30#ifndef _GLIBCXX_UNICODE_H
31#define _GLIBCXX_UNICODE_H 1
33#if __cplusplus >= 202002L
42namespace std _GLIBCXX_VISIBILITY(default)
44_GLIBCXX_BEGIN_NAMESPACE_VERSION
49 __is_scalar_value(
char32_t __c)
51 if (__c < 0xD800) [[likely]]
53 return 0xDFFF < __c && __c <= 0x10FFFF;
57 template<
typename _CharT>
59 __is_single_code_unit(
char32_t __c)
64 return __c < __gnu_cxx::__int_traits<_CharT>::__max
65 && __is_scalar_value(__c);
73 operator()() const noexcept
77 struct _Null_sentinel_t
79 template<input_iterator _It>
80 requires default_initializable<iter_value_t<_It>>
81 && equality_comparable_with<iter_reference_t<_It>, iter_value_t<_It>>
83 operator==(_It __it, _Null_sentinel_t)
84 {
return *__it == iter_value_t<_It>{}; }
87 template<
typename _FromFmt,
typename _ToFmt,
88 input_iterator _Iter, sentinel_for<_Iter> _Sent = _Iter,
89 typename _ErrorHandler = _Repl>
90 requires convertible_to<iter_value_t<_Iter>, _FromFmt>
93 static_assert(forward_iterator<_Iter> ||
noexcept(_ErrorHandler()()));
96 using value_type = _ToFmt;
97 using difference_type = iter_difference_t<_Iter>;
98 using reference = value_type;
99 using iterator_concept
100 = std::__detail::__clamp_iter_cat<__iter_category_t<_Iter>,
101 bidirectional_iterator_tag>;
103 constexpr _Utf_iterator() =
default;
106 _Utf_iterator(_Iter __first, _Iter __it, _Sent __last)
107 requires bidirectional_iterator<_Iter>
108 : _M_first_and_curr{__first, __it}, _M_last(__last)
110 if (_M_curr() != _M_last)
117 _Utf_iterator(_Iter __it, _Sent __last)
118 requires (!bidirectional_iterator<_Iter>)
119 : _M_first_and_curr{__it}, _M_last(__last)
121 if (_M_curr() != _M_last)
127 template<
class _Iter2,
class _Sent2>
128 requires convertible_to<_Iter2, _Iter> && convertible_to<_Sent2, _Sent>
130 _Utf_iterator(
const _Utf_iterator<_FromFmt, _ToFmt, _Iter2, _Sent2,
131 _ErrorHandler>& __other)
132 : _M_buf(__other._M_buf), _M_first_and_curr(__other._M_first_and_curr),
133 _M_buf_index(__other._M_buf_index), _M_buf_last(__other._M_buf_last),
134 _M_last(__other._M_last)
139 begin() const requires bidirectional_iterator<_Iter>
140 {
return _M_first(); }
144 end()
const {
return _M_last; }
148 base() const requires forward_iterator<_Iter>
149 {
return _M_curr(); }
153 operator*()
const {
return _M_buf[_M_buf_index]; }
155 constexpr _Utf_iterator&
158 if (_M_buf_index + 1 == _M_buf_last && _M_curr() != _M_last)
160 if constexpr (forward_iterator<_Iter>)
162 if (_M_curr() == _M_last)
167 else if (_M_buf_index + 1 < _M_buf_last)
172 constexpr _Utf_iterator
180 constexpr _Utf_iterator&
181 operator--()
requires bidirectional_iterator<_Iter>
183 if (!_M_buf_index && _M_curr() != _M_first())
185 else if (_M_buf_index)
190 constexpr _Utf_iterator
199 friend constexpr bool
200 operator==(_Utf_iterator __lhs, _Utf_iterator __rhs)
201 requires forward_iterator<_Iter> ||
requires (_Iter __i) { __i != __i; }
203 if constexpr (forward_iterator<_Iter>)
204 return __lhs._M_curr() == __rhs._M_curr()
205 && __lhs._M_buf_index == __rhs._M_buf_index;
206 else if (__lhs._M_curr() != __rhs._M_curr())
208 else if (__lhs._M_buf_index == __rhs._M_buf_index
209 && __lhs._M_buf_last == __rhs._M_buf_last)
