1// -*- C++ -*-
2//===-------------------------- __string ----------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP___STRING
11#define _LIBCPP___STRING
12
13#include <__config>
14#include <__algorithm/copy.h>
15#include <__algorithm/copy_backward.h>
16#include <__algorithm/copy_n.h>
17#include <__algorithm/fill_n.h>
18#include <__algorithm/find_first_of.h>
19#include <__algorithm/find_end.h>
20#include <__algorithm/min.h>
21#include <__functional/hash.h>     // for __murmur2_or_cityhash
22#include <__iterator/iterator_traits.h>
23#include <cstdio>      // for EOF
24#include <cstdint>     // for uint_least16_t
25#include <cstring>     // for memcpy
26#include <cwchar>      // for wmemcpy
27#include <type_traits> // for __libcpp_is_constant_evaluated
28
29#include <__debug>
30
31#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
32#pragma GCC system_header
33#endif
34
35_LIBCPP_PUSH_MACROS
36#include <__undef_macros>
37
38
39_LIBCPP_BEGIN_NAMESPACE_STD
40
41// The the extern template ABI lists are kept outside of <string> to improve the
42// readability of that header.
43
44// The extern template ABI lists are kept outside of <string> to improve the
45// readability of that header. We maintain 2 ABI lists:
46// - _LIBCPP_STRING_V1_EXTERN_TEMPLATE_LIST
47// - _LIBCPP_STRING_UNSTABLE_EXTERN_TEMPLATE_LIST
48// As the name implies, the ABI lists define the V1 (Stable) and unstable ABI.
49//
50// For unstable, we may explicitly remove function that are external in V1,
51// and add (new) external functions to better control inlining and compiler
52// optimization opportunities.
53//
54// For stable, the ABI list should rarely change, except for adding new
55// functions supporting new c++ version / API changes. Typically entries
56// must never be removed from the stable list.
57#define _LIBCPP_STRING_V1_EXTERN_TEMPLATE_LIST(_Func, _CharType) \
58  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::replace(size_type, size_type, value_type const*, size_type)) \
59  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::rfind(value_type const*, size_type, size_type) const) \
60  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::__init(value_type const*, size_type, size_type)) \
61  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::basic_string(basic_string const&)) \
62  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::replace(size_type, size_type, value_type const*)) \
63  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::basic_string(basic_string const&, allocator<_CharType> const&)) \
64  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find_last_not_of(value_type const*, size_type, size_type) const) \
65  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::~basic_string()) \
66  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find_first_not_of(value_type const*, size_type, size_type) const) \
67  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::insert(size_type, size_type, value_type)) \
68  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::operator=(value_type)) \
69  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::__init(value_type const*, size_type)) \
70  _Func(_LIBCPP_FUNC_VIS const _CharType& basic_string<_CharType>::at(size_type) const) \
71  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::insert(size_type, value_type const*, size_type)) \
72  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find_first_of(value_type const*, size_type, size_type) const) \
73  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::replace(size_type, size_type, size_type, value_type)) \
74  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::assign(value_type const*, size_type)) \
75  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::reserve(size_type)) \
76  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::append(value_type const*, size_type)) \
77  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::assign(basic_string const&, size_type, size_type)) \
78  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::copy(value_type*, size_type, size_type) const) \
79  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::basic_string(basic_string const&, size_type, size_type, allocator<_CharType> const&)) \
80  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find(value_type, size_type) const) \
81  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::__init(size_type, value_type)) \
82  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::insert(size_type, value_type const*)) \
83  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find_last_of(value_type const*, size_type, size_type) const) \
84  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::__grow_by(size_type, size_type, size_type, size_type, size_type, size_type)) \
85  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::__grow_by_and_replace(size_type, size_type, size_type, size_type, size_type, size_type, value_type const*)) \
86  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::push_back(value_type)) \
87  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::append(size_type, value_type)) \
88  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::rfind(value_type, size_type) const) \
89  _Func(_LIBCPP_FUNC_VIS const basic_string<_CharType>::size_type basic_string<_CharType>::npos) \
90  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::assign(size_type, value_type)) \
91  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::erase(size_type, size_type)) \
92  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::append(basic_string const&, size_type, size_type)) \
93  _Func(_LIBCPP_FUNC_VIS int basic_string<_CharType>::compare(value_type const*) const) \
94  _Func(_LIBCPP_FUNC_VIS int basic_string<_CharType>::compare(size_type, size_type, value_type const*) const) \
95  _Func(_LIBCPP_FUNC_VIS _CharType& basic_string<_CharType>::at(size_type)) \
96  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::assign(value_type const*)) \
