585da50d7d
This PR adds the code of Boost.Math as of version 1.89 into the third-party directory, as discussed in a recent RFC [1]. The goal is for this code to be used as a back-end for the C++17 Math Special Functions. As explained in third-paty/README.md, this code is cleared for usage inside libc++ for the Math Special functions, however the LLVM Foundation should be consulted before using this code anywhere else in the LLVM project, due to the fact that it is under the Boost Software License (as opposed to the usual LLVM license). See the RFC [1] for more details. [1]: https://discourse.llvm.org/t/rfc-libc-taking-a-dependency-on-boost-math-for-the-c-17-math-special-functions
86 lines
2.2 KiB
C++
86 lines
2.2 KiB
C++
// Copyright John Maddock 2016.
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// Copyright Matt Borland 2023.
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// Use, modification and distribution are subject to the
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// Boost Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_MATH_TOOLS_CONVERT_FROM_STRING_INCLUDED
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#define BOOST_MATH_TOOLS_CONVERT_FROM_STRING_INCLUDED
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#ifdef _MSC_VER
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#pragma once
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#endif
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#include <boost/math/tools/config.hpp>
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#include <type_traits>
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#ifndef BOOST_MATH_STANDALONE
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#if defined(_MSC_VER) || defined(__GNUC__)
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# pragma push_macro( "I" )
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# undef I
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#endif
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#include <boost/lexical_cast.hpp>
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#if defined(_MSC_VER) || defined(__GNUC__)
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# pragma pop_macro( "I" )
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#endif
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#endif
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namespace boost{ namespace math{ namespace tools{
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template <class T>
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struct convert_from_string_result
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{
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typedef typename std::conditional<std::is_constructible<T, const char*>::value, const char*, T>::type type;
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};
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template <class Real>
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Real convert_from_string(const char* p, const std::false_type&)
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{
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#ifdef BOOST_MATH_NO_LEXICAL_CAST
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// This function should not compile, we don't have the necessary functionality to support it:
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static_assert(sizeof(Real) == 0, "boost.lexical_cast is not supported in standalone mode.");
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(void)p; // Suppresses -Wunused-parameter
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return Real(0);
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#elif defined(BOOST_MATH_USE_CHARCONV_FOR_CONVERSION)
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if constexpr (std::is_arithmetic_v<Real>)
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{
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Real v {};
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std::from_chars(p, p + std::strlen(p), v);
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return v;
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}
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else
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{
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return boost::lexical_cast<Real>(p);
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}
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#else
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return boost::lexical_cast<Real>(p);
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#endif
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}
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template <class Real>
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constexpr const char* convert_from_string(const char* p, const std::true_type&) noexcept
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{
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return p;
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}
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template <class Real>
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constexpr typename convert_from_string_result<Real>::type convert_from_string(const char* p) noexcept((std::is_constructible<Real, const char*>::value))
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{
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return convert_from_string<Real>(p, std::is_constructible<Real, const char*>());
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}
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} // namespace tools
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} // namespace math
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} // namespace boost
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#endif // BOOST_MATH_TOOLS_CONVERT_FROM_STRING_INCLUDED
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