212 return __lhs._M_buf_index == __lhs._M_buf_last
213 && __rhs._M_buf_index == __rhs._M_buf_last;
217 friend constexpr bool
218 operator==(_Utf_iterator __lhs, _Sent __rhs)
220 if constexpr (forward_iterator<_Iter>)
221 return __lhs._M_curr() == __rhs;
223 return __lhs._M_curr() == __rhs
224 && __lhs._M_buf_index == __lhs._M_buf_last;
231 if constexpr (
sizeof(_FromFmt) ==
sizeof(uint8_t))
233 else if constexpr (
sizeof(_FromFmt) ==
sizeof(uint16_t))
237 static_assert(
sizeof(_FromFmt) ==
sizeof(uint32_t));
248 _Guard(
void*, _Iter&) { }
251 template<
typename _It>
requires forward_iterator<_It>
254 constexpr ~_Guard() { _M_this->_M_curr() =
std::move(_M_orig); }
255 _Utf_iterator* _M_this;
262 _Guard<_Iter> __g{
this, _M_curr()};
264 uint8_t __u = *_M_curr()++;
265 const uint8_t __lo_bound = 0x80, __hi_bound = 0xBF;
266 uint8_t __to_incr = 1;
268 if (__u <= 0x7F) [[likely]]
270 else if (__u < 0xC2) [[unlikely]]
272 else if (_M_curr() == _M_last) [[unlikely]]
274 else if (__u <= 0xDF)
279 if (__u < __lo_bound || __u > __hi_bound) [[unlikely]]
283 __c = (__c << 6) | (__u & 0x3F);
288 else if (__u <= 0xEF)
290 const uint8_t __lo_bound_2 = __u == 0xE0 ? 0xA0 : __lo_bound;
291 const uint8_t __hi_bound_2 = __u == 0xED ? 0x9F : __hi_bound;
296 if (__u < __lo_bound_2 || __u > __hi_bound_2) [[unlikely]]
298 else if (++_M_curr() == _M_last) [[unlikely]]
303 __c = (__c << 6) | (__u & 0x3F);
306 if (__u < __lo_bound || __u > __hi_bound) [[unlikely]]
310 __c = (__c << 6) | (__u & 0x3F);
316 else if (__u <= 0xF4)
318 const uint8_t __lo_bound_2 = __u == 0xF0 ? 0x90 : __lo_bound;
319 const uint8_t __hi_bound_2 = __u == 0xF4 ? 0x8F : __hi_bound;
324 if (__u < __lo_bound_2 || __u > __hi_bound_2) [[unlikely]]
326 else if (++_M_curr() == _M_last) [[unlikely]]
331 __c = (__c << 6) | (__u & 0x3F);
334 if (__u < __lo_bound || __u > __hi_bound) [[unlikely]]
336 else if (++_M_curr() == _M_last) [[unlikely]]
341 __c = (__c << 6) | (__u & 0x3F);
344 if (__u < __lo_bound || __u > __hi_bound) [[unlikely]]
348 __c = (__c << 6) | (__u & 0x3F);
358 _M_update(__c, __to_incr);
364 _Guard<_Iter> __g{
this, _M_curr()};
366 uint16_t __u = *_M_curr()++;
367 uint8_t __to_incr = 1;
369 if (__u < 0xD800 || __u > 0xDFFF) [[likely]]
371 else if (__u < 0xDC00 && _M_curr() != _M_last)
373 uint16_t __u2 = *_M_curr();
374 if (__u2 < 0xDC00 || __u2 > 0xDFFF) [[unlikely]]
380 uint32_t __x = (__u & 0x3F) << 10 | __u2 & 0x3FF;
381 uint32_t __w = (__u >> 6) & 0x1F;
382 __c = (__w + 1) << 16 | __x;
388 _M_update(__c, __to_incr);
394 _Guard<_Iter> __g{
this, _M_curr()};
395 char32_t __c = *_M_curr()++;
396 if (!__is_scalar_value(__c)) [[unlikely]]
403 _M_update(
char32_t __c, uint8_t __to_incr)
405 _M_to_increment = __to_incr;
407 if constexpr (
sizeof(_ToFmt) ==
sizeof(uint32_t))
412 else if constexpr (
sizeof(_ToFmt) ==
sizeof(uint16_t))
414 if (__is_single_code_unit<_ToFmt>(__c))
423 const char32_t __lead_offset = 0xD800 - (0x10000 >> 10);
424 char16_t __lead = __lead_offset + (__c >> 10);
425 char16_t __trail = 0xDC00 + (__c & 0x3FF);
433 static_assert(
sizeof(_ToFmt) == 1);
434 int __bits = std::bit_width((uint32_t)__c);
