 4, 8, 1, 4, 4, 5, 3, 1, 2, 5,
-        5, 8, 2, 0, 7, 6, 6, 0, 9, 1, 3, 4, 6, 7, 4, 0, 7, 2, 2, 6, 5, 6, 2, 5,
-        2, 9, 1, 0, 3, 8, 3, 0, 4, 5, 6, 7, 3, 3, 7, 0, 3, 6, 1, 3, 2, 8, 1, 2,
-        5, 1, 4, 5, 5, 1, 9, 1, 5, 2, 2, 8, 3, 6, 6, 8, 5, 1, 8, 0, 6, 6, 4, 0,
-        6, 2, 5, 7, 2, 7, 5, 9, 5, 7, 6, 1, 4, 1, 8, 3, 4, 2, 5, 9, 0, 3, 3, 2,
-        0, 3, 1, 2, 5, 3, 6, 3, 7, 9, 7, 8, 8, 0, 7, 0, 9, 1, 7, 1, 2, 9, 5, 1,
-        6, 6, 0, 1, 5, 6, 2, 5, 1, 8, 1, 8, 9, 8, 9, 4, 0, 3, 5, 4, 5, 8, 5, 6,
-        4, 7, 5, 8, 3, 0, 0, 7, 8, 1, 2, 5, 9, 0, 9, 4, 9, 4, 7, 0, 1, 7, 7, 2,
-        9, 2, 8, 2, 3, 7, 9, 1, 5, 0, 3, 9, 0, 6, 2, 5, 4, 5, 4, 7, 4, 7, 3, 5,
-        0, 8, 8, 6, 4, 6, 4, 1, 1, 8, 9, 5, 7, 5, 1, 9, 5, 3, 1, 2, 5, 2, 2, 7,
-        3, 7, 3, 6, 7, 5, 4, 4, 3, 2, 3, 2, 0, 5, 9, 4, 7, 8, 7, 5, 9, 7, 6, 5,
-        6, 2, 5, 1, 1, 3, 6, 8, 6, 8, 3, 7, 7, 2, 1, 6, 1, 6, 0, 2, 9, 7, 3, 9,
-        3, 7, 9, 8, 8, 2, 8, 1, 2, 5, 5, 6, 8, 4, 3, 4, 1, 8, 8, 6, 0, 8, 0, 8,
-        0, 1, 4, 8, 6, 9, 6, 8, 9, 9, 4, 1, 4, 0, 6, 2, 5, 2, 8, 4, 2, 1, 7, 0,
-        9, 4, 3, 0, 4, 0, 4, 0, 0, 7, 4, 3, 4, 8, 4, 4, 9, 7, 0, 7, 0, 3, 1, 2,
-        5, 1, 4, 2, 1, 0, 8, 5, 4, 7, 1, 5, 2, 0, 2, 0, 0, 3, 7, 1, 7, 4, 2, 2,
-        4, 8, 5, 3, 5, 1, 5, 6, 2, 5, 7, 1, 0, 5, 4, 2, 7, 3, 5, 7, 6, 0, 1, 0,
-        0, 1, 8, 5, 8, 7, 1, 1, 2, 4, 2, 6, 7, 5, 7, 8, 1, 2, 5, 3, 5, 5, 2, 7,
-        1, 3, 6, 7, 8, 8, 0, 0, 5, 0, 0, 9, 2, 9, 3, 5, 5, 6, 2, 1, 3, 3, 7, 8,
-        9, 0, 6, 2, 5, 1, 7, 7, 6, 3, 5, 6, 8, 3, 9, 4, 0, 0, 2, 5, 0, 4, 6, 4,
-        6, 7, 7, 8, 1, 0, 6, 6, 8, 9, 4, 5, 3, 1, 2, 5, 8, 8, 8, 1, 7, 8, 4, 1,
-        9, 7, 0, 0, 1, 2, 5, 2, 3, 2, 3, 3, 8, 9, 0, 5, 3, 3, 4, 4, 7, 2, 6, 5,
-        6, 2, 5, 4, 4, 4, 0, 8, 9, 2, 0, 9, 8, 5, 0, 0, 6, 2, 6, 1, 6, 1, 6, 9,
-        4, 5, 2, 6, 6, 7, 2, 3, 6, 3, 2, 8, 1, 2, 5, 2, 2, 2, 0, 4, 4, 6, 0, 4,
-        9, 2, 5, 0, 3, 1, 3, 0, 8, 0, 8, 4, 7, 2, 6, 3, 3, 3, 6, 1, 8, 1, 6, 4,
-        0, 6, 2, 5, 1, 1, 1, 0, 2, 2, 3, 0, 2, 4, 6, 2, 5, 1, 5, 6, 5, 4, 0, 4,
-        2, 3, 6, 3, 1, 6, 6, 8, 0, 9, 0, 8, 2, 0, 3, 1, 2, 5, 5, 5, 5, 1, 1, 1,
-        5, 1, 2, 3, 1, 2, 5, 7, 8, 2, 7, 0, 2, 1, 1, 8, 1, 5, 8, 3, 4, 0, 4, 5,
-        4, 1, 0, 1, 5, 6, 2, 5, 2, 7, 7, 5, 5, 5, 7, 5, 6, 1, 5, 6, 2, 8, 9, 1,
-        3, 5, 1, 0, 5, 9, 0, 7, 9, 1, 7, 0, 2, 2, 7, 0, 5, 0, 7, 8, 1, 2, 5, 1,
-        3, 8, 7, 7, 7, 8, 7, 8, 0, 7, 8, 1, 4, 4, 5, 6, 7, 5, 5, 2, 9, 5, 3, 9,
-        5, 8, 5, 1, 1, 3, 5, 2, 5, 3, 9, 0, 6, 2, 5, 6, 9, 3, 8, 8, 9, 3, 9, 0,
-        3, 9, 0, 7, 2, 2, 8, 3, 7, 7, 6, 4, 7, 6, 9, 7, 9, 2, 5, 5, 6, 7, 6, 2,
-        6, 9, 5, 3, 1, 2, 5, 3, 4, 6, 9, 4, 4, 6, 9, 5, 1, 9, 5, 3, 6, 1, 4, 1,
-        8, 8, 8, 2, 3, 8, 4, 8, 9, 6, 2, 7, 8, 3, 8, 1, 3, 4, 7, 6, 5, 6, 2, 5,
-        1, 7, 3, 4, 7, 2, 3, 4, 7, 5, 9, 7, 6, 8, 0, 7, 0, 9, 4, 4, 1, 1, 9, 2,
-        4, 4, 8, 1, 3, 9, 1, 9, 0, 6, 7, 3, 8, 2, 8, 1, 2, 5, 8, 6, 7, 3, 6, 1,
-        7, 3, 7, 9, 8, 8, 4, 0, 3, 5, 4, 7, 2, 0, 5, 9, 6, 2, 2, 4, 0, 6, 9, 5,
-        9, 5, 3, 3, 6, 9, 1, 4, 0, 6, 2, 5,
-  };
-  const uint8_t *pow5 =
-      &number_of_digits_decimal_left_shift_table_powers_of_5[pow5_a];
-  uint32_t i = 0;
-  uint32_t n = pow5_b - pow5_a;
-  for (; i < n; i++) {
-    if (i >= h.num_digits) {
-      return num_new_digits - 1;
-    } else if (h.digits[i] == pow5[i]) {
-      continue;
-    } else if (h.digits[i] < pow5[i]) {
-      return num_new_digits - 1;
-    } else {
-      return num_new_digits;
-    }
-  }
-  return num_new_digits;
-}
-
-inline uint64_t round(decimal &h) {
-  if ((h.num_digits == 0) || (h.decimal_point < 0)) {
-    return 0;
-  } else if (h.decimal_point > 18) {
-    return UINT64_MAX;
-  }
-  // at this point, we know that h.decimal_point >= 0
-  uint32_t dp = uint32_t(h.decimal_point);
-  uint64_t n = 0;
-  for (uint32_t i = 0; i < dp; i++) {
-    n = (10 * n) + ((i < h.num_digits) ? h.digits[i] : 0);
-  }
-  bool round_up = false;
-  if (dp < h.num_digits) {
-    round_up = h.digits[dp] >= 5; // normally, we round up  
-    // but we may need to round to even!
-    if ((h.digits[dp] == 5) && (dp + 1 == h.num_digits)) {
-      round_up = h.truncated || ((dp > 0) && (1 & h.digits[dp - 1]));
-    }
-  }
-  if (round_up) {
-    n++;
-  }
-  return n;
-}
-
-// computes h * 2^-shift
-inline void decimal_left_shift(decimal &h, uint32_t shift) {
-  if (h.num_digits == 0) {
-    return;
-  }
-  uint32_t num_new_digits = number_of_digits_decimal_left_shift(h, shift);
-  int32_t read_index = int32_t(h.num_digits - 1);
-  uint32_t write_index = h.num_digits - 1 + num_new_digits;
-  uint64_t n = 0;
-
-  while (read_index >= 0) {
-    n += uint64_t(h.digits[read_index]) << shift;
-    uint64_t quotient = n / 10;
-    uint64_t remainder = n - (10 * quotient);
-    if (write_index < max_digits) {
-      h.digits[write_index] = uint8_t(remainder);
-    } else if (remainder > 0) {
-      h.truncated = true;
-    }
-    n = quotient;
-    write_index--;
-    read_index--;
-  }
-  while (n > 0) {
-    uint64_t quotient = n / 10;
-    uint64_t remainder = n - (10 * quotient);
-    if (write_index < max_digits) {
-      h.digits[write_index] = uint8_t(remainder);
-    } else if (remainder > 0) {
-      h.truncated = true;
-    }
-    n = quotient;
-    write_index--;
-  }
-  h.num_digits += num_new_digits;
-  if (h.num_digits > max_digits) {
-    h.num_digits = max_digits;
-  }
-  h.decimal_point += int32_t(num_new_digits);
-  trim(h);
-}
-
-// computes h * 2^shift
-inline void decimal_right_shift(decimal &h, uint32_t shift) {
-  uint32_t read_index = 0;
-  uint32_t write_index = 0;
-
-  uint64_t n = 0;
-
-  while ((n >> shift) == 0) {
-    if (read_index < h.num_digits) {
-      n = (10 * n) + h.digits[read_index++];
-    } else if (n == 0) {
-      return;
-    } else {
-      while ((n >> shift) == 0) {
-        n = 10 * n;
-        read_index++;
-      }
-      break;
-    }
-  }
-  h.decimal_point -= int32_t(read_index - 1);
-  if (h.decimal_point < -decimal_point_range) { // it is zero
-    h.num_digits = 0;
-    h.decimal_point = 0;
-    h.negative = false;
-    h.truncated = false;
-    return;
-  }
-  uint64_t mask = (uint64_t(1) << shift) - 1;
-  while (read_index < h.num_digits) {
-    uint8_t new_digit = uint8_t(n >> shift);
-    n = (10 * (n & mask)) + h.digits[read_index++];
-    h.digits[write_index++] = new_digit;
-  }
-  while (n > 0) {
-    uint8_t new_digit = uint8_t(n >> shift);
-    n = 10 * (n & mask);
-    if (write_index < max_digits) {
-      h.digits[write_index++] = new_digit;
-    } else if (new_digit > 0) {
-      h.truncated = true;
-    }
-  }
-  h.num_digits = write_index;
-  trim(h);
-}
-
-} // namespace detail
-
-template <typename binary>
-adjusted_mantissa compute_float(decimal &d) {
-  adjusted_mantissa answer;
-  if (d.num_digits == 0) {
-    // should be zero
-    answer.power2 = 0;
-    answer.mantissa = 0;
-    return answer;
-  }
-  // At this point, going further, we can assume that d.num_digits > 0.
-  //
-  // We want to guard against excessive decimal point values because
-  // they can result in long running times. Indeed, we do
-  // shifts by at most 60 bits. We have that log(10**400)/log(2**60) ~= 22
-  // which is fine, but log(10**299995)/log(2**60) ~= 16609 which is not
-  // fine (runs for a long time).
-  //
-  if(d.decimal_point < -324) {
-    // We have something smaller than 1e-324 which is always zero
-    // in binary64 and binary32.
-    // It should be zero.
-    answer.power2 = 0;
-    answer.mantissa = 0;
-    return answer;
-  } else if(d.decimal_point >= 310) {
-    // We have something at least as large as 0.1e310 which is
-    // always infinite.  
-    answer.power2 = binary::infinite_power();
-    answer.mantissa = 0;
-    return answer;
-  }
-  static const uint32_t max_shift = 60;
-  static const uint32_t num_powers = 19;
-  static const uint8_t decimal_powers[19] = {
-      0,  3,  6,  9,  13, 16, 19, 23, 26, 29, //
-      33, 36, 39, 43, 46, 49, 53, 56, 59,     //
-  };
-  int32_t exp2 = 0;
-  while (d.decimal_point > 0) {
-    uint32_t n = uint32_t(d.decimal_point);
-    uint32_t shift = (n < num_powers) ? decimal_powers[n] : max_shift;
-    detail::decimal_right_shift(d, shift);
-    if (d.decimal_point < -decimal_point_range) {
-      // should be zero
-      answer.power2 = 0;
-      answer.mantissa = 0;
-      return answer;
-    }
-    exp2 += int32_t(shift);
-  }
-  // We shift left toward [1/2 ... 1].
-  while (d.decimal_point <= 0) {
-    uint32_t shift;
-    if (d.decimal_point == 0) {
-      if (d.digits[0] >= 5) {
-        break;
-      }
-      shift = (d.digits[0] < 2) ? 2 : 1;
-    } else {
-      uint32_t n = uint32_t(-d.decimal_point);
-      shift = (n < num_powers) ? decimal_powers[n] : max_shift;
-    }
-    detail::decimal_left_shift(d, shift);
-    if (d.decimal_point > decimal_point_range) {
-      // we want to get infinity:
-      answer.power2 = binary::infinite_power();
-      answer.mantissa = 0;
-      return answer;
-    }
-    exp2 -= int32_t(shift);
-  }
-  // We are now in the range [1/2 ... 1] but the binary format uses [1 ... 2].
-  exp2--;
-  constexpr int32_t minimum_exponent = binary::minimum_exponent();
-  while ((minimum_exponent + 1) > exp2) {
-    uint32_t n = uint32_t((minimum_exponent + 1) - exp2);
-    if (n > max_shift) {
-      n = max_shift;
-    }
-    detail::decimal_right_shift(d, n);
-    exp2 += int32_t(n);
-  }
-  if ((exp2 - minimum_exponent) >= binary::infinite_power()) {
-    answer.power2 = binary::infinite_power();
-    answer.mantissa = 0;
-    return answer;
-  }
-
-  const int mantissa_size_in_bits = binary::mantissa_explicit_bits() + 1;
-  detail::decimal_left_shift(d, mantissa_size_in_bits);
-
-  uint64_t mantissa = detail::round(d);
-  // It is possible that we have an overflow, in which case we need
-  // to shift back.
-  if(mantissa >= (uint64_t(1) << mantissa_size_in_bits)) {
-    detail::decimal_right_shift(d, 1);
-    exp2 += 1;
-    mantissa = detail::round(d);
-    if ((exp2 - minimum_exponent) >= binary::infinite_power()) {
-      answer.power2 = binary::infinite_power();
-      answer.mantissa = 0;
-      return answer;
-    }
-  }
-  answer.power2 = exp2  - binary::minimum_exponent();
-  if(mantissa < (uint64_t(1) << binary::mantissa_explicit_bits())) { answer.power2--; }
-  answer.mantissa = mantissa & ((uint64_t(1) << binary::mantissa_explicit_bits()) - 1);
-  return answer;
-}
-
-template <typename binary>
-adjusted_mantissa parse_long_mantissa(const char *first, const char* last, parse_options options) {
-    decimal d = parse_decimal(first, last, options);
-    return compute_float<binary>(d);
-}
-
-} // namespace fast_float
-#endif

