| // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef BASE_STRING16_H_ |
| #define BASE_STRING16_H_ |
| |
| // WHAT: |
| // A version of std::basic_string that provides 2-byte characters even when |
| // wchar_t is not implemented as a 2-byte type. You can access this class as |
| // string16. We also define char16, which string16 is based upon. |
| // |
| // WHY: |
| // On Windows, wchar_t is 2 bytes, and it can conveniently handle UTF-16/UCS-2 |
| // data. Plenty of existing code operates on strings encoded as UTF-16. |
| // |
| // On many other platforms, sizeof(wchar_t) is 4 bytes by default. We can make |
| // it 2 bytes by using the GCC flag -fshort-wchar. But then std::wstring fails |
| // at run time, because it calls some functions (like wcslen) that come from |
| // the system's native C library -- which was built with a 4-byte wchar_t! |
| // It's wasteful to use 4-byte wchar_t strings to carry UTF-16 data, and it's |
| // entirely improper on those systems where the encoding of wchar_t is defined |
| // as UTF-32. |
| // |
| // Here, we define string16, which is similar to std::wstring but replaces all |
| // libc functions with custom, 2-byte-char compatible routines. It is capable |
| // of carrying UTF-16-encoded data. |
| |
| #include <string> |
| |
| #include "base/basictypes.h" |
| |
| #if defined(WCHAR_T_IS_UTF16) |
| |
| typedef wchar_t char16; |
| typedef std::wstring string16; |
| |
| #elif defined(WCHAR_T_IS_UTF32) |
| |
| typedef uint16 char16; |
| |
| namespace base { |
| |
| // char16 versions of the functions required by string16_char_traits; these |
| // are based on the wide character functions of similar names ("w" or "wcs" |
| // instead of "c16"). |
| int c16memcmp(const char16* s1, const char16* s2, size_t n); |
| size_t c16len(const char16* s); |
| const char16* c16memchr(const char16* s, char16 c, size_t n); |
| char16* c16memmove(char16* s1, const char16* s2, size_t n); |
| char16* c16memcpy(char16* s1, const char16* s2, size_t n); |
| char16* c16memset(char16* s, char16 c, size_t n); |
| |
| struct string16_char_traits { |
| typedef char16 char_type; |
| typedef int int_type; |
| |
| // int_type needs to be able to hold each possible value of char_type, and in |
| // addition, the distinct value of eof(). |
| COMPILE_ASSERT(sizeof(int_type) > sizeof(char_type), unexpected_type_width); |
| |
| typedef std::streamoff off_type; |
| typedef mbstate_t state_type; |
| typedef std::fpos<state_type> pos_type; |
| |
| static void assign(char_type& c1, const char_type& c2) { |
| c1 = c2; |
| } |
| |
| static bool eq(const char_type& c1, const char_type& c2) { |
| return c1 == c2; |
| } |
| static bool lt(const char_type& c1, const char_type& c2) { |
| return c1 < c2; |
| } |
| |
| static int compare(const char_type* s1, const char_type* s2, size_t n) { |
| return c16memcmp(s1, s2, n); |
| } |
| |
| static size_t length(const char_type* s) { |
| return c16len(s); |
| } |
| |
| static const char_type* find(const char_type* s, size_t n, |
| const char_type& a) { |
| return c16memchr(s, a, n); |
| } |
| |
| static char_type* move(char_type* s1, const char_type* s2, int_type n) { |
| return c16memmove(s1, s2, n); |
| } |
| |
| static char_type* copy(char_type* s1, const char_type* s2, size_t n) { |
| return c16memcpy(s1, s2, n); |
| } |
| |
| static char_type* assign(char_type* s, size_t n, char_type a) { |
| return c16memset(s, a, n); |
| } |
| |
| static int_type not_eof(const int_type& c) { |
| return eq_int_type(c, eof()) ? 0 : c; |
| } |
| |
| static char_type to_char_type(const int_type& c) { |
| return char_type(c); |
| } |
| |
| static int_type to_int_type(const char_type& c) { |
| return int_type(c); |
| } |
| |
| static bool eq_int_type(const int_type& c1, const int_type& c2) { |
| return c1 == c2; |
| } |
| |
| static int_type eof() { |
| return static_cast<int_type>(EOF); |
| } |
| }; |
| |
| } // namespace base |
| |
| typedef std::basic_string<char16, base::string16_char_traits> string16; |
| |
| #endif // WCHAR_T_IS_UTF32 |
| |
| #endif // BASE_STRING16_H_ |