97  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find(value_type const*, size_type, size_type) const) \
98  _Func(_LIBCPP_FUNC_VIS int basic_string<_CharType>::compare(size_type, size_type, basic_string const&, size_type, size_type) const) \
99  _Func(_LIBCPP_FUNC_VIS int basic_string<_CharType>::compare(size_type, size_type, value_type const*, size_type) const) \
100  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::operator=(basic_string const&)) \
101  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::append(value_type const*)) \
102  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::replace(size_type, size_type, basic_string const&, size_type, size_type)) \
103  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::iterator basic_string<_CharType>::insert(basic_string::const_iterator, value_type)) \
104  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::resize(size_type, value_type)) \
105  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::insert(size_type, basic_string const&, size_type, size_type))
106
107#define _LIBCPP_STRING_UNSTABLE_EXTERN_TEMPLATE_LIST(_Func, _CharType) \
108  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::replace(size_type, size_type, value_type const*, size_type)) \
109  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::rfind(value_type const*, size_type, size_type) const) \
110  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::__init(value_type const*, size_type, size_type)) \
111  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::replace(size_type, size_type, value_type const*)) \
112  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find_last_not_of(value_type const*, size_type, size_type) const) \
113  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::~basic_string()) \
114  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find_first_not_of(value_type const*, size_type, size_type) const) \
115  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::insert(size_type, size_type, value_type)) \
116  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::operator=(value_type)) \
117  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::__init(value_type const*, size_type)) \
118  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::__init_copy_ctor_external(value_type const*, size_type)) \
119  _Func(_LIBCPP_FUNC_VIS const _CharType& basic_string<_CharType>::at(size_type) const) \
120  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::insert(size_type, value_type const*, size_type)) \
121  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find_first_of(value_type const*, size_type, size_type) const) \
122  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::replace(size_type, size_type, size_type, value_type)) \
123  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::__assign_external(value_type const*, size_type)) \
124  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::__assign_external(value_type const*)) \
125  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::reserve(size_type)) \
126  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::append(value_type const*, size_type)) \
127  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::assign(basic_string const&, size_type, size_type)) \
128  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::copy(value_type*, size_type, size_type) const) \
129  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::basic_string(basic_string const&, size_type, size_type, allocator<_CharType> const&)) \
130  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find(value_type, size_type) const) \
131  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::__init(size_type, value_type)) \
132  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::insert(size_type, value_type const*)) \
133  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find_last_of(value_type const*, size_type, size_type) const) \
134  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::__grow_by(size_type, size_type, size_type, size_type, size_type, size_type)) \
135  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::__grow_by_and_replace(size_type, size_type, size_type, size_type, size_type, size_type, value_type const*)) \
136  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::__assign_no_alias<false>(value_type const*, size_type)) \
137  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::__assign_no_alias<true>(value_type const*, size_type)) \
138  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::push_back(value_type)) \
139  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::append(size_type, value_type)) \
140  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::rfind(value_type, size_type) const) \
141  _Func(_LIBCPP_FUNC_VIS const basic_string<_CharType>::size_type basic_string<_CharType>::npos) \
142  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::assign(size_type, value_type)) \
143  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::__erase_external_with_move(size_type, size_type)) \
144  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::append(basic_string const&, size_type, size_type)) \
145  _Func(_LIBCPP_FUNC_VIS int basic_string<_CharType>::compare(value_type const*) const) \
146  _Func(_LIBCPP_FUNC_VIS int basic_string<_CharType>::compare(size_type, size_type, value_type const*) const) \
147  _Func(_LIBCPP_FUNC_VIS _CharType& basic_string<_CharType>::at(size_type)) \
148  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::size_type basic_string<_CharType>::find(value_type const*, size_type, size_type) const) \
149  _Func(_LIBCPP_FUNC_VIS int basic_string<_CharType>::compare(size_type, size_type, basic_string const&, size_type, size_type) const) \
150  _Func(_LIBCPP_FUNC_VIS int basic_string<_CharType>::compare(size_type, size_type, value_type const*, size_type) const) \
151  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::append(value_type const*)) \
152  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::replace(size_type, size_type, basic_string const&, size_type, size_type)) \