script/amalgamate.py

@@ -1,56 +1,122 @@
 # text parts
-processed_files = { }
+processed_files = {}
 
 # authors
-for filename in ['AUTHORS', 'CONTRIBUTORS']:
-  with open(filename) as f:
-    text = ''
+for filename in ["AUTHORS", "CONTRIBUTORS"]:
+    with open(filename, encoding="utf8") as f:
+        text = ""
         for line in f:
-      if filename == 'AUTHORS':
-        text += '// fast_float by ' + line
-      if filename == 'CONTRIBUTORS':
-        text += '// with contributions from ' + line
-    processed_files[filename] = text
+            if filename == "AUTHORS":
+                text += "// fast_float by " + line
+            if filename == "CONTRIBUTORS":
+                text += "// with contributions from " + line
+        processed_files[filename] = text + "//\n//\n"
 
 # licenses
-for filename in ['LICENSE-MIT', 'LICENSE-APACHE']:
-  with open(filename) as f:
-    text = ''
-    for line in f:
-      text += '// ' + line
+for filename in ["LICENSE-MIT", "LICENSE-APACHE", "LICENSE-BOOST"]:
+    lines = []
+    with open(filename, encoding="utf8") as f:
+        lines = f.readlines()
+
+    # Retrieve subset required for inclusion in source
+    if filename == "LICENSE-APACHE":
+        lines = ["   Copyright 2021 The fast_float authors\n", *lines[179:-1]]
+
+    text = ""
+    for line in lines:
+        line = line.strip()
+        if len(line):
+            line = "    " + line
+        text += "//" + line + "\n"
     processed_files[filename] = text
 
 # code
-for filename in [ 'fast_float.h', 'float_common.h', 'ascii_number.h', 
-                  'fast_table.h', 'decimal_to_binary.h', 'ascii_number.h', 
-                  'simple_decimal_conversion.h', 'parse_number.h']:
-  with open('include/fast_float/' + filename) as f:
-    text = ''
+for filename in [
+    "constexpr_feature_detect.h",
+    "float_common.h",
+    "fast_float.h",
+    "ascii_number.h",
+    "fast_table.h",
+    "decimal_to_binary.h",
+    "bigint.h",
+    "digit_comparison.h",
+    "parse_number.h",
+]:
+    with open("include/fast_float/" + filename, encoding="utf8") as f:
+        text = ""
         for line in f:
-      if line.startswith('#include "'): continue
+            if line.startswith('#include "'):
+                continue
             text += line
-    processed_files[filename] = text
+        processed_files[filename] = "\n" + text
 
 # command line
 import argparse
 
-parser = argparse.ArgumentParser(description='Amalgamate fast_float.')
-parser.add_argument('--license', default='MIT', help='choose license')
-parser.add_argument('--output', default='', help='output file (stdout if none')
+parser = argparse.ArgumentParser(description="Amalgamate fast_float.")
+parser.add_argument(
+    "--license",
+    default="TRIPLE",
+    choices=["DUAL", "TRIPLE", "MIT", "APACHE", "BOOST"],
+    help="choose license",
+)
+parser.add_argument("--output", default="", help="output file (stdout if none")
 
 args = parser.parse_args()
 
-text = '\n\n'.join([
-  processed_files['AUTHORS'], processed_files['CONTRIBUTORS'], 
-  processed_files['LICENSE-' + args.license],
-  processed_files['fast_float.h'], processed_files['float_common.h'], 
-  processed_files['ascii_number.h'], processed_files['fast_table.h'],
-  processed_files['decimal_to_binary.h'], processed_files['ascii_number.h'],
-  processed_files['simple_decimal_conversion.h'],
-  processed_files['parse_number.h']])
+
+def license_content(license_arg):
+    result = []
+    if license_arg == "TRIPLE":
+        result += [
+            "// Licensed under the Apache License, Version 2.0, or the\n",
+            "// MIT License or the Boost License. This file may not be copied,\n",
+            "// modified, or distributed except according to those terms.\n",
+            "//\n",
+        ]
+    if license_arg == "DUAL":
+        result += [
+            "// Licensed under the Apache License, Version 2.0, or the\n",
+            "// MIT License at your option. This file may not be copied,\n",
+            "// modified, or distributed except according to those terms.\n",
+            "//\n",
+        ]
+
+    if license_arg in ("DUAL", "TRIPLE", "MIT"):
+        result.append("// MIT License Notice\n//\n")
+        result.append(processed_files["LICENSE-MIT"])
+        result.append("//\n")
+    if license_arg in ("DUAL", "TRIPLE", "APACHE"):
+        result.append("// Apache License (Version 2.0) Notice\n//\n")
+        result.append(processed_files["LICENSE-APACHE"])
+        result.append("//\n")
+    if license_arg in ("TRIPLE", "BOOST"):
+        result.append("// BOOST License Notice\n//\n")
+        result.append(processed_files["LICENSE-BOOST"])
+        result.append("//\n")
+
+    return result
+
+
+text = "".join(
+    [
+        processed_files["AUTHORS"],
+        processed_files["CONTRIBUTORS"],
+        *license_content(args.license),
+        processed_files["constexpr_feature_detect.h"],
+        processed_files["float_common.h"],
+        processed_files["fast_float.h"],
+        processed_files["ascii_number.h"],
+        processed_files["fast_table.h"],
+        processed_files["decimal_to_binary.h"],
+        processed_files["bigint.h"],
+        processed_files["digit_comparison.h"],
+        processed_files["parse_number.h"],
+    ]
+)
 
 if args.output:
-  with open(args.output, 'wt') as f:
+    with open(args.output, "wt", encoding="utf8") as f:
         f.write(text)
 else:
     print(text)

script/analysis.py

@@ -1,36 +1,38 @@
+import sys
 from math import floor
 
+
 def log2(x):
     """returns ceil(log2(x)))"""
     y = 0
-   while((1<<y) < x):
+    while (1 << y) < x:
         y = y + 1
     return y
 
 
-for q in range(1,17+1):
-    d = 5**q
+for q in range(1, 17 + 1):
+    d = 5 ** q
     b = 127 + log2(d)
-    t = 2** b
-    c = t//d + 1
-    assert c < 2**128
-    assert c >= 2**127
-    K = 2**127
-    if(not(c * K * d<=( K + 1) * t)):
+    t = 2 ** b
+    c = t // d + 1
+    assert c < 2 ** 128
+    assert c >= 2 ** 127
+    K = 2 ** 127
+    if not (c * K * d <= (K + 1) * t):
         print(q)
-      top = floor(t/(c  * d - t))
+        top = floor(t / (c * d - t))
         sys.exit(-1)
 