435 if (__bits <= 7) [[likely]]
438 _M_buf[1] = _M_buf[2] = _M_buf[3] = 0;
441 else if (__bits <= 11)
443 _M_buf[0] = 0xC0 | (__c >> 6);
444 _M_buf[1] = 0x80 | (__c & 0x3F);
445 _M_buf[2] = _M_buf[3] = 0;
448 else if (__bits <= 16)
450 _M_buf[0] = 0xE0 | (__c >> 12);
451 _M_buf[1] = 0x80 | ((__c >> 6) & 0x3F);
452 _M_buf[2] = 0x80 | (__c & 0x3F);
458 _M_buf[0] = 0xF0 | ((__c >> 18) & 0x07);
459 _M_buf[1] = 0x80 | ((__c >> 12) & 0x3F);
460 _M_buf[2] = 0x80 | ((__c >> 6) & 0x3F);
461 _M_buf[3] = 0x80 | (__c & 0x3F);
470 char32_t __c = _ErrorHandler()();
471 __glibcxx_assert(__is_scalar_value(__c));
476 _M_first() const requires bidirectional_iterator<_Iter>
477 {
return _M_first_and_curr._M_first; }
480 _M_curr() {
return _M_first_and_curr._M_curr; }
483 _M_curr()
const {
return _M_first_and_curr._M_curr; }
485 array<value_type, 4 /
sizeof(_ToFmt)> _M_buf;
487 template<
typename _It>
488 struct _First_and_curr
490 _First_and_curr() =
default;
493 _First_and_curr(_It __curr) : _M_curr(__curr) { }
495 template<convertible_to<_It> _It2>
497 _First_and_curr(
const _First_and_curr<_It2>& __other)
498 : _M_curr(__other._M_curr) { }
503 template<
typename _It>
requires bidirectional_iterator<_It>
504 struct _First_and_curr<_It>
506 _First_and_curr() =
default;
509 _First_and_curr(_It __first, _It __curr)
510 : _M_first(__first), _M_curr(__curr) { }
512 template<convertible_to<_It> _It2>
514 _First_and_curr(
const _First_and_curr<_It2>& __other)
515 : _M_first(__other._M_first), _M_curr(__other._M_curr) { }
521 _First_and_curr<_Iter> _M_first_and_curr;
523 uint8_t _M_buf_index = 0;
524 uint8_t _M_buf_last = 0;
525 uint8_t _M_to_increment = 0;
527 [[no_unique_address]] _Sent _M_last;
529 template<
typename _FromFmt2,
typename _ToFmt2,
530 input_iterator _Iter2, sentinel_for<_Iter2> _Sent2,
531 typename _ErrHandler>
532 requires convertible_to<iter_value_t<_Iter2>, _FromFmt2>
533 friend class _Utf_iterator;
536 template<
typename _ToFormat, ranges::input_range _Range>
538 :
public ranges::view_interface<_Utf_view<_ToFormat, _Range>>
540 using _Iterator = _Utf_iterator<ranges::range_value_t<_Range>,
541 _ToFormat, ranges::iterator_t<_Range>,
542 ranges::sentinel_t<_Range>>;
544 template<
typename _Iter,
typename _Sent>
546 _M_begin(_Iter __first, _Sent __last)
548 if constexpr (bidirectional_iterator<_Iter>)
549 return _Iterator(__first, __first, __last);
551 return _Iterator(__first, __last);
554 template<
typename _Iter,
typename _Sent>
556 _M_end(_Iter __first, _Sent __last)
558 if constexpr (!is_same_v<_Iter, _Sent>)
560 else if constexpr (bidirectional_iterator<_Iter>)
561 return _Iterator(__first, __last, __last);
563 return _Iterator(__last, __last);
570 _Utf_view(_Range&& __r) : _M_base(
std::
forward<_Range>(__r)) { }
572 constexpr auto begin()
573 {
return _M_begin(ranges::begin(_M_base), ranges::end(_M_base)); }
576 {
return _M_end(ranges::begin(_M_base), ranges::end(_M_base)); }
578 constexpr bool empty()
const {
return ranges::empty(_M_base); }
582 template<
typename _View>
583 using _Utf8_view = _Utf_view<char8_t, _View>;
585 template<
typename _View>
586 using _Utf16_view = _Utf_view<char16_t, _View>;