153  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>::iterator basic_string<_CharType>::insert(basic_string::const_iterator, value_type)) \
154  _Func(_LIBCPP_FUNC_VIS void basic_string<_CharType>::resize(size_type, value_type)) \
155  _Func(_LIBCPP_FUNC_VIS basic_string<_CharType>& basic_string<_CharType>::insert(size_type, basic_string const&, size_type, size_type))
156
157
158// char_traits
159
160template <class _CharT>
161struct _LIBCPP_TEMPLATE_VIS char_traits
162{
163    typedef _CharT    char_type;
164    typedef int       int_type;
165    typedef streamoff off_type;
166    typedef streampos pos_type;
167    typedef mbstate_t state_type;
168
169    static inline void _LIBCPP_CONSTEXPR_AFTER_CXX14
170        assign(char_type& __c1, const char_type& __c2) _NOEXCEPT {__c1 = __c2;}
171    static inline _LIBCPP_CONSTEXPR bool eq(char_type __c1, char_type __c2) _NOEXCEPT
172        {return __c1 == __c2;}
173    static inline _LIBCPP_CONSTEXPR bool lt(char_type __c1, char_type __c2) _NOEXCEPT
174        {return __c1 < __c2;}
175
176    static _LIBCPP_CONSTEXPR_AFTER_CXX14
177    int compare(const char_type* __s1, const char_type* __s2, size_t __n);
178    _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
179    size_t length(const char_type* __s);
180    _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
181    const char_type* find(const char_type* __s, size_t __n, const char_type& __a);
182    static _LIBCPP_CONSTEXPR_AFTER_CXX17
183    char_type*       move(char_type* __s1, const char_type* __s2, size_t __n);
184    _LIBCPP_INLINE_VISIBILITY
185    static _LIBCPP_CONSTEXPR_AFTER_CXX17
186    char_type*       copy(char_type* __s1, const char_type* __s2, size_t __n);
187    _LIBCPP_INLINE_VISIBILITY
188    static _LIBCPP_CONSTEXPR_AFTER_CXX17
189    char_type*       assign(char_type* __s, size_t __n, char_type __a);
190
191    static inline _LIBCPP_CONSTEXPR int_type  not_eof(int_type __c) _NOEXCEPT
192        {return eq_int_type(__c, eof()) ? ~eof() : __c;}
193    static inline _LIBCPP_CONSTEXPR char_type to_char_type(int_type __c) _NOEXCEPT
194        {return char_type(__c);}
195    static inline _LIBCPP_CONSTEXPR int_type  to_int_type(char_type __c) _NOEXCEPT
196        {return int_type(__c);}
197    static inline _LIBCPP_CONSTEXPR bool      eq_int_type(int_type __c1, int_type __c2) _NOEXCEPT
198        {return __c1 == __c2;}
199    static inline _LIBCPP_CONSTEXPR int_type  eof() _NOEXCEPT
200        {return int_type(EOF);}
201};
202
203template <class _CharT>
204_LIBCPP_CONSTEXPR_AFTER_CXX14 int
205char_traits<_CharT>::compare(const char_type* __s1, const char_type* __s2, size_t __n)
206{
207    for (; __n; --__n, ++__s1, ++__s2)
208    {
209        if (lt(*__s1, *__s2))
210            return -1;
211        if (lt(*__s2, *__s1))
212            return 1;
213    }
214    return 0;
215}
216
217template <class _CharT>
218inline
219_LIBCPP_CONSTEXPR_AFTER_CXX14 size_t
220char_traits<_CharT>::length(const char_type* __s)
221{
222    size_t __len = 0;
223    for (; !eq(*__s, char_type(0)); ++__s)
224        ++__len;
225    return __len;
226}
227
228template <class _CharT>
229inline
230_LIBCPP_CONSTEXPR_AFTER_CXX14 const _CharT*
231char_traits<_CharT>::find(const char_type* __s, size_t __n, const char_type& __a)
232{
233    for (; __n; --__n)
234    {
235        if (eq(*__s, __a))
236            return __s;
237        ++__s;
238    }
239    return nullptr;
240}
241
242template <class _CharT>
243_LIBCPP_CONSTEXPR_AFTER_CXX17 _CharT*
244char_traits<_CharT>::move(char_type* __s1, const char_type* __s2, size_t __n)
245{
246    if (__n == 0) return __s1;
247    char_type* __r = __s1;
248    if (__s1 < __s2)
249    {
250        for (; __n; --__n, ++__s1, ++__s2)
251            assign(*__s1, *__s2);
252    }
253    else if (__s2 < __s1)
254    {
255        __s1 += __n;
256        __s2 += __n;
257        for (; __n; --__n)
258            assign(*--__s1, *--__s2);
259    }
260    return __r;
261}
262
263template <class _CharT>
264inline _LIBCPP_CONSTEXPR_AFTER_CXX17
265_CharT*
266char_traits<_CharT>::copy(char_type* __s1, const char_type* __s2, size_t __n)
267{
268    _LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
269    char_type* __r = __s1;
270    for (; __n; --__n, ++__s1, ++__s2)
271        assign(*__s1, *__s2);
272    return __r;
273}
274
275template <class _CharT>
276inline _LIBCPP_CONSTEXPR_AFTER_CXX17
277_CharT*
278char_traits<_CharT>::assign(char_type* __s, size_t __n, char_type __a)
279{
280    char_type* __r = __s;
281    for (; __n; --__n, ++__s)
282        assign(*__s, __a);
283    return __r;
284}
285
286// constexpr versions of move/copy/assign.
287
288template <class _CharT>
289static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
290_CharT* __move_constexpr(_CharT* __s1, const _CharT* __s2, size_t __n) _NOEXCEPT
291{
292    if (__n == 0) return __s1;
293    if (__s1 < __s2) {
294      _VSTD::copy(__s2, __s2 + __n, __s1);
295    } else if (__s2 < __s1) {
296      _VSTD::copy_backward(__s2, __s2 + __n, __s1 + __n);
297    }
298    return __s1;
299}
300
301template <class _CharT>
302static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
303_CharT* __copy_constexpr(_CharT* __s1, const _CharT* __s2, size_t __n) _NOEXCEPT
304{
305    _VSTD::copy_n(__s2, __n, __s1);
306    return __s1;
307}
308
309template <class _CharT>
310static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
311_CharT* __assign_constexpr(_CharT* __s, size_t __n, _CharT __a) _NOEXCEPT
312{
313     _VSTD::fill_n(__s, __n, __a);
314     return __s;
315}
316
317// char_traits<char>
318
319template <>
320struct _LIBCPP_TEMPLATE_VIS char_traits<char>
321{
322    typedef char      char_type;
323    typedef int       int_type;
324    typedef streamoff off_type;
325    typedef streampos pos_type;
326    typedef mbstate_t state_type;
327
328    static inline _LIBCPP_CONSTEXPR_AFTER_CXX14
329    void assign(char_type& __c1, const char_type& __c2) _NOEXCEPT {__c1 = __c2;}
