Revision control

Line Code
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
/* -*- 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>
# include "mozilla/Attributes.h"
  /**
   * 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:
  MOZ_IMPLICIT char16ptr_t(const char16_t* aPtr) : mPtr(aPtr) {}
  MOZ_IMPLICIT char16ptr_t(const wchar_t* aPtr) :
    mPtr(reinterpret_cast<const char16_t*>(aPtr))
  {}

  /* Without this, nullptr assignment would be ambiguous. */
  constexpr MOZ_IMPLICIT 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 wchar_t*()
  {
    return const_cast<wchar_t*>(reinterpret_cast<const wchar_t*>(mPtr));
  }

  operator const void*() const
  {
    return mPtr;
  }
  MOZ_IMPLICIT 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 */