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      1 // -*- C++ -*-
      2 //===-------------------------- __string ----------------------------------===//
      3 //
      4 //                     The LLVM Compiler Infrastructure
      5 //
      6 // This file is distributed under the University of Illinois Open Source
      7 // License. See LICENSE.TXT for details.
      8 //
      9 //===----------------------------------------------------------------------===//
     10 
     11 #ifndef _LIBCPP___STRING
     12 #define _LIBCPP___STRING
     13 
     14 /*
     15     string synopsis
     16 
     17 namespace std
     18 {
     19 
     20 template <class charT>
     21 struct char_traits
     22 {
     23     typedef charT     char_type;
     24     typedef ...       int_type;
     25     typedef streamoff off_type;
     26     typedef streampos pos_type;
     27     typedef mbstate_t state_type;
     28 
     29     static constexpr void assign(char_type& c1, const char_type& c2) noexcept;
     30     static constexpr bool eq(char_type c1, char_type c2) noexcept;
     31     static constexpr bool lt(char_type c1, char_type c2) noexcept;
     32 
     33     static constexpr int    compare(const char_type* s1, const char_type* s2, size_t n);
     34     static constexpr size_t length(const char_type* s);
     35     static constexpr const char_type* 
     36                             find(const char_type* s, size_t n, const char_type& a);
     37     static char_type*       move(char_type* s1, const char_type* s2, size_t n);
     38     static char_type*       copy(char_type* s1, const char_type* s2, size_t n);
     39     static char_type*       assign(char_type* s, size_t n, char_type a);
     40 
     41     static constexpr int_type  not_eof(int_type c) noexcept;
     42     static constexpr char_type to_char_type(int_type c) noexcept;
     43     static constexpr int_type  to_int_type(char_type c) noexcept;
     44     static constexpr bool      eq_int_type(int_type c1, int_type c2) noexcept;
     45     static constexpr int_type  eof() noexcept;
     46 };
     47 
     48 template <> struct char_traits<char>;
     49 template <> struct char_traits<wchar_t>;
     50 
     51 }  // std
     52 
     53 */
     54 
     55 #include <__config>
     56 #include <algorithm>  // for search and min
     57 #include <cstdio>     // For EOF.
     58 #include <memory>     // for __murmur2_or_cityhash
     59 
     60 #include <__undef_min_max>
     61 
     62 #include <__debug>
     63 
     64 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
     65 #pragma GCC system_header
     66 #endif
     67 
     68 _LIBCPP_BEGIN_NAMESPACE_STD
     69 
     70 // char_traits
     71 
     72 template <class _CharT>
     73 struct _LIBCPP_TEMPLATE_VIS char_traits
     74 {
     75     typedef _CharT    char_type;
     76     typedef int       int_type;
     77     typedef streamoff off_type;
     78     typedef streampos pos_type;
     79     typedef mbstate_t state_type;
     80 
     81     static inline void _LIBCPP_CONSTEXPR_AFTER_CXX14
     82         assign(char_type& __c1, const char_type& __c2) _NOEXCEPT {__c1 = __c2;}
     83     static inline _LIBCPP_CONSTEXPR bool eq(char_type __c1, char_type __c2) _NOEXCEPT
     84         {return __c1 == __c2;}
     85     static inline _LIBCPP_CONSTEXPR bool lt(char_type __c1, char_type __c2) _NOEXCEPT
     86         {return __c1 < __c2;}
     87 
     88     static _LIBCPP_CONSTEXPR_AFTER_CXX14
     89     int compare(const char_type* __s1, const char_type* __s2, size_t __n);
     90     _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
     91     size_t length(const char_type* __s);
     92     _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
     93     const char_type* find(const char_type* __s, size_t __n, const char_type& __a);
     94     static char_type*       move(char_type* __s1, const char_type* __s2, size_t __n);
     95     _LIBCPP_INLINE_VISIBILITY
     96     static char_type*       copy(char_type* __s1, const char_type* __s2, size_t __n);
     97     _LIBCPP_INLINE_VISIBILITY
     98     static char_type*       assign(char_type* __s, size_t __n, char_type __a);
     99 
    100     static inline _LIBCPP_CONSTEXPR int_type  not_eof(int_type __c) _NOEXCEPT