330    static inline _LIBCPP_CONSTEXPR bool eq(char_type __c1, char_type __c2) _NOEXCEPT
331            {return __c1 == __c2;}
332    static inline _LIBCPP_CONSTEXPR bool lt(char_type __c1, char_type __c2) _NOEXCEPT
333        {return (unsigned char)__c1 < (unsigned char)__c2;}
334
335    static _LIBCPP_CONSTEXPR_AFTER_CXX14
336    int compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
337    static inline size_t _LIBCPP_CONSTEXPR_AFTER_CXX14
338    length(const char_type* __s)  _NOEXCEPT {return __builtin_strlen(__s);}
339    static _LIBCPP_CONSTEXPR_AFTER_CXX14
340    const char_type* find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT;
341    static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
342    char_type* move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
343        {
344            return __libcpp_is_constant_evaluated()
345                       ? _VSTD::__move_constexpr(__s1, __s2, __n)
346                       : __n == 0 ? __s1 : (char_type*)_VSTD::memmove(__s1, __s2, __n);
347        }
348    static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
349    char_type* copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
350        {
351            _LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
352            return __libcpp_is_constant_evaluated()
353                       ? _VSTD::__copy_constexpr(__s1, __s2, __n)
354                       : __n == 0 ? __s1 : (char_type*)_VSTD::memcpy(__s1, __s2, __n);
355        }
356    static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
357    char_type* assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT
358        {
359            return __libcpp_is_constant_evaluated()
360                       ? _VSTD::__assign_constexpr(__s, __n, __a)
361                       : __n == 0 ? __s : (char_type*)_VSTD::memset(__s, to_int_type(__a), __n);
362        }
363
364    static inline _LIBCPP_CONSTEXPR int_type  not_eof(int_type __c) _NOEXCEPT
365        {return eq_int_type(__c, eof()) ? ~eof() : __c;}
366    static inline _LIBCPP_CONSTEXPR char_type to_char_type(int_type __c) _NOEXCEPT
367        {return char_type(__c);}
368    static inline _LIBCPP_CONSTEXPR int_type to_int_type(char_type __c) _NOEXCEPT
369        {return int_type((unsigned char)__c);}
370    static inline _LIBCPP_CONSTEXPR bool eq_int_type(int_type __c1, int_type __c2) _NOEXCEPT
371        {return __c1 == __c2;}
372    static inline _LIBCPP_CONSTEXPR int_type  eof() _NOEXCEPT
373        {return int_type(EOF);}
374};
375
376inline _LIBCPP_CONSTEXPR_AFTER_CXX14
377int
378char_traits<char>::compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
379{
380    if (__n == 0)
381        return 0;
382#if __has_feature(cxx_constexpr_string_builtins)
383    return __builtin_memcmp(__s1, __s2, __n);
384#elif _LIBCPP_STD_VER <= 14
385    return _VSTD::memcmp(__s1, __s2, __n);
386#else
387    for (; __n; --__n, ++__s1, ++__s2)
388    {
389        if (lt(*__s1, *__s2))
390            return -1;
391        if (lt(*__s2, *__s1))
392            return 1;
393    }
394    return 0;
395#endif
396}
397
398inline _LIBCPP_CONSTEXPR_AFTER_CXX14
399const char*
400char_traits<char>::find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT
401{
402    if (__n == 0)
403        return nullptr;
404#if __has_feature(cxx_constexpr_string_builtins)
405    return __builtin_char_memchr(__s, to_int_type(__a), __n);
406#elif _LIBCPP_STD_VER <= 14
407    return (const char_type*) _VSTD::memchr(__s, to_int_type(__a), __n);
408#else
409    for (; __n; --__n)
410    {
411        if (eq(*__s, __a))
412            return __s;
413        ++__s;
414    }
415    return nullptr;
416#endif
417}
418
419
420// char_traits<wchar_t>
421
422template <>
423struct _LIBCPP_TEMPLATE_VIS char_traits<wchar_t>
424{
425    typedef wchar_t   char_type;
426    typedef wint_t    int_type;
427    typedef streamoff off_type;
428    typedef streampos pos_type;
429    typedef mbstate_t state_type;
430
431    static inline _LIBCPP_CONSTEXPR_AFTER_CXX14
432    void assign(char_type& __c1, const char_type& __c2) _NOEXCEPT {__c1 = __c2;}
433    static inline _LIBCPP_CONSTEXPR bool eq(char_type __c1, char_type __c2) _NOEXCEPT
434        {return __c1 == __c2;}
435    static inline _LIBCPP_CONSTEXPR bool lt(char_type __c1, char_type __c2) _NOEXCEPT
436        {return __c1 < __c2;}
437
438    static _LIBCPP_CONSTEXPR_AFTER_CXX14
439    int compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
440    static _LIBCPP_CONSTEXPR_AFTER_CXX14
441    size_t length(const char_type* __s) _NOEXCEPT;
442    static _LIBCPP_CONSTEXPR_AFTER_CXX14
443    const char_type* find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT;
444    static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
445    char_type* move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
446        {
447            return __libcpp_is_constant_evaluated()
448                       ? _VSTD::__move_constexpr(__s1, __s2, __n)
449                       : __n == 0 ? __s1 : _VSTD::wmemmove(__s1, __s2, __n);
450        }
451    static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
452    char_type* copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
453        {
454            _LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
455            return __libcpp_is_constant_evaluated()
456                       ? _VSTD::__copy_constexpr(__s1, __s2, __n)
457                       : __n == 0 ? __s1 : _VSTD::wmemcpy(__s1, __s2, __n);
458        }
459    static inline _LIBCPP_CONSTEXPR_AFTER_CXX17
460    char_type* assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT
461        {
462            return __libcpp_is_constant_evaluated()
463                       ? _VSTD::__assign_constexpr(__s, __n, __a)
464                       : __n == 0 ? __s : _VSTD::wmemset(__s, __a, __n);
465        }
466    static inline _LIBCPP_CONSTEXPR int_type  not_eof(int_type __c) _NOEXCEPT
467        {return eq_int_type(__c, eof()) ? ~eof() : __c;}
