gcc/libstdc++-v3/include/std/string
Jonathan Wakely 0cb78ef4bc Define std::hash specializations for C++17 PMR strings
These hash specializations should have been added when the pmr::string
and related typedefs were added.

	* include/std/string (__hash_string_base): New class template defining
	operator() for hashing strings.
	(hash<pmr::string>, hash<pmr::u8string>, hash<pmr::u16string>)
	(hash<pmr::u32string>, hash<pmr::wstring>): Define for C++17.
	* testsuite/21_strings/basic_string/hash/hash.cc: New test.
	* testsuite/21_strings/basic_string/hash/hash_char8_t.cc: New test.

From-SVN: r270116
2019-04-03 10:47:47 +01:00

148 lines
4.5 KiB
C++

// Components for manipulating sequences of characters -*- C++ -*-
// Copyright (C) 1997-2019 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file include/string
* This is a Standard C++ Library header.
*/
//
// ISO C++ 14882: 21 Strings library
//
#ifndef _GLIBCXX_STRING
#define _GLIBCXX_STRING 1
#pragma GCC system_header
#include <bits/c++config.h>
#include <bits/stringfwd.h>
#include <bits/char_traits.h> // NB: In turn includes stl_algobase.h
#include <bits/allocator.h>
#include <bits/cpp_type_traits.h>
#include <bits/localefwd.h> // For operators >>, <<, and getline.
#include <bits/ostream_insert.h>
#include <bits/stl_iterator_base_types.h>
#include <bits/stl_iterator_base_funcs.h>
#include <bits/stl_iterator.h>
#include <bits/stl_function.h> // For less
#include <ext/numeric_traits.h>
#include <bits/stl_algobase.h>
#if __cplusplus > 201703L
# include <bits/stl_algo.h> // For remove and remove_if
#endif // C++20
#include <bits/range_access.h>
#include <bits/basic_string.h>
#include <bits/basic_string.tcc>
#if __cplusplus >= 201703L && _GLIBCXX_USE_CXX11_ABI
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
namespace pmr {
template<typename _Tp> class polymorphic_allocator;
template<typename _CharT, typename _Traits = char_traits<_CharT>>
using basic_string = std::basic_string<_CharT, _Traits,
polymorphic_allocator<_CharT>>;
using string = basic_string<char>;
#ifdef _GLIBCXX_USE_CHAR8_T
using u8string = basic_string<char8_t>;
#endif
using u16string = basic_string<char16_t>;
using u32string = basic_string<char32_t>;
#ifdef _GLIBCXX_USE_WCHAR_T
using wstring = basic_string<wchar_t>;
#endif
} // namespace pmr
template<typename _Str>
struct __hash_string_base
: public __hash_base<size_t, _Str>
{
size_t
operator()(const _Str& __s) const noexcept
{ return hash<basic_string_view<typename _Str::value_type>>{}(__s); }
};
template<>
struct hash<pmr::string>
: public __hash_string_base<pmr::string>
{ };
#ifdef _GLIBCXX_USE_CHAR8_T
template<>
struct hash<pmr::u8string>
: public __hash_string_base<pmr::u8string>
{ };
#endif
template<>
struct hash<pmr::u16string>
: public __hash_string_base<pmr::u16string>
{ };
template<>
struct hash<pmr::u32string>
: public __hash_string_base<pmr::u32string>
{ };
#ifdef _GLIBCXX_USE_WCHAR_T
template<>
struct hash<pmr::wstring>
: public __hash_string_base<pmr::wstring>
{ };
#endif
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // C++17
#if __cplusplus > 201703L
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
#define __cpp_lib_erase_if 201900L
template<typename _CharT, typename _Traits, typename _Alloc,
typename _Predicate>
inline typename basic_string<_CharT, _Traits, _Alloc>::size_type
erase_if(basic_string<_CharT, _Traits, _Alloc>& __cont, _Predicate __pred)
{
const auto __osz = __cont.size();
__cont.erase(std::remove_if(__cont.begin(), __cont.end(), __pred),
__cont.end());
return __osz - __cont.size();
}
template<typename _CharT, typename _Traits, typename _Alloc, typename _Up>
inline typename basic_string<_CharT, _Traits, _Alloc>::size_type
erase(basic_string<_CharT, _Traits, _Alloc>& __cont, const _Up& __value)
{
const auto __osz = __cont.size();
__cont.erase(std::remove(__cont.begin(), __cont.end(), __value),
__cont.end());
return __osz - __cont.size();
}
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#endif // C++20
#endif /* _GLIBCXX_STRING */