1 // Components for manipulating non-owning sequences of characters -*- C++ -*-
3 // Copyright (C) 2013-2020 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/>.
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
42 #include <bits/char_traits.h>
43 #include <bits/functional_hash.h>
44 #include <bits/range_access.h>
46 namespace std _GLIBCXX_VISIBILITY(default)
48 _GLIBCXX_BEGIN_NAMESPACE_VERSION
50 #define __cpp_lib_string_view 201803
52 // Helper for basic_string and basic_string_view members.
54 __sv_check(size_t __size, size_t __pos, const char* __s)
57 __throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > __size "
58 "(which is %zu)"), __s, __pos, __size);
62 // Helper for basic_string members.
63 // NB: __sv_limit doesn't check for a bad __pos value.
65 __sv_limit(size_t __size, size_t __pos, size_t __off) noexcept
67 const bool __testoff = __off < __size - __pos;
68 return __testoff ? __off : __size - __pos;
72 * @class basic_string_view <string_view>
73 * @brief A non-owning reference to a string.
78 * @tparam _CharT Type of character
79 * @tparam _Traits Traits for character type, defaults to
80 * char_traits<_CharT>.
82 * A basic_string_view looks like this:
89 template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
90 class basic_string_view
92 static_assert(!is_array_v<_CharT>);
93 static_assert(is_trivial_v<_CharT> && is_standard_layout_v<_CharT>);
94 static_assert(is_same_v<_CharT, typename _Traits::char_type>);
99 using traits_type = _Traits;
100 using value_type = _CharT;
101 using pointer = value_type*;
102 using const_pointer = const value_type*;
103 using reference = value_type&;
104 using const_reference = const value_type&;
105 using const_iterator = const value_type*;
106 using iterator = const_iterator;
107 using const_reverse_iterator = std::reverse_iterator<const_iterator>;
108 using reverse_iterator = const_reverse_iterator;
109 using size_type = size_t;
110 using difference_type = ptrdiff_t;
111 static constexpr size_type npos = size_type(-1);
113 // [string.view.cons], construction and assignment
116 basic_string_view() noexcept
117 : _M_len{0}, _M_str{nullptr}
120 constexpr basic_string_view(const basic_string_view&) noexcept = default;
122 __attribute__((__nonnull__)) constexpr
123 basic_string_view(const _CharT* __str) noexcept
124 : _M_len{traits_type::length(__str)},
129 basic_string_view(const _CharT* __str, size_type __len) noexcept
130 : _M_len{__len}, _M_str{__str}
133 #if __cplusplus > 201703L && __cpp_lib_concepts
134 template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
135 requires same_as<iter_value_t<_It>, _CharT>
136 && (!convertible_to<_End, size_type>)
138 basic_string_view(_It __first, _End __last)
139 : _M_len(__last - __first), _M_str(std::to_address(__first))
143 constexpr basic_string_view&
144 operator=(const basic_string_view&) noexcept = default;
146 // [string.view.iterators], iterator support
148 constexpr const_iterator
149 begin() const noexcept
150 { return this->_M_str; }
152 constexpr const_iterator
154 { return this->_M_str + this->_M_len; }
156 constexpr const_iterator
157 cbegin() const noexcept
158 { return this->_M_str; }
160 constexpr const_iterator
161 cend() const noexcept
162 { return this->_M_str + this->_M_len; }
164 constexpr const_reverse_iterator
165 rbegin() const noexcept
166 { return const_reverse_iterator(this->end()); }
168 constexpr const_reverse_iterator
169 rend() const noexcept
170 { return const_reverse_iterator(this->begin()); }
172 constexpr const_reverse_iterator
173 crbegin() const noexcept
174 { return const_reverse_iterator(this->end()); }
176 constexpr const_reverse_iterator
177 crend() const noexcept
178 { return const_reverse_iterator(this->begin()); }
180 // [string.view.capacity], capacity
183 size() const noexcept
184 { return this->_M_len; }
187 length() const noexcept
191 max_size() const noexcept
193 return (npos - sizeof(size_type) - sizeof(void*))
194 / sizeof(value_type) / 4;
197 [[nodiscard]] constexpr bool
198 empty() const noexcept
199 { return this->_M_len == 0; }
201 // [string.view.access], element access
203 constexpr const_reference
204 operator[](size_type __pos) const noexcept
206 // TODO: Assert to restore in a way compatible with the constexpr.