    101         {return eq_int_type(__c, eof()) ? ~eof() : __c;}
    102     static inline _LIBCPP_CONSTEXPR char_type to_char_type(int_type __c) _NOEXCEPT
    103         {return char_type(__c);}
    104     static inline _LIBCPP_CONSTEXPR int_type  to_int_type(char_type __c) _NOEXCEPT
    105         {return int_type(__c);}
    106     static inline _LIBCPP_CONSTEXPR bool      eq_int_type(int_type __c1, int_type __c2) _NOEXCEPT
    107         {return __c1 == __c2;}
    108     static inline _LIBCPP_CONSTEXPR int_type  eof() _NOEXCEPT
    109         {return int_type(EOF);}
    110 };
    111 
    112 template <class _CharT>
    113 _LIBCPP_CONSTEXPR_AFTER_CXX14 int
    114 char_traits<_CharT>::compare(const char_type* __s1, const char_type* __s2, size_t __n)
    115 {
    116     for (; __n; --__n, ++__s1, ++__s2)
    117     {
    118         if (lt(*__s1, *__s2))
    119             return -1;
    120         if (lt(*__s2, *__s1))
    121             return 1;
    122     }
    123     return 0;
    124 }
    125 
    126 template <class _CharT>
    127 inline
    128 _LIBCPP_CONSTEXPR_AFTER_CXX14 size_t
    129 char_traits<_CharT>::length(const char_type* __s)
    130 {
    131     size_t __len = 0;
    132     for (; !eq(*__s, char_type(0)); ++__s)
    133         ++__len;
    134     return __len;
    135 }
    136 
    137 template <class _CharT>
    138 inline
    139 _LIBCPP_CONSTEXPR_AFTER_CXX14 const _CharT*
    140 char_traits<_CharT>::find(const char_type* __s, size_t __n, const char_type& __a)
    141 {
    142     for (; __n; --__n)
    143     {
    144         if (eq(*__s, __a))
    145             return __s;
    146         ++__s;
    147     }
    148     return 0;
    149 }
    150 
    151 template <class _CharT>
    152 _CharT*
    153 char_traits<_CharT>::move(char_type* __s1, const char_type* __s2, size_t __n)
    154 {
    155     char_type* __r = __s1;
    156     if (__s1 < __s2)
    157     {
    158         for (; __n; --__n, ++__s1, ++__s2)
    159             assign(*__s1, *__s2);
    160     }
    161     else if (__s2 < __s1)
    162     {
    163         __s1 += __n;
    164         __s2 += __n;
    165         for (; __n; --__n)
    166             assign(*--__s1, *--__s2);
    167     }
    168     return __r;
    169 }
    170 
    171 template <class _CharT>
    172 inline
    173 _CharT*
    174 char_traits<_CharT>::copy(char_type* __s1, const char_type* __s2, size_t __n)
    175 {
    176     _LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
    177     char_type* __r = __s1;
    178     for (; __n; --__n, ++__s1, ++__s2)
    179         assign(*__s1, *__s2);
    180     return __r;
    181 }
    182 
    183 template <class _CharT>
    184 inline
    185 _CharT*
    186 char_traits<_CharT>::assign(char_type* __s, size_t __n, char_type __a)
    187 {
    188     char_type* __r = __s;
    189     for (; __n; --__n, ++__s)
    190         assign(*__s, __a);
    191     return __r;
    192 }
    193 
    194 // char_traits<char>
    195 
    196 template <>
    197 struct _LIBCPP_TEMPLATE_VIS char_traits<char>
    198 {
    199     typedef char      char_type;
    200     typedef int       int_type;
    201     typedef streamoff off_type;
    202     typedef streampos pos_type;
    203     typedef mbstate_t state_type;
    204 
    205     static inline _LIBCPP_CONSTEXPR_AFTER_CXX14
    206     void assign(char_type& __c1, const char_type& __c2) _NOEXCEPT {__c1 = __c2;}
    207     static inline _LIBCPP_CONSTEXPR bool eq(char_type __c1, char_type __c2) _NOEXCEPT
    208             {return __c1 == __c2;}
    209     static inline _LIBCPP_CONSTEXPR bool lt(char_type __c1, char_type __c2) _NOEXCEPT
    210         {return (unsigned char)__c1 < (unsigned char)__c2;}
    211 
    212     static _LIBCPP_CONSTEXPR_AFTER_CXX14
    213     int compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
    214     static inline size_t _LIBCPP_CONSTEXPR_AFTER_CXX14
    215     length(const char_type* __s)  _NOEXCEPT {return __builtin_strlen(__s);}
    216     static _LIBCPP_CONSTEXPR_AFTER_CXX14
    217     const char_type* find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT;
    218     static inline char_type* move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
