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gcc/libstdc++-v3/include/std/string_view
Jonathan Wakely 9af65c2b90 libstdc++: Reduce uses of std::numeric_limits 
This avoids unnecessary instantiations of std::numeric_limits or
inclusion of <limits> when a more lightweight alternative would work.
Some uses can be replaced with __gnu_cxx::__int_traits and some can just
use size_t(-1) directly where SIZE_MAX is needed.

libstdc++-v3/ChangeLog:

	* include/bits/regex.h: Use __int_traits<int> instead of
	std::numeric_limits<int>.
	* include/bits/uniform_int_dist.h: Use __int_traits<T>::__max
	instead of std::numeric_limits<T>::max().
	* include/bits/hashtable_policy.h: Use size_t(-1) instead of
	std::numeric_limits<size_t>::max().
	* include/std/regex: Include <ext/numeric_traits.h>.
	* include/std/string_view: Use typedef for __int_traits<int>.
	* src/c++11/hashtable_c++0x.cc: Use size_t(-1) instead of
	std::numeric_limits<size_t>::max().
	* testsuite/std/ranges/iota/96042.cc: Include <limits>.
	* testsuite/std/ranges/iota/difference_type.cc: Likewise.
	* testsuite/std/ranges/subrange/96042.cc: Likewise.
2020-10-06 00:05:11 +01:00

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// Components for manipulating non-owning sequences of characters -*- C++ -*-
// Copyright (C) 2013-2020 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 string_view
* This is a Standard C++ Library header.
*/
//
// N3762 basic_string_view library
//
#ifndef _GLIBCXX_STRING_VIEW
#define _GLIBCXX_STRING_VIEW 1
#pragma GCC system_header
#if __cplusplus >= 201703L
#include <iosfwd>
#include <bits/char_traits.h>
#include <bits/functional_hash.h>
#include <bits/range_access.h>
#include <bits/ranges_base.h>
#include <bits/ostream_insert.h>
#include <ext/numeric_traits.h>
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
# define __cpp_lib_string_view 201803L
#if __cplusplus > 201703L
# define __cpp_lib_constexpr_string_view 201811L
#endif
// Helper for basic_string and basic_string_view members.
constexpr size_t
__sv_check(size_t __size, size_t __pos, const char* __s)
{
if (__pos > __size)
__throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > __size "
"(which is %zu)"), __s, __pos, __size);
return __pos;
}
// Helper for basic_string members.
// NB: __sv_limit doesn't check for a bad __pos value.
constexpr size_t
__sv_limit(size_t __size, size_t __pos, size_t __off) noexcept
{
const bool __testoff = __off < __size - __pos;
return __testoff ? __off : __size - __pos;
}
/**
* @class basic_string_view <string_view>
* @brief A non-owning reference to a string.
*
* @ingroup strings
* @ingroup sequences
*
* @tparam _CharT Type of character
* @tparam _Traits Traits for character type, defaults to
* char_traits<_CharT>.
