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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
This commit is contained in:
Jonathan Wakely 2019-04-03 10:47:47 +01:00 committed by Jonathan Wakely
parent 3a3976b14e
commit 0cb78ef4bc
4 changed files with 162 additions and 0 deletions
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9
libstdc++-v3/ChangeLog
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@ -1,3 +1,12 @@
2019-04-03 Jonathan Wakely <jwakely@redhat.com>
* 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.
2019-04-01 Ville Voutilainen <ville.voutilainen@gmail.com>
Use single-visitation in variant assignment and swap and relops.

35
libstdc++-v3/include/std/string
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@ -74,6 +74,41 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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

57
libstdc++-v3/testsuite/21_strings/basic_string/hash/hash.cc Normal file
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@ -0,0 +1,57 @@
// Copyright (C) 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.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
// { dg-options "-std=gnu++17" }
// { dg-do run { target c++17 } }
#include <string>
#include <memory_resource>
#include <testsuite_hooks.h>
// C++17 24.3.5 [basic.string.hash]
// If S is one of these string types, SV is the corresponding string view type,
// and s is an object of type S, then hash<S>()(s) == hash<SV>()(SV(s)).
template<typename S>
bool
test(const S& s)
{
using std::hash;
using SV = std::basic_string_view<typename S::value_type>;
return hash<S>()(s) == hash<SV>()(SV(s));
}
void
test01()
{
VERIFY( test(std::string("a narrow string")) );
VERIFY( test(std::pmr::string("a narrow string, but with PMR!")) );
VERIFY( test(std::u16string(u"a utf-16 string")) );
VERIFY( test(std::pmr::u16string(u"a utf-16 string, but with PMR!")) );
VERIFY( test(std::u32string(U"a utf-32 string")) );
VERIFY( test(std::pmr::u32string(U"a utf-32 string, but with PMR!")) );
#if _GLIBCXX_USE_WCHAR_T
VERIFY( test(std::wstring(L"a wide string")) );
VERIFY( test(std::pmr::wstring(L"a wide string, but with PMR!")) );
#endif
}
int
main()
{
test01();
}

61
libstdc++-v3/testsuite/21_strings/basic_string/hash/hash_char8_t.cc Normal file
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@ -0,0 +1,61 @@
// Copyright (C) 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.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
// { dg-options "-std=gnu++2a" }
// { dg-do run { target c++2a } }
#include <string>
#include <memory_resource>
#include <testsuite_hooks.h>
// C++2a N4810 21.3.5 [basic.string.hash]
// If S is one of these string types, SV is the corresponding string view type,
// and s is an object of type S, then hash<S>()(s) == hash<SV>()(SV(s)).
template<typename S>
bool
test(const S& s)
{
using std::hash;
using SV = std::basic_string_view<typename S::value_type>;
return hash<S>()(s) == hash<SV>()(SV(s));
}
void
test01()
{
VERIFY( test(std::string("a narrow string")) );
VERIFY( test(std::pmr::string("a narrow string, but with PMR!")) );
VERIFY( test(std::u8string(u8"a utf-8 string")) );
VERIFY( test(std::pmr::u8string(u8"a utf-8 string, but with PMR!")) );
}
void
test02()
{
using std::hash;
std::string native("a string, a string, my stringdom for a string");
std::u8string utf8(u8"a string, a string, my stringdom for a string");
VERIFY( hash<std::string>()(native) == hash<std::u8string>()(utf8) );
}
int
main()
{
test01();
test02();
}