-for q in range(18, 344+1):
-    d = 5**q
-    b = 64 + 2*log2(d)
-    t = 2**b
-    c = t//d + 1
-    assert c > 2**(64 +log2(d))
-    K = 2**64
-    if(not(c * K * d<=( K + 1) * t)):
+for q in range(18, 344 + 1):
+    d = 5 ** q
+    b = 64 + 2 * log2(d)
+    t = 2 ** b
+    c = t // d + 1
+    assert c > 2 ** (64 + log2(d))
+    K = 2 ** 64
+    if not (c * K * d <= (K + 1) * t):
         print(q)
-      top = floor(t/(c  * d - t))
+        top = floor(t / (c * d - t))
         sys.exit(-1)
 
 print("all good")

script/mushtak_lemire.py

@@ -0,0 +1,81 @@
+#
+# Reference :
+# Noble Mushtak and Daniel Lemire, Fast Number Parsing Without Fallback (to appear)
+#
+
+all_tqs = []
+
+# Generates all possible values of T[q]
+# Appendix B of  Number parsing at a gigabyte per second.
+# Software: Practice and Experience 2021;51(8):1700–1727.
+for q in range(-342, -27):
+    power5 = 5 ** -q
+    z = 0
+    while (1 << z) < power5:
+        z += 1
+    b = 2 * z + 2 * 64
+    c = 2 ** b // power5 + 1
+    while c >= (1 << 128):
+        c //= 2
+    all_tqs.append(c)
+for q in range(-27, 0):
+    power5 = 5 ** -q
+    z = 0
+    while (1 << z) < power5:
+        z += 1
+    b = z + 127
+    c = 2 ** b // power5 + 1
+    all_tqs.append(c)
+for q in range(0, 308 + 1):
+    power5 = 5 ** q
+    while power5 < (1 << 127):
+        power5 *= 2
+    while power5 >= (1 << 128):
+        power5 //= 2
+    all_tqs.append(power5)
+
+# Returns the continued fraction of numer/denom as a list [a0; a1, a2, ..., an]
+def continued_fraction(numer, denom):
+    # (look at page numbers in top-left, not PDF page numbers)
+    cf = []
+    while denom != 0:
+        quot, rem = divmod(numer, denom)
+        cf.append(quot)
+        numer, denom = denom, rem
+    return cf
+
+
+# Given a continued fraction [a0; a1, a2, ..., an], returns
+# all the convergents of that continued fraction
+# as pairs of the form (numer, denom), where numer/denom is
+# a convergent of the continued fraction in simple form.
+def convergents(cf):
+    p_n_minus_2 = 0
+    q_n_minus_2 = 1
+    p_n_minus_1 = 1
+    q_n_minus_1 = 0
+    convergents = []
+    for a_n in cf:
+        p_n = a_n * p_n_minus_1 + p_n_minus_2
+        q_n = a_n * q_n_minus_1 + q_n_minus_2
+        convergents.append((p_n, q_n))
+        p_n_minus_2, q_n_minus_2, p_n_minus_1, q_n_minus_1 = (
+            p_n_minus_1,
+            q_n_minus_1,
+            p_n,
+            q_n,
+        )
+    return convergents
+
+
+# Enumerate through all the convergents of T[q] / 2^137 with denominators < 2^64
+found_solution = False
+for j, tq in enumerate(all_tqs):
+    for _, w in convergents(continued_fraction(tq, 2 ** 137)):
+        if w >= 2 ** 64:
+            break
+            if (tq * w) % 2 ** 137 > 2 ** 137 - 2 ** 64:
+                print(f"SOLUTION: q={j-342} T[q]={tq} w={w}")
+                found_solution = True
+if not found_solution:
+    print("No solutions!")

script/release.py

@@ -0,0 +1,183 @@
+#!/usr/bin/env python3
+########################################################################
+# Generates a new release.
+########################################################################
+import sys
+import re
+import subprocess
+import io
+import os
+import fileinput
+
+if sys.version_info < (3, 0):
+    sys.stdout.write("Sorry, requires Python 3.x or better\n")
+    sys.exit(1)
+
+
+def colored(r, g, b, text):
+    return f"\033[38;2;{r};{g};{b}m{text} \033[38;2;255;255;255m"
+
+
+def extractnumbers(s):
+    return tuple(map(int, re.findall(r"(\d+)\.(\d+)\.(\d+)", str(s))[0]))
+
+
+def toversionstring(major, minor, rev):
+    return f"{major}.{minor}.{rev}"
+
+
+print("Calling git rev-parse --abbrev-ref HEAD")
+pipe = subprocess.Popen(
+    ["git", "rev-parse", "--abbrev-ref", "HEAD"],
+    stdout=subprocess.PIPE,
+    stderr=subprocess.STDOUT,
+)
+branchresult = pipe.communicate()[0].decode().strip()
+
+if branchresult != "main":
+    print(
+        colored(
+            255,
+            0,
+            0,
+            f"We recommend that you release on main, you are on '{branchresult}'",
+        )
+    )
+
+ret = subprocess.call(["git", "remote", "update"])
+
+if ret != 0:
+    sys.exit(ret)
+print("Calling git log HEAD.. --oneline")
+pipe = subprocess.Popen(
+    ["git", "log", "HEAD..", "--oneline"],
+    stdout=subprocess.PIPE,
+    stderr=subprocess.STDOUT,
+)
+uptodateresult = pipe.communicate()[0].decode().strip()
+
+if len(uptodateresult) != 0:
+    print(uptodateresult)
+    sys.exit(-1)
+
+pipe = subprocess.Popen(
+    ["git", "rev-parse", "--show-toplevel"],
+    stdout=subprocess.PIPE,
+    stderr=subprocess.STDOUT,
+)
+maindir = pipe.communicate()[0].decode().strip()
+scriptlocation = os.path.dirname(os.path.abspath(__file__))
+
+print(f"repository: {maindir}")
+
+pipe = subprocess.Popen(
+    ["git", "describe", "--abbrev=0", "--tags"],
+    stdout=subprocess.PIPE,
+    stderr=subprocess.STDOUT,
+)
+versionresult = pipe.communicate()[0].decode().strip()
+
+print(f"last version: {versionresult}")
+try:
+    currentv = extractnumbers(versionresult)
+except:
+    currentv = [0, 0, 0]
+if len(sys.argv) != 2:
+    nextv = (currentv[0], currentv[1], currentv[2] + 1)
+    print(f"please specify version number, e.g. {toversionstring(*nextv)}")
+    sys.exit(-1)
+try:
+    newversion = extractnumbers(sys.argv[1])
+    print(newversion)
+except:
+    print(f"can't parse version number {sys.argv[1]}")
+    sys.exit(-1)
+
+print("checking that new version is valid")
+if newversion[0] != currentv[0]:
+    assert newversion[0] == currentv[0] + 1
+    assert newversion[1] == 0
+    assert newversion[2] == 0
+elif newversion[1] != currentv[1]:
+    assert newversion[1] == currentv[1] + 1
+    assert newversion[2] == 0
+else:
+    assert newversion[2] == currentv[2] + 1
+
+atleastminor = (currentv[0] != newversion[0]) or (currentv[1] != newversion[1])
+
+newmajorversionstring = str(newversion[0])
+newminorversionstring = str(newversion[1])
+newpatchversionstring = str(newversion[2])
+newversionstring = f"{newversion[0]}.{newversion[1]}.{newversion[2]}"
+cmakefile = f"{maindir}{os.sep}CMakeLists.txt"
+
+for line in fileinput.input(cmakefile, inplace=1, backup=".bak"):
+    line = re.sub(
+        r"project\(fast_float VERSION \d+\.\d+\.\d+ LANGUAGES CXX\)",
+        f"project(fast_float VERSION {newversionstring} LANGUAGES CXX)",
+        line.rstrip(),
+    )
+    print(line)
+
+print(f"modified {cmakefile}, a backup was made")
+
+versionfilerel = f"{os.sep}include{os.sep}fast_float{os.sep}float_common.h"
+versionfile = f"{maindir}{versionfilerel}"
+
+for line in fileinput.input(versionfile, inplace=1, backup=".bak"):
+    line = re.sub(
+        r"#define FASTFLOAT_VERSION_MAJOR \d+",
+        f"#define FASTFLOAT_VERSION_MAJOR {newmajorversionstring}",
+        line.rstrip(),
+    )
+    line = re.sub(
+        r"#define FASTFLOAT_VERSION_MINOR \d+",
+        f"#define FASTFLOAT_VERSION_MINOR {newminorversionstring}",
+        line.rstrip(),
+    )
+    line = re.sub(
+        r"#define FASTFLOAT_VERSION_PATCH \d+",
+        f"#define FASTFLOAT_VERSION_PATCH {newpatchversionstring}",
+        line.rstrip(),
+    )
+    print(line)
+
+print(f"{versionfile} modified")
+
+readmefile = f"{maindir}{os.sep}README.md"
+
+for line in fileinput.input(readmefile, inplace=1, backup=".bak"):
+    line = re.sub(
+        r"https://github.com/fastfloat/fast_float/releases/download/v(\d+\.\d+\.\d+)/fast_float.h",
+        f"https://github.com/fastfloat/fast_float/releases/download/v{newversionstring}/fast_float.h",
+        line.rstrip(),
+    )
+    line = re.sub(
+        r"GIT_TAG tags/v(\d+\.\d+\.\d+)",
+        f"GIT_TAG tags/v{newversionstring}",
+        line.rstrip(),
+    )
+    line = re.sub(
+        r"GIT_TAG v(\d+\.\d+\.\d+)\)", f"GIT_TAG v{newversionstring})", line.rstrip()
+    )
+    print(line)
+
+print(f"modified {readmefile}, a backup was made")
+
+print("running amalgamate.py")
+with open(f"{maindir}{os.sep}fast_float.h", "w") as outfile:
+    cp = subprocess.run(
+        [f"python3", f"{maindir}{os.sep}script{os.sep}amalgamate.py"], stdout=outfile
+    )
+
+if cp.returncode != 0:
+    print("Failed to run amalgamate")
+else:
+    print("amalgamate.py ran successfully")
+    print(f"You should upload {maindir}{os.sep}fast_float.h")
+
+print("Please run the tests before issuing a release.\n")
+print(
+    f'to issue release, enter\n git commit -a && git push && git tag -a v{toversionstring(*newversion)} -m "version {toversionstring(*newversion)}" && git push --tags\n'
+)

script/run-clangcldocker.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+set -e
+COMMAND=$*
+SCRIPTPATH="$( cd "$(dirname "$0")" ; pwd -P )"
+MAINSOURCE=$SCRIPTPATH/..
+ALL_FILES=$(cd $MAINSOURCE && git ls-tree --full-tree --name-only -r HEAD | grep -e ".*\.\(c\|h\|cc\|cpp\|hh\)\$" | grep -vFf clang-format-ignore.txt)
+
+if clang-format-17 --version  2>/dev/null | grep -qF 'version 17.'; then
+  cd $MAINSOURCE; clang-format-17 --style=file --verbose -i "$@" $ALL_FILES
+  exit 0
+elif clang-format --version  2>/dev/null | grep -qF 'version 17.'; then
+  cd $MAINSOURCE; clang-format --style=file --verbose -i "$@" $ALL_FILES
+  exit 0
+fi
+echo "Trying to use docker"
+command -v docker >/dev/null 2>&1 || { echo >&2 "Please install docker. E.g., go to https://www.docker.com/products/docker-desktop Type 'docker' to diagnose the problem."; exit 1; }
+docker info >/dev/null 2>&1 || { echo >&2 "Docker server is not running? type 'docker info'."; exit 1; }
+
+if [ -t 0 ]; then DOCKER_ARGS=-it; fi
+docker pull kszonek/clang-format-17
+
+docker run --rm $DOCKER_ARGS -v "$MAINSOURCE":"$MAINSOURCE":Z  -w "$MAINSOURCE" -u "$(id -u $USER):$(id -g $USER)" kszonek/clang-format-17 --style=file --verbose -i "$@" $ALL_FILES

script/table_generation.py

@@ -1,14 +1,15 @@
 def format(number):
-    upper = number // (1<<64)
-    lower = number % (1<<64)
-    print(""+hex(upper)+","+hex(lower)+",")
+    upper = number // (1 << 64)
+    lower = number % (1 << 64)
+    print("" + hex(upper) + "," + hex(lower) + ",")
 
