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
41 #include <bits/char_traits.h>
42 #include <bits/functional_hash.h>
43 #include <bits/int_limits.h>
44 #include <bits/range_access.h>
45 #include <bits/ostream_insert.h>
47 namespace std _GLIBCXX_VISIBILITY(default)
49 _GLIBCXX_BEGIN_NAMESPACE_VERSION
51 #define __cpp_lib_string_view 201803
53 // Helper for basic_string and basic_string_view members.
55 __sv_check(size_t __size, size_t __pos, const char* __s)
58 __throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > __size "
59 "(which is %zu)"), __s, __pos, __size);
63 // Helper for basic_string members.
64 // NB: __sv_limit doesn't check for a bad __pos value.
66 __sv_limit(size_t __size, size_t __pos, size_t __off) noexcept
68 const bool __testoff = __off < __size - __pos;
69 return __testoff ? __off : __size - __pos;
73 * @class basic_string_view <string_view>
74 * @brief A non-owning reference to a string.
79 * @tparam _CharT Type of character
80 * @tparam _Traits Traits for character type, defaults to
81 * char_traits<_CharT>.
83 * A basic_string_view looks like this:
90 template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
91 class basic_string_view
93 static_assert(!is_array_v<_CharT>);
94 static_assert(is_trivial_v<_CharT> && is_standard_layout_v<_CharT>);
95 static_assert(is_same_v<_CharT, typename _Traits::char_type>);
100 using traits_type = _Traits;
101 using value_type = _CharT;
102 using pointer = value_type*;
103 using const_pointer = const value_type*;
104 using reference = value_type&;
105 using const_reference = const value_type&;
106 using const_iterator = const value_type*;
107 using iterator = const_iterator;
108 using const_reverse_iterator = std::reverse_iterator<const_iterator>;
109 using reverse_iterator = const_reverse_iterator;
110 using size_type = size_t;
111 using difference_type = ptrdiff_t;
112 static constexpr size_type npos = size_type(-1);
114 // [string.view.cons], construction and assignment
117 basic_string_view() noexcept
118 : _M_len{0}, _M_str{nullptr}
121 constexpr basic_string_view(const basic_string_view&) noexcept = default;
123 __attribute__((__nonnull__)) constexpr
124 basic_string_view(const _CharT* __str) noexcept
125 : _M_len{traits_type::length(__str)},
130 basic_string_view(const _CharT* __str, size_type __len) noexcept
131 : _M_len{__len}, _M_str{__str}
134 #if __cplusplus > 201703L && __cpp_lib_concepts
135 template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
136 requires same_as<iter_value_t<_It>, _CharT>
137 && (!convertible_to<_End, size_type>)
139 basic_string_view(_It __first, _End __last)
140 : _M_len(__last - __first), _M_str(std::to_address(__first))
144 constexpr basic_string_view&
145 operator=(const basic_string_view&) noexcept = default;
147 // [string.view.iterators], iterator support
149 constexpr const_iterator
150 begin() const noexcept
151 { return this->_M_str; }
153 constexpr const_iterator
155 { return this->_M_str + this->_M_len; }
157 constexpr const_iterator
158 cbegin() const noexcept
159 { return this->_M_str; }
161 constexpr const_iterator
162 cend() const noexcept
163 { return this->_M_str + this->_M_len; }
165 constexpr const_reverse_iterator
166 rbegin() const noexcept
167 { return const_reverse_iterator(this->end()); }
169 constexpr const_reverse_iterator
170 rend() const noexcept
171 { return const_reverse_iterator(this->begin()); }
173 constexpr const_reverse_iterator
174 crbegin() const noexcept
175 { return const_reverse_iterator(this->end()); }
177 constexpr const_reverse_iterator
178 crend() const noexcept
179 { return const_reverse_iterator(this->begin()); }
181 // [string.view.capacity], capacity
184 size() const noexcept
185 { return this->_M_len; }
188 length() const noexcept
192 max_size() const noexcept
194 return (npos - sizeof(size_type) - sizeof(void*))
195 / sizeof(value_type) / 4;
198 [[nodiscard]] constexpr bool
199 empty() const noexcept
200 { return this->_M_len == 0; }
202 // [string.view.access], element access
204 constexpr const_reference
205 operator[](size_type __pos) const noexcept
207 // TODO: Assert to restore in a way compatible with the constexpr.