*
* A basic_string_view looks like this:
*
* @code
* _CharT* _M_str
* size_t _M_len
* @endcode
*/
template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
class basic_string_view
{
static_assert(!is_array_v<_CharT>);
static_assert(is_trivial_v<_CharT> && is_standard_layout_v<_CharT>);
static_assert(is_same_v<_CharT, typename _Traits::char_type>);
public:
// types
using traits_type = _Traits;
using value_type = _CharT;
using pointer = value_type*;
using const_pointer = const value_type*;
using reference = value_type&;
using const_reference = const value_type&;
using const_iterator = const value_type*;
using iterator = const_iterator;
using const_reverse_iterator = std::reverse_iterator<const_iterator>;
using reverse_iterator = const_reverse_iterator;
using size_type = size_t;
using difference_type = ptrdiff_t;
static constexpr size_type npos = size_type(-1);
// [string.view.cons], construction and assignment
constexpr
basic_string_view() noexcept
: _M_len{0}, _M_str{nullptr}
{ }
constexpr basic_string_view(const basic_string_view&) noexcept = default;
__attribute__((__nonnull__)) constexpr
basic_string_view(const _CharT* __str) noexcept
: _M_len{traits_type::length(__str)},
_M_str{__str}
{ }
constexpr
basic_string_view(const _CharT* __str, size_type __len) noexcept
: _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;
// [string.view.iterators], iterator support
constexpr const_iterator
begin() const noexcept
{ return this->_M_str; }
constexpr const_iterator
end() const noexcept
{ return this->_M_str + this->_M_len; }
constexpr const_iterator
cbegin() const noexcept
{ return this->_M_str; }
constexpr const_iterator
cend() const noexcept
{ return this->_M_str + this->_M_len; }
constexpr const_reverse_iterator
rbegin() const noexcept
{ return const_reverse_iterator(this->end()); }
constexpr const_reverse_iterator
rend() const noexcept
{ return const_reverse_iterator(this->begin()); }
constexpr const_reverse_iterator
crbegin() const noexcept
{ return const_reverse_iterator(this->end()); }
constexpr const_reverse_iterator
crend() const noexcept
{ return const_reverse_iterator(this->begin()); }
// [string.view.capacity], capacity
constexpr size_type
size() const noexcept
{ return this->_M_len; }
constexpr size_type
length() const noexcept
{ return _M_len; }
constexpr size_type
max_size() const noexcept
{
return (npos - sizeof(size_type) - sizeof(void*))
/ sizeof(value_type) / 4;
}
[[nodiscard]] constexpr bool
empty() const noexcept
{ return this->_M_len == 0; }
// [string.view.access], element access
constexpr const_reference
operator[](size_type __pos) const noexcept
{
__glibcxx_assert(__pos < this->_M_len);
return *(this->_M_str + __pos);
}
constexpr const_reference
at(size_type __pos) const
{
if (__pos >= _M_len)
__throw_out_of_range_fmt(__N("basic_string_view::at: __pos "
"(which is %zu) >= this->size() "
"(which is %zu)"), __pos, this->size());
return *(this->_M_str + __pos);
}
constexpr const_reference
front() const noexcept
{
__glibcxx_assert(this->_M_len > 0);
return *this->_M_str;
}
constexpr const_reference
back() const noexcept
{
__glibcxx_assert(this->_M_len > 0);
return *(this->_M_str + this->_M_len - 1);
}
constexpr const_pointer
data() const noexcept
{ return this->_M_str; }
// [string.view.modifiers], modifiers:
constexpr void
remove_prefix(size_type __n) noexcept
{
__glibcxx_assert(this->_M_len >= __n);
this->_M_str += __n;
this->_M_len -= __n;
}
constexpr void
remove_suffix(size_type __n) noexcept
{ this->_M_len -= __n; }
constexpr void
swap(basic_string_view& __sv) noexcept
{
auto __tmp = *this;
*this = __sv;
__sv = __tmp;
}
// [string.view.ops], string operations:
_GLIBCXX20_CONSTEXPR
size_type
copy(_CharT* __str, size_type __n, size_type __pos = 0) const
{
__glibcxx_requires_string_len(__str, __n);
__pos = std::__sv_check(size(), __pos, "basic_string_view::copy");
const size_type __rlen = std::min(__n, _M_len - __pos);
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2777. basic_string_view::copy should use char_traits::copy
traits_type::copy(__str, data() + __pos, __rlen);
return __rlen;
}
constexpr basic_string_view
substr(size_type __pos = 0, size_type __n = npos) const noexcept(false)
{
__pos = std::__sv_check(size(), __pos, "basic_string_view::substr");
const size_type __rlen = std::min(__n, _M_len - __pos);
return basic_string_view{_M_str + __pos, __rlen};
}
constexpr int
compare(basic_string_view __str) const noexcept