-for q in range(-342,0):
+
+for q in range(-342, 0):
     power5 = 5 ** -q
     z = 0
-    while( (1<<z) < power5) :
+    while (1 << z) < power5:
         z += 1
-    if(q >= -27):
+    if q >= -27:
         b = z + 127
         c = 2 ** b // power5 + 1
         format(c)
@@ -16,16 +17,16 @@ for q in range(-342,0):
         b = 2 * z + 2 * 64
         c = 2 ** b // power5 + 1
         # truncate
-        while(c >= (1<<128)):
+        while c >= (1 << 128):
             c //= 2
         format(c)
 
-for q in range(0,308+1):
+for q in range(0, 308 + 1):
     power5 = 5 ** q
     # move the most significant bit in position
-    while(power5 < (1<<127)):
+    while power5 < (1 << 127):
         power5 *= 2
     # *truncate*
-    while(power5 >= (1<<128)):
+    while power5 >= (1 << 128):
         power5 //= 2
     format(power5)

tests/BUILD.bazel

@@ -0,0 +1,116 @@
+cc_test(
+    name = "basictest",
+    srcs = ["basictest.cpp"],
+    deps = [
+        "//:fast_float",
+        "@doctest//doctest",
+    ],
+)
+
+cc_test(
+    name = "example_test",
+    srcs = ["example_test.cpp"],
+    deps = [
+        "//:fast_float",
+        "@doctest//doctest",
+    ],
+)
+
+cc_test(
+    name = "example_comma_test",
+    srcs = ["example_comma_test.cpp"],
+    deps = [
+        "//:fast_float",
+        "@doctest//doctest",
+    ],
+)
+
+cc_test(
+    name = "fast_int",
+    srcs = ["fast_int.cpp"],
+    deps = [
+        "//:fast_float",
+        "@doctest//doctest",
+    ],
+)
+
+cc_test(
+    name = "fixedwidthtest",
+    srcs = ["fixedwidthtest.cpp"],
+    deps = [
+        "//:fast_float",
+        "@doctest//doctest",
+    ],
+)
+
+cc_test(
+    name = "fortran",
+    srcs = ["fortran.cpp"],
+    deps = [
+        "//:fast_float",
+        "@doctest//doctest",
+    ],
+)
+
+cc_test(
+    name = "json_fmt",
+    srcs = ["json_fmt.cpp"],
+    deps = [
+        "//:fast_float",
+        "@doctest//doctest",
+    ],
+)
+
+cc_test(
+    name = "long_test",
+    srcs = ["long_test.cpp"],
+    deps = [
+        "//:fast_float",
+        "@doctest//doctest",
+    ],
+)
+
+cc_test(
+    name = "powersoffive_hardround",
+    srcs = ["powersoffive_hardround.cpp"],
+    deps = [
+        "//:fast_float",
+        "@doctest//doctest",
+    ],
+)
+
+cc_test(
+    name = "rcppfastfloat_test",
+    srcs = ["rcppfastfloat_test.cpp"],
+    deps = [
+        "//:fast_float",
+        "@doctest//doctest",
+    ],
+)
+
+cc_test(
+    name = "wide_char_test",
+    srcs = ["wide_char_test.cpp"],
+    deps = [
+        "//:fast_float",
+        "@doctest//doctest",
+    ],
+)
+
+cc_test(
+    name = "supported_chars_test",
+    srcs = ["supported_chars_test.cpp"],
+    deps = [
+        "//:fast_float",
+        "@doctest//doctest",
+    ],
+)
+
+cc_test(
+    name = "string_test",
+    srcs = ["string_test.cpp"],
+    deps = [
+        "//:fast_float",
+        "@doctest//doctest",
+    ],
+)

tests/CMakeLists.txt

@@ -5,40 +5,42 @@ cmake_minimum_required(VERSION 3.11 FATAL_ERROR)
 include(FetchContent)
 
 option(SYSTEM_DOCTEST "Use system copy of doctest" OFF)
+option(FASTFLOAT_SUPPLEMENTAL_TESTS "Run supplemental tests" ON)
 
 if (NOT SYSTEM_DOCTEST)
   FetchContent_Declare(doctest
-    GIT_REPOSITORY https://github.com/onqtam/doctest.git
-    GIT_TAG 2.4.6)
+    GIT_REPOSITORY https://github.com/lemire/doctest.git)
+else ()
+  find_package(doctest REQUIRED)
 endif()
-FetchContent_Declare(supplemental_test_files
+if (FASTFLOAT_SUPPLEMENTAL_TESTS)
+  FetchContent_Declare(supplemental_test_files
     GIT_REPOSITORY https://github.com/fastfloat/supplemental_test_files.git
     GIT_TAG origin/main)
-
+endif()
 
 
 # FetchContent_MakeAvailable() was only introduced in 3.14
 # https://cmake.org/cmake/help/v3.14/release/3.14.html#modules
-# FetchContent_MakeAvailable(doctest)
 if (NOT SYSTEM_DOCTEST)
-  FetchContent_GetProperties(doctest)
-  if(NOT doctest_POPULATED)
-    FetchContent_Populate(doctest)
-    add_subdirectory(${doctest_SOURCE_DIR} ${doctest_BINARY_DIR})
-  endif()
-endif()
-FetchContent_GetProperties(supplemental_test_files)
-if(NOT supplemental_test_files_POPULATED)
-  message(STATUS "Tests enabled. Retrieving test files.")
-  FetchContent_Populate(supplemental_test_files)
-  message(STATUS "Test files retrieved.")
-  add_subdirectory(${supplemental_test_files_SOURCE_DIR} ${supplemental_test_files_BINARY_DIR})
+  FetchContent_MakeAvailable(doctest)
 endif()
+
 add_library(supplemental-data INTERFACE)
-target_compile_definitions(supplemental-data INTERFACE SUPPLEMENTAL_TEST_DATA_DIR="${supplemental_test_files_BINARY_DIR}/data")
+if (FASTFLOAT_SUPPLEMENTAL_TESTS)
+  message(STATUS "Supplemental tests enabled. Retrieving test files.")
+  FetchContent_MakeAvailable(supplemental_test_files)
+  message(STATUS "Supplemental test files retrieved.")
+  target_compile_definitions(supplemental-data INTERFACE SUPPLEMENTAL_TEST_DATA_DIR="${supplemental_test_files_BINARY_DIR}/data")
+endif()
+
 function(fast_float_add_cpp_test TEST_NAME)
     add_executable(${TEST_NAME} ${TEST_NAME}.cpp)
-    add_test(${TEST_NAME} ${TEST_NAME})
+    if(CMAKE_CROSSCOMPILING)
+        set(ccemulator ${CMAKE_CROSSCOMPILING_EMULATOR})
+    endif()
+    add_test(NAME ${TEST_NAME}
+        COMMAND ${ccemulator} $<TARGET_FILE:${TEST_NAME}>)
     if(CMAKE_CXX_COMPILER_ID MATCHES "MSVC")
       target_compile_options(${TEST_NAME} PUBLIC /EHsc)
     endif()
@@ -49,24 +51,52 @@ function(fast_float_add_cpp_test TEST_NAME)
     target_link_libraries(${TEST_NAME} PUBLIC fast_float supplemental-data)
     if (NOT SYSTEM_DOCTEST)
       target_link_libraries(${TEST_NAME} PUBLIC doctest)
+    else ()
+      target_link_libraries(${TEST_NAME} PUBLIC doctest::doctest)
     endif()
 endfunction(fast_float_add_cpp_test)
 
-
+fast_float_add_cpp_test(rcppfastfloat_test)
+fast_float_add_cpp_test(wide_char_test)
+fast_float_add_cpp_test(supported_chars_test)
 fast_float_add_cpp_test(example_test)
 fast_float_add_cpp_test(example_comma_test)
+fast_float_add_cpp_test(example_integer_times_pow10)
 fast_float_add_cpp_test(basictest)
-
-
+option(FASTFLOAT_CONSTEXPR_TESTS "Require constexpr tests (build will fail if the compiler won't support it)" OFF)
+if (FASTFLOAT_CONSTEXPR_TESTS)
+  target_compile_features(basictest PRIVATE cxx_std_20)
+  target_compile_definitions(basictest PRIVATE FASTFLOAT_CONSTEXPR_TESTS)
+else()
+  target_compile_features(basictest PRIVATE cxx_std_17)
+endif()
+if (FASTFLOAT_SUPPLEMENTAL_TESTS)
+  target_compile_definitions(basictest PRIVATE FASTFLOAT_SUPPLEMENTAL_TESTS)
+endif()
+fast_float_add_cpp_test(p2497)
+fast_float_add_cpp_test(long_test)
+fast_float_add_cpp_test(powersoffive_hardround)
+fast_float_add_cpp_test(string_test)
+fast_float_add_cpp_test(fast_int)
+target_compile_features(fast_int PRIVATE cxx_std_17)
+fast_float_add_cpp_test(json_fmt)
+fast_float_add_cpp_test(fortran)
+if(CMAKE_CXX_STANDARD GREATER_EQUAL 23)
+  option(FASTFLOAT_FIXEDWIDTH_TESTS "Require fixed width test for C++23 (build will fail if the compiler won't support it)" ON)
+else()
+  option(FASTFLOAT_FIXEDWIDTH_TESTS "Require fixed width test for C++23 (build will fail if the compiler won't support it)" OFF)
+endif()
+if (FASTFLOAT_FIXEDWIDTH_TESTS)
+  fast_float_add_cpp_test(fixedwidthtest)
+  target_compile_features(fixedwidthtest PUBLIC cxx_std_23)
+endif()
 
 option(FASTFLOAT_EXHAUSTIVE "Exhaustive tests" OFF)
 
 if (FASTFLOAT_EXHAUSTIVE)
-  fast_float_add_cpp_test(powersoffive_hardround)
   fast_float_add_cpp_test(short_random_string)
   fast_float_add_cpp_test(exhaustive32_midpoint)
   fast_float_add_cpp_test(random_string)
-  fast_float_add_cpp_test(string_test)
   fast_float_add_cpp_test(exhaustive32)
   fast_float_add_cpp_test(exhaustive32_64)
   fast_float_add_cpp_test(long_exhaustive32)
@@ -76,3 +106,4 @@ if (FASTFLOAT_EXHAUSTIVE)
 endif(FASTFLOAT_EXHAUSTIVE)
 
 add_subdirectory(build_tests)
+add_subdirectory(bloat_analysis)

tests/bloat_analysis/CMakeLists.txt

@@ -0,0 +1,5 @@
+add_executable(bloaty main.cpp a1.cpp a2.cpp a3.cpp a4.cpp a4.cpp a5.cpp a6.cpp a7.cpp a8.cpp a9.cpp a10.cpp)
+target_link_libraries(bloaty PUBLIC fast_float)
+
+add_executable(bloatyref main_ref.cpp)
+target_link_libraries(bloatyref PUBLIC fast_float)

tests/bloat_analysis/a1.cpp

@@ -0,0 +1,11 @@
+#include "fast_float/fast_float.h"
+
+double get1(char const *input) {
+  double result_value;
+  auto result =
+      fast_float::from_chars(input, input + strlen(input), result_value);
+  if (result.ec != std::errc()) {
+    return 1;
+  }
+  return result_value;
+}

tests/bloat_analysis/a10.cpp

@@ -0,0 +1,11 @@
+#include "fast_float/fast_float.h"
+
+double get10(char const *input) {
+  double result_value;
+  auto result =
+      fast_float::from_chars(input, input + strlen(input), result_value);
+  if (result.ec != std::errc()) {
+    return 10;
+  }
+  return result_value;
+}

tests/bloat_analysis/a2.cpp

@@ -0,0 +1,11 @@
+#include "fast_float/fast_float.h"
+
+double get2(char const *input) {
+  double result_value;
+  auto result =
+      fast_float::from_chars(input, input + strlen(input), result_value);
+  if (result.ec != std::errc()) {
+    return 2;
+  }
+  return result_value;
+}

