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gcc/libstdc++-v3/include/bits/char_traits.h
Jonathan Wakely b376b1ef38 libstdc++: Simplify constexpr checks in std::char_traits [PR 91488] 
This removes the helper functions added by r8-1294 to detect whether the
char_traits member functions can be evaluated at compile time. Instead,
we can just use __builtin_constant_evaluated directly, which is well
supported by non-GCC compilers by now.

As a result, there is a chance that those members will no longer be
usable in constant expressions when using old versions of non-GCC
compilers. Make the relevant feature test macros depend on the
availability of __builtin_constant_evaluated, so they are defined only
when the feature is actualyl available.

The new testcase from the PR is added to the libitm testsuite, because
that's where we can be sure it's OK to use the -fgnu-tm option.

Signed-off-by: Jonathan Wakely <jwakely@redhat.com>

	PR libstdc++/91488

libstdc++-v3/ChangeLog:

	* include/bits/basic_string.h (__cpp_lib_constexpr_string): Only
	define when is_constant_evaluated is available.
	* include/bits/char_traits.h (__cpp_lib_constexpr_char_traits):
	Likewise.
	(__constant_string_p, __constant_array_p): Remove.
	(char_traits): Use is_constant_evaluated directly.
	* include/std/version (__cpp_lib_constexpr_char_traits)
	(__cpp_lib_constexpr_string): Only define when
	is_constant_evaluated is available.

libitm/ChangeLog:

	* testsuite/libitm.c++/libstdc++-pr91488.C: New test.
2021-06-17 22:00:58 +01:00

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// Character Traits for use by standard string and iostream -*- C++ -*-
// Copyright (C) 1997-2021 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 bits/char_traits.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{string}
*/
//
// ISO C++ 14882: 21 Strings library
//
#ifndef _CHAR_TRAITS_H
#define _CHAR_TRAITS_H 1
#pragma GCC system_header
#include <bits/stl_algobase.h> // std::copy, std::fill_n
#include <bits/postypes.h> // For streampos
#include <cwchar> // For WEOF, wmemmove, wmemset, etc.
#if __cplusplus > 201703L
# include <compare>
#endif
#ifndef _GLIBCXX_ALWAYS_INLINE
# define _GLIBCXX_ALWAYS_INLINE inline __attribute__((__always_inline__))
#endif
namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @brief Mapping from character type to associated types.
*
* @note This is an implementation class for the generic version
* of char_traits. It defines int_type, off_type, pos_type, and
* state_type. By default these are unsigned long, streamoff,
* streampos, and mbstate_t. Users who need a different set of
* types, but who don't need to change the definitions of any function
* defined in char_traits, can specialize __gnu_cxx::_Char_types
* while leaving __gnu_cxx::char_traits alone. */
template<typename _CharT>
struct _Char_types
{
typedef unsigned long int_type;
typedef std::streampos pos_type;
typedef std::streamoff off_type;
typedef std::mbstate_t state_type;
};
/**
* @brief Base class used to implement std::char_traits.
*
* @note For any given actual character type, this definition is
* probably wrong. (Most of the member functions are likely to be
* right, but the int_type and state_type typedefs, and the eof()
* member function, are likely to be wrong.) The reason this class
* exists is so users can specialize it. Classes in namespace std
* may not be specialized for fundamental types, but classes in
* namespace __gnu_cxx may be.
*
* See https://gcc.gnu.org/onlinedocs/libstdc++/manual/strings.html#strings.string.character_types
* for advice on how to make use of this class for @a unusual character
* types. Also, check out include/ext/pod_char_traits.h.