468    static inline _LIBCPP_CONSTEXPR char_type to_char_type(int_type __c) _NOEXCEPT
469        {return char_type(__c);}
470    static inline _LIBCPP_CONSTEXPR int_type to_int_type(char_type __c) _NOEXCEPT
471        {return int_type(__c);}
472    static inline _LIBCPP_CONSTEXPR bool eq_int_type(int_type __c1, int_type __c2) _NOEXCEPT
473        {return __c1 == __c2;}
474    static inline _LIBCPP_CONSTEXPR int_type eof() _NOEXCEPT
475        {return int_type(WEOF);}
476};
477
478inline _LIBCPP_CONSTEXPR_AFTER_CXX14
479int
480char_traits<wchar_t>::compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
481{
482    if (__n == 0)
483        return 0;
484#if __has_feature(cxx_constexpr_string_builtins)
485    return __builtin_wmemcmp(__s1, __s2, __n);
486#elif _LIBCPP_STD_VER <= 14
487    return _VSTD::wmemcmp(__s1, __s2, __n);
488#else
489    for (; __n; --__n, ++__s1, ++__s2)
490    {
491        if (lt(*__s1, *__s2))
492            return -1;
493        if (lt(*__s2, *__s1))
494            return 1;
495    }
496    return 0;
497#endif
498}
499
500
501template <class _Traits>
502_LIBCPP_INLINE_VISIBILITY
503_LIBCPP_CONSTEXPR
504inline size_t __char_traits_length_checked(const typename _Traits::char_type* __s) _NOEXCEPT {
505#if _LIBCPP_DEBUG_LEVEL >= 1
506  return __s ? _Traits::length(__s) : (_VSTD::__libcpp_debug_function(_VSTD::__libcpp_debug_info(__FILE__, __LINE__, "p == nullptr", "null pointer pass to non-null argument of char_traits<...>::length")), 0);
507#else
508  return _Traits::length(__s);
509#endif
510}
511
512inline _LIBCPP_CONSTEXPR_AFTER_CXX14
513size_t
514char_traits<wchar_t>::length(const char_type* __s) _NOEXCEPT
515{
516#if __has_feature(cxx_constexpr_string_builtins)
517    return __builtin_wcslen(__s);
518#elif _LIBCPP_STD_VER <= 14
519    return _VSTD::wcslen(__s);
520#else
521    size_t __len = 0;
522    for (; !eq(*__s, char_type(0)); ++__s)
523        ++__len;
524    return __len;
525#endif
526}
527
528inline _LIBCPP_CONSTEXPR_AFTER_CXX14
529const wchar_t*
530char_traits<wchar_t>::find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT
531{
532    if (__n == 0)
533        return nullptr;
534#if __has_feature(cxx_constexpr_string_builtins)
535    return __builtin_wmemchr(__s, __a, __n);
536#elif _LIBCPP_STD_VER <= 14
537    return _VSTD::wmemchr(__s, __a, __n);
538#else
539    for (; __n; --__n)
540    {
541        if (eq(*__s, __a))
542            return __s;
543        ++__s;
544    }
545    return nullptr;
546#endif
547}
548
549
550#ifndef _LIBCPP_HAS_NO_CHAR8_T
551
552template <>
553struct _LIBCPP_TEMPLATE_VIS char_traits<char8_t>
554{
555    typedef char8_t        char_type;
556    typedef unsigned int   int_type;
557    typedef streamoff      off_type;
558    typedef u8streampos    pos_type;
559    typedef mbstate_t      state_type;
560
561    static inline constexpr void assign(char_type& __c1, const char_type& __c2) noexcept
562        {__c1 = __c2;}
563    static inline constexpr bool eq(char_type __c1, char_type __c2) noexcept
564        {return __c1 == __c2;}
565    static inline constexpr bool lt(char_type __c1, char_type __c2) noexcept
566        {return __c1 < __c2;}
567
568    static constexpr
569    int              compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
570
571    static constexpr
572    size_t           length(const char_type* __s) _NOEXCEPT;
573
574    _LIBCPP_INLINE_VISIBILITY static constexpr
575    const char_type* find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT;
576
577    static _LIBCPP_CONSTEXPR_AFTER_CXX17
578    char_type*       move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
579        {
580            return __libcpp_is_constant_evaluated()
581                       ? _VSTD::__move_constexpr(__s1, __s2, __n)
582                       : __n == 0 ? __s1 : (char_type*)_VSTD::memmove(__s1, __s2, __n);
583        }
584
585    static _LIBCPP_CONSTEXPR_AFTER_CXX17
586    char_type*       copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
587       {
588            _LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
589            return __libcpp_is_constant_evaluated()
590                       ? _VSTD::__copy_constexpr(__s1, __s2, __n)
591                       : __n == 0 ? __s1 : (char_type*)_VSTD::memcpy(__s1, __s2, __n);
592        }
593
594    static _LIBCPP_CONSTEXPR_AFTER_CXX17
595    char_type*       assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT
596        {
597            return __libcpp_is_constant_evaluated()
598                       ? _VSTD::__assign_constexpr(__s, __n, __a)
599                       : __n == 0 ? __s : (char_type*)_VSTD::memset(__s, to_int_type(__a), __n);
600        }
601
602    static inline constexpr int_type  not_eof(int_type __c) noexcept
603        {return eq_int_type(__c, eof()) ? ~eof() : __c;}
604    static inline constexpr char_type to_char_type(int_type __c) noexcept
605        {return char_type(__c);}
606    static inline constexpr int_type to_int_type(char_type __c) noexcept
607        {return int_type(__c);}
608    static inline constexpr bool eq_int_type(int_type __c1, int_type __c2) noexcept
609        {return __c1 == __c2;}
610    static inline constexpr int_type eof() noexcept
611        {return int_type(EOF);}
612};
613
614// TODO use '__builtin_strlen' if it ever supports char8_t ??
615inline constexpr
616size_t
617char_traits<char8_t>::length(const char_type* __s) _NOEXCEPT
618{
619    size_t __len = 0;
620    for (; !eq(*__s, char_type(0)); ++__s)
621        ++__len;
622    return __len;
623}
624
625inline constexpr
626int
627char_traits<char8_t>::compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
628{
629#if __has_feature(cxx_constexpr_string_builtins)
630    return __builtin_memcmp(__s1, __s2, __n);
631#else
632    for (; __n; --__n, ++__s1, ++__s2)
633    {
634        if (lt(*__s1, *__s2))
635            return -1;
636        if (lt(*__s2, *__s1))
637            return 1;
638    }
639    return 0;
640#endif
641}
642
643// TODO use '__builtin_char_memchr' if it ever supports char8_t ??