tests/bloat_analysis/a3.cpp

@@ -0,0 +1,11 @@
+#include "fast_float/fast_float.h"
+
+double get3(char const *input) {
+  double result_value;
+  auto result =
+      fast_float::from_chars(input, input + strlen(input), result_value);
+  if (result.ec != std::errc()) {
+    return 3;
+  }
+  return result_value;
+}

tests/bloat_analysis/a4.cpp

@@ -0,0 +1,11 @@
+#include "fast_float/fast_float.h"
+
+double get4(char const *input) {
+  double result_value;
+  auto result =
+      fast_float::from_chars(input, input + strlen(input), result_value);
+  if (result.ec != std::errc()) {
+    return 4;
+  }
+  return result_value;
+}

tests/bloat_analysis/a5.cpp

@@ -0,0 +1,11 @@
+#include "fast_float/fast_float.h"
+
+double get5(char const *input) {
+  double result_value;
+  auto result =
+      fast_float::from_chars(input, input + strlen(input), result_value);
+  if (result.ec != std::errc()) {
+    return 5;
+  }
+  return result_value;
+}

tests/bloat_analysis/a6.cpp

@@ -0,0 +1,11 @@
+#include "fast_float/fast_float.h"
+
+double get6(char const *input) {
+  double result_value;
+  auto result =
+      fast_float::from_chars(input, input + strlen(input), result_value);
+  if (result.ec != std::errc()) {
+    return 6;
+  }
+  return result_value;
+}

tests/bloat_analysis/a7.cpp

@@ -0,0 +1,11 @@
+#include "fast_float/fast_float.h"
+
+double get7(char const *input) {
+  double result_value;
+  auto result =
+      fast_float::from_chars(input, input + strlen(input), result_value);
+  if (result.ec != std::errc()) {
+    return 7;
+  }
+  return result_value;
+}

tests/bloat_analysis/a8.cpp

@@ -0,0 +1,11 @@
+#include "fast_float/fast_float.h"
+
+double get8(char const *input) {
+  double result_value;
+  auto result =
+      fast_float::from_chars(input, input + strlen(input), result_value);
+  if (result.ec != std::errc()) {
+    return 8;
+  }
+  return result_value;
+}

tests/bloat_analysis/a9.cpp

@@ -0,0 +1,11 @@
+#include "fast_float/fast_float.h"
+
+double get9(char const *input) {
+  double result_value;
+  auto result =
+      fast_float::from_chars(input, input + strlen(input), result_value);
+  if (result.ec != std::errc()) {
+    return 9;
+  }
+  return result_value;
+}

tests/bloat_analysis/main.cpp

@@ -0,0 +1,20 @@
+
+
+double get1(char const *input);
+double get2(char const *input);
+double get3(char const *input);
+double get4(char const *input);
+double get5(char const *input);
+double get6(char const *input);
+double get7(char const *input);
+double get8(char const *input);
+double get9(char const *input);
+double get10(char const *input);
+
+int main(int arg, char **argv) {
+  double x = get1(argv[0]) + get2(argv[0]) + get3(argv[0]) + get4(argv[0]) +
+             get5(argv[0]) + get6(argv[0]) + get7(argv[0]) + get8(argv[0]) +
+             get9(argv[0]) + get10(argv[0]);
+
+  return int(x);
+}

tests/bloat_analysis/main_ref.cpp

@@ -0,0 +1,16 @@
+#include "fast_float/fast_float.h"
+
+double get(char const *input) {
+  double result_value;
+  auto result =
+      fast_float::from_chars(input, input + strlen(input), result_value);
+  if (result.ec != std::errc()) {
+    return 10;
+  }
+  return result_value;
+}
+
+int main(int arg, char **argv) {
+  double x = get(argv[0]);
+  return int(x);
+}

tests/build_tests/issue72/foo.cpp

@@ -1,2 +1,3 @@
 #include "test.h"
-void foo() { }
+
+void foo() {}

tests/build_tests/issue72/main.cpp

@@ -1,2 +1,3 @@
 #include "test.h"
+
 int main() { return 0; }

tests/example_comma_test.cpp

@@ -1,13 +1,19 @@
 
 #include "fast_float/fast_float.h"
 #include <iostream>
+#include <string>
+#include <system_error>
 
 int main() {
-    const std::string input =  "3,1416 xyz ";
+  std::string const input = "3,1416 xyz ";
   double result;
   fast_float::parse_options options{fast_float::chars_format::general, ','};
-    auto answer = fast_float::from_chars_advanced(input.data(), input.data()+input.size(), result, options);
-    if((answer.ec != std::errc()) || ((result != 3.1416))) { std::cerr << "parsing failure\n"; return EXIT_FAILURE; }
+  auto answer = fast_float::from_chars_advanced(
+      input.data(), input.data() + input.size(), result, options);
+  if ((answer.ec != std::errc()) || ((result != 3.1416))) {
+    std::cerr << "parsing failure\n";
+    return EXIT_FAILURE;
+  }
   std::cout << "parsed the number " << result << std::endl;
   return EXIT_SUCCESS;
 }

tests/example_integer_times_pow10.cpp

@@ -0,0 +1,36 @@
+#include "fast_float/fast_float.h"
+
+#include <iostream>
+
+void default_overload() {
+  const uint64_t W = 12345678901234567;
+  const int Q = 23;
+  const double result = fast_float::integer_times_pow10(W, Q);
+  std::cout.precision(17);
+  std::cout << W << " * 10^" << Q << " = " << result << " ("
+            << (result == 12345678901234567e23 ? "==" : "!=") << "expected)\n";
+}
+
+void double_specialization() {
+  const uint64_t W = 12345678901234567;
+  const int Q = 23;
+  const double result = fast_float::integer_times_pow10<double>(W, Q);
+  std::cout.precision(17);
+  std::cout << "double: " << W << " * 10^" << Q << " = " << result << " ("
+            << (result == 12345678901234567e23 ? "==" : "!=") << "expected)\n";
+}
+
+void float_specialization() {
+  const uint64_t W = 12345678;
+  const int Q = 23;
+  const float result = fast_float::integer_times_pow10<float>(W, Q);
+  std::cout.precision(9);
+  std::cout << "float: " << W << " * 10^" << Q << " = " << result << " ("
+            << (result == 12345678e23f ? "==" : "!=") << "expected)\n";
+}
+
+int main() {
+  default_overload();
+  double_specialization();
+  float_specialization();
+}

tests/example_test.cpp

@@ -1,12 +1,158 @@
 
 #include "fast_float/fast_float.h"
 #include <iostream>
+#include <string>
+#include <system_error>
+
+bool many() {
+  std::string const input = "234532.3426362,7869234.9823,324562.645";
+  double result;
+  auto answer =
+      fast_float::from_chars(input.data(), input.data() + input.size(), result);
+  if (answer.ec != std::errc()) {
+    return false;
+  }
+  if (result != 234532.3426362) {
+    return false;
+  }
+  if (answer.ptr[0] != ',') {
+    return false;
+  }
+  answer = fast_float::from_chars(answer.ptr + 1, input.data() + input.size(),
+                                  result);
+  if (answer.ec != std::errc()) {
+    return false;
+  }
+  if (result != 7869234.9823) {
+    return false;
+  }
+  if (answer.ptr[0] != ',') {
+    return false;
+  }
+  answer = fast_float::from_chars(answer.ptr + 1, input.data() + input.size(),
+                                  result);
+  if (answer.ec != std::errc()) {
+    return false;
+  }
+  if (result != 324562.645) {
+    return false;
+  }
+  return true;
+}
+
+void many_loop() {
+  std::string const input = "234532.3426362,7869234.9823,324562.645";
+  double result;
+  char const *pointer = input.data();
+  char const *end_pointer = input.data() + input.size();
+
+  while (pointer < end_pointer) {
+    auto answer = fast_float::from_chars(pointer, end_pointer, result);
+    if (answer.ec != std::errc()) {
+      std::cerr << "error while parsing" << std::endl;
+      break;
+    }
+    std::cout << "parsed: " << result << std::endl;
+    pointer = answer.ptr;
+    if ((answer.ptr < end_pointer) && (*pointer == ',')) {
+      pointer++;
+    }
+  }
+}
+
+#if FASTFLOAT_IS_CONSTEXPR
+// consteval forces compile-time evaluation of the function in C++20.
+consteval double parse(std::string_view input) {
+  double result;
+  auto answer =
+      fast_float::from_chars(input.data(), input.data() + input.size(), result);
+  if (answer.ec != std::errc()) {
+    return -1.0;
+  }
+  return result;
+}
+
+// This function should compile to a function which
+// merely returns 3.1415.
+constexpr double constexptest() { return parse("3.1415 input"); }
+#endif
+
+bool small() {
+  double result = -1;
+  std::string str = "3e-1000";
+  auto r = fast_float::from_chars(str.data(), str.data() + str.size(), result);
+  if (r.ec != std::errc::result_out_of_range) {
+    return false;
+  }
+  if (r.ptr != str.data() + 7) {
+    return false;
+  }
+  if (result != 0) {
+    return false;
+  }
+  printf("small values go to zero\n");
+  return true;
+}
+
+bool large() {
+  double result = -1;
+  std::string str = "3e1000";
+  auto r = fast_float::from_chars(str.data(), str.data() + str.size(), result);
+  if (r.ec != std::errc::result_out_of_range) {
+    return false;
+  }
+  if (r.ptr != str.data() + 6) {
+    return false;
+  }
+  if (result != std::numeric_limits<double>::infinity()) {
+    return false;
+  }
+  printf("large values go to infinity\n");
+  return true;
+}
 
 int main() {
-    const std::string input =  "3.1416 xyz ";
+  std::string input = "3.1416 xyz ";
   double result;
-    auto answer = fast_float::from_chars(input.data(), input.data()+input.size(), result);
-    if((answer.ec != std::errc()) || ((result != 3.1416))) { std::cerr << "parsing failure\n"; return EXIT_FAILURE; }
+  auto answer =
+      fast_float::from_chars(input.data(), input.data() + input.size(), result);
+  if ((answer.ec != std::errc()) || ((result != 3.1416))) {
+    std::cerr << "parsing failure\n";
+    return EXIT_FAILURE;
+  }
   std::cout << "parsed the number " << result << std::endl;
+#ifdef __STDCPP_FLOAT16_T__
+  printf("16-bit float\n");
+  // Parse as 16-bit float
+  std::float16_t parsed_16{};
+  input = "10000e-1452";
+  auto fast_float_r16 = fast_float::from_chars(
+      input.data(), input.data() + input.size(), parsed_16);
+  if (fast_float_r16.ec != std::errc() &&
+      fast_float_r16.ec != std::errc::result_out_of_range) {
+    std::cerr << "16-bit fast_float parsing failure for: " + input + "\n";
+    return false;
+  }
+  std::cout << "parsed the 16-bit value " << float(parsed_16) << std::endl;
+#endif
+  if (!small()) {
+    printf("Bug\n");
+    return EXIT_FAILURE;
+  }
+  if (!large()) {
+    printf("Bug\n");
+    return EXIT_FAILURE;
+  }
+
+  if (!many()) {
+    printf("Bug\n");
+    return EXIT_FAILURE;
+  }
+  many_loop();
+#if FASTFLOAT_IS_CONSTEXPR
+  if constexpr (constexptest() != 3.1415) {
+    return EXIT_FAILURE;
+  }
+#endif
   return EXIT_SUCCESS;
 }

tests/exhaustive32.cpp

@@ -1,9 +1,13 @@
 
 #include "fast_float/fast_float.h"
 
-#include <iostream>
 #include <cassert>
 #include <cmath>
+#include <cstdio>
+#include <ios>
+#include <iostream>
+#include <limits>
+#include <system_error>
 
 template <typename T> char *to_string(T d, char *buffer) {
   auto written = std::snprintf(buffer, 64, "%.*e",
@@ -23,10 +27,15 @@ void allvalues() {
     memcpy(&v, &word, sizeof(v));
 