*/
template<typename _CharT>
struct char_traits
{
typedef _CharT char_type;
typedef typename _Char_types<_CharT>::int_type int_type;
typedef typename _Char_types<_CharT>::pos_type pos_type;
typedef typename _Char_types<_CharT>::off_type off_type;
typedef typename _Char_types<_CharT>::state_type state_type;
#if __cpp_lib_three_way_comparison
using comparison_category = std::strong_ordering;
#endif
static _GLIBCXX14_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2)
{ __c1 = __c2; }
static _GLIBCXX_CONSTEXPR bool
eq(const char_type& __c1, const char_type& __c2)
{ return __c1 == __c2; }
static _GLIBCXX_CONSTEXPR bool
lt(const char_type& __c1, const char_type& __c2)
{ return __c1 < __c2; }
static _GLIBCXX14_CONSTEXPR int
compare(const char_type* __s1, const char_type* __s2, std::size_t __n);
static _GLIBCXX14_CONSTEXPR std::size_t
length(const char_type* __s);
static _GLIBCXX14_CONSTEXPR const char_type*
find(const char_type* __s, std::size_t __n, const char_type& __a);
static _GLIBCXX20_CONSTEXPR char_type*
move(char_type* __s1, const char_type* __s2, std::size_t __n);
static _GLIBCXX20_CONSTEXPR char_type*
copy(char_type* __s1, const char_type* __s2, std::size_t __n);
static _GLIBCXX20_CONSTEXPR char_type*
assign(char_type* __s, std::size_t __n, char_type __a);
static _GLIBCXX_CONSTEXPR char_type
to_char_type(const int_type& __c)
{ return static_cast<char_type>(__c); }
static _GLIBCXX_CONSTEXPR int_type
to_int_type(const char_type& __c)
{ return static_cast<int_type>(__c); }
static _GLIBCXX_CONSTEXPR bool
eq_int_type(const int_type& __c1, const int_type& __c2)
{ return __c1 == __c2; }
static _GLIBCXX_CONSTEXPR int_type
eof()
{ return static_cast<int_type>(_GLIBCXX_STDIO_EOF); }
static _GLIBCXX_CONSTEXPR int_type
not_eof(const int_type& __c)
{ return !eq_int_type(__c, eof()) ? __c : to_int_type(char_type()); }
};
template<typename _CharT>
_GLIBCXX14_CONSTEXPR int
char_traits<_CharT>::
compare(const char_type* __s1, const char_type* __s2, std::size_t __n)
{
for (std::size_t __i = 0; __i < __n; ++__i)
if (lt(__s1[__i], __s2[__i]))
return -1;
else if (lt(__s2[__i], __s1[__i]))
return 1;
return 0;
}
template<typename _CharT>
_GLIBCXX14_CONSTEXPR std::size_t
char_traits<_CharT>::
length(const char_type* __p)
{
std::size_t __i = 0;
while (!eq(__p[__i], char_type()))
++__i;
return __i;
}
template<typename _CharT>
_GLIBCXX14_CONSTEXPR const typename char_traits<_CharT>::char_type*
char_traits<_CharT>::
find(const char_type* __s, std::size_t __n, const char_type& __a)
{
for (std::size_t __i = 0; __i < __n; ++__i)
if (eq(__s[__i], __a))
return __s + __i;
return 0;
}
template<typename _CharT>
_GLIBCXX20_CONSTEXPR
typename char_traits<_CharT>::char_type*
char_traits<_CharT>::
move(char_type* __s1, const char_type* __s2, std::size_t __n)
{
if (__n == 0)
return __s1;
#ifdef __cpp_lib_is_constant_evaluated
if (std::is_constant_evaluated())
{
if (__s1 > __s2 && __s1 < __s2 + __n)
std::copy_backward(__s2, __s2 + __n, __s1 + __n);
else
std::copy(__s2, __s2 + __n, __s1);
return __s1;
}
#endif
return static_cast<_CharT*>(__builtin_memmove(__s1, __s2,
__n * sizeof(char_type)));
}
template<typename _CharT>
_GLIBCXX20_CONSTEXPR
typename char_traits<_CharT>::char_type*
char_traits<_CharT>::
copy(char_type* __s1, const char_type* __s2, std::size_t __n)
{
// NB: Inline std::copy so no recursive dependencies.
std::copy(__s2, __s2 + __n, __s1);
return __s1;
}
template<typename _CharT>
_GLIBCXX20_CONSTEXPR
typename char_traits<_CharT>::char_type*
char_traits<_CharT>::
assign(char_type* __s, std::size_t __n, char_type __a)
{
// NB: Inline std::fill_n so no recursive dependencies.
std::fill_n(__s, __n, __a);
return __s;
}
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
#ifdef __cpp_lib_is_constant_evaluated
// Unofficial macro indicating P1032R1 support in C++20
# define __cpp_lib_constexpr_char_traits 201811L
#elif __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
// Unofficial macro indicating P0426R1 support in C++17
# define __cpp_lib_constexpr_char_traits 201611L
#endif
// 21.1
/**
* @brief Basis for explicit traits specializations.