644inline constexpr
645const char8_t*
646char_traits<char8_t>::find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT
647{
648    for (; __n; --__n)
649    {
650        if (eq(*__s, __a))
651            return __s;
652        ++__s;
653    }
654    return nullptr;
655}
656
657#endif // #_LIBCPP_HAS_NO_CHAR8_T
658
659#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
660
661template <>
662struct _LIBCPP_TEMPLATE_VIS char_traits<char16_t>
663{
664    typedef char16_t       char_type;
665    typedef uint_least16_t int_type;
666    typedef streamoff      off_type;
667    typedef u16streampos   pos_type;
668    typedef mbstate_t      state_type;
669
670    static inline _LIBCPP_CONSTEXPR_AFTER_CXX14
671    void assign(char_type& __c1, const char_type& __c2) _NOEXCEPT {__c1 = __c2;}
672    static inline _LIBCPP_CONSTEXPR bool eq(char_type __c1, char_type __c2) _NOEXCEPT
673        {return __c1 == __c2;}
674    static inline _LIBCPP_CONSTEXPR bool lt(char_type __c1, char_type __c2) _NOEXCEPT
675        {return __c1 < __c2;}
676
677    _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
678    int              compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
679    _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
680    size_t           length(const char_type* __s) _NOEXCEPT;
681    _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
682    const char_type* find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT;
683    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
684    static char_type*       move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
685    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
686    static char_type*       copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
687    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
688    static char_type*       assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT;
689
690    static inline _LIBCPP_CONSTEXPR int_type  not_eof(int_type __c) _NOEXCEPT
691        {return eq_int_type(__c, eof()) ? ~eof() : __c;}
692    static inline _LIBCPP_CONSTEXPR char_type to_char_type(int_type __c) _NOEXCEPT
693        {return char_type(__c);}
694    static inline _LIBCPP_CONSTEXPR int_type to_int_type(char_type __c) _NOEXCEPT
695        {return int_type(__c);}
696    static inline _LIBCPP_CONSTEXPR bool eq_int_type(int_type __c1, int_type __c2) _NOEXCEPT
697        {return __c1 == __c2;}
698    static inline _LIBCPP_CONSTEXPR int_type eof() _NOEXCEPT
699        {return int_type(0xFFFF);}
700};
701
702inline _LIBCPP_CONSTEXPR_AFTER_CXX14
703int
704char_traits<char16_t>::compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
705{
706    for (; __n; --__n, ++__s1, ++__s2)
707    {
708        if (lt(*__s1, *__s2))
709            return -1;
710        if (lt(*__s2, *__s1))
711            return 1;
712    }
713    return 0;
714}
715
716inline _LIBCPP_CONSTEXPR_AFTER_CXX14
717size_t
718char_traits<char16_t>::length(const char_type* __s) _NOEXCEPT
719{
720    size_t __len = 0;
721    for (; !eq(*__s, char_type(0)); ++__s)
722        ++__len;
723    return __len;
724}
725
726inline _LIBCPP_CONSTEXPR_AFTER_CXX14
727const char16_t*
728char_traits<char16_t>::find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT
729{
730    for (; __n; --__n)
731    {
732        if (eq(*__s, __a))
733            return __s;
734        ++__s;
735    }
736    return nullptr;
737}
738
739inline _LIBCPP_CONSTEXPR_AFTER_CXX17
740char16_t*
741char_traits<char16_t>::move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
742{
743    if (__n == 0) return __s1;
744    char_type* __r = __s1;
745    if (__s1 < __s2)
746    {
747        for (; __n; --__n, ++__s1, ++__s2)
748            assign(*__s1, *__s2);
749    }
750    else if (__s2 < __s1)
751    {
752        __s1 += __n;
753        __s2 += __n;
754        for (; __n; --__n)
755            assign(*--__s1, *--__s2);
756    }
757    return __r;
758}
759
760inline _LIBCPP_CONSTEXPR_AFTER_CXX17
761char16_t*
762char_traits<char16_t>::copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
763{
764    _LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
765    char_type* __r = __s1;
766    for (; __n; --__n, ++__s1, ++__s2)
767        assign(*__s1, *__s2);
768    return __r;
769}
770
771inline _LIBCPP_CONSTEXPR_AFTER_CXX17
772char16_t*
773char_traits<char16_t>::assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT
774{
775    char_type* __r = __s;
776    for (; __n; --__n, ++__s)
777        assign(*__s, __a);
778    return __r;
779}
780
781template <>
782struct _LIBCPP_TEMPLATE_VIS char_traits<char32_t>
783{
784    typedef char32_t       char_type;
785    typedef uint_least32_t int_type;
786    typedef streamoff      off_type;
787    typedef u32streampos   pos_type;
788    typedef mbstate_t      state_type;
789
790    static inline _LIBCPP_CONSTEXPR_AFTER_CXX14
791    void assign(char_type& __c1, const char_type& __c2) _NOEXCEPT {__c1 = __c2;}
792    static inline _LIBCPP_CONSTEXPR bool eq(char_type __c1, char_type __c2) _NOEXCEPT
793        {return __c1 == __c2;}
794    static inline _LIBCPP_CONSTEXPR bool lt(char_type __c1, char_type __c2) _NOEXCEPT
795        {return __c1 < __c2;}
796
797    _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
798    int              compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
799    _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
800    size_t           length(const char_type* __s) _NOEXCEPT;
801    _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
