diff -r 000000000000 -r 6474c204b198 mfbt/Char16.h --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mfbt/Char16.h Wed Dec 31 06:09:35 2014 +0100 @@ -0,0 +1,202 @@ +/* -*- 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 + +#ifdef __cplusplus + +/* + * C++11 introduces a char16_t type and support for UTF-16 string and character + * literals. C++11's char16_t is a distinct builtin type. Technically, char16_t + * is a 16-bit code unit of a Unicode code point, not a "character". + */ + +#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 + * _CHAR16T here in order to prevent yvals.h from overriding our char16_t + * typedefs, which we set to wchar_t for C++ code. + * + * In addition, #defining _CHAR16T will prevent yvals.h from defining a + * char32_t type, so we have to undo that damage here and provide our own, + * which is identical to the yvals.h type. + */ +# define MOZ_UTF16_HELPER(s) L##s +# define _CHAR16T + typedef wchar_t char16_t; + typedef unsigned int char32_t; +#else + /* 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 +# ifdef WIN32 +# define MOZ_USE_CHAR16_WRAPPER +# endif +#endif + +#ifdef MOZ_USE_CHAR16_WRAPPER +# include + /** + * Win32 API extensively uses wchar_t, which is represented by a separated + * builtin type than char16_t per spec. It's not the case for MSVC, but GCC + * follows the spec. We want to mix wchar_t and char16_t on Windows builds. + * This class is supposed to make it easier. It stores char16_t const pointer, + * but provides implicit casts for wchar_t as well. On other platforms, we + * simply use |typedef const char16_t* char16ptr_t|. Here, we want to make + * the class as similar to this typedef, including providing some casts that + * are allowed by the typedef. + */ +class char16ptr_t +{ + private: + const char16_t* ptr; + static_assert(sizeof(char16_t) == sizeof(wchar_t), "char16_t and wchar_t sizes differ"); + + public: + char16ptr_t(const char16_t* p) : ptr(p) {} + char16ptr_t(const wchar_t* p) : ptr(reinterpret_cast(p)) {} + + /* Without this, nullptr assignment would be ambiguous. */ + constexpr char16ptr_t(decltype(nullptr)) : ptr(nullptr) {} + + operator const char16_t*() const { + return ptr; + } + operator const wchar_t*() const { + return reinterpret_cast(ptr); + } + operator const void*() const { + return ptr; + } + operator bool() const { + return ptr != nullptr; + } + operator std::wstring() const { + return std::wstring(static_cast(*this)); + } + + /* Explicit cast operators to allow things like (char16_t*)str. */ + explicit operator char16_t*() const { + return const_cast(ptr); + } + explicit operator wchar_t*() const { + return const_cast(static_cast(*this)); + } + explicit operator int() const { + return reinterpret_cast(ptr); + } + explicit operator unsigned int() const { + return reinterpret_cast(ptr); + } + explicit operator long() const { + return reinterpret_cast(ptr); + } + explicit operator unsigned long() const { + return reinterpret_cast(ptr); + } + explicit operator long long() const { + return reinterpret_cast(ptr); + } + explicit operator unsigned long long() const { + return reinterpret_cast(ptr); + } + + /** + * Some Windows API calls accept BYTE* but require that data actually be WCHAR*. + * Supporting this requires explicit operators to support the requisite explicit + * casts. + */ + explicit operator const char*() const { + return reinterpret_cast(ptr); + } + explicit operator const unsigned char*() const { + return reinterpret_cast(ptr); + } + explicit operator unsigned char*() const { + return const_cast(reinterpret_cast(ptr)); + } + explicit operator void*() const { + return const_cast(ptr); + } + + /* Some operators used on pointers. */ + char16_t operator[](size_t i) const { + return ptr[i]; + } + bool operator==(const char16ptr_t &x) const { + return ptr == x.ptr; + } + bool operator==(decltype(nullptr)) const { + return ptr == nullptr; + } + bool operator!=(const char16ptr_t &x) const { + return ptr != x.ptr; + } + bool operator!=(decltype(nullptr)) const { + return ptr != nullptr; + } + char16ptr_t operator+(int aValue) const { + return char16ptr_t(ptr + aValue); + } + char16ptr_t operator+(unsigned int aValue) const { + return char16ptr_t(ptr + aValue); + } + char16ptr_t operator+(long aValue) const { + return char16ptr_t(ptr + aValue); + } + char16ptr_t operator+(unsigned long aValue) const { + return char16ptr_t(ptr + aValue); + } + char16ptr_t operator+(long long aValue) const { + return char16ptr_t(ptr + aValue); + } + char16ptr_t operator+(unsigned long long aValue) const { + return char16ptr_t(ptr + aValue); + } + ptrdiff_t operator-(const char16ptr_t &other) const { + return ptr - other.ptr; + } +}; + +inline decltype((char*)0-(char*)0) +operator-(const char16_t* x, const char16ptr_t y) { + return x - static_cast(y); +} + +#else + +typedef const char16_t* char16ptr_t; + +#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 + +#endif /* mozilla_Char16_h */