*
* @note For any given actual character type, this definition is
* probably wrong. Since this is just a thin wrapper around
* __gnu_cxx::char_traits, it is possible to achieve a more
* appropriate definition by specializing __gnu_cxx::char_traits.
*
* See https://gcc.gnu.org/onlinedocs/libstdc++/manual/strings.html#strings.string.character_types
* for advice on how to make use of this class for @a unusual character
* types. Also, check out include/ext/pod_char_traits.h.
*/
template<class _CharT>
struct char_traits : public __gnu_cxx::char_traits<_CharT>
{ };
/// 21.1.3.1 char_traits specializations
template<>
struct char_traits<char>
{
typedef char char_type;
typedef int int_type;
typedef streampos pos_type;
typedef streamoff off_type;
typedef mbstate_t state_type;
#if __cpp_lib_three_way_comparison
using comparison_category = strong_ordering;
#endif
static _GLIBCXX17_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
{ __c1 = __c2; }
static _GLIBCXX_CONSTEXPR bool
eq(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
{ return __c1 == __c2; }
static _GLIBCXX_CONSTEXPR bool
lt(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
{
// LWG 467.
return (static_cast<unsigned char>(__c1)
< static_cast<unsigned char>(__c2));
}
static _GLIBCXX17_CONSTEXPR int
compare(const char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return 0;
#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
if (__builtin_is_constant_evaluated())
{
for (size_t __i = 0; __i < __n; ++__i)
if (lt(__s1[__i], __s2[__i]))
return -1;
else if (lt(__s2[__i], __s1[__i]))
return 1;
return 0;
}
#endif
return __builtin_memcmp(__s1, __s2, __n);
}
static _GLIBCXX17_CONSTEXPR size_t
length(const char_type* __s)
{
#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
if (__builtin_is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::length(__s);
#endif
return __builtin_strlen(__s);
}
static _GLIBCXX17_CONSTEXPR const char_type*
find(const char_type* __s, size_t __n, const char_type& __a)
{
if (__n == 0)
return 0;
#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
if (__builtin_is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::find(__s, __n, __a);
#endif
return static_cast<const char_type*>(__builtin_memchr(__s, __a, __n));
}
static _GLIBCXX20_CONSTEXPR char_type*
move(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
#ifdef __cpp_lib_is_constant_evaluated
if (std::is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
#endif
return static_cast<char_type*>(__builtin_memmove(__s1, __s2, __n));
}
static _GLIBCXX20_CONSTEXPR char_type*
copy(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
#ifdef __cpp_lib_is_constant_evaluated
if (std::is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
#endif
return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));
}
static _GLIBCXX20_CONSTEXPR char_type*
assign(char_type* __s, size_t __n, char_type __a)
{
if (__n == 0)
return __s;
#ifdef __cpp_lib_is_constant_evaluated
if (std::is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::assign(__s, __n, __a);
#endif
return static_cast<char_type*>(__builtin_memset(__s, __a, __n));
}
static _GLIBCXX_CONSTEXPR char_type
to_char_type(const int_type& __c) _GLIBCXX_NOEXCEPT
{ return static_cast<char_type>(__c); }
// To keep both the byte 0xff and the eof symbol 0xffffffff
// from ending up as 0xffffffff.