     {
-      const char *string_end = to_string(v, buffer);
+      char const *string_end = to_string(v, buffer);
       float result_value;
       auto result = fast_float::from_chars(buffer, string_end, result_value);
-      if (result.ec != std::errc()) {
+      // Starting with version 4.0 for fast_float, we return result_out_of_range
+      // if the value is either too small (too close to zero) or too large
+      // (effectively infinity). So std::errc::result_out_of_range is normal for
+      // well-formed input strings.
+      if (result.ec != std::errc() &&
+          result.ec != std::errc::result_out_of_range) {
         std::cerr << "parsing error ? " << buffer << std::endl;
         abort();
       }
@@ -35,9 +44,9 @@ void allvalues() {
           std::cerr << "not nan" << buffer << std::endl;
           abort();
         }
-      } else if(copysign(1,result_value) != copysign(1,v)) {
-        std::cerr << "I got " << std::hexfloat << result_value << " but I was expecting " << v
-              << std::endl;
+      } else if (copysign(1, result_value) != copysign(1, v)) {
+        std::cerr << "I got " << std::hexfloat << result_value
+                  << " but I was expecting " << v << std::endl;
         abort();
       } else if (result_value != v) {
         std::cerr << "no match ? " << buffer << std::endl;

tests/exhaustive32_64.cpp

@@ -1,9 +1,14 @@
 
 #include "fast_float/fast_float.h"
 
-#include <iostream>
 #include <cassert>
 #include <cmath>
+#include <cstdio>
+#include <ios>
+#include <iostream>
+#include <limits>
+#include <string>
+#include <system_error>
 
 template <typename T> char *to_string(T d, char *buffer) {
   auto written = std::snprintf(buffer, 64, "%.*e",
@@ -11,12 +16,11 @@ template <typename T> char *to_string(T d, char *buffer) {
   return buffer + written;
 }
 
-
 bool basic_test_64bit(std::string vals, double val) {
   double result_value;
   auto result = fast_float::from_chars(vals.data(), vals.data() + vals.size(),
                                        result_value);
-  if (result.ec != std::errc()) {
+  if (result.ec != std::errc() && result.ec != std::errc::result_out_of_range) {
     std::cerr << " I could not parse " << vals << std::endl;
     return false;
   }
@@ -26,14 +30,14 @@ bool basic_test_64bit(std::string vals, double val) {
       std::cerr << "not nan" << result_value << std::endl;
       return false;
     }
-  } else if(copysign(1,result_value) != copysign(1,val)) {
-    std::cerr << "I got " << std::hexfloat << result_value << " but I was expecting " << val
-              << std::endl;
+  } else if (copysign(1, result_value) != copysign(1, val)) {
+    std::cerr << "I got " << std::hexfloat << result_value
+              << " but I was expecting " << val << std::endl;
     return false;
   } else if (result_value != val) {
     std::cerr << vals << std::endl;
-    std::cerr << "I got " << std::hexfloat << result_value << " but I was expecting " << val
-              << std::endl;
+    std::cerr << "I got " << std::hexfloat << result_value
+              << " but I was expecting " << val << std::endl;
     std::cerr << std::dec;
     std::cerr << "string: " << vals << std::endl;
     return false;
@@ -41,7 +45,6 @@ bool basic_test_64bit(std::string vals, double val) {
   return true;
 }
 
-
 void all_32bit_values() {
   char buffer[64];
   for (uint64_t w = 0; w <= 0xFFFFFFFF; w++) {
@@ -55,9 +58,9 @@ void all_32bit_values() {
     double v = v32;
 
     {
-      const char *string_end = to_string(v, buffer);
-      std::string s(buffer, size_t(string_end-buffer));
-      if(!basic_test_64bit(s,v)) {
+      char const *string_end = to_string(v, buffer);
+      std::string s(buffer, size_t(string_end - buffer));
+      if (!basic_test_64bit(s, v)) {
         return;
       }
     }

tests/exhaustive32_midpoint.cpp

@@ -1,8 +1,12 @@
 #include "fast_float/fast_float.h"
 
-#include <iostream>
 #include <cassert>
 #include <cmath>
+#include <cstdio>
+#include <ios>
+#include <iostream>
+#include <limits>
+#include <stdexcept>
 
 #if defined(__CYGWIN__) || defined(__MINGW32__) || defined(__MINGW64__)
 // Anything at all that is related to cygwin, msys and so forth will
@@ -10,29 +14,39 @@
 // gcc.
 #include <locale>
 #include <sstream>
+
 // workaround for CYGWIN
-double cygwin_strtod_l(const char* start, char** end) {
+double cygwin_strtod_l(char const *start, char **end) {
   double d;
   std::stringstream ss;
   ss.imbue(std::locale::classic());
   ss << start;
   ss >> d;
-    if(ss.fail()) { *end = nullptr; }
-    if(ss.eof()) { ss.clear(); }
+  if (ss.fail()) {
+    *end = nullptr;
+  }
+  if (ss.eof()) {
+    ss.clear();
+  }
   auto nread = ss.tellg();
-    *end = const_cast<char*>(start) + nread;
+  *end = const_cast<char *>(start) + nread;
   return d;
 }
-float cygwin_strtof_l(const char* start, char** end) {
+
+float cygwin_strtof_l(char const *start, char **end) {
   float d;
   std::stringstream ss;
   ss.imbue(std::locale::classic());
   ss << start;
   ss >> d;
-    if(ss.fail()) { *end = nullptr; }
-    if(ss.eof()) { ss.clear(); }
+  if (ss.fail()) {
+    *end = nullptr;
+  }
+  if (ss.eof()) {
+    ss.clear();
+  }
   auto nread = ss.tellg();
-    *end = const_cast<char*>(start) + nread;
+  *end = const_cast<char *>(start) + nread;
   return d;
 }
 #endif
@@ -43,9 +57,10 @@ template <typename T> char *to_string(T d, char *buffer) {
   return buffer + written;
 }
 
-void strtof_from_string(const char * st, float& d) {
+void strtof_from_string(char const *st, float &d) {
   char *pr = (char *)st;
-#if defined(__CYGWIN__) || defined(__MINGW32__) || defined(__MINGW64__)  || defined(sun) || defined(__sun)
+#if defined(__CYGWIN__) || defined(__MINGW32__) || defined(__MINGW64__) ||     \
+    defined(sun) || defined(__sun)
   d = cygwin_strtof_l(st, &pr);
 #elif defined(_WIN32)
   static _locale_t c_locale = _create_locale(LC_ALL, "C");
@@ -69,10 +84,14 @@ bool allvalues() {
     }
     uint32_t word = uint32_t(w);
     memcpy(&v, &word, sizeof(v));
-    if(std::isfinite(v)) { 
+    if (std::isfinite(v)) {
       float nextf = std::nextafterf(v, INFINITY);
-      if(copysign(1,v) != copysign(1,nextf)) { continue; }
-      if(!std::isfinite(nextf)) { continue; }
+      if (copysign(1, v) != copysign(1, nextf)) {
+        continue;
+      }
+      if (!std::isfinite(nextf)) {
+        continue;
+      }
       double v1{v};
       assert(float(v1) == v);
       double v2{nextf};
@@ -80,13 +99,18 @@ bool allvalues() {
       double midv{v1 + (v2 - v1) / 2};
       float expected_midv = float(midv);
 
-      const char *string_end = to_string(midv, buffer);
+      char const *string_end = to_string(midv, buffer);
       float str_answer;
       strtof_from_string(buffer, str_answer);
 
       float result_value;
       auto result = fast_float::from_chars(buffer, string_end, result_value);
-      if (result.ec != std::errc()) {
+      // Starting with version 4.0 for fast_float, we return result_out_of_range
+      // if the value is either too small (too close to zero) or too large
+      // (effectively infinity). So std::errc::result_out_of_range is normal for
+      // well-formed input strings.
+      if (result.ec != std::errc() &&
+          result.ec != std::errc::result_out_of_range) {
         std::cerr << "parsing error ? " << buffer << std::endl;
         return false;
       }
@@ -96,26 +120,30 @@ bool allvalues() {
           std::cerr << "v " << std::hexfloat << v << std::endl;
           std::cerr << "v2 " << std::hexfloat << v2 << std::endl;
           std::cerr << "midv " << std::hexfloat << midv << std::endl;
-          std::cerr << "expected_midv " << std::hexfloat << expected_midv << std::endl;
+          std::cerr << "expected_midv " << std::hexfloat << expected_midv
+                    << std::endl;
           return false;
         }
-      } else if(copysign(1,result_value) != copysign(1,v)) {
+      } else if (copysign(1, result_value) != copysign(1, v)) {
         std::cerr << buffer << std::endl;
         std::cerr << "v " << std::hexfloat << v << std::endl;
         std::cerr << "v2 " << std::hexfloat << v2 << std::endl;
         std::cerr << "midv " << std::hexfloat << midv << std::endl;
-        std::cerr << "expected_midv " << std::hexfloat << expected_midv << std::endl;
-        std::cerr << "I got " << std::hexfloat << result_value << " but I was expecting " << v
+        std::cerr << "expected_midv " << std::hexfloat << expected_midv
                   << std::endl;
+        std::cerr << "I got " << std::hexfloat << result_value
+                  << " but I was expecting " << v << std::endl;
         return false;
       } else if (result_value != str_answer) {
         std::cerr << "no match ? " << buffer << std::endl;
         std::cerr << "v " << std::hexfloat << v << std::endl;
         std::cerr << "v2 " << std::hexfloat << v2 << std::endl;
         std::cerr << "midv " << std::hexfloat << midv << std::endl;
-        std::cerr << "expected_midv " << std::hexfloat << expected_midv << std::endl;
+        std::cerr << "expected_midv " << std::hexfloat << expected_midv
+                  << std::endl;
         std::cout << "started with " << std::hexfloat << midv << std::endl;
-        std::cout << "round down to " << std::hexfloat << str_answer << std::endl;
+        std::cout << "round down to " << std::hexfloat << str_answer
+                  << std::endl;
         std::cout << "got back " << std::hexfloat << result_value << std::endl;
         std::cout << std::dec;
         return false;
@@ -127,15 +155,25 @@ bool allvalues() {
 }
 
 inline void Assert(bool Assertion) {
-#if defined(__CYGWIN__) || defined(__MINGW32__) || defined(__MINGW64__)  || defined(sun) || defined(__sun)
-  if (!Assertion) { std::cerr << "Omitting hard falure on msys/cygwin/sun systems."; }
+#if defined(__CYGWIN__) || defined(__MINGW32__) || defined(__MINGW64__) ||     \
+    defined(sun) || defined(__sun)
+  if (!Assertion) {
+    std::cerr << "Omitting hard failure on msys/cygwin/sun systems.";
+  }
 #else
-  if (!Assertion) { throw std::runtime_error("bug"); }
+  if (!Assertion) {
+    throw std::runtime_error("bug");
+  }
 #endif
 }
+
 int main() {
-#if defined(__CYGWIN__) || defined(__MINGW32__) || defined(__MINGW64__) || defined(sun) || defined(__sun)
-  std::cout << "Warning: msys/cygwin or solaris detected. This particular test is likely to generate false failures due to our reliance on the underlying runtime library as a gold standard." << std::endl;
+#if defined(__CYGWIN__) || defined(__MINGW32__) || defined(__MINGW64__) ||     \
+    defined(sun) || defined(__sun)
+  std::cout << "Warning: msys/cygwin or solaris detected. This particular test "
+               "is likely to generate false failures due to our reliance on "
+               "the underlying runtime library as a gold standard."
+            << std::endl;
 #endif
   Assert(allvalues());
   std::cout << std::endl;