    219         {return __n == 0 ? __s1 : (char_type*) memmove(__s1, __s2, __n);}
    220     static inline char_type* copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
    221         {
    222             _LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
    223             return __n == 0 ? __s1 : (char_type*)memcpy(__s1, __s2, __n);
    224         }
    225     static inline char_type* assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT
    226         {return __n == 0 ? __s : (char_type*)memset(__s, to_int_type(__a), __n);}
    227 
    228     static inline _LIBCPP_CONSTEXPR int_type  not_eof(int_type __c) _NOEXCEPT
    229         {return eq_int_type(__c, eof()) ? ~eof() : __c;}
    230     static inline _LIBCPP_CONSTEXPR char_type to_char_type(int_type __c) _NOEXCEPT
    231         {return char_type(__c);}
    232     static inline _LIBCPP_CONSTEXPR int_type to_int_type(char_type __c) _NOEXCEPT
    233         {return int_type((unsigned char)__c);}
    234     static inline _LIBCPP_CONSTEXPR bool eq_int_type(int_type __c1, int_type __c2) _NOEXCEPT
    235         {return __c1 == __c2;}
    236     static inline _LIBCPP_CONSTEXPR int_type  eof() _NOEXCEPT
    237         {return int_type(EOF);}
    238 };
    239 
    240 inline _LIBCPP_CONSTEXPR_AFTER_CXX14
    241 int
    242 char_traits<char>::compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
    243 {
    244     if (__n == 0)
    245         return 0;
    246 #if __has_feature(cxx_constexpr_string_builtins)
    247     return __builtin_memcmp(__s1, __s2, __n);
    248 #elif _LIBCPP_STD_VER <= 14
    249     return memcmp(__s1, __s2, __n);
    250 #else
    251     for (; __n; --__n, ++__s1, ++__s2)
    252     {
    253         if (lt(*__s1, *__s2))
    254             return -1;
    255         if (lt(*__s2, *__s1))
    256             return 1;
    257     }
    258     return 0;
    259 #endif
    260 }
    261 
    262 inline _LIBCPP_CONSTEXPR_AFTER_CXX14
    263 const char*
    264 char_traits<char>::find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT
    265 {
    266     if (__n == 0)
    267         return NULL;
    268 #if __has_feature(cxx_constexpr_string_builtins)
    269     return __builtin_char_memchr(__s, to_int_type(__a), __n);
    270 #elif _LIBCPP_STD_VER <= 14
    271     return (const char_type*) memchr(__s, to_int_type(__a), __n);
    272 #else
    273     for (; __n; --__n)
    274     {
    275         if (eq(*__s, __a))
    276             return __s;
    277         ++__s;
    278     }
    279     return NULL;
    280 #endif
    281 }
    282 
    283 
    284 // char_traits<wchar_t>
    285 
    286 template <>
    287 struct _LIBCPP_TEMPLATE_VIS char_traits<wchar_t>
    288 {
    289     typedef wchar_t   char_type;
    290     typedef wint_t    int_type;
    291     typedef streamoff off_type;
    292     typedef streampos pos_type;
    293     typedef mbstate_t state_type;
    294 
    295     static inline _LIBCPP_CONSTEXPR_AFTER_CXX14
    296     void assign(char_type& __c1, const char_type& __c2) _NOEXCEPT {__c1 = __c2;}
    297     static inline _LIBCPP_CONSTEXPR bool eq(char_type __c1, char_type __c2) _NOEXCEPT
    298         {return __c1 == __c2;}
    299     static inline _LIBCPP_CONSTEXPR bool lt(char_type __c1, char_type __c2) _NOEXCEPT
    300         {return __c1 < __c2;}
    301 
    302     static _LIBCPP_CONSTEXPR_AFTER_CXX14
    303     int compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
    304     static _LIBCPP_CONSTEXPR_AFTER_CXX14
    305     size_t length(const char_type* __s) _NOEXCEPT;
    306     static _LIBCPP_CONSTEXPR_AFTER_CXX14
    307     const char_type* find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT;
    308     static inline char_type* move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
    309         {return __n == 0 ? __s1 : (char_type*)wmemmove(__s1, __s2, __n);}
    310     static inline char_type* copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
    311         {
    312             _LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
    313             return __n == 0 ? __s1 : (char_type*)wmemcpy(__s1, __s2, __n);
    314         }
    315     static inline char_type* assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT
    316         {return __n == 0 ? __s : (char_type*)wmemset(__s, __a, __n);}
    317 
    318     static inline _LIBCPP_CONSTEXPR int_type  not_eof(int_type __c) _NOEXCEPT
    319         {return eq_int_type(__c, eof()) ? ~eof() : __c;}
    320     static inline _LIBCPP_CONSTEXPR char_type to_char_type(int_type __c) _NOEXCEPT
    321         {return char_type(__c);}
    322     static inline _LIBCPP_CONSTEXPR int_type to_int_type(char_type __c) _NOEXCEPT
    323         {return int_type(__c);}
    324     static inline _LIBCPP_CONSTEXPR bool eq_int_type(int_type __c1, int_type __c2) _NOEXCEPT
    325         {return __c1 == __c2;}
    326     static inline _LIBCPP_CONSTEXPR int_type eof() _NOEXCEPT
    327         {return int_type(WEOF);}
    328 };
    329 
    330 inline _LIBCPP_CONSTEXPR_AFTER_CXX14
    331 int
    332 char_traits<wchar_t>::compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
    333 {
    334     if (__n == 0)
    335         return 0;
    336 #if __has_feature(cxx_constexpr_string_builtins)
    337     return __builtin_wmemcmp(__s1, __s2, __n);
    338 #elif _LIBCPP_STD_VER <= 14
    339     return wmemcmp(__s1, __s2, __n);
    340 #else
    341     for (; __n; --__n, ++__s1, ++__s2)
    342     {
    343         if (lt(*__s1, *__s2))
    344             return -1;
    345         if (lt(*__s2, *__s1))
    346             return 1;
    347     }
    348     return 0;
    349 #endif
    350 }
    351 
    352 inline _LIBCPP_CONSTEXPR_AFTER_CXX14
    353 size_t
    354 char_traits<wchar_t>::length(const char_type* __s) _NOEXCEPT
    355 {
    356 #if __has_feature(cxx_constexpr_string_builtins)
    357     return __builtin_wcslen(__s);
    358 #elif _LIBCPP_STD_VER <= 14
    359     return wcslen(__s);
    360 #else
    361     size_t __len = 0;
    362     for (; !eq(*__s, char_type(0)); ++__s)
    363         ++__len;
    364     return __len;
    365 #endif
    366 }
    367 
    368 inline _LIBCPP_CONSTEXPR_AFTER_CXX14
    369 const wchar_t*
    370 char_traits<wchar_t>::find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT
    371 {
    372     if (__n == 0)
    373         return NULL;
    374 #if __has_feature(cxx_constexpr_string_builtins)
    375         return __builtin_wmemchr(__s, __a, __n);
    376 #elif _LIBCPP_STD_VER <= 14
    377     return wmemchr(__s, __a, __n);
    378 #else
    379     for (; __n; --__n)
    380     {
    381         if (eq(*__s, __a))
    382             return __s;
    383         ++__s;
    384     }
    385     return NULL;
    386 #endif
    387 }
    388 
    389 
    390 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
    391 
    392 template <>
    393 struct _LIBCPP_TEMPLATE_VIS char_traits<char16_t>
    394 {
    395     typedef char16_t       char_type;
    396     typedef uint_least16_t int_type;
    397     typedef streamoff      off_type;
    398     typedef u16streampos   pos_type;
    399     typedef mbstate_t      state_type;
    400 
    401     static inline _LIBCPP_CONSTEXPR_AFTER_CXX14
    402     void assign(char_type& __c1, const char_type& __c2) _NOEXCEPT {__c1 = __c2;}
    403     static inline _LIBCPP_CONSTEXPR bool eq(char_type __c1, char_type __c2) _NOEXCEPT
    404         {return __c1 == __c2;}
    405     static inline _LIBCPP_CONSTEXPR bool lt(char_type __c1, char_type __c2) _NOEXCEPT
    406         {return __c1 < __c2;}
    407 
    408     _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
    409     int              compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
    410     _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
    411     size_t           length(const char_type* __s) _NOEXCEPT;
    412     _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
    413     const char_type* find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT;
    414     _LIBCPP_INLINE_VISIBILITY
    415     static char_type*       move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
    416     _LIBCPP_INLINE_VISIBILITY
    417     static char_type*       copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
    418     _LIBCPP_INLINE_VISIBILITY
    419     static char_type*       assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT;