207 // __glibcxx_assert(__pos < this->_M_len);
208 return *(this->_M_str + __pos);
211 constexpr const_reference
212 at(size_type __pos) const
215 __throw_out_of_range_fmt(__N("basic_string_view::at: __pos "
216 "(which is %zu) >= this->size() "
217 "(which is %zu)"), __pos, this->size());
218 return *(this->_M_str + __pos);
221 constexpr const_reference
222 front() const noexcept
224 // TODO: Assert to restore in a way compatible with the constexpr.
225 // __glibcxx_assert(this->_M_len > 0);
226 return *this->_M_str;
229 constexpr const_reference
230 back() const noexcept
232 // TODO: Assert to restore in a way compatible with the constexpr.
233 // __glibcxx_assert(this->_M_len > 0);
234 return *(this->_M_str + this->_M_len - 1);
237 constexpr const_pointer
238 data() const noexcept
239 { return this->_M_str; }
241 // [string.view.modifiers], modifiers:
244 remove_prefix(size_type __n) noexcept
246 __glibcxx_assert(this->_M_len >= __n);
252 remove_suffix(size_type __n) noexcept
253 { this->_M_len -= __n; }
256 swap(basic_string_view& __sv) noexcept
263 // [string.view.ops], string operations:
266 copy(_CharT* __str, size_type __n, size_type __pos = 0) const
268 __glibcxx_requires_string_len(__str, __n);
269 __pos = std::__sv_check(size(), __pos, "basic_string_view::copy");
270 const size_type __rlen = std::min(__n, _M_len - __pos);
271 // _GLIBCXX_RESOLVE_LIB_DEFECTS
272 // 2777. basic_string_view::copy should use char_traits::copy
273 traits_type::copy(__str, data() + __pos, __rlen);
277 constexpr basic_string_view
278 substr(size_type __pos = 0, size_type __n = npos) const noexcept(false)
280 __pos = std::__sv_check(size(), __pos, "basic_string_view::substr");
281 const size_type __rlen = std::min(__n, _M_len - __pos);
282 return basic_string_view{_M_str + __pos, __rlen};
286 compare(basic_string_view __str) const noexcept
288 const size_type __rlen = std::min(this->_M_len, __str._M_len);
289 int __ret = traits_type::compare(this->_M_str, __str._M_str, __rlen);
291 __ret = _S_compare(this->_M_len, __str._M_len);
296 compare(size_type __pos1, size_type __n1, basic_string_view __str) const
297 { return this->substr(__pos1, __n1).compare(__str); }
300 compare(size_type __pos1, size_type __n1,
301 basic_string_view __str, size_type __pos2, size_type __n2) const
303 return this->substr(__pos1, __n1).compare(__str.substr(__pos2, __n2));
306 __attribute__((__nonnull__)) constexpr int
307 compare(const _CharT* __str) const noexcept
308 { return this->compare(basic_string_view{__str}); }
310 __attribute__((__nonnull__)) constexpr int
311 compare(size_type __pos1, size_type __n1, const _CharT* __str) const
312 { return this->substr(__pos1, __n1).compare(basic_string_view{__str}); }
315 compare(size_type __pos1, size_type __n1,
316 const _CharT* __str, size_type __n2) const noexcept(false)
318 return this->substr(__pos1, __n1)
319 .compare(basic_string_view(__str, __n2));
322 #if __cplusplus > 201703L
324 starts_with(basic_string_view __x) const noexcept
325 { return this->substr(0, __x.size()) == __x; }
328 starts_with(_CharT __x) const noexcept
329 { return !this->empty() && traits_type::eq(this->front(), __x); }
332 starts_with(const _CharT* __x) const noexcept
333 { return this->starts_with(basic_string_view(__x)); }
336 ends_with(basic_string_view __x) const noexcept
338 return this->size() >= __x.size()
339 && this->compare(this->size() - __x.size(), npos, __x) == 0;
343 ends_with(_CharT __x) const noexcept
344 { return !this->empty() && traits_type::eq(this->back(), __x); }
347 ends_with(const _CharT* __x) const noexcept
348 { return this->ends_with(basic_string_view(__x)); }
351 // [string.view.find], searching
