From 36d22d82aa202bb199967e9512281e9a53db42c9 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 21:33:14 +0200 Subject: Adding upstream version 115.7.0esr. Signed-off-by: Daniel Baumann --- ipc/chromium/src/base/string16.h | 161 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 161 insertions(+) create mode 100644 ipc/chromium/src/base/string16.h (limited to 'ipc/chromium/src/base/string16.h') diff --git a/ipc/chromium/src/base/string16.h b/ipc/chromium/src/base/string16.h new file mode 100644 index 0000000000..8c3bda91fd --- /dev/null +++ b/ipc/chromium/src/base/string16.h @@ -0,0 +1,161 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +// 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 +#include + +#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_t 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 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(EOF); } +}; + +} // 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 (string) and std::basic_string (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 std::basic_string; + +typedef std::basic_string string16; + +extern std::ostream& operator<<(std::ostream& out, const string16& str); + +#endif // WCHAR_T_IS_UTF32 + +#endif // BASE_STRING16_H_ -- cgit v1.2.3