    420 
    421     static inline _LIBCPP_CONSTEXPR int_type  not_eof(int_type __c) _NOEXCEPT
    422         {return eq_int_type(__c, eof()) ? ~eof() : __c;}
    423     static inline _LIBCPP_CONSTEXPR char_type to_char_type(int_type __c) _NOEXCEPT
    424         {return char_type(__c);}
    425     static inline _LIBCPP_CONSTEXPR int_type to_int_type(char_type __c) _NOEXCEPT
    426         {return int_type(__c);}
    427     static inline _LIBCPP_CONSTEXPR bool eq_int_type(int_type __c1, int_type __c2) _NOEXCEPT
    428         {return __c1 == __c2;}
    429     static inline _LIBCPP_CONSTEXPR int_type eof() _NOEXCEPT
    430         {return int_type(0xFFFF);}
    431 };
    432 
    433 inline _LIBCPP_CONSTEXPR_AFTER_CXX14
    434 int
    435 char_traits<char16_t>::compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
    436 {
    437     for (; __n; --__n, ++__s1, ++__s2)
    438     {
    439         if (lt(*__s1, *__s2))
    440             return -1;
    441         if (lt(*__s2, *__s1))
    442             return 1;
    443     }
    444     return 0;
    445 }
    446 
    447 inline _LIBCPP_CONSTEXPR_AFTER_CXX14
    448 size_t
    449 char_traits<char16_t>::length(const char_type* __s) _NOEXCEPT
    450 {
    451     size_t __len = 0;
    452     for (; !eq(*__s, char_type(0)); ++__s)
    453         ++__len;
    454     return __len;
    455 }
    456 
    457 inline _LIBCPP_CONSTEXPR_AFTER_CXX14
    458 const char16_t*
    459 char_traits<char16_t>::find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT
    460 {
    461     for (; __n; --__n)
    462     {
    463         if (eq(*__s, __a))
    464             return __s;
    465         ++__s;
    466     }
    467     return 0;
    468 }
    469 
    470 inline
    471 char16_t*
    472 char_traits<char16_t>::move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
    473 {
    474     char_type* __r = __s1;
    475     if (__s1 < __s2)
    476     {
    477         for (; __n; --__n, ++__s1, ++__s2)
    478             assign(*__s1, *__s2);
    479     }
    480     else if (__s2 < __s1)
    481     {
    482         __s1 += __n;
    483         __s2 += __n;
    484         for (; __n; --__n)
    485             assign(*--__s1, *--__s2);
    486     }
    487     return __r;
    488 }
    489 
    490 inline
    491 char16_t*
    492 char_traits<char16_t>::copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
    493 {
    494     _LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
    495     char_type* __r = __s1;
    496     for (; __n; --__n, ++__s1, ++__s2)
    497         assign(*__s1, *__s2);
    498     return __r;
    499 }
    500 
    501 inline
    502 char16_t*
    503 char_traits<char16_t>::assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT
    504 {
    505     char_type* __r = __s;
    506     for (; __n; --__n, ++__s)
    507         assign(*__s, __a);
    508     return __r;
    509 }
    510 
    511 template <>
    512 struct _LIBCPP_TEMPLATE_VIS char_traits<char32_t>
    513 {
    514     typedef char32_t       char_type;
    515     typedef uint_least32_t int_type;
    516     typedef streamoff      off_type;
    517     typedef u32streampos   pos_type;
    518     typedef mbstate_t      state_type;
    519 
    520     static inline _LIBCPP_CONSTEXPR_AFTER_CXX14
    521     void assign(char_type& __c1, const char_type& __c2) _NOEXCEPT {__c1 = __c2;}
    522     static inline _LIBCPP_CONSTEXPR bool eq(char_type __c1, char_type __c2) _NOEXCEPT
    523         {return __c1 == __c2;}
    524     static inline _LIBCPP_CONSTEXPR bool lt(char_type __c1, char_type __c2) _NOEXCEPT
    525         {return __c1 < __c2;}
    526 
    527     _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
    528     int              compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
    529     _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
    530     size_t           length(const char_type* __s) _NOEXCEPT;
    531     _LIBCPP_INLINE_VISIBILITY static _LIBCPP_CONSTEXPR_AFTER_CXX14
    532     const char_type* find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT;
    533     _LIBCPP_INLINE_VISIBILITY
    534     static char_type*       move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
    535     _LIBCPP_INLINE_VISIBILITY
    536     static char_type*       copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT;
    537     _LIBCPP_INLINE_VISIBILITY
    538     static char_type*       assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT;
    539 
    540     static inline _LIBCPP_CONSTEXPR int_type  not_eof(int_type __c) _NOEXCEPT
    541         {return eq_int_type(__c, eof()) ? ~eof() : __c;}
    542     static inline _LIBCPP_CONSTEXPR char_type to_char_type(int_type __c) _NOEXCEPT
    543         {return char_type(__c);}
    544     static inline _LIBCPP_CONSTEXPR int_type to_int_type(char_type __c) _NOEXCEPT
    545         {return int_type(__c);}
    546     static inline _LIBCPP_CONSTEXPR bool eq_int_type(int_type __c1, int_type __c2) _NOEXCEPT
    547         {return __c1 == __c2;}
    548     static inline _LIBCPP_CONSTEXPR int_type eof() _NOEXCEPT
    549         {return int_type(0xFFFFFFFF);}
    550 };
    551 
    552 inline _LIBCPP_CONSTEXPR_AFTER_CXX14
    553 int
    554 char_traits<char32_t>::compare(const char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
    555 {
    556     for (; __n; --__n, ++__s1, ++__s2)
    557     {
    558         if (lt(*__s1, *__s2))
    559             return -1;
    560         if (lt(*__s2, *__s1))
    561             return 1;
    562     }
    563     return 0;
    564 }
    565 
    566 inline _LIBCPP_CONSTEXPR_AFTER_CXX14
    567 size_t
    568 char_traits<char32_t>::length(const char_type* __s) _NOEXCEPT
    569 {
    570     size_t __len = 0;
    571     for (; !eq(*__s, char_type(0)); ++__s)
    572         ++__len;
    573     return __len;
    574 }
    575 
    576 inline _LIBCPP_CONSTEXPR_AFTER_CXX14
    577 const char32_t*
    578 char_traits<char32_t>::find(const char_type* __s, size_t __n, const char_type& __a) _NOEXCEPT
    579 {
    580     for (; __n; --__n)
    581     {
    582         if (eq(*__s, __a))
    583             return __s;
    584         ++__s;
    585     }
    586     return 0;
    587 }
    588 
    589 inline
    590 char32_t*
    591 char_traits<char32_t>::move(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
    592 {
    593     char_type* __r = __s1;
    594     if (__s1 < __s2)
    595     {
    596         for (; __n; --__n, ++__s1, ++__s2)
    597             assign(*__s1, *__s2);
    598     }
    599     else if (__s2 < __s1)
    600     {
    601         __s1 += __n;
    602         __s2 += __n;
    603         for (; __n; --__n)
    604             assign(*--__s1, *--__s2);
    605     }
    606     return __r;
    607 }
    608 
    609 inline
    610 char32_t*
    611 char_traits<char32_t>::copy(char_type* __s1, const char_type* __s2, size_t __n) _NOEXCEPT
    612 {
    613     _LIBCPP_ASSERT(__s2 < __s1 || __s2 >= __s1+__n, "char_traits::copy overlapped range");
    614     char_type* __r = __s1;
    615     for (; __n; --__n, ++__s1, ++__s2)
    616         assign(*__s1, *__s2);
    617     return __r;
    618 }
    619 
    620 inline
    621 char32_t*
    622 char_traits<char32_t>::assign(char_type* __s, size_t __n, char_type __a) _NOEXCEPT
    623 {
    624     char_type* __r = __s;
    625     for (; __n; --__n, ++__s)
    626         assign(*__s, __a);
    627     return __r;
    628 }
    629 
    630 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
    631 
    632 // helper fns for basic_string and string_view
    633 
    634 // __str_find
    635 template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
    636 inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
    637 __str_find(const _CharT *__p, _SizeT __sz, 
    638              _CharT __c, _SizeT __pos) _NOEXCEPT
    639 {
    640     if (__pos >= __sz)
    641         return __npos;
    642     const _CharT* __r = _Traits::find(__p + __pos, __sz - __pos, __c);
    643     if (__r == 0)
    644         return __npos;
    645     return static_cast<_SizeT>(__r - __p);
    646 }
    647 
    648 template <class _CharT, class _Traits>
    649 inline _LIBCPP_CONSTEXPR_AFTER_CXX11 const _CharT *
    650 __search_substring(const _CharT *__first1, const _CharT *__last1,
    651                    const _CharT *__first2, const _CharT *__last2) {
    652   // Take advantage of knowing source and pattern lengths.