tests/fixedwidthtest.cpp

@@ -0,0 +1,70 @@
+#include <cstdlib>
+#include <iostream>
+#include <vector>
+#include <cstring>
+#include "fast_float/fast_float.h"
+#include <cstdint>
+
+#if __cplusplus >= 202300L
+#include <stdfloat>
+#endif
+
+int main() {
+  // Write some testcases for the parsing of floating point numbers in the
+  // float32_t type. We use the from_chars function defined in this library.
+#ifdef __STDCPP_FLOAT32_T__
+  std::vector<std::float32_t> const float32_test_expected{
+      123.456f, -78.9f, 0.0001f, 3.40282e+038f};
+  std::vector<std::string_view> const float32_test{"123.456", "-78.9", "0.0001",
+                                                   "3.40282e+038"};
+  std::cout << "runing float32 test" << std::endl;
+  for (std::size_t i = 0; i < float32_test.size(); ++i) {
+    auto const &f = float32_test[i];
+    std::float32_t result;
+    auto answer = fast_float::from_chars(f.data(), f.data() + f.size(), result);
+
+    if (answer.ec != std::errc()) {
+      std::cerr << "Failed to parse: \"" << f << "\"" << std::endl;
+      return EXIT_FAILURE;
+    }
+    if (result != float32_test_expected[i]) {
+      std::cerr << "Test failed for input: \"" << f << "\" expected "
+                << float32_test_expected[i] << " got " << result << std::endl;
+      return EXIT_FAILURE;
+    }
+  }
+#else
+  std::cout << "No std::float32_t type available." << std::endl;
+#endif
+
+#ifdef __STDCPP_FLOAT64_T__
+  // Test cases for std::float64_t
+  std::vector<std::float64_t> const float64_test_expected{
+      1.23e4, -5.67e-8, 1.7976931348623157e+308, -1.7976931348623157e+308};
+  std::vector<std::string_view> const float64_test{"1.23e4", "-5.67e-8",
+                                                   "1.7976931348623157e+308",
+                                                   "-1.7976931348623157e+308"};
+  std::cout << "runing float64 test" << std::endl;
+  for (std::size_t i = 0; i < float64_test.size(); ++i) {
+    auto const &f = float64_test[i];
+    std::float64_t result;
+    auto answer = fast_float::from_chars(f.data(), f.data() + f.size(), result);
+
+    if (answer.ec != std::errc()) {
+      std::cerr << "Failed to parse: \"" << f << "\"" << std::endl;
+      return EXIT_FAILURE;
+    }
+    if (result != float64_test_expected[i]) {
+      std::cerr << "Test failed for input: \"" << f << "\" expected "
+                << float64_test_expected[i] << " got " << result << std::endl;
+      return EXIT_FAILURE;
+    }
+  }
+#else
+  std::cout << "No std::float64_t type available." << std::endl;
+#endif
+  std::cout << "All tests passed successfully." << std::endl;
+  return EXIT_SUCCESS;
+
+  return 0;
+}

tests/fortran.cpp

@@ -0,0 +1,75 @@
+/*
+ * Exercise the Fortran conversion option.
+ */
+#include <cstdlib>
+#include <iostream>
+#include <vector>
+#include "fast_float/fast_float.h"
+
+int main_readme() {
+  std::string const input = "1d+4";
+  double result;
+  fast_float::parse_options options{
+      fast_float::chars_format::fortran |
+      fast_float::chars_format::allow_leading_plus};
+  auto answer = fast_float::from_chars_advanced(
+      input.data(), input.data() + input.size(), result, options);
+  if ((answer.ec != std::errc()) || ((result != 10000))) {
+    std::cerr << "parsing failure\n" << result << "\n";
+    return EXIT_FAILURE;
+  }
+  std::cout << "parsed the number " << result << std::endl;
+  return EXIT_SUCCESS;
+}
+
+int main() {
+  std::vector<double> const expected{10000, 1000, 100,  10,   1,
+                                     .1,    .01,  .001, .0001};
+  std::vector<std::string> const fmt1{"1+4", "1+3", "1+2", "1+1", "1+0",
+                                      "1-1", "1-2", "1-3", "1-4"};
+  std::vector<std::string> const fmt2{"1d+4", "1d+3", "1d+2", "1d+1", "1d+0",
+                                      "1d-1", "1d-2", "1d-3", "1d-4"};
+  std::vector<std::string> const fmt3{"+1+4", "+1+3", "+1+2", "+1+1", "+1+0",
+                                      "+1-1", "+1-2", "+1-3", "+1-4"};
+  fast_float::parse_options const options{
+      fast_float::chars_format::fortran |
+      fast_float::chars_format::allow_leading_plus};
+
+  for (auto const &f : fmt1) {
+    auto d{std::distance(&fmt1[0], &f)};
+    double result;
+    auto answer{fast_float::from_chars_advanced(f.data(), f.data() + f.size(),
+                                                result, options)};
+    if (answer.ec != std::errc() || result != expected[std::size_t(d)]) {
+      std::cerr << "parsing failure on " << f << std::endl;
+      return EXIT_FAILURE;
+    }
+  }
+
+  for (auto const &f : fmt2) {
+    auto d{std::distance(&fmt2[0], &f)};
+    double result;
+    auto answer{fast_float::from_chars_advanced(f.data(), f.data() + f.size(),
+                                                result, options)};
+    if (answer.ec != std::errc() || result != expected[std::size_t(d)]) {
+      std::cerr << "parsing failure on " << f << std::endl;
+      return EXIT_FAILURE;
+    }
+  }
+
+  for (auto const &f : fmt3) {
+    auto d{std::distance(&fmt3[0], &f)};
+    double result;
+    auto answer{fast_float::from_chars_advanced(f.data(), f.data() + f.size(),
+                                                result, options)};
+    if (answer.ec != std::errc() || result != expected[std::size_t(d)]) {
+      std::cerr << "parsing failure on " << f << std::endl;
+      return EXIT_FAILURE;
+    }
+  }
+  if (main_readme() != EXIT_SUCCESS) {
+    return EXIT_FAILURE;
+  }
+
+  return EXIT_SUCCESS;
+}

tests/installation_tests/find/CMakeLists.txt

@@ -1,8 +1,9 @@
 cmake_minimum_required(VERSION 3.15)
 
-project(test_simdjson_install VERSION 0.1.0 LANGUAGES CXX)
+project(test_install VERSION 0.1.0 LANGUAGES CXX)
 
-set(CMAKE_CXX_STANDARD 17)
+set(FASTFLOAT_CXX_STANDARD 17 CACHE STRING "the C++ standard to use for fastfloat")
+set(CMAKE_CXX_STANDARD ${FASTFLOAT_CXX_STANDARD})
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 if(MSVC_VERSION GREATER 1910)
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -permissive-")
@@ -16,10 +17,10 @@ file(WRITE main.cpp "
 #include <iostream>
 
 int main() {
-    const std::string input =  \"3.1416 xyz \";
+    std::string input = \"3.1416 xyz \";
     double result;
     auto answer = fast_float::from_chars(input.data(), input.data()+input.size(), result);
-    if(answer.ec != std::errc()) { std::cerr << \"parsing failure\\n\"; return EXIT_FAILURE; }
+    if (answer.ec != std::errc()) { std::cerr << \"parsing failure\\n\"; return EXIT_FAILURE; }
     std::cout << \"parsed the number \" << result << std::endl;
     return EXIT_SUCCESS;
 }")

tests/json_fmt.cpp

@@ -0,0 +1,170 @@
+
+#include <cstdlib>
+#include <iostream>
+#include <vector>
+#include "fast_float/fast_float.h"
+
+int main_readme() {
+  std::string const input = "+.1"; // not valid
+  double result;
+  fast_float::parse_options options{
+      fast_float::chars_format::json |
+      fast_float::chars_format::allow_leading_plus}; // should be ignored
+  auto answer = fast_float::from_chars_advanced(
+      input.data(), input.data() + input.size(), result, options);
+  if (answer.ec == std::errc()) {
+    std::cerr << "should have failed\n";
+    return EXIT_FAILURE;
+  }
+  return EXIT_SUCCESS;
+}
+
+int main_readme2() {
+  std::string const input = "inf"; // not valid in JSON
+  double result;
+  fast_float::parse_options options{
+      fast_float::chars_format::json |
+      fast_float::chars_format::allow_leading_plus}; // should be ignored
+  auto answer = fast_float::from_chars_advanced(
+      input.data(), input.data() + input.size(), result, options);
+  if (answer.ec == std::errc()) {
+    std::cerr << "should have failed\n";
+    return EXIT_FAILURE;
+  }
+  return EXIT_SUCCESS;
+}
+
+int main_readme3() {
+  std::string const input =
+      "inf"; // not valid in JSON but we allow it with json_or_infnan
+  double result;
+  fast_float::parse_options options{
+      fast_float::chars_format::json_or_infnan |
+      fast_float::chars_format::allow_leading_plus}; // should be ignored
+  auto answer = fast_float::from_chars_advanced(
+      input.data(), input.data() + input.size(), result, options);
+  if (answer.ec != std::errc() || (!std::isinf(result))) {
+    std::cerr << "should have parsed infinity\n";
+    return EXIT_FAILURE;
+  }
+  return EXIT_SUCCESS;
+}
+
+struct ExpectedResult {
+  double value;
+  std::string junk_chars;
+};
+
+struct AcceptedValue {
+  std::string input;
+  ExpectedResult expected;
+};
+
+struct RejectReason {
+  fast_float::parse_error error;
+  intptr_t location_offset;
+};
+
+struct RejectedValue {
+  std::string input;
+  RejectReason reason;
+};
+
+int main() {
+  std::vector<AcceptedValue> const accept{
+      {"-0.2", {-0.2, ""}},
+      {"0.02", {0.02, ""}},
+      {"0.002", {0.002, ""}},
+      {"1e+0000", {1., ""}},
+      {"0e-2", {0., ""}},
+      {"1e", {1., "e"}},
+      {"1e+", {1., "e+"}},
+      {"inf", {std::numeric_limits<double>::infinity(), ""}}};
+  std::vector<RejectedValue> const reject{
+      {"-.2", {fast_float::parse_error::missing_integer_after_sign, 1}},
+      {"00.02", {fast_float::parse_error::leading_zeros_in_integer_part, 0}},
+      {"0.e+1", {fast_float::parse_error::no_digits_in_fractional_part, 2}},
+      {"00.e+1", {fast_float::parse_error::leading_zeros_in_integer_part, 0}},
+      {".25", {fast_float::parse_error::no_digits_in_integer_part, 0}},
+      // The following cases already start as invalid JSON, so they are
+      // handled as trailing junk and the error is for not having digits in the
+      // empty string before the invalid token.
+      {"+0.25", {fast_float::parse_error::no_digits_in_integer_part, 0}},
+      {"inf", {fast_float::parse_error::no_digits_in_integer_part, 0}},
+      {"nan(snan)", {fast_float::parse_error::no_digits_in_integer_part, 0}}};
+
+  for (std::size_t i = 0; i < accept.size(); ++i) {
+    auto const &s = accept[i].input;
+    auto const &expected = accept[i].expected;
+    double result;
+    auto answer =
+        fast_float::from_chars(s.data(), s.data() + s.size(), result,
+                               fast_float::chars_format::json_or_infnan);
+    if (answer.ec != std::errc()) {
+      std::cerr << "json fmt rejected valid json " << s << std::endl;
+      return EXIT_FAILURE;
+    }
+    if (result != expected.value) {
+      std::cerr << "json fmt gave wrong result " << s << " (expected "
+                << expected.value << " got " << result << ")" << std::endl;
+      return EXIT_FAILURE;
+    }
+    if (std::string(answer.ptr) != expected.junk_chars) {
+      std::cerr << "json fmt has wrong trailing characters " << s
+                << " (expected " << expected.junk_chars << " got " << answer.ptr
+                << ")" << std::endl;
+      return EXIT_FAILURE;
+    }
+  }
+
+  for (std::size_t i = 0; i < reject.size(); ++i) {
+    auto const &s = reject[i].input;
+    double result;
+    auto answer = fast_float::from_chars(s.data(), s.data() + s.size(), result,
+                                         fast_float::chars_format::json);
+    if (answer.ec == std::errc()) {
+      std::cerr << "json fmt accepted invalid json " << s << std::endl;
+      return EXIT_FAILURE;
+    }
+  }
+
+  for (std::size_t i = 0; i < reject.size(); ++i) {
+    auto const &f = reject[i].input;
+    auto const &expected_reason = reject[i].reason;
+    auto answer = fast_float::parse_number_string<true>(
+        f.data(), f.data() + f.size(),
+        fast_float::parse_options(
+            fast_float::chars_format::json |
+            fast_float::chars_format::allow_leading_plus)); // should be ignored
+    if (answer.valid) {
+      std::cerr << "json parse accepted invalid json " << f << std::endl;
+      return EXIT_FAILURE;
+    }
+    if (answer.error != expected_reason.error) {
+      std::cerr << "json parse failure had invalid error reason " << f
+                << std::endl;
+      return EXIT_FAILURE;
+    }
+    intptr_t error_location = answer.lastmatch - f.data();
+    if (error_location != expected_reason.location_offset) {
+      std::cerr << "json parse failure had invalid error location " << f
+                << " (expected " << expected_reason.location_offset << " got "
+                << error_location << ")" << std::endl;
+      return EXIT_FAILURE;
+    }
+  }
+
+  if (main_readme() != EXIT_SUCCESS) {
+    return EXIT_FAILURE;
+  }
+  if (main_readme2() != EXIT_SUCCESS) {
+    return EXIT_FAILURE;
+  }
+#ifndef __FAST_MATH__
+  if (main_readme3() != EXIT_SUCCESS) {
+    return EXIT_FAILURE;
+  }
+#endif
+
+  return EXIT_SUCCESS;
+}