{
const size_type __rlen = std::min(this->_M_len, __str._M_len);
int __ret = traits_type::compare(this->_M_str, __str._M_str, __rlen);
if (__ret == 0)
__ret = _S_compare(this->_M_len, __str._M_len);
return __ret;
}
constexpr int
compare(size_type __pos1, size_type __n1, basic_string_view __str) const
{ return this->substr(__pos1, __n1).compare(__str); }
constexpr int
compare(size_type __pos1, size_type __n1,
basic_string_view __str, size_type __pos2, size_type __n2) const
{
return this->substr(__pos1, __n1).compare(__str.substr(__pos2, __n2));
}
__attribute__((__nonnull__)) constexpr int
compare(const _CharT* __str) const noexcept
{ return this->compare(basic_string_view{__str}); }
__attribute__((__nonnull__)) constexpr int
compare(size_type __pos1, size_type __n1, const _CharT* __str) const
{ return this->substr(__pos1, __n1).compare(basic_string_view{__str}); }
constexpr int
compare(size_type __pos1, size_type __n1,
const _CharT* __str, size_type __n2) const noexcept(false)
{
return this->substr(__pos1, __n1)
.compare(basic_string_view(__str, __n2));
}
#if __cplusplus > 201703L
#define __cpp_lib_starts_ends_with 201711L
constexpr bool
starts_with(basic_string_view __x) const noexcept
{ return this->substr(0, __x.size()) == __x; }
constexpr bool
starts_with(_CharT __x) const noexcept
{ return !this->empty() && traits_type::eq(this->front(), __x); }
constexpr bool
starts_with(const _CharT* __x) const noexcept
{ return this->starts_with(basic_string_view(__x)); }
constexpr bool
ends_with(basic_string_view __x) const noexcept
{
return this->size() >= __x.size()
&& this->compare(this->size() - __x.size(), npos, __x) == 0;
}
constexpr bool
ends_with(_CharT __x) const noexcept
{ return !this->empty() && traits_type::eq(this->back(), __x); }
constexpr bool
ends_with(const _CharT* __x) const noexcept
{ return this->ends_with(basic_string_view(__x)); }
#endif // C++20
// [string.view.find], searching
constexpr size_type
find(basic_string_view __str, size_type __pos = 0) const noexcept
{ return this->find(__str._M_str, __pos, __str._M_len); }
constexpr size_type
find(_CharT __c, size_type __pos = 0) const noexcept;
constexpr size_type
find(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
__attribute__((__nonnull__)) constexpr size_type
find(const _CharT* __str, size_type __pos = 0) const noexcept
{ return this->find(__str, __pos, traits_type::length(__str)); }
constexpr size_type
rfind(basic_string_view __str, size_type __pos = npos) const noexcept
{ return this->rfind(__str._M_str, __pos, __str._M_len); }
constexpr size_type
rfind(_CharT __c, size_type __pos = npos) const noexcept;
constexpr size_type
rfind(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
__attribute__((__nonnull__)) constexpr size_type
rfind(const _CharT* __str, size_type __pos = npos) const noexcept
{ return this->rfind(__str, __pos, traits_type::length(__str)); }
constexpr size_type
find_first_of(basic_string_view __str, size_type __pos = 0) const noexcept
{ return this->find_first_of(__str._M_str, __pos, __str._M_len); }
constexpr size_type
find_first_of(_CharT __c, size_type __pos = 0) const noexcept
{ return this->find(__c, __pos); }
constexpr size_type
find_first_of(const _CharT* __str, size_type __pos,
size_type __n) const noexcept;
__attribute__((__nonnull__)) constexpr size_type
find_first_of(const _CharT* __str, size_type __pos = 0) const noexcept
{ return this->find_first_of(__str, __pos, traits_type::length(__str)); }
constexpr size_type
find_last_of(basic_string_view __str,
size_type __pos = npos) const noexcept
{ return this->find_last_of(__str._M_str, __pos, __str._M_len); }
constexpr size_type
find_last_of(_CharT __c, size_type __pos=npos) const noexcept
{ return this->rfind(__c, __pos); }
constexpr size_type
find_last_of(const _CharT* __str, size_type __pos,
size_type __n) const noexcept;
__attribute__((__nonnull__)) constexpr size_type
find_last_of(const _CharT* __str, size_type __pos = npos) const noexcept
{ return this->find_last_of(__str, __pos, traits_type::length(__str)); }
constexpr size_type
find_first_not_of(basic_string_view __str,
size_type __pos = 0) const noexcept
{ return this->find_first_not_of(__str._M_str, __pos, __str._M_len); }
constexpr size_type
find_first_not_of(_CharT __c, size_type __pos = 0) const noexcept;
constexpr size_type
find_first_not_of(const _CharT* __str,
size_type __pos, size_type __n) const noexcept;