    653   // Stop short when source is smaller than pattern.
    654   const ptrdiff_t __len2 = __last2 - __first2;
    655   if (__len2 == 0)
    656     return __first1;
    657 
    658   ptrdiff_t __len1 = __last1 - __first1;
    659   if (__len1 < __len2)
    660     return __last1;
    661 
    662   // First element of __first2 is loop invariant.
    663   _CharT __f2 = *__first2;
    664   while (true) {
    665     __len1 = __last1 - __first1;
    666     // Check whether __first1 still has at least __len2 bytes.
    667     if (__len1 < __len2)
    668       return __last1;
    669 
    670     // Find __f2 the first byte matching in __first1.
    671     __first1 = _Traits::find(__first1, __len1 - __len2 + 1, __f2);
    672     if (__first1 == 0)
    673       return __last1;
    674 
    675     // It is faster to compare from the first byte of __first1 even if we
    676     // already know that it matches the first byte of __first2: this is because
    677     // __first2 is most likely aligned, as it is user's "pattern" string, and
    678     // __first1 + 1 is most likely not aligned, as the match is in the middle of
    679     // the string.
    680     if (_Traits::compare(__first1, __first2, __len2) == 0)
    681       return __first1;
    682 
    683     ++__first1;
    684   }
    685 }
    686 
    687 template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
    688 inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
    689 __str_find(const _CharT *__p, _SizeT __sz, 
    690        const _CharT* __s, _SizeT __pos, _SizeT __n) _NOEXCEPT
    691 {
    692     if (__pos > __sz)
    693         return __npos;
    694 
    695     if (__n == 0) // There is nothing to search, just return __pos.
    696         return __pos;
    697 
    698     const _CharT *__r = __search_substring<_CharT, _Traits>(
    699         __p + __pos, __p + __sz, __s, __s + __n);
    700 
    701     if (__r == __p + __sz)
    702         return __npos;
    703     return static_cast<_SizeT>(__r - __p);
    704 }
    705 
    706 
    707 // __str_rfind
    708 
    709 template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
    710 inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
    711 __str_rfind(const _CharT *__p, _SizeT __sz, 
    712               _CharT __c, _SizeT __pos) _NOEXCEPT
    713 {
    714     if (__sz < 1)
    715         return __npos;
    716     if (__pos < __sz)
    717         ++__pos;
    718     else
    719         __pos = __sz;
    720     for (const _CharT* __ps = __p + __pos; __ps != __p;)
    721     {
    722         if (_Traits::eq(*--__ps, __c))
    723             return static_cast<_SizeT>(__ps - __p);
    724     }
    725     return __npos;
    726 }
    727 
    728 template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
    729 inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
    730 __str_rfind(const _CharT *__p, _SizeT __sz, 
    731         const _CharT* __s, _SizeT __pos, _SizeT __n) _NOEXCEPT
    732 {
    733     __pos = _VSTD::min(__pos, __sz);
    734     if (__n < __sz - __pos)
    735         __pos += __n;
    736     else
    737         __pos = __sz;
    738     const _CharT* __r = _VSTD::__find_end(
    739                   __p, __p + __pos, __s, __s + __n, _Traits::eq, 
    740                         random_access_iterator_tag(), random_access_iterator_tag());
    741     if (__n > 0 && __r == __p + __pos)
    742         return __npos;
    743     return static_cast<_SizeT>(__r - __p);
    744 }
    745 
    746 // __str_find_first_of
    747 template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
    748 inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
    749 __str_find_first_of(const _CharT *__p, _SizeT __sz,
    750                 const _CharT* __s, _SizeT __pos, _SizeT __n) _NOEXCEPT
    751 {
    752     if (__pos >= __sz || __n == 0)
    753         return __npos;
    754     const _CharT* __r = _VSTD::__find_first_of_ce
    755         (__p + __pos, __p + __sz, __s, __s + __n, _Traits::eq );
    756     if (__r == __p + __sz)
    757         return __npos;
    758     return static_cast<_SizeT>(__r - __p);
    759 }
    760 
    761 
    762 // __str_find_last_of