587 template<
typename _View>
588 using _Utf32_view = _Utf_view<char32_t, _View>;
590inline namespace __v15_1_0
592#define _GLIBCXX_GET_UNICODE_DATA 150100
594#ifdef _GLIBCXX_GET_UNICODE_DATA
595# error "Invalid unicode data"
600 __field_width(
char32_t __c)
noexcept
602 if (__c < __width_edges[0]) [[likely]]
605 auto* __p = std::upper_bound(__width_edges,
std::end(__width_edges), __c);
606 return (__p - __width_edges) % 2 + 1;
610 constexpr _Gcb_property
611 __grapheme_cluster_break_property(
char32_t __c)
noexcept
613 constexpr uint32_t __mask = (1 << __gcb_shift_bits) - 1;
614 auto* __end =
std::end(__gcb_edges);
615 auto* __p = std::lower_bound(__gcb_edges, __end,
616 (__c << __gcb_shift_bits) | __mask);
617 return _Gcb_property(__p[-1] & __mask);
621 __is_incb_linker(
char32_t __c)
noexcept
623 const auto __end =
std::end(__incb_linkers);
625 return std::find(__incb_linkers, __end, __c) != __end;
630 __incb_property(
char32_t __c)
noexcept
632 if ((__c << 2) < __incb_edges[0]) [[likely]]
635 constexpr uint32_t __mask = 0x3;
636 auto* __end =
std::end(__incb_edges);
637 auto* __p = std::lower_bound(__incb_edges, __end, (__c << 2) | __mask);
638 return _InCB(__p[-1] & __mask);
642 __is_extended_pictographic(
char32_t __c)
644 if (__c < __xpicto_edges[0]) [[likely]]
647 auto* __p = std::upper_bound(__xpicto_edges,
std::end(__xpicto_edges), __c);
648 return (__p - __xpicto_edges) % 2;
651 struct _Grapheme_cluster_iterator_base
654 _Gcb_property _M_prop;
655 enum class _XPicto :
unsigned char { _Init, _Zwj, _Matched, _Failed };
656 _XPicto _M_xpicto_seq_state = _XPicto::_Init;
657 unsigned char _M_RI_count = 0;
658 bool _M_incb_linker_seen =
false;
661 _M_reset(
char32_t __c, _Gcb_property __p)
665 _M_xpicto_seq_state = _XPicto::_Init;
667 _M_incb_linker_seen =
false;
671 _M_update_xpicto_seq_state(
char32_t __c, _Gcb_property __p)
673 if (_M_xpicto_seq_state == _XPicto::_Failed)
676 auto __next_state = _XPicto::_Failed;
677 if (_M_xpicto_seq_state != _XPicto::_Zwj)
679 if (__p == _Gcb_property::_Gcb_ZWJ)
681 if (_M_xpicto_seq_state == _XPicto::_Matched)
682 __next_state = _XPicto::_Zwj;
685 else if (__is_extended_pictographic(_M_c))
686 __next_state = _XPicto::_Zwj;
688 else if (__p == _Gcb_property::_Gcb_Extend)
689 __next_state = _M_xpicto_seq_state;
695 if (__p == _Gcb_property::_Gcb_Other
696 && __is_extended_pictographic(__c))
697 __next_state = _XPicto::_Matched;
699 _M_xpicto_seq_state = __next_state;
703 _M_update_ri_count(_Gcb_property __p)
705 if (__p == _Gcb_property::_Gcb_Regional_Indicator)
712 _M_update_incb_state(
char32_t __c, _Gcb_property)
714 if (__is_incb_linker(__c))
715 _M_incb_linker_seen =
true;
720 template<ranges::forward_range _View>
requires ranges::view<_View>
721 class _Grapheme_cluster_view
722 :
public ranges::view_interface<_Grapheme_cluster_view<_View>>
727 _Grapheme_cluster_view(_View __v)
728 : _M_begin(_Utf32_view<_View>(
std::
move(__v)).begin())
731 constexpr auto begin()
const {
return _M_begin; }
732 constexpr auto end()
const {
return _M_begin.end(); }
735 struct _Iterator :
private _Grapheme_cluster_iterator_base
