mirror of
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c5fea3fa51
Differential Revision: https://phabricator.services.mozilla.com/D144777
143 lines
4.9 KiB
C++
143 lines
4.9 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/* Implements a UTF-16 character type. */
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#ifndef mozilla_Char16_h
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#define mozilla_Char16_h
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#ifdef __cplusplus
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/*
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* C++11 introduces a char16_t type and support for UTF-16 string and character
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* literals. C++11's char16_t is a distinct builtin type. Technically, char16_t
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* is a 16-bit code unit of a Unicode code point, not a "character".
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*/
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# ifdef WIN32
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# define MOZ_USE_CHAR16_WRAPPER
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# include <cstdint>
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# include "mozilla/Attributes.h"
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/**
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* Win32 API extensively uses wchar_t, which is represented by a separated
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* builtin type than char16_t per spec. It's not the case for MSVC prior to
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* MSVC 2015, but other compilers follow the spec. We want to mix wchar_t and
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* char16_t on Windows builds. This class is supposed to make it easier. It
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* stores char16_t const pointer, but provides implicit casts for wchar_t as
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* well. On other platforms, we simply use
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* |typedef const char16_t* char16ptr_t|. Here, we want to make the class as
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* similar to this typedef, including providing some casts that are allowed
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* by the typedef.
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*/
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class char16ptr_t {
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private:
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const char16_t* mPtr;
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static_assert(sizeof(char16_t) == sizeof(wchar_t),
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"char16_t and wchar_t sizes differ");
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public:
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constexpr MOZ_IMPLICIT char16ptr_t(const char16_t* aPtr) : mPtr(aPtr) {}
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MOZ_IMPLICIT char16ptr_t(const wchar_t* aPtr)
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: mPtr(reinterpret_cast<const char16_t*>(aPtr)) {}
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/* Without this, nullptr assignment would be ambiguous. */
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constexpr MOZ_IMPLICIT char16ptr_t(decltype(nullptr)) : mPtr(nullptr) {}
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constexpr operator const char16_t*() const { return mPtr; }
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operator const wchar_t*() const {
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return reinterpret_cast<const wchar_t*>(mPtr);
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}
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operator wchar_t*() {
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return const_cast<wchar_t*>(reinterpret_cast<const wchar_t*>(mPtr));
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}
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constexpr operator const void*() const { return mPtr; }
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constexpr explicit operator bool() const { return mPtr != nullptr; }
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explicit operator int() const { return reinterpret_cast<intptr_t>(mPtr); }
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explicit operator unsigned int() const {
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return reinterpret_cast<uintptr_t>(mPtr);
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}
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explicit operator long() const { return reinterpret_cast<intptr_t>(mPtr); }
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explicit operator unsigned long() const {
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return reinterpret_cast<uintptr_t>(mPtr);
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}
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explicit operator long long() const {
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return reinterpret_cast<intptr_t>(mPtr);
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}
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explicit operator unsigned long long() const {
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return reinterpret_cast<uintptr_t>(mPtr);
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}
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/**
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* Some Windows API calls accept BYTE* but require that data actually be
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* WCHAR*. Supporting this requires explicit operators to support the
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* requisite explicit casts.
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*/
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explicit operator const char*() const {
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return reinterpret_cast<const char*>(mPtr);
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}
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explicit operator const unsigned char*() const {
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return reinterpret_cast<const unsigned char*>(mPtr);
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}
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explicit operator unsigned char*() const {
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return const_cast<unsigned char*>(
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reinterpret_cast<const unsigned char*>(mPtr));
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}
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explicit operator void*() const { return const_cast<char16_t*>(mPtr); }
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/* Some operators used on pointers. */
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char16_t operator[](size_t aIndex) const { return mPtr[aIndex]; }
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bool operator==(const char16ptr_t& aOther) const {
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return mPtr == aOther.mPtr;
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}
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bool operator==(decltype(nullptr)) const { return mPtr == nullptr; }
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bool operator!=(const char16ptr_t& aOther) const {
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return mPtr != aOther.mPtr;
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}
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bool operator!=(decltype(nullptr)) const { return mPtr != nullptr; }
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char16ptr_t operator+(int aValue) const { return char16ptr_t(mPtr + aValue); }
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char16ptr_t operator+(unsigned int aValue) const {
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return char16ptr_t(mPtr + aValue);
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}
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char16ptr_t operator+(long aValue) const {
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return char16ptr_t(mPtr + aValue);
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}
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char16ptr_t operator+(unsigned long aValue) const {
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return char16ptr_t(mPtr + aValue);
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}
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char16ptr_t operator+(long long aValue) const {
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return char16ptr_t(mPtr + aValue);
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}
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char16ptr_t operator+(unsigned long long aValue) const {
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return char16ptr_t(mPtr + aValue);
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}
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ptrdiff_t operator-(const char16ptr_t& aOther) const {
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return mPtr - aOther.mPtr;
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}
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};
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inline decltype((char*)0 - (char*)0) operator-(const char16_t* aX,
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const char16ptr_t aY) {
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return aX - static_cast<const char16_t*>(aY);
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}
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# else
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typedef const char16_t* char16ptr_t;
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# endif
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static_assert(sizeof(char16_t) == 2, "Is char16_t type 16 bits?");
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static_assert(char16_t(-1) > char16_t(0), "Is char16_t type unsigned?");
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static_assert(sizeof(u'A') == 2, "Is unicode char literal 16 bits?");
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static_assert(sizeof(u""[0]) == 2, "Is unicode string char 16 bits?");
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#endif
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#endif /* mozilla_Char16_h */
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