1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
3 /* This Source Code Form is subject to the terms of the Mozilla Public
4 * License, v. 2.0. If a copy of the MPL was not distributed with this
5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
7 /* Implements a UTF-16 character type. */
9 #ifndef mozilla_Char16_h
10 #define mozilla_Char16_h
15 * C++11 introduces a char16_t type and support for UTF-16 string and character
16 * literals. C++11's char16_t is a distinct builtin type. Technically, char16_t
17 * is a 16-bit code unit of a Unicode code point, not a "character".
21 # define MOZ_USE_CHAR16_WRAPPER
23 # include "mozilla/Attributes.h"
25 * Win32 API extensively uses wchar_t, which is represented by a separated
26 * builtin type than char16_t per spec. It's not the case for MSVC prior to
27 * MSVC 2015, but other compilers follow the spec. We want to mix wchar_t and
28 * char16_t on Windows builds. This class is supposed to make it easier. It
29 * stores char16_t const pointer, but provides implicit casts for wchar_t as
30 * well. On other platforms, we simply use
31 * |typedef const char16_t* char16ptr_t|. Here, we want to make the class as
32 * similar to this typedef, including providing some casts that are allowed
38 static_assert(sizeof(char16_t
) == sizeof(wchar_t),
39 "char16_t and wchar_t sizes differ");
42 MOZ_IMPLICIT
char16ptr_t(const char16_t
* aPtr
) : mPtr(aPtr
) {}
43 MOZ_IMPLICIT
char16ptr_t(const wchar_t* aPtr
)
44 : mPtr(reinterpret_cast<const char16_t
*>(aPtr
)) {}
46 /* Without this, nullptr assignment would be ambiguous. */
47 constexpr MOZ_IMPLICIT
char16ptr_t(decltype(nullptr)) : mPtr(nullptr) {}
49 operator const char16_t
*() const { return mPtr
; }
50 operator const wchar_t*() const {
51 return reinterpret_cast<const wchar_t*>(mPtr
);
55 return const_cast<wchar_t*>(reinterpret_cast<const wchar_t*>(mPtr
));
58 operator const void*() const { return mPtr
; }
59 explicit operator bool() const { return mPtr
!= nullptr; }
61 /* Explicit cast operators to allow things like (char16_t*)str. */
62 explicit operator char16_t
*() const { return const_cast<char16_t
*>(mPtr
); }
63 explicit operator wchar_t*() const {
64 return const_cast<wchar_t*>(static_cast<const wchar_t*>(*this));
66 explicit operator int() const { return reinterpret_cast<intptr_t>(mPtr
); }
67 explicit operator unsigned int() const {
68 return reinterpret_cast<uintptr_t>(mPtr
);
70 explicit operator long() const { return reinterpret_cast<intptr_t>(mPtr
); }
71 explicit operator unsigned long() const {
72 return reinterpret_cast<uintptr_t>(mPtr
);
74 explicit operator long long() const {
75 return reinterpret_cast<intptr_t>(mPtr
);
77 explicit operator unsigned long long() const {
78 return reinterpret_cast<uintptr_t>(mPtr
);
82 * Some Windows API calls accept BYTE* but require that data actually be
83 * WCHAR*. Supporting this requires explicit operators to support the
84 * requisite explicit casts.
86 explicit operator const char*() const {
87 return reinterpret_cast<const char*>(mPtr
);
89 explicit operator const unsigned char*() const {
90 return reinterpret_cast<const unsigned char*>(mPtr
);
92 explicit operator unsigned char*() const {
93 return const_cast<unsigned char*>(
94 reinterpret_cast<const unsigned char*>(mPtr
));
96 explicit operator void*() const { return const_cast<char16_t
*>(mPtr
); }
98 /* Some operators used on pointers. */
99 char16_t
operator[](size_t aIndex
) const { return mPtr
[aIndex
]; }
100 bool operator==(const char16ptr_t
& aOther
) const {
101 return mPtr
== aOther
.mPtr
;
103 bool operator==(decltype(nullptr)) const { return mPtr
== nullptr; }
104 bool operator!=(const char16ptr_t
& aOther
) const {
105 return mPtr
!= aOther
.mPtr
;
107 bool operator!=(decltype(nullptr)) const { return mPtr
!= nullptr; }
108 char16ptr_t
operator+(int aValue
) const { return char16ptr_t(mPtr
+ aValue
); }
109 char16ptr_t
operator+(unsigned int aValue
) const {
110 return char16ptr_t(mPtr
+ aValue
);
112 char16ptr_t
operator+(long aValue
) const {
113 return char16ptr_t(mPtr
+ aValue
);
115 char16ptr_t
operator+(unsigned long aValue
) const {
116 return char16ptr_t(mPtr
+ aValue
);
118 char16ptr_t
operator+(long long aValue
) const {
119 return char16ptr_t(mPtr
+ aValue
);
121 char16ptr_t
operator+(unsigned long long aValue
) const {
122 return char16ptr_t(mPtr
+ aValue
);
124 ptrdiff_t operator-(const char16ptr_t
& aOther
) const {
125 return mPtr
- aOther
.mPtr
;
129 inline decltype((char*)0 - (char*)0) operator-(const char16_t
* aX
,
130 const char16ptr_t aY
) {
131 return aX
- static_cast<const char16_t
*>(aY
);
136 typedef const char16_t
* char16ptr_t
;
140 static_assert(sizeof(char16_t
) == 2, "Is char16_t type 16 bits?");
141 static_assert(char16_t(-1) > char16_t(0), "Is char16_t type unsigned?");
142 static_assert(sizeof(u
'A') == 2, "Is unicode char literal 16 bits?");
143 static_assert(sizeof(u
""[0]) == 2, "Is unicode string char 16 bits?");
147 #endif /* mozilla_Char16_h */