208 // __glibcxx_assert(__pos < this->_M_len);
209 return *(this->_M_str + __pos);
212 constexpr const_reference
213 at(size_type __pos) const
216 __throw_out_of_range_fmt(__N("basic_string_view::at: __pos "
217 "(which is %zu) >= this->size() "
218 "(which is %zu)"), __pos, this->size());
219 return *(this->_M_str + __pos);
222 constexpr const_reference
223 front() const noexcept
225 // TODO: Assert to restore in a way compatible with the constexpr.
226 // __glibcxx_assert(this->_M_len > 0);
227 return *this->_M_str;
230 constexpr const_reference
231 back() const noexcept
233 // TODO: Assert to restore in a way compatible with the constexpr.
234 // __glibcxx_assert(this->_M_len > 0);
235 return *(this->_M_str + this->_M_len - 1);
238 constexpr const_pointer
239 data() const noexcept
240 { return this->_M_str; }
242 // [string.view.modifiers], modifiers:
245 remove_prefix(size_type __n) noexcept
247 __glibcxx_assert(this->_M_len >= __n);
253 remove_suffix(size_type __n) noexcept
254 { this->_M_len -= __n; }
257 swap(basic_string_view& __sv) noexcept
264 // [string.view.ops], string operations:
268 copy(_CharT* __str, size_type __n, size_type __pos = 0) const
270 __glibcxx_requires_string_len(__str, __n);
271 __pos = std::__sv_check(size(), __pos, "basic_string_view::copy");
272 const size_type __rlen = std::min(__n, _M_len - __pos);
273 // _GLIBCXX_RESOLVE_LIB_DEFECTS
274 // 2777. basic_string_view::copy should use char_traits::copy
275 traits_type::copy(__str, data() + __pos, __rlen);
279 constexpr basic_string_view
280 substr(size_type __pos = 0, size_type __n = npos) const noexcept(false)
282 __pos = std::__sv_check(size(), __pos, "basic_string_view::substr");
283 const size_type __rlen = std::min(__n, _M_len - __pos);
284 return basic_string_view{_M_str + __pos, __rlen};
288 compare(basic_string_view __str) const noexcept
290 const size_type __rlen = std::min(this->_M_len, __str._M_len);
291 int __ret = traits_type::compare(this->_M_str, __str._M_str, __rlen);
293 __ret = _S_compare(this->_M_len, __str._M_len);
298 compare(size_type __pos1, size_type __n1, basic_string_view __str) const
299 { return this->substr(__pos1, __n1).compare(__str); }
302 compare(size_type __pos1, size_type __n1,
303 basic_string_view __str, size_type __pos2, size_type __n2) const
305 return this->substr(__pos1, __n1).compare(__str.substr(__pos2, __n2));
308 __attribute__((__nonnull__)) constexpr int
309 compare(const _CharT* __str) const noexcept
310 { return this->compare(basic_string_view{__str}); }
312 __attribute__((__nonnull__)) constexpr int
313 compare(size_type __pos1, size_type __n1, const _CharT* __str) const
314 { return this->substr(__pos1, __n1).compare(basic_string_view{__str}); }
317 compare(size_type __pos1, size_type __n1,
318 const _CharT* __str, size_type __n2) const noexcept(false)
320 return this->substr(__pos1, __n1)
321 .compare(basic_string_view(__str, __n2));
324 #if __cplusplus > 201703L
326 starts_with(basic_string_view __x) const noexcept
327 { return this->substr(0, __x.size()) == __x; }
330 starts_with(_CharT __x) const noexcept
331 { return !this->empty() && traits_type::eq(this->front(), __x); }
334 starts_with(const _CharT* __x) const noexcept
335 { return this->starts_with(basic_string_view(__x)); }
338 ends_with(basic_string_view __x) const noexcept
340 return this->size() >= __x.size()
341 && this->compare(this->size() - __x.size(), npos, __x) == 0;
345 ends_with(_CharT __x) const noexcept
346 { return !this->empty() && traits_type::eq(this->back(), __x); }
349 ends_with(const _CharT* __x) const noexcept
350 { return this->ends_with(basic_string_view(__x)); }
353 // [string.view.find], searching
356 find(basic_string_view __str, size_type __pos = 0) const noexcept
357 { return this->find(__str._M_str, __pos, __str._M_len); }
360 find(_CharT __c, size_type __pos = 0) const noexcept;
363 find(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
365 __attribute__((__nonnull__)) constexpr size_type