__attribute__((__nonnull__)) constexpr size_type
find_first_not_of(const _CharT* __str, size_type __pos = 0) const noexcept
{
return this->find_first_not_of(__str, __pos,
traits_type::length(__str));
}
constexpr size_type
find_last_not_of(basic_string_view __str,
size_type __pos = npos) const noexcept
{ return this->find_last_not_of(__str._M_str, __pos, __str._M_len); }
constexpr size_type
find_last_not_of(_CharT __c, size_type __pos = npos) const noexcept;
constexpr size_type
find_last_not_of(const _CharT* __str,
size_type __pos, size_type __n) const noexcept;
__attribute__((__nonnull__)) constexpr size_type
find_last_not_of(const _CharT* __str,
size_type __pos = npos) const noexcept
{
return this->find_last_not_of(__str, __pos,
traits_type::length(__str));
}
private:
static constexpr int
_S_compare(size_type __n1, size_type __n2) noexcept
{
using __limits = __gnu_cxx::__int_traits<int>;
const difference_type __diff = __n1 - __n2;
if (__diff > __limits::__max)
return __limits::__max;
if (__diff < __limits::__min)
return __limits::__min;
return static_cast<int>(__diff);
}
size_t _M_len;
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
// context, so that only one argument participates in template argument
// deduction and the other argument gets implicitly converted to the deduced
// type (see N3766).
template<typename _CharT, typename _Traits>
constexpr bool
operator==(basic_string_view<_CharT, _Traits> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.size() == __y.size() && __x.compare(__y) == 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator==(basic_string_view<_CharT, _Traits> __x,
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return __x.size() == __y.size() && __x.compare(__y) == 0; }
#if __cpp_lib_three_way_comparison
template<typename _CharT, typename _Traits>
constexpr auto
operator<=>(basic_string_view<_CharT, _Traits> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
-> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
{ return __detail::__char_traits_cmp_cat<_Traits>(__x.compare(__y)); }
template<typename _CharT, typename _Traits>
constexpr auto
operator<=>(basic_string_view<_CharT, _Traits> __x,
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
-> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
{ return __detail::__char_traits_cmp_cat<_Traits>(__x.compare(__y)); }
#else
template<typename _CharT, typename _Traits>
constexpr bool
operator==(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.size() == __y.size() && __x.compare(__y) == 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator!=(basic_string_view<_CharT, _Traits> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return !(__x == __y); }
template<typename _CharT, typename _Traits>
constexpr bool
operator!=(basic_string_view<_CharT, _Traits> __x,
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return !(__x == __y); }
template<typename _CharT, typename _Traits>
constexpr bool
operator!=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return !(__x == __y); }
template<typename _CharT, typename _Traits>
constexpr bool
operator< (basic_string_view<_CharT, _Traits> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.compare(__y) < 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator< (basic_string_view<_CharT, _Traits> __x,
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return __x.compare(__y) < 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.compare(__y) < 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator> (basic_string_view<_CharT, _Traits> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.compare(__y) > 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator> (basic_string_view<_CharT, _Traits> __x,
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return __x.compare(__y) > 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator> (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.compare(__y) > 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator<=(basic_string_view<_CharT, _Traits> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.compare(__y) <= 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator<=(basic_string_view<_CharT, _Traits> __x,
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return __x.compare(__y) <= 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator<=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.compare(__y) <= 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator>=(basic_string_view<_CharT, _Traits> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.compare(__y) >= 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator>=(basic_string_view<_CharT, _Traits> __x,