739 using _U32_iterator = ranges::iterator_t<_Utf32_view<_View>>;
747 using value_type = char32_t;
748 using iterator_concept = forward_iterator_tag;
749 using difference_type = ptrdiff_t;
752 _Iterator(_U32_iterator __i)
755 if (__i != __i.end())
758 _M_prop = __grapheme_cluster_break_property(_M_c);
775 const auto __end = _M_base.end();
776 if (_M_base != __end)
778 auto __p_prev = _M_prop;
780 while (++__it != __end)
782 char32_t __c = *__it;
783 auto __p = __grapheme_cluster_break_property(*__it);
784 _M_update_xpicto_seq_state(__c, __p);
785 _M_update_ri_count(__p);
786 _M_update_incb_state(__c, __p);
787 if (_M_is_break(__p_prev, __p, __it))
809 operator==(
const _Iterator& __i)
const
810 {
return _M_base == __i._M_base; }
814 operator==(
const ranges::sentinel_t<_View>& __i)
const
815 {
return _M_base == __i; }
818 constexpr auto base()
const {
return _M_base.base(); }
821 constexpr auto end()
const {
return _M_base.end(); }
825 width() const noexcept
826 {
return __field_width(_M_c); }
829 _U32_iterator _M_base;
837 _M_is_break(_Gcb_property __p1, _Gcb_property __p2,
838 _U32_iterator __curr)
const
840 using enum _Gcb_property;
842 if (__p1 == _Gcb_Control || __p1 == _Gcb_LF)
846 return __p2 != _Gcb_LF;
849 if (__p2 == _Gcb_Control || __p2 == _Gcb_CR || __p2 == _Gcb_LF)
866 if (__p1 == _Gcb_LV || __p1 == _Gcb_V)
877 if (__p1 == _Gcb_LVT || __p1 == _Gcb_T)
878 return __p2 != _Gcb_T;
881 if (__p2 == _Gcb_Extend || __p2 == _Gcb_ZWJ)
888 if (__p2 == _Gcb_SpacingMark)
891 if (__p1 == _Gcb_Prepend)
897 if (_M_incb_linker_seen
898 && __incb_property(_M_c) == _InCB::_Consonant
899 && __incb_property(*__curr) == _InCB::_Consonant)
903 bool __have_linker =
false;
905 while (++__it != __curr)
907 if (__is_incb_linker(*__it))
908 __have_linker =
true;
911 auto __incb = __incb_property(*__it);
912 if (__incb == _InCB::_Consonant)
913 __have_linker =
false;
914 else if (__incb != _InCB::_Extend)
918 if (__it == __curr && __have_linker)
925 if (__p1 == _Gcb_ZWJ && _M_xpicto_seq_state == _XPicto::_Matched)
932 if (__p1 == _Gcb_property::_Gcb_Regional_Indicator && __p1 == __p2)
933 return (_M_RI_count & 1) == 0;
946 template<
typename _CharT>
948 __field_width(basic_string_view<_CharT> __s)
950 if (__s.empty()) [[unlikely]]
952 _Grapheme_cluster_view<basic_string_view<_CharT>> __gc(__s);
953 auto __it = __gc.begin();
954 const auto __end = __gc.end();
955 size_t __n = __it.width();
956 while (++__it != __end)
963 template<
typename _CharT>
965 __truncate(basic_string_view<_CharT>& __s,
size_t __max)
967 if (__s.empty()) [[unlikely]]
970 _Grapheme_cluster_view<basic_string_view<_CharT>> __gc(__s);
971 auto __it = __gc.begin();
972 const auto __end = __gc.end();
973 size_t __n = __it.width();
979 while (++__it != __end)
981 size_t __n2 = __n + __it.width();
984 __s = basic_string_view<_CharT>(__s.begin(), __it.base());
992 template<
typename _CharT>
994 __literal_encoding_is_unicode()
996 if constexpr (is_same_v<_CharT, char16_t>)
998 else if constexpr (is_same_v<_CharT, char32_t>)
1001 else if constexpr (is_same_v<_CharT, char8_t>)
1005 const char* __enc =
"";
1007#ifdef __GNUC_EXECUTION_CHARSET_NAME
1008 auto __remove_iso10646_prefix = [](