static _GLIBCXX_CONSTEXPR int_type
to_int_type(const char_type& __c) _GLIBCXX_NOEXCEPT
{ return static_cast<int_type>(static_cast<unsigned char>(__c)); }
static _GLIBCXX_CONSTEXPR bool
eq_int_type(const int_type& __c1, const int_type& __c2) _GLIBCXX_NOEXCEPT
{ return __c1 == __c2; }
static _GLIBCXX_CONSTEXPR int_type
eof() _GLIBCXX_NOEXCEPT
{ return static_cast<int_type>(_GLIBCXX_STDIO_EOF); }
static _GLIBCXX_CONSTEXPR int_type
not_eof(const int_type& __c) _GLIBCXX_NOEXCEPT
{ return (__c == eof()) ? 0 : __c; }
};
#ifdef _GLIBCXX_USE_WCHAR_T
/// 21.1.3.2 char_traits specializations
template<>
struct char_traits<wchar_t>
{
typedef wchar_t char_type;
typedef wint_t int_type;
typedef streamoff off_type;
typedef wstreampos pos_type;
typedef mbstate_t state_type;
#if __cpp_lib_three_way_comparison
using comparison_category = strong_ordering;
#endif
static _GLIBCXX17_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
{ __c1 = __c2; }
static _GLIBCXX_CONSTEXPR bool
eq(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
{ return __c1 == __c2; }
static _GLIBCXX_CONSTEXPR bool
lt(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
{ return __c1 < __c2; }
static _GLIBCXX17_CONSTEXPR int
compare(const char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return 0;
#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
if (__builtin_is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::compare(__s1, __s2, __n);
#endif
return wmemcmp(__s1, __s2, __n);
}
static _GLIBCXX17_CONSTEXPR size_t
length(const char_type* __s)
{
#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
if (__builtin_is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::length(__s);
#endif
return wcslen(__s);
}
static _GLIBCXX17_CONSTEXPR const char_type*
find(const char_type* __s, size_t __n, const char_type& __a)
{
if (__n == 0)
return 0;
#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
if (__builtin_is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::find(__s, __n, __a);
#endif
return wmemchr(__s, __a, __n);
}
static _GLIBCXX20_CONSTEXPR char_type*
move(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
#ifdef __cpp_lib_is_constant_evaluated
if (std::is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
#endif
return wmemmove(__s1, __s2, __n);
}
static _GLIBCXX20_CONSTEXPR char_type*
copy(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
#ifdef __cpp_lib_is_constant_evaluated
if (std::is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
#endif
return wmemcpy(__s1, __s2, __n);
}
static _GLIBCXX20_CONSTEXPR char_type*
assign(char_type* __s, size_t __n, char_type __a)
{
if (__n == 0)
return __s;
#ifdef __cpp_lib_is_constant_evaluated
if (std::is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::assign(__s, __n, __a);
#endif
return wmemset(__s, __a, __n);
}
static _GLIBCXX_CONSTEXPR char_type
to_char_type(const int_type& __c) _GLIBCXX_NOEXCEPT
{ return char_type(__c); }
static _GLIBCXX_CONSTEXPR int_type
to_int_type(const char_type& __c) _GLIBCXX_NOEXCEPT
{ return int_type(__c); }
static _GLIBCXX_CONSTEXPR bool
eq_int_type(const int_type& __c1, const int_type& __c2) _GLIBCXX_NOEXCEPT
{ return __c1 == __c2; }
static _GLIBCXX_CONSTEXPR int_type
eof() _GLIBCXX_NOEXCEPT
{ return static_cast<int_type>(WEOF); }
static _GLIBCXX_CONSTEXPR int_type
not_eof(const int_type& __c) _GLIBCXX_NOEXCEPT
{ return eq_int_type(__c, eof()) ? 0 : __c; }
};
#endif //_GLIBCXX_USE_WCHAR_T
#ifdef _GLIBCXX_USE_CHAR8_T
template<>
struct char_traits<char8_t>
{
typedef char8_t char_type;
typedef unsigned int int_type;
typedef u8streampos pos_type;
typedef streamoff off_type;
typedef mbstate_t state_type;
#if __cpp_lib_three_way_comparison
using comparison_category = strong_ordering;
#endif
static _GLIBCXX17_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
{ __c1 = __c2; }
static _GLIBCXX_CONSTEXPR bool
eq(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
{ return __c1 == __c2; }
static _GLIBCXX_CONSTEXPR bool
lt(const char_type& __c1, const char_type& __c2) _GLIBCXX_NOEXCEPT
{ return __c1 < __c2; }
static _GLIBCXX17_CONSTEXPR int
compare(const char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return 0;
#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
