From 591996e21ac2bc8a64f6ad63cb4b37c74f8abaf8 Mon Sep 17 00:00:00 2001
From: John Wellbelove <jwellbelove@users.noreply.github.com>
Date: Fri, 4 Aug 2023 11:57:49 +0100
Subject: [PATCH] Added C++20 four iterator std::equal variants

---
 include/etl/algorithm.h           | 27 ++++++++++++++++++++++++---
 test/test_span_dynamic_extent.cpp | 10 +++++-----
 test/test_span_fixed_extent.cpp   |  5 +++++
 3 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/include/etl/algorithm.h b/include/etl/algorithm.h
index cb287de1..a2b06182 100644
--- a/include/etl/algorithm.h
+++ b/include/etl/algorithm.h
@@ -560,6 +560,7 @@ namespace etl
   //***************************************************************************
   // equal
 #if ETL_USING_STL && ETL_USING_CPP20
+  // Three parameter
   template <typename TIterator1, typename TIterator2>
   [[nodiscard]]
   constexpr
@@ -568,6 +569,7 @@ namespace etl
     return std::equal(first1, last1, first2);
   }
 
+  // Three parameter + predicate
   template <typename TIterator1, typename TIterator2, typename TPredicate>
   [[nodiscard]]
   constexpr
@@ -575,8 +577,27 @@ namespace etl
   {
     return std::equal(first1, last1, first2, predicate);
   }
+
+  // Four parameter
+  template <typename TIterator1, typename TIterator2>
+  [[nodiscard]]
+  constexpr
+  bool equal(TIterator1 first1, TIterator1 last1, TIterator2 first2, TIterator2 last2)
+  {
+    return std::equal(first1, last1, first2, last2);
+  }
+
+  // Four parameter + Predicate
+  template <typename TIterator1, typename TIterator2, typename TPredicate>
+  [[nodiscard]]
+  constexpr
+  bool equal(TIterator1 first1, TIterator1 last1, TIterator2 first2, TIterator2 last2, TPredicate predicate)
+  {
+    return std::equal(first1, last1, first2, last2, predicate);
+  }
+
 #else
-  // Not pointer types or not trivially copyable.
+
   template <typename TIterator1, typename TIterator2>
   ETL_NODISCARD
   ETL_CONSTEXPR14
@@ -639,8 +660,8 @@ namespace etl
   // Four parameter, Predicate
   template <typename TIterator1, typename TIterator2, typename TPredicate>
   ETL_NODISCARD
-    ETL_CONSTEXPR14
-    bool equal(TIterator1 first1, TIterator1 last1, TIterator2 first2, TIterator2 last2, TPredicate predicate)
+  ETL_CONSTEXPR14
+  bool equal(TIterator1 first1, TIterator1 last1, TIterator2 first2, TIterator2 last2, TPredicate predicate)
   {
     while ((first1 != last1) && (first2 != last2))
     {
diff --git a/test/test_span_dynamic_extent.cpp b/test/test_span_dynamic_extent.cpp
index 8e1a62c5..cf62fcf6 100644
--- a/test/test_span_dynamic_extent.cpp
+++ b/test/test_span_dynamic_extent.cpp
@@ -42,12 +42,12 @@ namespace
   {
     static const size_t SIZE = 10UL;
 
-    typedef etl::array<int, SIZE> EtlData;
-    typedef std::array<int, SIZE> StlData;
-    typedef std::vector<int> StlVData;
+    using EtlData  = etl::array<int, SIZE>;
+    using StlData  = std::array<int, SIZE>;
+    using StlVData = std::vector<int>;
 
-    typedef etl::span<int> View;
-    typedef etl::span<const int> CView;
+    using View  = etl::span<int>;
+    using CView = etl::span<const int>;
 
     EtlData etldata = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
     StlData stldata = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
diff --git a/test/test_span_fixed_extent.cpp b/test/test_span_fixed_extent.cpp
index 26469511..a4307e69 100644
--- a/test/test_span_fixed_extent.cpp
+++ b/test/test_span_fixed_extent.cpp
@@ -47,6 +47,7 @@ namespace
     typedef std::vector<int> StlVData;
 
     typedef etl::span<int, 10U> View;
+    typedef etl::span<int, 9U> SView;
     typedef etl::span<const int, 10U> CView;
 
     EtlData etldata = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
@@ -998,6 +999,7 @@ namespace
       etl::array<int, 10> data1{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
       etl::array<int, 10> data2{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
       etl::array<int, 10> data3{ 0, 1, 2, 3, 4, 4, 6, 7, 8, 9 };
+      etl::array<int, 9>  data4{ 0, 1, 2, 3, 4, 5, 6, 7, 8 };
 
       View view1{ data1 };
       View view2{ data1 };
@@ -1005,18 +1007,21 @@ namespace
       View view4{ data3 };
       View view6;
       View view7;
+      SView view8{ data4 };
 
       CHECK_TRUE(etl::equal(view1, view2));
       CHECK_TRUE(etl::equal(view1, view3));
       CHECK_FALSE(etl::equal(view1, view4));
       CHECK_TRUE(etl::equal(view6, view6));
       CHECK_TRUE(etl::equal(view6, view7));
+      CHECK_FALSE(etl::equal(view1, view8));
 
       CHECK_TRUE(view1 == view2);
       CHECK_FALSE(view1 == view3);
       CHECK_FALSE(view1 == view4);
       CHECK_TRUE(view6 == view6);
       CHECK_TRUE(view6 == view7);
+      CHECK_FALSE(view1 == view8);
     }
 
     //*************************************************************************