tests/long_exhaustive32.cpp

@@ -1,13 +1,15 @@
 
 #include "fast_float/fast_float.h"
 
-#include <iostream>
 #include <cassert>
 #include <cmath>
+#include <cstdio>
+#include <ios>
+#include <iostream>
+#include <system_error>
 
 template <typename T> char *to_string(T d, char *buffer) {
-  auto written = std::snprintf(buffer, 128, "%.*e",
-                               64, d);
+  auto written = std::snprintf(buffer, 128, "%.*e", 64, d);
   return buffer + written;
 }
 
@@ -23,10 +25,15 @@ void allvalues() {
     memcpy(&v, &word, sizeof(v));
 
     {
-      const char *string_end = to_string(v, buffer);
+      char const *string_end = to_string(v, buffer);
       float result_value;
       auto result = fast_float::from_chars(buffer, string_end, result_value);
-      if (result.ec != std::errc()) {
+      // Starting with version 4.0 for fast_float, we return result_out_of_range
+      // if the value is either too small (too close to zero) or too large
+      // (effectively infinity). So std::errc::result_out_of_range is normal for
+      // well-formed input strings.
+      if (result.ec != std::errc() &&
+          result.ec != std::errc::result_out_of_range) {
         std::cerr << "parsing error ? " << buffer << std::endl;
         abort();
       }
@@ -35,13 +42,14 @@ void allvalues() {
           std::cerr << "not nan" << buffer << std::endl;
           abort();
         }
-      } else if(copysign(1,result_value) != copysign(1,v)) {
+      } else if (copysign(1, result_value) != copysign(1, v)) {
         std::cerr << buffer << std::endl;
-        std::cerr << "I got " << std::hexfloat << result_value << " but I was expecting " << v
-              << std::endl;
+        std::cerr << "I got " << std::hexfloat << result_value
+                  << " but I was expecting " << v << std::endl;
         abort();
       } else if (result_value != v) {
-        std::cerr << "no match ? " << buffer << " got " <<  result_value << " expected " << v << std::endl;
+        std::cerr << "no match ? " << buffer << " got " << result_value
+                  << " expected " << v << std::endl;
         std::cout << "started with " << std::hexfloat << v << std::endl;
         std::cout << "got back " << std::hexfloat << result_value << std::endl;
         std::cout << std::dec;

tests/long_exhaustive32_64.cpp

@@ -1,12 +1,13 @@
 #include "fast_float/fast_float.h"
 
-#include <iostream>
 #include <cassert>
 #include <cmath>
+#include <cstdio>
+#include <ios>
+#include <iostream>
 
 template <typename T> char *to_string(T d, char *buffer) {
-  auto written = std::snprintf(buffer, 128, "%.*e",
-                               64, d);
+  auto written = std::snprintf(buffer, 128, "%.*e", 64, d);
   return buffer + written;
 }
 
@@ -23,16 +24,26 @@ void all_32bit_values() {
     double v = v32;
 
     {
-      const char *string_end = to_string(v, buffer);
+      char const *string_end = to_string(v, buffer);
       double result_value;
       auto result = fast_float::from_chars(buffer, string_end, result_value);
-      if (result.ec != std::errc()) {
+      // Starting with version 4.0 for fast_float, we return result_out_of_range
+      // if the value is either too small (too close to zero) or too large
+      // (effectively infinity). So std::errc::result_out_of_range is normal for
+      // well-formed input strings.
+      if (result.ec != std::errc() &&
+          result.ec != std::errc::result_out_of_range) {
         std::cerr << "parsing error ? " << buffer << std::endl;
         abort();
       }
-      if(copysign(1,result_value) != copysign(1,v)) {
-        std::cerr << "I got " << std::hexfloat << result_value << " but I was expecting " << v
-              << std::endl;
+      if (std::isnan(v)) {
+        if (!std::isnan(result_value)) {
+          std::cerr << "not nan" << buffer << std::endl;
+          abort();
+        }
+      } else if (copysign(1, result_value) != copysign(1, v)) {
+        std::cerr << "I got " << std::hexfloat << result_value
+                  << " but I was expecting " << v << std::endl;
         abort();
       } else if (std::isnan(v)) {
         if (!std::isnan(result_value)) {

tests/long_random64.cpp

@@ -1,12 +1,14 @@
 #include "fast_float/fast_float.h"
 
-#include <iostream>
 #include <cassert>
 #include <cmath>
+#include <cstdio>
+#include <ios>
+#include <iostream>
+#include <system_error>
 
 template <typename T> char *to_string(T d, char *buffer) {
-  auto written = std::snprintf(buffer, 128, "%.*e",
-                               64, d);
+  auto written = std::snprintf(buffer, 128, "%.*e", 64, d);
   return buffer + written;
 }
 
@@ -30,7 +32,8 @@ static inline void lehmer64_seed(uint64_t seed) {
 }
 
 static inline uint64_t lehmer64() {
-  fast_float::value128 v = fast_float::full_multiplication(g_lehmer64_state.low,UINT64_C(0xda942042e4dd58b5));
+  fast_float::value128 v = fast_float::full_multiplication(
+      g_lehmer64_state.low, UINT64_C(0xda942042e4dd58b5));
   v.high += g_lehmer64_state.high * UINT64_C(0xda942042e4dd58b5);
   g_lehmer64_state = v;
   return v.high;
@@ -50,15 +53,21 @@ void random_values(size_t N) {
     double v;
     memcpy(&v, &word, sizeof(v));
     {
-      const char *string_end = to_string(v, buffer);
+      char const *string_end = to_string(v, buffer);
       double result_value;
       auto result = fast_float::from_chars(buffer, string_end, result_value);
-      if (result.ec != std::errc()) {
+      // Starting with version 4.0 for fast_float, we return result_out_of_range
+      // if the value is either too small (too close to zero) or too large
+      // (effectively infinity). So std::errc::result_out_of_range is normal for
+      // well-formed input strings.
+      if (result.ec != std::errc() &&
+          result.ec != std::errc::result_out_of_range) {
         std::cerr << "parsing error ? " << buffer << std::endl;
         errors++;
         if (errors > 10) {
           abort();
         }
+        continue;
       }
       if (std::isnan(v)) {
         if (!std::isnan(result_value)) {
@@ -68,10 +77,10 @@ void random_values(size_t N) {
             abort();
           }
         }
-      } else if(copysign(1,result_value) != copysign(1,v)) {
+      } else if (copysign(1, result_value) != copysign(1, v)) {
         std::cerr << buffer << std::endl;
-        std::cerr << "I got " << std::hexfloat << result_value << " but I was expecting " << v
-              << std::endl;
+        std::cerr << "I got " << std::hexfloat << result_value
+                  << " but I was expecting " << v << std::endl;
         abort();
       } else if (result_value != v) {
         std::cerr << "no match ? '" << buffer << "'" << std::endl;
@@ -90,7 +99,8 @@ void random_values(size_t N) {
 
 int main() {
   errors = 0;
-  size_t N = size_t(1) << (sizeof(size_t) * 4); // shift: 32 for 64bit, 16 for 32bit
+  size_t N =
+      size_t(1) << (sizeof(size_t) * 4); // shift: 32 for 64bit, 16 for 32bit
   random_values(N);
   if (errors == 0) {
     std::cout << std::endl;

tests/long_test.cpp

@@ -1,38 +1,49 @@
 #include "fast_float/fast_float.h"
 
+#include <cctype>
+#include <iostream>
+#include <stdexcept>
+#include <string>
+#include <system_error>
 #include <vector>
 
 inline void Assert(bool Assertion) {
-  if (!Assertion) { throw std::runtime_error("bug"); }
+  if (!Assertion) {
+    throw std::runtime_error("bug");
+  }
 }
 
-template <typename T>
-bool test() {
-  std::string input = "0.156250000000000000000000000000000000000000  3.14159265358979323846264338327950288419716939937510 2.71828182845904523536028747135266249775724709369995";
-  std::vector<T> answers = {T(0.15625), T(3.141592653589793), T(2.718281828459045)};
-  const char * begin = input.data();
-  const char * end = input.data() + input.size();
-  for(size_t i = 0; i < answers.size(); i++) {
+template <typename T> bool test() {
+  std::string input = "0.156250000000000000000000000000000000000000  "
+                      "3.14159265358979323846264338327950288419716939937510 "
+                      "2.71828182845904523536028747135266249775724709369995";
+  std::vector<T> answers = {T(0.15625), T(3.141592653589793),
+                            T(2.718281828459045)};
+  char const *begin = input.data();
+  char const *end = input.data() + input.size();
+  for (size_t i = 0; i < answers.size(); i++) {
     T result_value;
-    auto result = fast_float::from_chars(begin, end,
-                                      result_value);
-    if (result.ec != std::errc()) {
+    while ((begin < end) && (std::isspace(*begin))) {
+      begin++;
+    }
+    auto result = fast_float::from_chars(begin, end, result_value);
+    if (result.ec != std::errc() &&
+        result.ec != std::errc::result_out_of_range) {
       printf("parsing %.*s\n", int(end - begin), begin);
       std::cerr << " I could not parse " << std::endl;
       return false;
     }
-    if(result_value != answers[i]) {
+    if (result_value != answers[i]) {
       printf("parsing %.*s\n", int(end - begin), begin);
       std::cerr << " Mismatch " << std::endl;
       std::cerr << " Expected " << answers[i] << std::endl;
       std::cerr << " Got      " << result_value << std::endl;
 
       return false;
-
     }
     begin = result.ptr;
   }
-  if(begin != end) {
+  if (begin != end) {
     std::cerr << " bad ending " << std::endl;
     return false;
   }