354 find(basic_string_view __str, size_type __pos = 0) const noexcept
355 { return this->find(__str._M_str, __pos, __str._M_len); }
358 find(_CharT __c, size_type __pos = 0) const noexcept;
361 find(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
363 __attribute__((__nonnull__)) constexpr size_type
364 find(const _CharT* __str, size_type __pos = 0) const noexcept
365 { return this->find(__str, __pos, traits_type::length(__str)); }
368 rfind(basic_string_view __str, size_type __pos = npos) const noexcept
369 { return this->rfind(__str._M_str, __pos, __str._M_len); }
372 rfind(_CharT __c, size_type __pos = npos) const noexcept;
375 rfind(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
377 __attribute__((__nonnull__)) constexpr size_type
378 rfind(const _CharT* __str, size_type __pos = npos) const noexcept
379 { return this->rfind(__str, __pos, traits_type::length(__str)); }
382 find_first_of(basic_string_view __str, size_type __pos = 0) const noexcept
383 { return this->find_first_of(__str._M_str, __pos, __str._M_len); }
386 find_first_of(_CharT __c, size_type __pos = 0) const noexcept
387 { return this->find(__c, __pos); }
390 find_first_of(const _CharT* __str, size_type __pos,
391 size_type __n) const noexcept;
393 __attribute__((__nonnull__)) constexpr size_type
394 find_first_of(const _CharT* __str, size_type __pos = 0) const noexcept
395 { return this->find_first_of(__str, __pos, traits_type::length(__str)); }
398 find_last_of(basic_string_view __str,
399 size_type __pos = npos) const noexcept
400 { return this->find_last_of(__str._M_str, __pos, __str._M_len); }
403 find_last_of(_CharT __c, size_type __pos=npos) const noexcept
404 { return this->rfind(__c, __pos); }
407 find_last_of(const _CharT* __str, size_type __pos,
408 size_type __n) const noexcept;
410 __attribute__((__nonnull__)) constexpr size_type
411 find_last_of(const _CharT* __str, size_type __pos = npos) const noexcept
412 { return this->find_last_of(__str, __pos, traits_type::length(__str)); }
415 find_first_not_of(basic_string_view __str,
416 size_type __pos = 0) const noexcept
417 { return this->find_first_not_of(__str._M_str, __pos, __str._M_len); }
420 find_first_not_of(_CharT __c, size_type __pos = 0) const noexcept;
423 find_first_not_of(const _CharT* __str,
424 size_type __pos, size_type __n) const noexcept;
426 __attribute__((__nonnull__)) constexpr size_type
427 find_first_not_of(const _CharT* __str, size_type __pos = 0) const noexcept
429 return this->find_first_not_of(__str, __pos,
430 traits_type::length(__str));
434 find_last_not_of(basic_string_view __str,
435 size_type __pos = npos) const noexcept
436 { return this->find_last_not_of(__str._M_str, __pos, __str._M_len); }
439 find_last_not_of(_CharT __c, size_type __pos = npos) const noexcept;
442 find_last_not_of(const _CharT* __str,
443 size_type __pos, size_type __n) const noexcept;
445 __attribute__((__nonnull__)) constexpr size_type
446 find_last_not_of(const _CharT* __str,
447 size_type __pos = npos) const noexcept
449 return this->find_last_not_of(__str, __pos,
450 traits_type::length(__str));
456 _S_compare(size_type __n1, size_type __n2) noexcept
458 const difference_type __diff = __n1 - __n2;
459 if (__diff > std::numeric_limits<int>::max())
460 return std::numeric_limits<int>::max();
461 if (__diff < std::numeric_limits<int>::min())
462 return std::numeric_limits<int>::min();
463 return static_cast<int>(__diff);
467 const _CharT* _M_str;
470 #if __cplusplus > 201703L && __cpp_lib_concepts && __cpp_deduction_guides
471 template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
472 basic_string_view(_It, _End) -> basic_string_view<iter_value_t<_It>>;
475 // [string.view.comparison], non-member basic_string_view comparison function
