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- ///////////////////////////////////////////////////////////////
- // Copyright 2019 John Maddock. Distributed under the Boost
- // Software License, Version 1.0. (See accompanying file
- // LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt
- #ifndef BOOST_MP_CONSTEXPR_HPP
- #define BOOST_MP_CONSTEXPR_HPP
- #include <boost/config.hpp>
- namespace boost {
- namespace multiprecision {
- namespace std_constexpr {
- template <class T>
- inline BOOST_CXX14_CONSTEXPR void swap(T& a, T& b)
- {
- T t(a);
- a = b;
- b = t;
- }
- template <class InputIterator, class OutputIterator>
- inline BOOST_CXX14_CONSTEXPR OutputIterator copy(InputIterator first, InputIterator last, OutputIterator result)
- {
- //
- // There are 3 branches here, only one of which is selected at compile time:
- //
- #ifndef BOOST_MP_NO_CONSTEXPR_DETECTION
- if (BOOST_MP_IS_CONST_EVALUATED(*first))
- {
- // constexpr safe code, never generates runtime code:
- while (first != last)
- {
- *result = *first;
- ++first;
- ++result;
- }
- return result;
- }
- else
- #endif
- {
- #ifndef BOOST_NO_CXX17_IF_CONSTEXPR
- if constexpr (std::is_pointer<InputIterator>::value && std::is_pointer<OutputIterator>::value && std::is_trivially_copyable<typename std::remove_reference<decltype(*first)>::type>::value)
- {
- // The normal runtime branch:
- std::memcpy(result, first, (last - first) * sizeof(*first));
- return result + (last - first);
- }
- else
- #endif
- {
- // Alternate runtime branch:
- while (first != last)
- {
- *result = *first;
- ++first;
- ++result;
- }
- return result;
- }
- }
- }
- template <class I>
- inline BOOST_CXX14_CONSTEXPR bool equal(const I* first, const I* last, const I* other)
- {
- while (first != last)
- {
- if (*first != *other)
- return false;
- ++first;
- ++other;
- }
- return true;
- }
- }
- }
- } // namespace boost::multiprecision::std_constexpr
- #endif
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