366 find(const _CharT* __str, size_type __pos = 0) const noexcept
367 { return this->find(__str, __pos, traits_type::length(__str)); }
370 rfind(basic_string_view __str, size_type __pos = npos) const noexcept
371 { return this->rfind(__str._M_str, __pos, __str._M_len); }
374 rfind(_CharT __c, size_type __pos = npos) const noexcept;
377 rfind(const _CharT* __str, size_type __pos, size_type __n) const noexcept;
379 __attribute__((__nonnull__)) constexpr size_type
380 rfind(const _CharT* __str, size_type __pos = npos) const noexcept
381 { return this->rfind(__str, __pos, traits_type::length(__str)); }
384 find_first_of(basic_string_view __str, size_type __pos = 0) const noexcept
385 { return this->find_first_of(__str._M_str, __pos, __str._M_len); }
388 find_first_of(_CharT __c, size_type __pos = 0) const noexcept
389 { return this->find(__c, __pos); }
392 find_first_of(const _CharT* __str, size_type __pos,
393 size_type __n) const noexcept;
395 __attribute__((__nonnull__)) constexpr size_type
396 find_first_of(const _CharT* __str, size_type __pos = 0) const noexcept
397 { return this->find_first_of(__str, __pos, traits_type::length(__str)); }
400 find_last_of(basic_string_view __str,
401 size_type __pos = npos) const noexcept
402 { return this->find_last_of(__str._M_str, __pos, __str._M_len); }
405 find_last_of(_CharT __c, size_type __pos=npos) const noexcept
406 { return this->rfind(__c, __pos); }
409 find_last_of(const _CharT* __str, size_type __pos,
410 size_type __n) const noexcept;
412 __attribute__((__nonnull__)) constexpr size_type
413 find_last_of(const _CharT* __str, size_type __pos = npos) const noexcept
414 { return this->find_last_of(__str, __pos, traits_type::length(__str)); }
417 find_first_not_of(basic_string_view __str,
418 size_type __pos = 0) const noexcept
419 { return this->find_first_not_of(__str._M_str, __pos, __str._M_len); }
422 find_first_not_of(_CharT __c, size_type __pos = 0) const noexcept;
425 find_first_not_of(const _CharT* __str,
426 size_type __pos, size_type __n) const noexcept;
428 __attribute__((__nonnull__)) constexpr size_type
429 find_first_not_of(const _CharT* __str, size_type __pos = 0) const noexcept
431 return this->find_first_not_of(__str, __pos,
432 traits_type::length(__str));
436 find_last_not_of(basic_string_view __str,
437 size_type __pos = npos) const noexcept
438 { return this->find_last_not_of(__str._M_str, __pos, __str._M_len); }
441 find_last_not_of(_CharT __c, size_type __pos = npos) const noexcept;
444 find_last_not_of(const _CharT* __str,
445 size_type __pos, size_type __n) const noexcept;
447 __attribute__((__nonnull__)) constexpr size_type
448 find_last_not_of(const _CharT* __str,
449 size_type __pos = npos) const noexcept
451 return this->find_last_not_of(__str, __pos,
452 traits_type::length(__str));
458 _S_compare(size_type __n1, size_type __n2) noexcept
460 const difference_type __diff = __n1 - __n2;
461 if (__diff > __detail::__int_limits<int>::max())
462 return __detail::__int_limits<int>::max();
463 if (__diff < __detail::__int_limits<int>::min())
464 return __detail::__int_limits<int>::min();
465 return static_cast<int>(__diff);
469 const _CharT* _M_str;
472 #if __cplusplus > 201703L && __cpp_lib_concepts && __cpp_deduction_guides
473 template<contiguous_iterator _It, sized_sentinel_for<_It> _End>
474 basic_string_view(_It, _End) -> basic_string_view<iter_value_t<_It>>;
477 // [string.view.comparison], non-member basic_string_view comparison function
479 // Several of these functions use type_identity_t to create a non-deduced
480 // context, so that only one argument participates in template argument
481 // deduction and the other argument gets implicitly converted to the deduced
484 template<typename _CharT, typename _Traits>
486 operator==(basic_string_view<_CharT, _Traits> __x,
487 basic_string_view<_CharT, _Traits> __y) noexcept
488 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
490 template<typename _CharT, typename _Traits>