477 // Several of these functions use type_identity_t to create a non-deduced
478 // context, so that only one argument participates in template argument
479 // deduction and the other argument gets implicitly converted to the deduced
482 template<typename _CharT, typename _Traits>
484 operator==(basic_string_view<_CharT, _Traits> __x,
485 basic_string_view<_CharT, _Traits> __y) noexcept
486 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
488 template<typename _CharT, typename _Traits>
490 operator==(basic_string_view<_CharT, _Traits> __x,
491 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
493 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
495 template<typename _CharT, typename _Traits>
497 operator==(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
498 basic_string_view<_CharT, _Traits> __y) noexcept
499 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
501 template<typename _CharT, typename _Traits>
503 operator!=(basic_string_view<_CharT, _Traits> __x,
504 basic_string_view<_CharT, _Traits> __y) noexcept
505 { return !(__x == __y); }
507 template<typename _CharT, typename _Traits>
509 operator!=(basic_string_view<_CharT, _Traits> __x,
510 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
512 { return !(__x == __y); }
514 template<typename _CharT, typename _Traits>
516 operator!=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
517 basic_string_view<_CharT, _Traits> __y) noexcept
518 { return !(__x == __y); }
520 template<typename _CharT, typename _Traits>
522 operator< (basic_string_view<_CharT, _Traits> __x,
523 basic_string_view<_CharT, _Traits> __y) noexcept
524 { return __x.compare(__y) < 0; }
526 template<typename _CharT, typename _Traits>
528 operator< (basic_string_view<_CharT, _Traits> __x,
529 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
531 { return __x.compare(__y) < 0; }
533 template<typename _CharT, typename _Traits>
535 operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
536 basic_string_view<_CharT, _Traits> __y) noexcept
537 { return __x.compare(__y) < 0; }
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.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.compare(__y) > 0; }
552 template<typename _CharT, typename _Traits>
554 operator> (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
555 basic_string_view<_CharT, _Traits> __y) noexcept
556 { return __x.compare(__y) > 0; }
558 template<typename _CharT, typename _Traits>
560 operator<=(basic_string_view<_CharT, _Traits> __x,
561 basic_string_view<_CharT, _Traits> __y) noexcept
562 { return __x.compare(__y) <= 0; }
564 template<typename _CharT, typename _Traits>
566 operator<=(basic_string_view<_CharT, _Traits> __x,
567 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
569 { return __x.compare(__y) <= 0; }
571 template<typename _CharT, typename _Traits>
573 operator<=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
574 basic_string_view<_CharT, _Traits> __y) noexcept
575 { return __x.compare(__y) <= 0; }
577 template<typename _CharT, typename _Traits>
579 operator>=(basic_string_view<_CharT, _Traits> __x,
580 basic_string_view<_CharT, _Traits> __y) noexcept
581 { return __x.compare(__y) >= 0; }
583 template<typename _CharT, typename _Traits>
585 operator>=(basic_string_view<_CharT, _Traits> __x,
586 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
588 { return __x.compare(__y) >= 0; }
590 template<typename _CharT, typename _Traits>
592 operator>=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
593 basic_string_view<_CharT, _Traits> __y) noexcept
594 { return __x.compare(__y) >= 0; }
596 // [string.view.io], Inserters and extractors
597 template<typename _CharT, typename _Traits>
