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Diffstat (limited to 'mfbt/Char16.h')
| -rw-r--r-- | mfbt/Char16.h | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/mfbt/Char16.h b/mfbt/Char16.h new file mode 100644 index 000000000..3c2f254aa --- /dev/null +++ b/mfbt/Char16.h @@ -0,0 +1,194 @@ +/* -*- 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 WIN32 +# define MOZ_USE_CHAR16_WRAPPER +# include <cstdint> + /** + * 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 prior to + * MSVC 2015, but other compilers follow 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* mPtr; + static_assert(sizeof(char16_t) == sizeof(wchar_t), + "char16_t and wchar_t sizes differ"); + +public: + char16ptr_t(const char16_t* aPtr) : mPtr(aPtr) {} + char16ptr_t(const wchar_t* aPtr) : + mPtr(reinterpret_cast<const char16_t*>(aPtr)) + {} + + /* Without this, nullptr assignment would be ambiguous. */ + constexpr char16ptr_t(decltype(nullptr)) : mPtr(nullptr) {} + + operator const char16_t*() const + { + return mPtr; + } + operator const wchar_t*() const + { + return reinterpret_cast<const wchar_t*>(mPtr); + } + operator const void*() const + { + return mPtr; + } + operator bool() const + { + return mPtr != nullptr; + } + + /* Explicit cast operators to allow things like (char16_t*)str. */ + explicit operator char16_t*() const + { + return const_cast<char16_t*>(mPtr); + } + explicit operator wchar_t*() const + { + return const_cast<wchar_t*>(static_cast<const wchar_t*>(*this)); + } + explicit operator int() const + { + return reinterpret_cast<intptr_t>(mPtr); + } + explicit operator unsigned int() const + { + return reinterpret_cast<uintptr_t>(mPtr); + } + explicit operator long() const + { + return reinterpret_cast<intptr_t>(mPtr); + } + explicit operator unsigned long() const + { + return reinterpret_cast<uintptr_t>(mPtr); + } + explicit operator long long() const + { + return reinterpret_cast<intptr_t>(mPtr); + } + explicit operator unsigned long long() const + { + return reinterpret_cast<uintptr_t>(mPtr); + } + + /** + * 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<const char*>(mPtr); + } + explicit operator const unsigned char*() const + { + return reinterpret_cast<const unsigned char*>(mPtr); + } + explicit operator unsigned char*() const + { + return + const_cast<unsigned char*>(reinterpret_cast<const unsigned char*>(mPtr)); + } + explicit operator void*() const + { + return const_cast<char16_t*>(mPtr); + } + + /* Some operators used on pointers. */ + char16_t operator[](size_t aIndex) const + { + return mPtr[aIndex]; + } + bool operator==(const char16ptr_t& aOther) const + { + return mPtr == aOther.mPtr; + } + bool operator==(decltype(nullptr)) const + { + return mPtr == nullptr; + } + bool operator!=(const char16ptr_t& aOther) const + { + return mPtr != aOther.mPtr; + } + bool operator!=(decltype(nullptr)) const + { + return mPtr != nullptr; + } + char16ptr_t operator+(int aValue) const + { + return char16ptr_t(mPtr + aValue); + } + char16ptr_t operator+(unsigned int aValue) const + { + return char16ptr_t(mPtr + aValue); + } + char16ptr_t operator+(long aValue) const + { + return char16ptr_t(mPtr + aValue); + } + char16ptr_t operator+(unsigned long aValue) const + { + return char16ptr_t(mPtr + aValue); + } + char16ptr_t operator+(long long aValue) const + { + return char16ptr_t(mPtr + aValue); + } + char16ptr_t operator+(unsigned long long aValue) const + { + return char16ptr_t(mPtr + aValue); + } + ptrdiff_t operator-(const char16ptr_t& aOther) const + { + return mPtr - aOther.mPtr; + } +}; + +inline decltype((char*)0-(char*)0) +operator-(const char16_t* aX, const char16ptr_t aY) +{ + return aX - static_cast<const char16_t*>(aY); +} + +#else + +typedef const char16_t* char16ptr_t; + +#endif + +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(u'A') == 2, "Is unicode char literal 16 bits?"); +static_assert(sizeof(u""[0]) == 2, "Is unicode string char 16 bits?"); + +#endif + +#endif /* mozilla_Char16_h */ |