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libstdc++: add range constructor for std::string_view (P1391R4)

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* include/std/string_view (basic_string_view(It, End)): Add range
	constructor and deduction guide from P1391R4.
	* testsuite/21_strings/basic_string_view/cons/char/range.cc: New test.

From-SVN: r278371
This commit is contained in:
Jonathan Wakely 2019-11-17 01:32:55 +00:00 committed by Jonathan Wakely
parent 37f33df706
commit 8857080c81
3 changed files with 61 additions and 0 deletions
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4
libstdc++-v3/ChangeLog
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@ -1,5 +1,9 @@
2019-11-17 Jonathan Wakely <jwakely@redhat.com>
* include/std/string_view (basic_string_view(It, End)): Add range
constructor and deduction guide from P1391R4.
* testsuite/21_strings/basic_string_view/cons/char/range.cc: New test.
* include/bits/regex.h (match_results): Specialize __enable_view_impl.
* include/bits/stl_set.h (set): Likewise.
* include/bits/unordered_set.h (unordered_set, unordered_multiset):

15
libstdc++-v3/include/std/string_view
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@ -130,6 +130,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
: _M_len{__len}, _M_str{__str}
{ }
#if __cplusplus > 201703L && __cpp_lib_concepts
template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
requires same_as<iter_value_t<_It>, _CharT>
&& (!convertible_to<_End, size_type>)
constexpr
basic_string_view(_It __first, _End __last)
: _M_len(__last - __first), _M_str(std::to_address(__first))
{ }
#endif
constexpr basic_string_view&
operator=(const basic_string_view&) noexcept = default;
@ -457,6 +467,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
const _CharT* _M_str;
};
#if __cplusplus > 201703L && __cpp_lib_concepts && __cpp_deduction_guides
template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
basic_string_view(_It, _End) -> basic_string_view<iter_value_t<_It>>;
#endif
// [string.view.comparison], non-member basic_string_view comparison function
// Several of these functions use type_identity_t to create a non-deduced

42
libstdc++-v3/testsuite/21_strings/basic_string_view/cons/char/range.cc Normal file
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@ -0,0 +1,42 @@
// 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_view>
#include <vector>
#include <testsuite_hooks.h>
constexpr char str[] = "abcdefg";
constexpr std::basic_string_view s(std::begin(str), std::cend(str) - 1);
static_assert( s == str );
static_assert( s.data() == str );
void
test01()
{
std::vector<char> v{'a', 'b', 'c'};
std::basic_string_view s(v.begin(), v.end());
VERIFY( s.data() == v.data() );
}
int
main()
{
test01();
}