492 operator==(basic_string_view<_CharT, _Traits> __x,
493 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
495 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
497 #if __cpp_lib_three_way_comparison
498 template<typename _CharT, typename _Traits>
500 operator<=>(basic_string_view<_CharT, _Traits> __x,
501 basic_string_view<_CharT, _Traits> __y) noexcept
502 -> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
503 { return __detail::__char_traits_cmp_cat<_Traits>(__x.compare(__y)); }
505 template<typename _CharT, typename _Traits>
507 operator<=>(basic_string_view<_CharT, _Traits> __x,
508 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
510 -> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
511 { return __detail::__char_traits_cmp_cat<_Traits>(__x.compare(__y)); }
513 template<typename _CharT, typename _Traits>
515 operator==(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
516 basic_string_view<_CharT, _Traits> __y) noexcept
517 { return __x.size() == __y.size() && __x.compare(__y) == 0; }
519 template<typename _CharT, typename _Traits>
521 operator!=(basic_string_view<_CharT, _Traits> __x,
522 basic_string_view<_CharT, _Traits> __y) noexcept
523 { return !(__x == __y); }
525 template<typename _CharT, typename _Traits>
527 operator!=(basic_string_view<_CharT, _Traits> __x,
528 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
530 { return !(__x == __y); }
532 template<typename _CharT, typename _Traits>
534 operator!=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
535 basic_string_view<_CharT, _Traits> __y) noexcept
536 { return !(__x == __y); }
538 template<typename _CharT, typename _Traits>
540 operator< (basic_string_view<_CharT, _Traits> __x,
541 basic_string_view<_CharT, _Traits> __y) noexcept
542 { return __x.compare(__y) < 0; }
544 template<typename _CharT, typename _Traits>
546 operator< (basic_string_view<_CharT, _Traits> __x,
547 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
549 { return __x.compare(__y) < 0; }
551 template<typename _CharT, typename _Traits>
553 operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
554 basic_string_view<_CharT, _Traits> __y) noexcept
555 { return __x.compare(__y) < 0; }
557 template<typename _CharT, typename _Traits>
559 operator> (basic_string_view<_CharT, _Traits> __x,
560 basic_string_view<_CharT, _Traits> __y) noexcept
561 { return __x.compare(__y) > 0; }
563 template<typename _CharT, typename _Traits>
565 operator> (basic_string_view<_CharT, _Traits> __x,
566 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
568 { return __x.compare(__y) > 0; }
570 template<typename _CharT, typename _Traits>
572 operator> (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
573 basic_string_view<_CharT, _Traits> __y) noexcept
574 { return __x.compare(__y) > 0; }
576 template<typename _CharT, typename _Traits>
578 operator<=(basic_string_view<_CharT, _Traits> __x,
579 basic_string_view<_CharT, _Traits> __y) noexcept
580 { return __x.compare(__y) <= 0; }
582 template<typename _CharT, typename _Traits>
584 operator<=(basic_string_view<_CharT, _Traits> __x,
585 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
587 { return __x.compare(__y) <= 0; }
589 template<typename _CharT, typename _Traits>
591 operator<=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
592 basic_string_view<_CharT, _Traits> __y) noexcept
593 { return __x.compare(__y) <= 0; }
595 template<typename _CharT, typename _Traits>
597 operator>=(basic_string_view<_CharT, _Traits> __x,
598 basic_string_view<_CharT, _Traits> __y) noexcept
599 { return __x.compare(__y) >= 0; }
601 template<typename _CharT, typename _Traits>
603 operator>=(basic_string_view<_CharT, _Traits> __x,
604 __type_identity_t<basic_string_view<_CharT, _Traits>> __y)
606 { return __x.compare(__y) >= 0; }
608 template<typename _CharT, typename _Traits>
610 operator>=(__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
611 basic_string_view<_CharT, _Traits> __y) noexcept