if (__builtin_is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::compare(__s1, __s2, __n);
#endif
return __builtin_memcmp(__s1, __s2, __n);
}
static _GLIBCXX17_CONSTEXPR size_t
length(const char_type* __s)
{
#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
if (__builtin_is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::length(__s);
#endif
size_t __i = 0;
while (!eq(__s[__i], char_type()))
++__i;
return __i;
}
static _GLIBCXX17_CONSTEXPR const char_type*
find(const char_type* __s, size_t __n, const char_type& __a)
{
if (__n == 0)
return 0;
#if __cplusplus >= 201703L && _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
if (__builtin_is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::find(__s, __n, __a);
#endif
return static_cast<const char_type*>(__builtin_memchr(__s, __a, __n));
}
static _GLIBCXX20_CONSTEXPR char_type*
move(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
#ifdef __cpp_lib_is_constant_evaluated
if (std::is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
#endif
return static_cast<char_type*>(__builtin_memmove(__s1, __s2, __n));
}
static _GLIBCXX20_CONSTEXPR char_type*
copy(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
#ifdef __cpp_lib_is_constant_evaluated
if (std::is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
#endif
return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));
}
static _GLIBCXX20_CONSTEXPR char_type*
assign(char_type* __s, size_t __n, char_type __a)
{
if (__n == 0)
return __s;
#ifdef __cpp_lib_is_constant_evaluated
if (std::is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::assign(__s, __n, __a);
#endif
return static_cast<char_type*>(__builtin_memset(__s, __a, __n));
}
static _GLIBCXX_CONSTEXPR char_type
to_char_type(const int_type& __c) _GLIBCXX_NOEXCEPT
{ return char_type(__c); }
static _GLIBCXX_CONSTEXPR int_type
to_int_type(const char_type& __c) _GLIBCXX_NOEXCEPT
{ return int_type(__c); }
static _GLIBCXX_CONSTEXPR bool
eq_int_type(const int_type& __c1, const int_type& __c2) _GLIBCXX_NOEXCEPT
{ return __c1 == __c2; }
static _GLIBCXX_CONSTEXPR int_type
eof() _GLIBCXX_NOEXCEPT
{ return static_cast<int_type>(-1); }
static _GLIBCXX_CONSTEXPR int_type
not_eof(const int_type& __c) _GLIBCXX_NOEXCEPT
{ return eq_int_type(__c, eof()) ? 0 : __c; }
};
#endif //_GLIBCXX_USE_CHAR8_T
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#if __cplusplus >= 201103L
#include <cstdint>
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
template<>
struct char_traits<char16_t>
{
typedef char16_t char_type;
#ifdef _GLIBCXX_USE_C99_STDINT_TR1
typedef uint_least16_t int_type;
#elif defined __UINT_LEAST16_TYPE__
typedef __UINT_LEAST16_TYPE__ int_type;
#else
typedef make_unsigned<char16_t>::type int_type;
#endif
typedef streamoff off_type;
typedef u16streampos pos_type;
typedef mbstate_t state_type;
#if __cpp_lib_three_way_comparison
using comparison_category = strong_ordering;
#endif
static _GLIBCXX17_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2) noexcept
{ __c1 = __c2; }
static constexpr bool
eq(const char_type& __c1, const char_type& __c2) noexcept
{ return __c1 == __c2; }
static constexpr bool
lt(const char_type& __c1, const char_type& __c2) noexcept
{ return __c1 < __c2; }
static _GLIBCXX17_CONSTEXPR int
compare(const char_type* __s1, const char_type* __s2, size_t __n)
{
for (size_t __i = 0; __i < __n; ++__i)
if (lt(__s1[__i], __s2[__i]))
return -1;
else if (lt(__s2[__i], __s1[__i]))
return 1;
return 0;
}
static _GLIBCXX17_CONSTEXPR size_t
length(const char_type* __s)
{
size_t __i = 0;
while (!eq(__s[__i], char_type()))
++__i;
return __i;
}
static _GLIBCXX17_CONSTEXPR const char_type*
find(const char_type* __s, size_t __n, const char_type& __a)
{
for (size_t __i = 0; __i < __n; ++__i)
if (eq(__s[__i], __a))
return __s + __i;
return 0;
}
static _GLIBCXX20_CONSTEXPR char_type*
move(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
#ifdef __cpp_lib_is_constant_evaluated
if (std::is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
#endif
return (static_cast<char_type*>
(__builtin_memmove(__s1, __s2, __n * sizeof(char_type))));
}
static _GLIBCXX20_CONSTEXPR char_type*
copy(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
