Move base to DEPS

base/strings/string16.h

-// Copyright 2013 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_STRINGS_STRING16_H_
-#define BASE_STRINGS_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 <stdio.h>
-#include <string>
-
-#include "base/base_export.h"
-#include "base/basictypes.h"
-
-#if defined(WCHAR_T_IS_UTF16)
-
-namespace base {
-
-typedef wchar_t char16;
-typedef std::wstring string16;
-typedef std::char_traits<wchar_t> string16_char_traits;
-
-}  // namespace base
-
-#elif defined(WCHAR_T_IS_UTF32)
-
-namespace base {
-
-typedef uint16 char16;
-
-// 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").
-BASE_EXPORT int c16memcmp(const char16* s1, const char16* s2, size_t n);
-BASE_EXPORT size_t c16len(const char16* s);
-BASE_EXPORT const char16* c16memchr(const char16* s, char16 c, size_t n);
-BASE_EXPORT char16* c16memmove(char16* s1, const char16* s2, size_t n);
-BASE_EXPORT char16* c16memcpy(char16* s1, const char16* s2, size_t n);
-BASE_EXPORT 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, size_t 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);
-  }
-};
-
-typedef std::basic_string<char16, base::string16_char_traits> string16;
-
-BASE_EXPORT extern std::ostream& operator<<(std::ostream& out,
-                                            const string16& str);
-
-// This is required by googletest to print a readable output on test failures.
-BASE_EXPORT extern void PrintTo(const string16& str, std::ostream* out);
-
-}  // namespace base
-
-// The string class will be explicitly instantiated only once, in string16.cc.
-//
-// std::basic_string<> in GNU libstdc++ contains a static data member,
-// _S_empty_rep_storage, to represent empty strings.  When an operation such
-// as assignment or destruction is performed on a string, causing its existing
-// data member to be invalidated, it must not be freed if this static data
-// member is being used.  Otherwise, it counts as an attempt to free static
-// (and not allocated) data, which is a memory error.
-//
-// Generally, due to C++ template magic, _S_empty_rep_storage will be marked
-// as a coalesced symbol, meaning that the linker will combine multiple
-// instances into a single one when generating output.
-//
-// If a string class is used by multiple shared libraries, a problem occurs.
-// Each library will get its own copy of _S_empty_rep_storage.  When strings
-// are passed across a library boundary for alteration or destruction, memory
-// errors will result.  GNU libstdc++ contains a configuration option,
-// --enable-fully-dynamic-string (_GLIBCXX_FULLY_DYNAMIC_STRING), which
-// disables the static data member optimization, but it's a good optimization
-// and non-STL code is generally at the mercy of the system's STL
-// configuration.  Fully-dynamic strings are not the default for GNU libstdc++
-// libstdc++ itself or for the libstdc++ installations on the systems we care
-// about, such as Mac OS X and relevant flavors of Linux.
-//
-// See also http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24196 .
-//
-// To avoid problems, string classes need to be explicitly instantiated only
-// once, in exactly one library.  All other string users see it via an "extern"
-// declaration.  This is precisely how GNU libstdc++ handles
-// std::basic_string<char> (string) and std::basic_string<wchar_t> (wstring).
-//
-// This also works around a Mac OS X linker bug in ld64-85.2.1 (Xcode 3.1.2),
-// in which the linker does not fully coalesce symbols when dead code
-// stripping is enabled.  This bug causes the memory errors described above
-// to occur even when a std::basic_string<> does not cross shared library
-// boundaries, such as in statically-linked executables.
-//
-// TODO(mark): File this bug with Apple and update this note with a bug number.
-
-extern template
-class BASE_EXPORT std::basic_string<base::char16, base::string16_char_traits>;
-
-#endif  // WCHAR_T_IS_UTF32
-
-#endif  // BASE_STRINGS_STRING16_H_