612 { return __x.compare(__y) >= 0; }
613 #endif // three-way comparison
615 // [string.view.io], Inserters and extractors
616 template<typename _CharT, typename _Traits>
617 inline basic_ostream<_CharT, _Traits>&
618 operator<<(basic_ostream<_CharT, _Traits>& __os,
619 basic_string_view<_CharT,_Traits> __str)
620 { return __ostream_insert(__os, __str.data(), __str.size()); }
623 // basic_string_view typedef names
625 using string_view = basic_string_view<char>;
626 #ifdef _GLIBCXX_USE_WCHAR_T
627 using wstring_view = basic_string_view<wchar_t>;
629 #ifdef _GLIBCXX_USE_CHAR8_T
630 using u8string_view = basic_string_view<char8_t>;
632 using u16string_view = basic_string_view<char16_t>;
633 using u32string_view = basic_string_view<char32_t>;
635 // [string.view.hash], hash support:
637 template<typename _Tp>
641 struct hash<string_view>
642 : public __hash_base<size_t, string_view>
645 operator()(const string_view& __str) const noexcept
646 { return std::_Hash_impl::hash(__str.data(), __str.length()); }
650 struct __is_fast_hash<hash<string_view>> : std::false_type
653 #ifdef _GLIBCXX_USE_WCHAR_T
655 struct hash<wstring_view>
656 : public __hash_base<size_t, wstring_view>
659 operator()(const wstring_view& __s) const noexcept
660 { return std::_Hash_impl::hash(__s.data(),
661 __s.length() * sizeof(wchar_t)); }
665 struct __is_fast_hash<hash<wstring_view>> : std::false_type
669 #ifdef _GLIBCXX_USE_CHAR8_T
671 struct hash<u8string_view>
672 : public __hash_base<size_t, u8string_view>
675 operator()(const u8string_view& __str) const noexcept
676 { return std::_Hash_impl::hash(__str.data(), __str.length()); }
680 struct __is_fast_hash<hash<u8string_view>> : std::false_type
685 struct hash<u16string_view>
686 : public __hash_base<size_t, u16string_view>
689 operator()(const u16string_view& __s) const noexcept
690 { return std::_Hash_impl::hash(__s.data(),
691 __s.length() * sizeof(char16_t)); }
695 struct __is_fast_hash<hash<u16string_view>> : std::false_type
699 struct hash<u32string_view>
700 : public __hash_base<size_t, u32string_view>
703 operator()(const u32string_view& __s) const noexcept
704 { return std::_Hash_impl::hash(__s.data(),
705 __s.length() * sizeof(char32_t)); }
709 struct __is_fast_hash<hash<u32string_view>> : std::false_type
712 inline namespace literals
714 inline namespace string_view_literals
716 #pragma GCC diagnostic push
717 #pragma GCC diagnostic ignored "-Wliteral-suffix"
718 inline constexpr basic_string_view<char>
719 operator""sv(const char* __str, size_t __len) noexcept
720 { return basic_string_view<char>{__str, __len}; }
722 #ifdef _GLIBCXX_USE_WCHAR_T
723 inline constexpr basic_string_view<wchar_t>
724 operator""sv(const wchar_t* __str, size_t __len) noexcept
725 { return basic_string_view<wchar_t>{__str, __len}; }
728 #ifdef _GLIBCXX_USE_CHAR8_T
729 inline constexpr basic_string_view<char8_t>
730 operator""sv(const char8_t* __str, size_t __len) noexcept
731 { return basic_string_view<char8_t>{__str, __len}; }
734 inline constexpr basic_string_view<char16_t>
735 operator""sv(const char16_t* __str, size_t __len) noexcept
736 { return basic_string_view<char16_t>{__str, __len}; }
738 inline constexpr basic_string_view<char32_t>
739 operator""sv(const char32_t* __str, size_t __len) noexcept
740 { return basic_string_view<char32_t>{__str, __len}; }
742 #pragma GCC diagnostic pop
743 } // namespace string_literals
744 } // namespace literals
746 #if __cpp_lib_concepts
749 // Opt-in to borrowed_range concept
750 template<typename _CharT, typename _Traits>
751 inline constexpr bool
752 enable_borrowed_range<basic_string_view<_CharT, _Traits>> = true;
754 // Opt-in to view concept
755 template<typename _CharT, typename _Traits>
756 inline constexpr bool
757 enable_view<basic_string_view<_CharT, _Traits>> = true;
760 _GLIBCXX_END_NAMESPACE_VERSION
763 #include <bits/string_view.tcc>
765 #endif // __cplusplus <= 201402L
767 #endif // _GLIBCXX_EXPERIMENTAL_STRING_VIEW