#ifdef __cpp_lib_is_constant_evaluated
if (std::is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
#endif
return (static_cast<char_type*>
(__builtin_memcpy(__s1, __s2, __n * sizeof(char_type))));
}
static _GLIBCXX20_CONSTEXPR char_type*
assign(char_type* __s, size_t __n, char_type __a)
{
for (size_t __i = 0; __i < __n; ++__i)
assign(__s[__i], __a);
return __s;
}
static constexpr char_type
to_char_type(const int_type& __c) noexcept
{ return char_type(__c); }
static constexpr int_type
to_int_type(const char_type& __c) noexcept
{ return __c == eof() ? int_type(0xfffd) : int_type(__c); }
static constexpr bool
eq_int_type(const int_type& __c1, const int_type& __c2) noexcept
{ return __c1 == __c2; }
static constexpr int_type
eof() noexcept
{ return static_cast<int_type>(-1); }
static constexpr int_type
not_eof(const int_type& __c) noexcept
{ return eq_int_type(__c, eof()) ? 0 : __c; }
};
template<>
struct char_traits<char32_t>
{
typedef char32_t char_type;
#ifdef _GLIBCXX_USE_C99_STDINT_TR1
typedef uint_least32_t int_type;
#elif defined __UINT_LEAST32_TYPE__
typedef __UINT_LEAST32_TYPE__ int_type;
#else
typedef make_unsigned<char32_t>::type int_type;
#endif
typedef streamoff off_type;
typedef u32streampos pos_type;
typedef mbstate_t state_type;
#if __cpp_lib_three_way_comparison
using comparison_category = strong_ordering;
#endif
static _GLIBCXX17_CONSTEXPR void
assign(char_type& __c1, const char_type& __c2) noexcept
{ __c1 = __c2; }
static constexpr bool
eq(const char_type& __c1, const char_type& __c2) noexcept
{ return __c1 == __c2; }
static constexpr bool
lt(const char_type& __c1, const char_type& __c2) noexcept
{ return __c1 < __c2; }
static _GLIBCXX17_CONSTEXPR int
compare(const char_type* __s1, const char_type* __s2, size_t __n)
{
for (size_t __i = 0; __i < __n; ++__i)
if (lt(__s1[__i], __s2[__i]))
return -1;
else if (lt(__s2[__i], __s1[__i]))
return 1;
return 0;
}
static _GLIBCXX17_CONSTEXPR size_t
length(const char_type* __s)
{
size_t __i = 0;
while (!eq(__s[__i], char_type()))
++__i;
return __i;
}
static _GLIBCXX17_CONSTEXPR const char_type*
find(const char_type* __s, size_t __n, const char_type& __a)
{
for (size_t __i = 0; __i < __n; ++__i)
if (eq(__s[__i], __a))
return __s + __i;
return 0;
}
static _GLIBCXX20_CONSTEXPR char_type*
move(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
#ifdef __cpp_lib_is_constant_evaluated
if (std::is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::move(__s1, __s2, __n);
#endif
return (static_cast<char_type*>
(__builtin_memmove(__s1, __s2, __n * sizeof(char_type))));
}
static _GLIBCXX20_CONSTEXPR char_type*
copy(char_type* __s1, const char_type* __s2, size_t __n)
{
if (__n == 0)
return __s1;
#ifdef __cpp_lib_is_constant_evaluated
if (std::is_constant_evaluated())
return __gnu_cxx::char_traits<char_type>::copy(__s1, __s2, __n);
#endif
return (static_cast<char_type*>
(__builtin_memcpy(__s1, __s2, __n * sizeof(char_type))));
}
static _GLIBCXX20_CONSTEXPR char_type*
assign(char_type* __s, size_t __n, char_type __a)
{
for (size_t __i = 0; __i < __n; ++__i)
assign(__s[__i], __a);
return __s;
}
static constexpr char_type
to_char_type(const int_type& __c) noexcept
{ return char_type(__c); }
static constexpr int_type
to_int_type(const char_type& __c) noexcept
{ return int_type(__c); }
static constexpr bool
eq_int_type(const int_type& __c1, const int_type& __c2) noexcept
{ return __c1 == __c2; }
static constexpr int_type
eof() noexcept
{ return static_cast<int_type>(-1); }
static constexpr int_type
not_eof(const int_type& __c) noexcept
{ return eq_int_type(__c, eof()) ? 0 : __c; }
};
#if __cpp_lib_three_way_comparison
namespace __detail
{
template<typename _ChTraits>
constexpr auto
__char_traits_cmp_cat(int __cmp) noexcept
{
if constexpr (requires { typename _ChTraits::comparison_category; })
{
using _Cat = typename _ChTraits::comparison_category;
static_assert( !is_void_v<common_comparison_category_t<_Cat>> );
return static_cast<_Cat>(__cmp <=> 0);
}
else
return static_cast<weak_ordering>(__cmp <=> 0);
}
} // namespace __detail
#endif // C++20
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif // C++11
#endif // _CHAR_TRAITS_H
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