1// Components for manipulating non-owning sequences of characters -*- C++ -*-
3// Copyright (C) 2013-2022 Free Software Foundation, Inc.
5// This file is part of the GNU ISO C++ Library. This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23// <http://www.gnu.org/licenses/>.
25/** @file include/string_view
26 * This is a Standard C++ Library header.
30// N3762 basic_string_view library
33#ifndef _GLIBCXX_STRING_VIEW
34#define _GLIBCXX_STRING_VIEW 1
36#pragma GCC system_header
38#if __cplusplus >= 201703L
41#include <bits/char_traits.h>
42#include <bits/functexcept.h>
43#include <bits/functional_hash.h>
44#include <bits/range_access.h>
45#include <bits/ostream_insert.h>
46#include <bits/stl_algobase.h>
47#include <ext/numeric_traits.h>
49#if __cplusplus >= 202002L
50# include <bits/ranges_base.h>
53namespace std _GLIBCXX_VISIBILITY(default)
55_GLIBCXX_BEGIN_NAMESPACE_VERSION
57# define __cpp_lib_string_view 201803L
58#if __cplusplus > 201703L
59# define __cpp_lib_constexpr_string_view 201811L
62 // Helper for basic_string and basic_string_view members.
64 __sv_check(size_t __size, size_t __pos, const char* __s)
67 __throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > __size "
68 "(which is %zu)"), __s, __pos, __size);
72 // Helper for basic_string members.
73 // NB: __sv_limit doesn't check for a bad __pos value.
75 __sv_limit(size_t __size, size_t __pos, size_t __off) noexcept
77 const bool __testoff = __off < __size - __pos;
78 return __testoff ? __off : __size - __pos;
82 * @class basic_string_view <string_view>
83 * @brief A non-owning reference to a string.
88 * @tparam _CharT Type of character
89 * @tparam _Traits Traits for character type, defaults to
90 * char_traits<_CharT>.
92 * A basic_string_view looks like this:
99 template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
100 class basic_string_view
102 static_assert(!is_array_v<_CharT>);
103 static_assert(is_trivial_v<_CharT> && is_standard_layout_v<_CharT>);
104 static_assert(is_same_v<_CharT, typename _Traits::char_type>);
109 using traits_type = _Traits;
110 using value_type = _CharT;
111 using pointer = value_type*;
112 using const_pointer = const value_type*;
113 using reference = value_type&;
114 using const_reference = const value_type&;
115 using const_iterator = const value_type*;
116 using iterator = const_iterator;
117 using const_reverse_iterator = std::reverse_iterator<const_iterator>;
118 using reverse_iterator = const_reverse_iterator;
119 using size_type = size_t;
120 using difference_type = ptrdiff_t;
121 static constexpr size_type npos = size_type(-1);
123 // [string.view.cons], construction and assignment
126 basic_string_view() noexcept
127 : _M_len{0}, _M_str{nullptr}
130 constexpr basic_string_view(const basic_string_view&) noexcept = default;
132 __attribute__((__nonnull__)) constexpr
133 basic_string_view(const _CharT* __str) noexcept
134 : _M_len{traits_type::length(__str)},
139 basic_string_view(const _CharT* __str, size_type __len) noexcept
140 : _M_len{__len}, _M_str{__str}
143#if __cplusplus >= 202002L && __cpp_lib_concepts
144 template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
145 requires same_as<iter_value_t<_It>, _CharT>
146 && (!convertible_to<_End, size_type>)
148 basic_string_view(_It __first, _End __last)
149 noexcept(noexcept(__last - __first))
150 : _M_len(__last - __first), _M_str(std::to_address(__first))
153#if __cplusplus > 202002L
154 template<typename _Range, typename _DRange = remove_cvref_t<_Range>>
155 requires (!is_same_v<_DRange, basic_string_view>)
156 && ranges::contiguous_range<_Range>
