FM / 11

/usr/include/c++/11

Name	Size	Mode	Actions
backward/	-	0755	rm
bits/	-	0755	rm
debug/	-	0755	rm
decimal/	-	0755	rm
experimental/	-	0755	rm
ext/	-	0755	rm
parallel/	-	0755	rm
pstl/	-	0755	rm
tr1/	-	0755	rm
tr2/	-	0755	rm
algorithm	3045	0644	edit dl rm
any	18758	0644	edit dl rm
array	13820	0644	edit dl rm
atomic	48800	0644	edit dl rm
barrier	8026	0644	edit dl rm
bit	12187	0644	edit dl rm
bitset	45995	0644	edit dl rm
cassert	1648	0644	edit dl rm
ccomplex	1335	0644	edit dl rm
cctype	2409	0644	edit dl rm
cerrno	1770	0644	edit dl rm
cfenv	2051	0644	edit dl rm
cfloat	1889	0644	edit dl rm
charconv	19761	0644	edit dl rm
chrono	97212	0644	edit dl rm
cinttypes	2157	0644	edit dl rm
ciso646	1464	0644	edit dl rm
climits	1913	0644	edit dl rm
clocale	1905	0644	edit dl rm
cmath	49382	0644	edit dl rm
codecvt	5275	0644	edit dl rm
compare	28271	0644	edit dl rm
complex	56703	0644	edit dl rm
complex.h	1596	0644	edit dl rm
concepts	12230	0644	edit dl rm
condition_variable	12780	0644	edit dl rm
coroutine	9156	0644	edit dl rm
csetjmp	1949	0644	edit dl rm
csignal	1855	0644	edit dl rm
cstdalign	1407	0644	edit dl rm
cstdarg	1868	0644	edit dl rm
cstdbool	1401	0644	edit dl rm
cstddef	6690	0644	edit dl rm
cstdint	2335	0644	edit dl rm
cstdio	4439	0644	edit dl rm
cstdlib	6325	0644	edit dl rm
cstring	3156	0644	edit dl rm
ctgmath	1360	0644	edit dl rm
ctime	2298	0644	edit dl rm
cuchar	2210	0644	edit dl rm
cwchar	6542	0644	edit dl rm
cwctype	2793	0644	edit dl rm
cxxabi.h	22280	0644	edit dl rm
deque	3973	0644	edit dl rm
exception	5017	0644	edit dl rm
execution	1803	0644	edit dl rm
fenv.h	2020	0644	edit dl rm
filesystem	1645	0644	edit dl rm
forward_list	2690	0644	edit dl rm
fstream	40680	0644	edit dl rm
functional	40200	0644	edit dl rm
future	52278	0644	edit dl rm
initializer_list	3038	0644	edit dl rm
iomanip	16547	0644	edit dl rm
ios	1601	0644	edit dl rm
iosfwd	7513	0644	edit dl rm
iostream	2697	0644	edit dl rm
istream	34098	0644	edit dl rm
iterator	2751	0644	edit dl rm
latch	2732	0644	edit dl rm
limits	71674	0644	edit dl rm
list	3657	0644	edit dl rm
locale	1488	0644	edit dl rm
map	3929	0644	edit dl rm
math.h	4573	0644	edit dl rm
memory	4513	0644	edit dl rm
memory_resource	21113	0644	edit dl rm
mutex	24223	0644	edit dl rm
new	8349	0644	edit dl rm
numbers	6244	0644	edit dl rm
numeric	26110	0644	edit dl rm
optional	40170	0644	edit dl rm
ostream	25976	0644	edit dl rm
queue	2467	0644	edit dl rm
random	1692	0644	edit dl rm
ranges	107201	0644	edit dl rm
ratio	20108	0644	edit dl rm
regex	2861	0644	edit dl rm
scoped_allocator	17649	0644	edit dl rm
semaphore	3000	0644	edit dl rm
set	3799	0644	edit dl rm
shared_mutex	24588	0644	edit dl rm
source_location	2747	0644	edit dl rm
span	13131	0644	edit dl rm
sstream	39231	0644	edit dl rm
stack	2391	0644	edit dl rm
stdexcept	9878	0644	edit dl rm
stdlib.h	2248	0644	edit dl rm
stop_token	15982	0644	edit dl rm
streambuf	29890	0644	edit dl rm
string	4645	0644	edit dl rm
string_view	26157	0644	edit dl rm
syncstream	8330	0644	edit dl rm
system_error	15006	0644	edit dl rm
tgmath.h	1360	0644	edit dl rm
thread	5919	0644	edit dl rm
tuple	62767	0644	edit dl rm
typeindex	3512	0644	edit dl rm
typeinfo	7746	0644	edit dl rm
type_traits	107667	0644	edit dl rm
unordered_map	3467	0644	edit dl rm
unordered_set	3340	0644	edit dl rm
utility	14816	0644	edit dl rm
valarray	40695	0644	edit dl rm
variant	62866	0644	edit dl rm
vector	4275	0644	edit dl rm
version	9264	0644	edit dl rm

Edit: /usr/include/c++/11/string_view (26157B)

// Components for manipulating non-owning sequences of characters -*- C++ -*-

// Copyright (C) 2013-2021 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_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/ostream_insert.h>
#include <ext/numeric_traits.h>

#if __cplusplus >= 202002L
# include <bits/ranges_base.h>
#endif

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 >= 202002L && __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)
	noexcept(noexcept(__last - __first))
	: _M_len(__last - __first), _M_str(std::to_address(__first))
	{ }

#if __cplusplus > 202002L
      template<typename _Range, typename _DRange = remove_cvref_t<_Range>>
	requires (!is_same_v<_DRange, basic_string_view>)
	  && ranges::contiguous_range<_Range>
	  && ranges::sized_range<_Range>
	  && is_same_v<ranges::range_value_t<_Range>, _CharT>
	  && (!is_convertible_v<_Range, const _CharT*>)
	  && (!requires (_DRange& __d) {
		__d.operator ::std::basic_string_view<_CharT, _Traits>();
	      })
	  && (!requires { typename _DRange::traits_type; }
	      || is_same_v<typename _DRange::traits_type, _Traits>)
	constexpr explicit
	basic_string_view(_Range&& __r)
	noexcept(noexcept(ranges::size(__r)) && noexcept(ranges::data(__r)))
	: _M_len(ranges::size(__r)), _M_str(ranges::data(__r))
	{ }
#endif // C++23
#endif // C++20

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
      {
	const auto __len = this->size();
	const auto __xlen = __x.size();
	return __len >= __xlen
	  && traits_type::compare(end() - __xlen, __x.data(), __xlen) == 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

#if __cplusplus > 202002L
#define __cpp_lib_string_contains 202011L
      constexpr bool
      contains(basic_string_view __x) const noexcept
      { return this->find(__x) != npos; }

constexpr bool
      contains(_CharT __x) const noexcept
      { return this->find(__x) != npos; }

constexpr bool
      contains(const _CharT* __x) const noexcept
      { return this->find(__x) != npos; }
#endif // C++23

// [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>>;

#if __cplusplus > 202002L
  template<ranges::contiguous_range _Range>
    basic_string_view(_Range&&)
      -> basic_string_view<ranges::range_value_t<_Range>>;
#endif
#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

cmd: