mirror of
https://github.com/fastfloat/fast_float.git
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118 lines
3.8 KiB
C++
118 lines
3.8 KiB
C++
#ifndef FASTFLOAT_CONSTEXPR_FEATURE_DETECT_H
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#define FASTFLOAT_CONSTEXPR_FEATURE_DETECT_H
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#ifdef __has_include
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#if __has_include(<version>)
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#include <version>
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#endif
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#endif
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// C++14 constexpr
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#if defined(__cpp_constexpr) && __cpp_constexpr >= 201304L
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#define FASTFLOAT_CONSTEXPR14 constexpr
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#elif defined(__cplusplus) && __cplusplus >= 201402L
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#define FASTFLOAT_CONSTEXPR14 constexpr
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#elif defined(_MSC_VER) && defined(_MSVC_LANG) && _MSVC_LANG >= 201402L
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#define FASTFLOAT_CONSTEXPR14 constexpr
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#else
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#define FASTFLOAT_CONSTEXPR14
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#endif
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// C++14 variable templates
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#if defined(__cpp_variable_templates) && __cpp_variable_templates >= 201304L
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#define FASTFLOAT_HAS_VARIABLE_TEMPLATES 1
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#elif defined(__cplusplus) && __cplusplus >= 201402L
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#define FASTFLOAT_HAS_VARIABLE_TEMPLATES 1
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#elif defined(_MSC_FULL_VER) && _MSC_FULL_VER >= 190023918L && \
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defined(_MSVC_LANG) && _MSVC_LANG >= 201402L
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#define FASTFLOAT_HAS_VARIABLE_TEMPLATES 1
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#else
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#define FASTFLOAT_HAS_VARIABLE_TEMPLATES 0
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#endif
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// C++17 if constexpr
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#if defined(__cpp_if_constexpr) && __cpp_if_constexpr >= 201606L
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#define FASTFLOAT_CONSTEXPR17 constexpr
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#elif defined(__cpp_constexpr) && __cpp_constexpr >= 201603L
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#define FASTFLOAT_CONSTEXPR17 constexpr
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#elif defined(__cplusplus) && __cplusplus >= 201703L
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#define FASTFLOAT_CONSTEXPR17 constexpr
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#elif defined(_MSC_VER) && defined(_MSVC_LANG) && _MSVC_LANG >= 201703L
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#define FASTFLOAT_CONSTEXPR17 constexpr
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#else
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#define FASTFLOAT_CONSTEXPR17
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#endif
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// C++17 inline variables
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#if defined(__cpp_inline_variables) && __cpp_inline_variables >= 201606L
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#define FASTFLOAT_INLINE_VARIABLE inline constexpr
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#elif defined(__cplusplus) && __cplusplus >= 201703L
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#define FASTFLOAT_INLINE_VARIABLE inline constexpr
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#elif defined(_MSC_VER) && defined(_MSVC_LANG) && _MSVC_LANG >= 201703L
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#define FASTFLOAT_INLINE_VARIABLE inline constexpr
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#else
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#define FASTFLOAT_INLINE_VARIABLE static constexpr
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#endif
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// Before C++17, constexpr variables may need an out-of-class definition.
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#if (defined(__cplusplus) && __cplusplus >= 201703L) || \
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(defined(_MSVC_LANG) && _MSVC_LANG >= 201703L)
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#define FASTFLOAT_DETAIL_MUST_DEFINE_CONSTEXPR_VARIABLE 0
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#else
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#define FASTFLOAT_DETAIL_MUST_DEFINE_CONSTEXPR_VARIABLE 1
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#endif
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// C++20 std::bit_cast
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#if defined(__cpp_lib_bit_cast) && __cpp_lib_bit_cast >= 201806L
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#define FASTFLOAT_HAS_BIT_CAST 1
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#else
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#define FASTFLOAT_HAS_BIT_CAST 0
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#endif
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// C++20 std::is_constant_evaluated
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#if defined(__cpp_lib_is_constant_evaluated) && \
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__cpp_lib_is_constant_evaluated >= 201811L
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#define FASTFLOAT_HAS_IS_CONSTANT_EVALUATED 1
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#define FASTFLOAT_CONSTEVAL consteval
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#else
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#define FASTFLOAT_HAS_IS_CONSTANT_EVALUATED 0
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#define FASTFLOAT_CONSTEVAL FASTFLOAT_CONSTEXPR14
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#endif
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// C++20 constexpr library support, including std::is_constant_evaluated(),
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// std::bit_cast(), and constexpr algorithms. Therefore all required library
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// feature macros must be present.
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#if FASTFLOAT_HAS_IS_CONSTANT_EVALUATED && FASTFLOAT_HAS_BIT_CAST && \
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defined(__cpp_lib_constexpr_algorithms) && \
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__cpp_lib_constexpr_algorithms >= 201806L
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#define FASTFLOAT_CONSTEXPR20 constexpr
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#define FASTFLOAT_IS_CONSTEXPR 1
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#else
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#define FASTFLOAT_CONSTEXPR20
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#define FASTFLOAT_IS_CONSTEXPR 0
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#endif
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// C++20 std::byteswap
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#if defined(__cpp_lib_byteswap) && __cpp_lib_byteswap >= 202110L
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#define FASTFLOAT_HAS_BYTESWAP 1
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#else
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#define FASTFLOAT_HAS_BYTESWAP 0
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#endif
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#if defined(__has_builtin)
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#define FASTFLOAT_HAS_BUILTIN(x) __has_builtin(x)
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#else
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#define FASTFLOAT_HAS_BUILTIN(x) false
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#endif
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#if defined(FASTFLOAT_ASSUME)
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// user provided solution
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#elif defined(__cpp_attrubute_assume)
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// For support attribute [[assume]] is declared in P1774
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#define FASTFLOAT_ASSUME(expr) [[assume(expr)]]
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#else
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#define FASTFLOAT_ASSUME(expr)
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#endif
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#endif // FASTFLOAT_CONSTEXPR_FEATURE_DETECT_H
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