157 && ranges::sized_range<_Range>
158 && is_same_v<ranges::range_value_t<_Range>, _CharT>
159 && (!is_convertible_v<_Range, const _CharT*>)
160 && (!requires (_DRange& __d) {
161 __d.operator ::std::basic_string_view<_CharT, _Traits>();
164 basic_string_view(_Range&& __r)
165 noexcept(noexcept(ranges::size(__r)) && noexcept(ranges::data(__r)))
166 : _M_len(ranges::size(__r)), _M_str(ranges::data(__r))
169 basic_string_view(nullptr_t) = delete;
174 constexpr basic_string_view&
175 operator=(const basic_string_view&) noexcept = default;
177 // [string.view.iterators], iterator support
179 constexpr const_iterator
180 begin() const noexcept
181 { return this->_M_str; }
183 constexpr const_iterator
185 { return this->_M_str + this->_M_len; }
187 constexpr const_iterator
188 cbegin() const noexcept
189 { return this->_M_str; }
191 constexpr const_iterator
192 cend() const noexcept
193 { return this->_M_str + this->_M_len; }
195 constexpr const_reverse_iterator
196 rbegin() const noexcept
197 { return const_reverse_iterator(this->end()); }
199 constexpr const_reverse_iterator
200 rend() const noexcept
201 { return const_reverse_iterator(this->begin()); }
203 constexpr const_reverse_iterator
204 crbegin() const noexcept
205 { return const_reverse_iterator(this->end()); }
207 constexpr const_reverse_iterator
208 crend() const noexcept
209 { return const_reverse_iterator(this->begin()); }
211 // [string.view.capacity], capacity
214 size() const noexcept
215 { return this->_M_len; }
218 length() const noexcept
222 max_size() const noexcept
224 return (npos - sizeof(size_type) - sizeof(void*))
225 / sizeof(value_type) / 4;
228 [[nodiscard]] constexpr bool
229 empty() const noexcept
230 { return this->_M_len == 0; }
232 // [string.view.access], element access
234 constexpr const_reference
235 operator[](size_type __pos) const noexcept
237 __glibcxx_assert(__pos < this->_M_len);
238 return *(this->_M_str + __pos);
241 constexpr const_reference
242 at(size_type __pos) const
245 __throw_out_of_range_fmt(__N("basic_string_view::at: __pos "
246 "(which is %zu) >= this->size() "
247 "(which is %zu)"), __pos, this->size());
248 return *(this->_M_str + __pos);
251 constexpr const_reference
252 front() const noexcept
254 __glibcxx_assert(this->_M_len > 0);
255 return *this->_M_str;
258 constexpr const_reference
259 back() const noexcept
261 __glibcxx_assert(this->_M_len > 0);
262 return *(this->_M_str + this->_M_len - 1);
265 constexpr const_pointer
266 data() const noexcept
267 { return this->_M_str; }
269 // [string.view.modifiers], modifiers:
272 remove_prefix(size_type __n) noexcept
274 __glibcxx_assert(this->_M_len >= __n);
280 remove_suffix(size_type __n) noexcept
282 __glibcxx_assert(this->_M_len >= __n);
287 swap(basic_string_view& __sv) noexcept
294 // [string.view.ops], string operations:
298 copy(_CharT* __str, size_type __n, size_type __pos = 0) const
300 __glibcxx_requires_string_len(__str, __n);
301 __pos = std::__sv_check(size(), __pos, "basic_string_view::copy");
302 const size_type __rlen = std::min(__n, _M_len - __pos);
303 // _GLIBCXX_RESOLVE_LIB_DEFECTS
304 // 2777. basic_string_view::copy should use char_traits::copy
305 traits_type::copy(__str, data() + __pos, __rlen);
309 constexpr basic_string_view
310 substr(size_type __pos = 0, size_type __n = npos) const noexcept(false)
312 __pos = std::__sv_check(size(), __pos, "basic_string_view::substr");
313 const size_type __rlen = std::min(__n, _M_len - __pos);
314 return basic_string_view{_M_str + __pos, __rlen};
318 compare(basic_string_view __str) const noexcept
320 const size_type __rlen = std::min(this->_M_len, __str._M_len);
321 int __ret = traits_type::compare(this->_M_str, __str._M_str, __rlen);
323 __ret = _S_compare(this->_M_len, __str._M_len);
328 compare(size_type __pos1, size_type __n1, basic_string_view __str) const
329 { return this->substr(__pos1, __n1).compare(__str); }
332 compare(size_type __pos1, size_type __n1,
333 basic_string_view __str, size_type __pos2, size_type __n2) const
335 return this->substr(__pos1, __n1).compare(__str.substr(__pos2, __n2));
338 __attribute__((__nonnull__)) constexpr int
339 compare(const _CharT* __str) const noexcept
340 { return this->compare(basic_string_view{__str}); }
342 __attribute__((__nonnull__)) constexpr int
343 compare(size_type __pos1, size_type __n1, const _CharT* __str) const
344 { return this->substr(__pos1, __n1).compare(basic_string_view{__str}); }
347 compare(size_type __pos1, size_type __n1,
348 const _CharT* __str, size_type __n2) const noexcept(false)
350 return this->substr(__pos1, __n1)
351 .compare(basic_string_view(__str, __n2));
354#if __cplusplus > 201703L
355#define __cpp_lib_starts_ends_with 201711L
357 starts_with(basic_string_view __x) const noexcept
358 { return this->substr(0, __x.size()) == __x; }
361 starts_with(_CharT __x) const noexcept
362 { return !this->empty() && traits_type::eq(this->front(), __x); }
365 starts_with(const _CharT* __x) const noexcept
366 { return this->starts_with(basic_string_view(__x)); }
369 ends_with(basic_string_view __x) const noexcept
371 const auto __len = this->size();
372 const auto __xlen = __x.size();
373 return __len >= __xlen
374 && traits_type::compare(end() - __xlen, __x.data(), __xlen) == 0;
378 ends_with(_CharT __x) const noexcept
379 { return !this->empty() && traits_type::eq(this->back(), __x); }
382 ends_with(const _CharT* __x) const noexcept
383 { return this->ends_with(basic_string_view(__x)); }
386#if __cplusplus > 202002L
387#define __cpp_lib_string_contains 202011L
389 contains(basic_string_view __x) const noexcept
390 { return this->find(__x) != npos; }
393 contains(_CharT __x) const noexcept
394 { return this->find(__x) != npos; }
397 contains(const _CharT* __x) const noexcept
398 { return this->find(__x) != npos; }
401 // [string.view.find], searching
404 find(basic_string_view __str, size_type __pos = 0) const noexcept
405 { return this->find(__str._M_str, __pos, __str._M_len); }
408 find(_CharT __c, size_type __pos = 0) const noexcept;
411 find(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
413 __attribute__((__nonnull__)) constexpr size_type
414 find(const _CharT* __str, size_type __pos = 0) const noexcept
415 { return this->find(__str, __pos, traits_type::length(__str)); }
418 rfind(basic_string_view __str, size_type __pos = npos) const noexcept
419 { return this->rfind(__str._M_str, __pos, __str._M_len); }
422 rfind(_CharT __c, size_type __pos = npos) const noexcept;
425 rfind(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
427 __attribute__((__nonnull__)) constexpr size_type
428 rfind(const _CharT* __str, size_type __pos = npos) const noexcept
429 { return this->rfind(__str, __pos, traits_type::length(__str)); }
432 find_first_of(basic_string_view __str, size_type __pos = 0) const noexcept
433 { return this->find_first_of(__str._M_str, __pos, __str._M_len); }
436 find_first_of(_CharT __c, size_type __pos = 0) const noexcept
437 { return this->find(__c, __pos); }
440 find_first_of(const _CharT* __str, size_type __pos,
441 size_type __n) const noexcept;
443 __attribute__((__nonnull__)) constexpr size_type
444 find_first_of(const _CharT* __str, size_type __pos = 0) const noexcept
445 { return this->find_first_of(__str, __pos, traits_type::length(__str)); }
448 find_last_of(basic_string_view __str,
449 size_type __pos = npos) const noexcept
450 { return this->find_last_of(__str._M_str, __pos, __str._M_len); }
453 find_last_of(_CharT __c, size_type __pos=npos) const noexcept
454 { return this->rfind(__c, __pos); }
457 find_last_of(const _CharT* __str, size_type __pos,
458 size_type __n) const noexcept;
460 __attribute__((__nonnull__)) constexpr size_type
461 find_last_of(const _CharT* __str, size_type __pos = npos) const noexcept
462 { return this->find_last_of(__str, __pos, traits_type::length(__str)); }
465 find_first_not_of(basic_string_view __str,
466 size_type __pos = 0) const noexcept
467 { return this->find_first_not_of(__str._M_str, __pos, __str._M_len); }
470 find_first_not_of(_CharT __c, size_type __pos = 0) const noexcept;
473 find_first_not_of(const _CharT* __str,
474 size_type __pos, size_type __n) const noexcept;
476 __attribute__((__nonnull__)) constexpr size_type
477 find_first_not_of(const _CharT* __str, size_type __pos = 0) const noexcept
479 return this->find_first_not_of(__str, __pos,
480 traits_type::length(__str));
484 find_last_not_of(basic_string_view __str,
485 size_type __pos = npos) const noexcept
486 { return this->find_last_not_of(__str._M_str, __pos, __str._M_len); }
489 find_last_not_of(_CharT __c, size_type __pos = npos) const noexcept;
492 find_last_not_of(const _CharT* __str,
493 size_type __pos, size_type __n) const noexcept;
495 __attribute__((__nonnull__)) constexpr size_type
496 find_last_not_of(const _CharT* __str,
497 size_type __pos = npos) const noexcept
499 return this->find_last_not_of(__str, __pos,
500 traits_type::length(__str));
506 _S_compare(size_type __n1, size_type __n2) noexcept
508 using __limits = __gnu_cxx::__int_traits<int>;
509 const difference_type __diff = __n1 - __n2;
510 if (__diff > __limits::__max)
511 return __limits::__max;
512 if (__diff < __limits::__min)
513 return __limits::__min;
514 return static_cast<int>(__diff);
518 const _CharT* _M_str;
521#if __cplusplus > 201703L && __cpp_lib_concepts && __cpp_deduction_guides
522 template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
523 basic_string_view(_It, _End) -> basic_string_view<iter_value_t<_It>>;
525#if __cplusplus > 202002L
526 template<ranges::contiguous_range _Range>
527 basic_string_view(_Range&&)
528 -> basic_string_view<ranges::range_value_t<_Range>>;
532 // [string.view.comparison], non-member basic_string_view comparison function
534 // Several of these functions use type_identity_t to create a non-deduced
535 // context, so that only one argument participates in template argument
536 // deduction and the other argument gets implicitly converted to the deduced
539 template<typename _CharT, typename _Traits>
541 operator==(basic_string_view<_CharT, _Traits> __x,
542 basic_string_view<_CharT, _Traits> __y) noexcept
543 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
545 template<typename _CharT, typename _Traits>
547 operator==(basic_string_view<_CharT, _Traits> __x,
548 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
550 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
552#if __cpp_lib_three_way_comparison
553 template<typename _CharT, typename _Traits>
555 operator<=>(basic_string_view<_CharT, _Traits> __x,
556 basic_string_view<_CharT, _Traits> __y) noexcept
557 -> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
558 { return __detail::__char_traits_cmp_cat<_Traits>(__x.compare(__y)); }
560 template<typename _CharT, typename _Traits>
562 operator<=>(basic_string_view<_CharT, _Traits> __x,