__type_identity_t<basic_string_view<_CharT, _Traits>> __y)
noexcept
{ return __x.compare(__y) >= 0; }
template<typename _CharT, typename _Traits>
constexpr bool
operator>=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
basic_string_view<_CharT, _Traits> __y) noexcept
{ return __x.compare(__y) >= 0; }
#endif // three-way comparison
// [string.view.io], Inserters and extractors
template<typename _CharT, typename _Traits>
inline basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os,
basic_string_view<_CharT,_Traits> __str)
{ return __ostream_insert(__os, __str.data(), __str.size()); }
// basic_string_view typedef names
using string_view = basic_string_view<char>;
#ifdef _GLIBCXX_USE_WCHAR_T
using wstring_view = basic_string_view<wchar_t>;
#endif
#ifdef _GLIBCXX_USE_CHAR8_T
using u8string_view = basic_string_view<char8_t>;
#endif
using u16string_view = basic_string_view<char16_t>;
using u32string_view = basic_string_view<char32_t>;
// [string.view.hash], hash support:
template<typename _Tp>
struct hash;
template<>
struct hash<string_view>
: public __hash_base<size_t, string_view>
{
size_t
operator()(const string_view& __str) const noexcept
{ return std::_Hash_impl::hash(__str.data(), __str.length()); }
};
template<>
struct __is_fast_hash<hash<string_view>> : std::false_type
{ };
#ifdef _GLIBCXX_USE_WCHAR_T
template<>
struct hash<wstring_view>
: public __hash_base<size_t, wstring_view>
{
size_t
operator()(const wstring_view& __s) const noexcept
{ return std::_Hash_impl::hash(__s.data(),
__s.length() * sizeof(wchar_t)); }
};
template<>
struct __is_fast_hash<hash<wstring_view>> : std::false_type
{ };
#endif
#ifdef _GLIBCXX_USE_CHAR8_T
template<>
struct hash<u8string_view>
: public __hash_base<size_t, u8string_view>
{
size_t
operator()(const u8string_view& __str) const noexcept
{ return std::_Hash_impl::hash(__str.data(), __str.length()); }
};
template<>
struct __is_fast_hash<hash<u8string_view>> : std::false_type
{ };
#endif
template<>
struct hash<u16string_view>
: public __hash_base<size_t, u16string_view>
{
size_t
operator()(const u16string_view& __s) const noexcept
{ return std::_Hash_impl::hash(__s.data(),
__s.length() * sizeof(char16_t)); }
};
template<>
struct __is_fast_hash<hash<u16string_view>> : std::false_type
{ };
template<>
struct hash<u32string_view>
: public __hash_base<size_t, u32string_view>
{
size_t
operator()(const u32string_view& __s) const noexcept
{ return std::_Hash_impl::hash(__s.data(),
__s.length() * sizeof(char32_t)); }
};
template<>
struct __is_fast_hash<hash<u32string_view>> : std::false_type
{ };
inline namespace literals
{
inline namespace string_view_literals
{
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wliteral-suffix"
inline constexpr basic_string_view<char>
operator""sv(const char* __str, size_t __len) noexcept
{ return basic_string_view<char>{__str, __len}; }
#ifdef _GLIBCXX_USE_WCHAR_T
inline constexpr basic_string_view<wchar_t>
operator""sv(const wchar_t* __str, size_t __len) noexcept
{ return basic_string_view<wchar_t>{__str, __len}; }
#endif
#ifdef _GLIBCXX_USE_CHAR8_T
inline constexpr basic_string_view<char8_t>
operator""sv(const char8_t* __str, size_t __len) noexcept
{ return basic_string_view<char8_t>{__str, __len}; }
#endif
inline constexpr basic_string_view<char16_t>
operator""sv(const char16_t* __str, size_t __len) noexcept
{ return basic_string_view<char16_t>{__str, __len}; }
inline constexpr basic_string_view<char32_t>
operator""sv(const char32_t* __str, size_t __len) noexcept
{ return basic_string_view<char32_t>{__str, __len}; }
#pragma GCC diagnostic pop
} // namespace string_literals
} // namespace literals
#if __cpp_lib_concepts
namespace ranges
{
// Opt-in to borrowed_range concept
template<typename _CharT, typename _Traits>
inline constexpr bool
enable_borrowed_range<basic_string_view<_CharT, _Traits>> = true;
// Opt-in to view concept
template<typename _CharT, typename _Traits>
inline constexpr bool
enable_view<basic_string_view<_CharT, _Traits>> = true;
}
#endif
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
#include <bits/string_view.tcc>
#endif // __cplusplus <= 201402L
#endif // _GLIBCXX_EXPERIMENTAL_STRING_VIEW
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