802    const char_type* find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT;
803    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
804    static char_type*       move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
805    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
806    static char_type*       copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
807    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
808    static char_type*       assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT;
809
810    static inline _LIBCPP_CONSTEXPR int_type  not_eof(int_type __c) _NOEXCEPT
811        {return eq_int_type(__c, eof()) ? ~eof() : __c;}
812    static inline _LIBCPP_CONSTEXPR char_type to_char_type(int_type __c) _NOEXCEPT
813        {return char_type(__c);}
814    static inline _LIBCPP_CONSTEXPR int_type to_int_type(char_type __c) _NOEXCEPT
815        {return int_type(__c);}
816    static inline _LIBCPP_CONSTEXPR bool eq_int_type(int_type __c1, int_type __c2) _NOEXCEPT
817        {return __c1 == __c2;}
818    static inline _LIBCPP_CONSTEXPR int_type eof() _NOEXCEPT
819        {return int_type(0xFFFFFFFF);}
820};
821
822inline _LIBCPP_CONSTEXPR_AFTER_CXX14
823int
824char_traits<char32_t>::compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
825{
826    for (; __n; --__n, ++__s1, ++__s2)
827    {
828        if (lt(*__s1, *__s2))
829            return -1;
830        if (lt(*__s2, *__s1))
831            return 1;
832    }
833    return 0;
834}
835
836inline _LIBCPP_CONSTEXPR_AFTER_CXX14
837size_t
838char_traits<char32_t>::length(const char_type* __s) _NOEXCEPT
839{
840    size_t __len = 0;
841    for (; !eq(*__s, char_type(0)); ++__s)
842        ++__len;
843    return __len;
844}
845
846inline _LIBCPP_CONSTEXPR_AFTER_CXX14
847const char32_t*
848char_traits<char32_t>::find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT
849{
850    for (; __n; --__n)
851    {
852        if (eq(*__s, __a))
853            return __s;
854        ++__s;
855    }
856    return nullptr;
857}
858
859inline _LIBCPP_CONSTEXPR_AFTER_CXX17
860char32_t*
861char_traits<char32_t>::move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
862{
863    if (__n == 0) return __s1;
864    char_type* __r = __s1;
865    if (__s1 < __s2)
866    {
867        for (; __n; --__n, ++__s1, ++__s2)
868            assign(*__s1, *__s2);
869    }
870    else if (__s2 < __s1)
871    {
872        __s1 += __n;
873        __s2 += __n;
874        for (; __n; --__n)
875            assign(*--__s1, *--__s2);
876    }
877    return __r;
878}
879
880inline _LIBCPP_CONSTEXPR_AFTER_CXX17
881char32_t*
882char_traits<char32_t>::copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
883{
884    _LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
885    char_type* __r = __s1;
886    for (; __n; --__n, ++__s1, ++__s2)
887        assign(*__s1, *__s2);
888    return __r;
889}
890
891inline _LIBCPP_CONSTEXPR_AFTER_CXX17
892char32_t*
893char_traits<char32_t>::assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT
894{
895    char_type* __r = __s;
896    for (; __n; --__n, ++__s)
897        assign(*__s, __a);
898    return __r;
899}
900
901#endif // _LIBCPP_HAS_NO_UNICODE_CHARS
902
903// helper fns for basic_string and string_view
904
905// __str_find
906template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
907inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
908__str_find(const _CharT *__p, _SizeT __sz,
909             _CharT __c, _SizeT __pos) _NOEXCEPT
910{
911    if (__pos >= __sz)
912        return __npos;
913    const _CharT* __r = _Traits::find(__p + __pos, __sz - __pos, __c);
914    if (__r == nullptr)
915        return __npos;
916    return static_cast<_SizeT>(__r - __p);
917}
918
919template <class _CharT, class _Traits>
920inline _LIBCPP_CONSTEXPR_AFTER_CXX11 const _CharT *
921__search_substring(const _CharT *__first1, const _CharT *__last1,
922                   const _CharT *__first2, const _CharT *__last2) _NOEXCEPT {
923  // Take advantage of knowing source and pattern lengths.
924  // Stop short when source is smaller than pattern.
925  const ptrdiff_t __len2 = __last2 - __first2;
926  if (__len2 == 0)
927    return __first1;
928
929  ptrdiff_t __len1 = __last1 - __first1;
930  if (__len1 < __len2)
931    return __last1;
932
933  // First element of __first2 is loop invariant.
934  _CharT __f2 = *__first2;
935  while (true) {
936    __len1 = __last1 - __first1;
937    // Check whether __first1 still has at least __len2 bytes.
938    if (__len1 < __len2)
939      return __last1;
940
941    // Find __f2 the first byte matching in __first1.
942    __first1 = _Traits::find(__first1, __len1 - __len2 + 1, __f2);
943    if (__first1 == nullptr)
944      return __last1;
945
946    // It is faster to compare from the first byte of __first1 even if we
947    // already know that it matches the first byte of __first2: this is because
948    // __first2 is most likely aligned, as it is user's "pattern" string, and
949    // __first1 + 1 is most likely not aligned, as the match is in the middle of
950    // the string.
951    if (_Traits::compare(__first1, __first2, __len2) == 0)
952      return __first1;
953
954    ++__first1;
955  }
956}
957
958template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
959inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
960__str_find(const _CharT *__p, _SizeT __sz,
961       const _CharT* __s, _SizeT __pos, _SizeT __n) _NOEXCEPT
962{
963    if (__pos > __sz)
964        return __npos;
965
966    if (__n == 0) // There is nothing to search, just return __pos.