563 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
565 -> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
566 { return __detail::__char_traits_cmp_cat<_Traits>(__x.compare(__y)); }
568 template<typename _CharT, typename _Traits>
570 operator==(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
571 basic_string_view<_CharT, _Traits> __y) noexcept
572 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
574 template<typename _CharT, typename _Traits>
576 operator!=(basic_string_view<_CharT, _Traits> __x,
577 basic_string_view<_CharT, _Traits> __y) noexcept
578 { return !(__x == __y); }
580 template<typename _CharT, typename _Traits>
582 operator!=(basic_string_view<_CharT, _Traits> __x,
583 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
585 { return !(__x == __y); }
587 template<typename _CharT, typename _Traits>
589 operator!=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
590 basic_string_view<_CharT, _Traits> __y) noexcept
591 { return !(__x == __y); }
593 template<typename _CharT, typename _Traits>
595 operator< (basic_string_view<_CharT, _Traits> __x,
596 basic_string_view<_CharT, _Traits> __y) noexcept
597 { return __x.compare(__y) < 0; }
599 template<typename _CharT, typename _Traits>
601 operator< (basic_string_view<_CharT, _Traits> __x,
602 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
604 { return __x.compare(__y) < 0; }
606 template<typename _CharT, typename _Traits>
608 operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
609 basic_string_view<_CharT, _Traits> __y) noexcept
610 { return __x.compare(__y) < 0; }
612 template<typename _CharT, typename _Traits>
614 operator> (basic_string_view<_CharT, _Traits> __x,
615 basic_string_view<_CharT, _Traits> __y) noexcept
616 { return __x.compare(__y) > 0; }
618 template<typename _CharT, typename _Traits>
620 operator> (basic_string_view<_CharT, _Traits> __x,
621 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
623 { return __x.compare(__y) > 0; }
625 template<typename _CharT, typename _Traits>
627 operator> (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
628 basic_string_view<_CharT, _Traits> __y) noexcept
629 { return __x.compare(__y) > 0; }
631 template<typename _CharT, typename _Traits>
633 operator<=(basic_string_view<_CharT, _Traits> __x,
634 basic_string_view<_CharT, _Traits> __y) noexcept
635 { return __x.compare(__y) <= 0; }
637 template<typename _CharT, typename _Traits>
639 operator<=(basic_string_view<_CharT, _Traits> __x,
640 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
642 { return __x.compare(__y) <= 0; }
644 template<typename _CharT, typename _Traits>
646 operator<=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
647 basic_string_view<_CharT, _Traits> __y) noexcept
648 { return __x.compare(__y) <= 0; }
650 template<typename _CharT, typename _Traits>
652 operator>=(basic_string_view<_CharT, _Traits> __x,
653 basic_string_view<_CharT, _Traits> __y) noexcept
654 { return __x.compare(__y) >= 0; }
656 template<typename _CharT, typename _Traits>
658 operator>=(basic_string_view<_CharT, _Traits> __x,
659 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
661 { return __x.compare(__y) >= 0; }
663 template<typename _CharT, typename _Traits>
665 operator>=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
666 basic_string_view<_CharT, _Traits> __y) noexcept
667 { return __x.compare(__y) >= 0; }
668#endif // three-way comparison
670 // [string.view.io], Inserters and extractors
671 template<typename _CharT, typename _Traits>
672 inline basic_ostream<_CharT, _Traits>&
673 operator<<(basic_ostream<_CharT, _Traits>& __os,