    763 template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
    764 inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
    765 __str_find_last_of(const _CharT *__p, _SizeT __sz,
    766                const _CharT* __s, _SizeT __pos, _SizeT __n) _NOEXCEPT
    767     {
    768     if (__n != 0)
    769     {
    770         if (__pos < __sz)
    771             ++__pos;
    772         else
    773             __pos = __sz;
    774         for (const _CharT* __ps = __p + __pos; __ps != __p;)
    775         {
    776             const _CharT* __r = _Traits::find(__s, __n, *--__ps);
    777             if (__r)
    778                 return static_cast<_SizeT>(__ps - __p);
    779         }
    780     }
    781     return __npos;
    782 }
    783 
    784 
    785 // __str_find_first_not_of
    786 template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
    787 inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
    788 __str_find_first_not_of(const _CharT *__p, _SizeT __sz,
    789                     const _CharT* __s, _SizeT __pos, _SizeT __n) _NOEXCEPT
    790 {
    791     if (__pos < __sz)
    792     {
    793         const _CharT* __pe = __p + __sz;
    794         for (const _CharT* __ps = __p + __pos; __ps != __pe; ++__ps)
    795             if (_Traits::find(__s, __n, *__ps) == 0)
    796                 return static_cast<_SizeT>(__ps - __p);
    797     }
    798     return __npos;
    799 }
    800 
    801 
    802 template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
    803 inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
    804 __str_find_first_not_of(const _CharT *__p, _SizeT __sz,
    805                           _CharT __c, _SizeT __pos) _NOEXCEPT
    806 {
    807     if (__pos < __sz)
    808     {
    809         const _CharT* __pe = __p + __sz;
    810         for (const _CharT* __ps = __p + __pos; __ps != __pe; ++__ps)
    811             if (!_Traits::eq(*__ps, __c))
    812                 return static_cast<_SizeT>(__ps - __p);
    813     }
    814     return __npos;
    815 }
    816 
    817 
    818 // __str_find_last_not_of
    819 template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
    820 inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
    821 __str_find_last_not_of(const _CharT *__p, _SizeT __sz,
    822                    const _CharT* __s, _SizeT __pos, _SizeT __n) _NOEXCEPT
    823 {
    824     if (__pos < __sz)
    825         ++__pos;
    826     else
    827         __pos = __sz;
    828     for (const _CharT* __ps = __p + __pos; __ps != __p;)
    829         if (_Traits::find(__s, __n, *--__ps) == 0)
    830             return static_cast<_SizeT>(__ps - __p);
    831     return __npos;
    832 }
    833 
    834 
    835 template<class _CharT, class _SizeT, class _Traits, _SizeT __npos>
    836 inline _SizeT _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
    837 __str_find_last_not_of(const _CharT *__p, _SizeT __sz,
    838                          _CharT __c, _SizeT __pos) _NOEXCEPT
    839 {
    840     if (__pos < __sz)
    841         ++__pos;
    842     else
    843         __pos = __sz;
    844     for (const _CharT* __ps = __p + __pos; __ps != __p;)
    845         if (!_Traits::eq(*--__ps, __c))
    846             return static_cast<_SizeT>(__ps - __p);
    847     return __npos;
    848 }
    849 
    850 template<class _Ptr>
    851 inline _LIBCPP_INLINE_VISIBILITY
    852 size_t __do_string_hash(_Ptr __p, _Ptr __e)
    853 {
    854     typedef typename iterator_traits<_Ptr>::value_type value_type;
    855     return __murmur2_or_cityhash<size_t>()(__p, (__e-__p)*sizeof(value_type));
    856 }
    857 
    858 template <class _CharT, class _Iter, class _Traits=char_traits<_CharT> >
    859 struct __quoted_output_proxy
    860 {
    861     _Iter  __first;
    862     _Iter  __last;
    863     _CharT  __delim;
    864     _CharT  __escape;
    865 
    866     __quoted_output_proxy(_Iter __f, _Iter __l, _CharT __d, _CharT __e)
    867     : __first(__f), __last(__l), __delim(__d), __escape(__e) {}
    868     //  This would be a nice place for a string_ref 
    869 };
    870 
    871 _LIBCPP_END_NAMESPACE_STD
    872 
    873 #endif  // _LIBCPP___STRING
    874