mirror of
https://github.com/mozilla/gecko-dev.git
synced 2024-11-01 14:45:29 +00:00
64 lines
2.6 KiB
C
64 lines
2.6 KiB
C
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
|
|
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
|
|
/* This Source Code Form is subject to the terms of the Mozilla Public
|
|
* License, v. 2.0. If a copy of the MPL was not distributed with this
|
|
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
|
|
|
|
/* Implements a UTF-16 character type. */
|
|
|
|
#ifndef mozilla_Char16_h
|
|
#define mozilla_Char16_h
|
|
|
|
#include "mozilla/Assertions.h"
|
|
|
|
/*
|
|
* C11 and C++11 introduce a char16_t type and support for UTF-16 string and
|
|
* character literals. C++11's char16_t is a distinct builtin type. C11's
|
|
* char16_t is a typedef for uint_least16_t. Technically, char16_t is a 16-bit
|
|
* code unit of a Unicode code point, not a "character".
|
|
*
|
|
* For now, Char16.h only supports C++ because we don't want mix different C
|
|
* and C++ definitions of char16_t in the same code base.
|
|
*/
|
|
|
|
#ifdef _MSC_VER
|
|
/*
|
|
* C++11 says char16_t is a distinct builtin type, but Windows's yvals.h
|
|
* typedefs char16_t as an unsigned short. We would like to alias char16_t
|
|
* to Windows's 16-bit wchar_t so we can declare UTF-16 literals as constant
|
|
* expressions (and pass char16_t pointers to Windows APIs). We #define our
|
|
* char16_t as a macro to override yval.h's typedef of the same name.
|
|
*/
|
|
# define MOZ_UTF16_HELPER(s) L##s
|
|
# include <yvals.h>
|
|
# define char16_t wchar_t
|
|
#elif defined(__cplusplus) && \
|
|
(__cplusplus >= 201103L || defined(__GXX_EXPERIMENTAL_CXX0X__))
|
|
/* C++11 has a builtin char16_t type. */
|
|
# define MOZ_UTF16_HELPER(s) u##s
|
|
/**
|
|
* This macro is used to distinguish when char16_t would be a distinct
|
|
* typedef from wchar_t.
|
|
*/
|
|
# define MOZ_CHAR16_IS_NOT_WCHAR
|
|
#else
|
|
# error "Char16.h requires C++11 (or something like it) for UTF-16 support."
|
|
#endif
|
|
|
|
/*
|
|
* Macro arguments used in concatenation or stringification won't be expanded.
|
|
* Therefore, in order for |MOZ_UTF16(FOO)| to work as expected (which is to
|
|
* expand |FOO| before doing whatever |MOZ_UTF16| needs to do to it) a helper
|
|
* macro, |MOZ_UTF16_HELPER| needs to be inserted in between to allow the macro
|
|
* argument to expand. See "3.10.6 Separate Expansion of Macro Arguments" of the
|
|
* CPP manual for a more accurate and precise explanation.
|
|
*/
|
|
#define MOZ_UTF16(s) MOZ_UTF16_HELPER(s)
|
|
|
|
static_assert(sizeof(char16_t) == 2, "Is char16_t type 16 bits?");
|
|
static_assert(char16_t(-1) > char16_t(0), "Is char16_t type unsigned?");
|
|
static_assert(sizeof(MOZ_UTF16('A')) == 2, "Is char literal 16 bits?");
|
|
static_assert(sizeof(MOZ_UTF16("")[0]) == 2, "Is string char 16 bits?");
|
|
|
|
#endif /* mozilla_Char16_h */
|