674 basic_string_view<_CharT,_Traits> __str)
675 { return __ostream_insert(__os, __str.data(), __str.size()); }
678 // basic_string_view typedef names
680 using string_view = basic_string_view<char>;
681 using wstring_view = basic_string_view<wchar_t>;
682#ifdef _GLIBCXX_USE_CHAR8_T
683 using u8string_view = basic_string_view<char8_t>;
685 using u16string_view = basic_string_view<char16_t>;
686 using u32string_view = basic_string_view<char32_t>;
688 // [string.view.hash], hash support:
690 template<typename _Tp>
694 struct hash<string_view>
695 : public __hash_base<size_t, string_view>
698 operator()(const string_view& __str) const noexcept
699 { return std::_Hash_impl::hash(__str.data(), __str.length()); }
703 struct __is_fast_hash<hash<string_view>> : std::false_type
707 struct hash<wstring_view>
708 : public __hash_base<size_t, wstring_view>
711 operator()(const wstring_view& __s) const noexcept
712 { return std::_Hash_impl::hash(__s.data(),
713 __s.length() * sizeof(wchar_t)); }
717 struct __is_fast_hash<hash<wstring_view>> : std::false_type
720#ifdef _GLIBCXX_USE_CHAR8_T
722 struct hash<u8string_view>
723 : public __hash_base<size_t, u8string_view>
726 operator()(const u8string_view& __str) const noexcept
727 { return std::_Hash_impl::hash(__str.data(), __str.length()); }
731 struct __is_fast_hash<hash<u8string_view>> : std::false_type
736 struct hash<u16string_view>
737 : public __hash_base<size_t, u16string_view>
740 operator()(const u16string_view& __s) const noexcept
741 { return std::_Hash_impl::hash(__s.data(),
742 __s.length() * sizeof(char16_t)); }
746 struct __is_fast_hash<hash<u16string_view>> : std::false_type
750 struct hash<u32string_view>
751 : public __hash_base<size_t, u32string_view>
754 operator()(const u32string_view& __s) const noexcept
755 { return std::_Hash_impl::hash(__s.data(),
756 __s.length() * sizeof(char32_t)); }
760 struct __is_fast_hash<hash<u32string_view>> : std::false_type
763 inline namespace literals
765 inline namespace string_view_literals
767#pragma GCC diagnostic push
768#pragma GCC diagnostic ignored "-Wliteral-suffix"
769 inline constexpr basic_string_view<char>
770 operator""sv(const char* __str, size_t __len) noexcept
771 { return basic_string_view<char>{__str, __len}; }
773 inline constexpr basic_string_view<wchar_t>
774 operator""sv(const wchar_t* __str, size_t __len) noexcept
775 { return basic_string_view<wchar_t>{__str, __len}; }
777#ifdef _GLIBCXX_USE_CHAR8_T
778 inline constexpr basic_string_view<char8_t>
779 operator""sv(const char8_t* __str, size_t __len) noexcept
780 { return basic_string_view<char8_t>{__str, __len}; }
783 inline constexpr basic_string_view<char16_t>
784 operator""sv(const char16_t* __str, size_t __len) noexcept
785 { return basic_string_view<char16_t>{__str, __len}; }
787 inline constexpr basic_string_view<char32_t>
788 operator""sv(const char32_t* __str, size_t __len) noexcept
789 { return basic_string_view<char32_t>{__str, __len}; }
791#pragma GCC diagnostic pop
792 } // namespace string_literals
793 } // namespace literals
795#if __cpp_lib_concepts
798 // Opt-in to borrowed_range concept
799 template<typename _CharT, typename _Traits>
800 inline constexpr bool
801 enable_borrowed_range<basic_string_view<_CharT, _Traits>> = true;
803 // Opt-in to view concept
804 template<typename _CharT, typename _Traits>
805 inline constexpr bool
806 enable_view<basic_string_view<_CharT, _Traits>> = true;
809_GLIBCXX_END_NAMESPACE_VERSION
812#include <bits/string_view.tcc>
814#endif // __cplusplus <= 201402L
816#endif // _GLIBCXX_EXPERIMENTAL_STRING_VIEW