const char* __s) {
1010 if (__s[0] ==
'I' || __s[0] ==
'i')
1011 if (__s[1] ==
'S' || __s[1] ==
's')
1012 if (__s[2] ==
'O' || __s[2] ==
'o')
1013 if (string_view(__s + 3).starts_with(
"-10646/"))
1018 if constexpr (is_same_v<_CharT, char>)
1019 __enc = __remove_iso10646_prefix(__GNUC_EXECUTION_CHARSET_NAME);
1020# if defined _GLIBCXX_USE_WCHAR_T && defined __GNUC_WIDE_EXECUTION_CHARSET_NAME
1022 __enc = __remove_iso10646_prefix(__GNUC_WIDE_EXECUTION_CHARSET_NAME);
1025 if ((__enc[0] ==
'U' || __enc[0] ==
'u')
1026 && (__enc[1] ==
'T' || __enc[1] ==
't')
1027 && (__enc[2] ==
'F' || __enc[2] ==
'f'))
1030 if (__enc[0] ==
'-')
1032 if (__enc[0] ==
'8')
1033 return __enc[1] ==
'\0' || string_view(__enc + 1) ==
"//";
1034 else if constexpr (!is_same_v<_CharT, char>)
1036 string_view __s(__enc);
1037 if (__s.ends_with(
"//"))
1038 __s.remove_suffix(2);
1039 return __s ==
"16" || __s ==
"32";
1042#elif defined __clang_literal_encoding__
1043 if constexpr (is_same_v<_CharT, char>)
1044 __enc = __clang_literal_encoding__;
1045# if defined _GLIBCXX_USE_WCHAR_T && defined __clang_wide_literal_encoding__
1047 __enc = __clang_wide_literal_encoding__;
1050 string_view __s(__enc);
1053 else if constexpr (!is_same_v<_CharT, char>)
1054 return __s ==
"UTF-16" || __s ==
"UTF-32";
1061 __literal_encoding_is_utf8()
1062 {
return __literal_encoding_is_unicode<char>(); }
1065 __literal_encoding_is_extended_ascii()
1067 return '0' == 0x30 &&
'A' == 0x41 &&
'Z' == 0x5a
1068 &&
'a' == 0x61 &&
'z' == 0x7a;
1073 __charset_alias_match(string_view __a, string_view __b)
1076 auto __map = [](
char __c,
bool& __num) ->
unsigned char {
1077 if (__c ==
'0') [[unlikely]]
1078 return __num ? 0 : 127;
1079 const auto __v = __detail::__from_chars_alnum_to_val(__c);
1084 auto __ptr_a = __a.begin(), __end_a = __a.end();
1085 auto __ptr_b = __b.begin(), __end_b = __b.end();
1086 bool __num_a =
false, __num_b =
false;
1091 unsigned char __val_a{}, __val_b{};
1092 while (__ptr_a != __end_a
1093 && (__val_a = __map(*__ptr_a, __num_a)) == 127)
1095 while (__ptr_b != __end_b
1096 && (__val_b = __map(*__ptr_b, __num_b)) == 127)
1099 if (__ptr_a == __end_a)
1100 return __ptr_b == __end_b;
1101 else if (__ptr_b == __end_b)
1103 else if (__val_a != __val_b)
1115 template<
typename _To,
typename _Range>
1116 inline constexpr bool
1117 enable_borrowed_range<std::__unicode::_Utf_view<_To, _Range>>
1118 = enable_borrowed_range<_Range>;
1120 template<
typename _Range>
1121 inline constexpr bool
1122 enable_borrowed_range<std::__unicode::_Grapheme_cluster_view<_Range>>
1123 = enable_borrowed_range<_Range>;
1126_GLIBCXX_END_NAMESPACE_VERSION
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
constexpr _Tp && forward(typename std::remove_reference< _Tp >::type &__t) noexcept
Forward an lvalue.
_Tp * end(valarray< _Tp > &__va) noexcept
Return an iterator pointing to one past the last element of the valarray.
ISO C++ entities toplevel namespace is std.
constexpr void advance(_InputIterator &__i, _Distance __n)
A generalization of pointer arithmetic.
__numeric_traits_integer< _Tp > __int_traits
Convenience alias for __numeric_traits<integer-type>.