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Catch2/src/catch2/internal/catch_container_nonmembers.hpp
2021-02-19 23:22:43 +01:00

74 lines
2.1 KiB
C++

// Copyright Catch2 Authors
// 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)
// SPDX-License-Identifier: BSL-1.0
#ifndef CATCH_CONTAINER_NONMEMBERS_HPP_INCLUDED
#define CATCH_CONTAINER_NONMEMBERS_HPP_INCLUDED
#include <catch2/internal/catch_compiler_capabilities.hpp>
#include <cstddef>
#include <initializer_list>
// We want a simple polyfill over `std::empty`, `std::size` and so on
// for C++14 or C++ libraries with incomplete support.
// We also have to handle that MSVC std lib will happily provide these
// under older standards.
#if defined(CATCH_CPP17_OR_GREATER) || defined(_MSC_VER)
// We are already using this header either way, so there shouldn't
// be much additional overhead in including it to get the feature
// test macros
#include <string>
# if !defined(__cpp_lib_nonmember_container_access)
# define CATCH_CONFIG_POLYFILL_NONMEMBER_CONTAINER_ACCESS
# endif
#else
#define CATCH_CONFIG_POLYFILL_NONMEMBER_CONTAINER_ACCESS
#endif
namespace Catch {
namespace Detail {
#if defined(CATCH_CONFIG_POLYFILL_NONMEMBER_CONTAINER_ACCESS)
template <typename Container>
constexpr auto empty(Container const& cont) -> decltype(cont.empty()) {
return cont.empty();
}
template <typename T, std::size_t N>
constexpr bool empty(const T (&)[N]) noexcept {
// GCC < 7 does not support the const T(&)[] parameter syntax
// so we have to ignore the length explicitly
(void)N;
return false;
}
template <typename T>
constexpr bool empty(std::initializer_list<T> list) noexcept {
return list.size() > 0;
}
template <typename Container>
constexpr auto size(Container const& cont) -> decltype(cont.size()) {
return cont.size();
}
template <typename T, std::size_t N>
constexpr std::size_t size(const T(&)[N]) noexcept {
return N;
}
#endif // CATCH_CONFIG_POLYFILL_NONMEMBER_CONTAINER_ACCESS
} // end namespace Detail
} // end namespace Catch
#endif // CATCH_CONTAINER_NONMEMBERS_HPP_INCLUDED