598 inline basic_ostream<_CharT, _Traits>&
599 operator<<(basic_ostream<_CharT, _Traits>& __os,
600 basic_string_view<_CharT,_Traits> __str)
601 { return __ostream_insert(__os, __str.data(), __str.size()); }
604 // basic_string_view typedef names
606 using string_view = basic_string_view<char>;
607 #ifdef _GLIBCXX_USE_WCHAR_T
608 using wstring_view = basic_string_view<wchar_t>;
610 #ifdef _GLIBCXX_USE_CHAR8_T
611 using u8string_view = basic_string_view<char8_t>;
613 using u16string_view = basic_string_view<char16_t>;
614 using u32string_view = basic_string_view<char32_t>;
616 // [string.view.hash], hash support:
618 template<typename _Tp>
622 struct hash<string_view>
623 : public __hash_base<size_t, string_view>
626 operator()(const string_view& __str) const noexcept
627 { return std::_Hash_impl::hash(__str.data(), __str.length()); }
631 struct __is_fast_hash<hash<string_view>> : std::false_type
634 #ifdef _GLIBCXX_USE_WCHAR_T
636 struct hash<wstring_view>
637 : public __hash_base<size_t, wstring_view>
640 operator()(const wstring_view& __s) const noexcept
641 { return std::_Hash_impl::hash(__s.data(),
642 __s.length() * sizeof(wchar_t)); }
646 struct __is_fast_hash<hash<wstring_view>> : std::false_type
650 #ifdef _GLIBCXX_USE_CHAR8_T
652 struct hash<u8string_view>
653 : public __hash_base<size_t, u8string_view>
656 operator()(const u8string_view& __str) const noexcept
657 { return std::_Hash_impl::hash(__str.data(), __str.length()); }
661 struct __is_fast_hash<hash<u8string_view>> : std::false_type
666 struct hash<u16string_view>
667 : public __hash_base<size_t, u16string_view>
670 operator()(const u16string_view& __s) const noexcept
671 { return std::_Hash_impl::hash(__s.data(),
672 __s.length() * sizeof(char16_t)); }
676 struct __is_fast_hash<hash<u16string_view>> : std::false_type
680 struct hash<u32string_view>
681 : public __hash_base<size_t, u32string_view>
684 operator()(const u32string_view& __s) const noexcept
685 { return std::_Hash_impl::hash(__s.data(),
686 __s.length() * sizeof(char32_t)); }
690 struct __is_fast_hash<hash<u32string_view>> : std::false_type
693 inline namespace literals
695 inline namespace string_view_literals
697 #pragma GCC diagnostic push
698 #pragma GCC diagnostic ignored "-Wliteral-suffix"
699 inline constexpr basic_string_view<char>
700 operator""sv(const char* __str, size_t __len) noexcept
701 { return basic_string_view<char>{__str, __len}; }
703 #ifdef _GLIBCXX_USE_WCHAR_T
704 inline constexpr basic_string_view<wchar_t>
705 operator""sv(const wchar_t* __str, size_t __len) noexcept
706 { return basic_string_view<wchar_t>{__str, __len}; }
709 #ifdef _GLIBCXX_USE_CHAR8_T
710 inline constexpr basic_string_view<char8_t>
711 operator""sv(const char8_t* __str, size_t __len) noexcept
712 { return basic_string_view<char8_t>{__str, __len}; }
715 inline constexpr basic_string_view<char16_t>
716 operator""sv(const char16_t* __str, size_t __len) noexcept
717 { return basic_string_view<char16_t>{__str, __len}; }
719 inline constexpr basic_string_view<char32_t>
720 operator""sv(const char32_t* __str, size_t __len) noexcept
721 { return basic_string_view<char32_t>{__str, __len}; }
723 #pragma GCC diagnostic pop
724 } // namespace string_literals
725 } // namespace literals
727 #if __cpp_lib_concepts
730 template<typename> extern inline const bool enable_safe_range;
731 // Opt-in to safe_range concept
732 template<typename _CharT, typename _Traits>
733 inline constexpr bool
734 enable_safe_range<basic_string_view<_CharT, _Traits>> = true;
737 _GLIBCXX_END_NAMESPACE_VERSION
740 #include <bits/string_view.tcc>
742 #endif // __cplusplus <= 201402L
744 #endif // _GLIBCXX_EXPERIMENTAL_STRING_VIEW