967        return __pos;
968
969    const _CharT *__r = __search_substring<_CharT, _Traits>(
970        __p + __pos, __p + __sz, __s, __s + __n);
971
972    if (__r == __p + __sz)
973        return __npos;
974    return static_cast<_SizeT>(__r - __p);
975}
976
977
978// __str_rfind
979
980template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
981inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
982__str_rfind(const _CharT *__p, _SizeT __sz,
983              _CharT __c, _SizeT __pos) _NOEXCEPT
984{
985    if (__sz < 1)
986        return __npos;
987    if (__pos < __sz)
988        ++__pos;
989    else
990        __pos = __sz;
991    for (const _CharT* __ps = __p + __pos; __ps != __p;)
992    {
993        if (_Traits::eq(*--__ps, __c))
994            return static_cast<_SizeT>(__ps - __p);
995    }
996    return __npos;
997}
998
999template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
1000inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1001__str_rfind(const _CharT *__p, _SizeT __sz,
1002        const _CharT* __s, _SizeT __pos, _SizeT __n) _NOEXCEPT
1003{
1004    __pos = _VSTD::min(__pos, __sz);
1005    if (__n < __sz - __pos)
1006        __pos += __n;
1007    else
1008        __pos = __sz;
1009    const _CharT* __r = _VSTD::__find_end(
1010                  __p, __p + __pos, __s, __s + __n, _Traits::eq,
1011                        random_access_iterator_tag(), random_access_iterator_tag());
1012    if (__n > 0 && __r == __p + __pos)
1013        return __npos;
1014    return static_cast<_SizeT>(__r - __p);
1015}
1016
1017// __str_find_first_of
1018template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
1019inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1020__str_find_first_of(const _CharT *__p, _SizeT __sz,
1021                const _CharT* __s, _SizeT __pos, _SizeT __n) _NOEXCEPT
1022{
1023    if (__pos >= __sz || __n == 0)
1024        return __npos;
1025    const _CharT* __r = _VSTD::__find_first_of_ce
1026        (__p + __pos, __p + __sz, __s, __s + __n, _Traits::eq );
1027    if (__r == __p + __sz)
1028        return __npos;
1029    return static_cast<_SizeT>(__r - __p);
1030}
1031
1032
1033// __str_find_last_of
1034template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
1035inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1036__str_find_last_of(const _CharT *__p, _SizeT __sz,
1037               const _CharT* __s, _SizeT __pos, _SizeT __n) _NOEXCEPT
1038    {
1039    if (__n != 0)
1040    {
1041        if (__pos < __sz)
1042            ++__pos;
1043        else
1044            __pos = __sz;
1045        for (const _CharT* __ps = __p + __pos; __ps != __p;)
1046        {
1047            const _CharT* __r = _Traits::find(__s, __n, *--__ps);
1048            if (__r)
1049                return static_cast<_SizeT>(__ps - __p);
1050        }
1051    }
1052    return __npos;
1053}
1054
1055
1056// __str_find_first_not_of
1057template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
1058inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1059__str_find_first_not_of(const _CharT *__p, _SizeT __sz,
1060                    const _CharT* __s, _SizeT __pos, _SizeT __n) _NOEXCEPT
1061{
1062    if (__pos < __sz)
1063    {
1064        const _CharT* __pe = __p + __sz;
1065        for (const _CharT* __ps = __p + __pos; __ps != __pe; ++__ps)
1066            if (_Traits::find(__s, __n, *__ps) == nullptr)
1067                return static_cast<_SizeT>(__ps - __p);
1068    }
1069    return __npos;
1070}
1071
1072
1073template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
1074inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1075__str_find_first_not_of(const _CharT *__p, _SizeT __sz,
1076                          _CharT __c, _SizeT __pos) _NOEXCEPT
1077{
1078    if (__pos < __sz)
1079    {
1080        const _CharT* __pe = __p + __sz;
1081        for (const _CharT* __ps = __p + __pos; __ps != __pe; ++__ps)
1082            if (!_Traits::eq(*__ps, __c))
1083                return static_cast<_SizeT>(__ps - __p);
1084    }
1085    return __npos;
1086}
1087
1088
1089// __str_find_last_not_of
1090template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
1091inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1092__str_find_last_not_of(const _CharT *__p, _SizeT __sz,
1093                   const _CharT* __s, _SizeT __pos, _SizeT __n) _NOEXCEPT
1094{
1095    if (__pos < __sz)
1096        ++__pos;
1097    else
1098        __pos = __sz;
1099    for (const _CharT* __ps = __p + __pos; __ps != __p;)
1100        if (_Traits::find(__s, __n, *--__ps) == nullptr)
1101            return static_cast<_SizeT>(__ps - __p);
1102    return __npos;
1103}
1104
1105
1106template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
1107inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
1108__str_find_last_not_of(const _CharT *__p, _SizeT __sz,
1109                         _CharT __c, _SizeT __pos) _NOEXCEPT
1110{
1111    if (__pos < __sz)
1112        ++__pos;
1113    else
1114        __pos = __sz;
1115    for (const _CharT* __ps = __p + __pos; __ps != __p;)
1116        if (!_Traits::eq(*--__ps, __c))
1117            return static_cast<_SizeT>(__ps - __p);
1118    return __npos;
1119}
1120
1121template<class _Ptr>
1122inline _LIBCPP_INLINE_VISIBILITY
1123size_t __do_string_hash(_Ptr __p, _Ptr __e)
1124{
1125    typedef typename iterator_traits<_Ptr>::value_type value_type;
1126    return __murmur2_or_cityhash<size_t>()(__p, (__e-__p)*sizeof(value_type));
1127}
1128
1129template <class _CharT, class _Iter, class _Traits=char_traits<_CharT> >
1130struct __quoted_output_proxy
1131{
1132    _Iter  __first;
1133    _Iter  __last;
1134    _CharT  __delim;
1135    _CharT  __escape;
1136
1137    __quoted_output_proxy(_Iter __f, _Iter __l, _CharT __d, _CharT __e)
1138    : __first(__f), __last(__l), __delim(__d), __escape(__e) {}
1139    //  This would be a nice place for a string_ref
1140};
1141
1142_LIBCPP_END_NAMESPACE_STD
1143
1144_LIBCPP_POP_MACROS
1145
1146#endif // _LIBCPP___STRING
1147