summaryrefslogtreecommitdiff
path: root/base/string_piece.cc
blob: bf6291c28075b9e06c0a3a960d1ac959c3408142 (plain)
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
202
203
204
205
206
207
208
209
210
211
212
213
214
// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Copied from strings/stringpiece.cc with modifications

#include <algorithm>
#include <ostream>

#include "base/string_piece.h"

namespace base {

typedef StringPiece::size_type size_type;

bool operator==(const StringPiece& x, const StringPiece& y) {
  if (x.size() != y.size())
    return false;

  return StringPiece::wordmemcmp(x.data(), y.data(), x.size()) == 0;
}

void StringPiece::CopyToString(std::string* target) const {
  target->assign(!empty() ? data() : "", size());
}

void StringPiece::AppendToString(std::string* target) const {
  if (!empty())
    target->append(data(), size());
}

size_type StringPiece::copy(char* buf, size_type n, size_type pos) const {
  size_type ret = std::min(length_ - pos, n);
  memcpy(buf, ptr_ + pos, ret);
  return ret;
}

size_type StringPiece::find(const StringPiece& s, size_type pos) const {
  if (pos > length_)
    return npos;

  const char* result = std::search(ptr_ + pos, ptr_ + length_,
                                   s.ptr_, s.ptr_ + s.length_);
  const size_type xpos = result - ptr_;
  return xpos + s.length_ <= length_ ? xpos : npos;
}

size_type StringPiece::find(char c, size_type pos) const {
  if (pos >= length_)
    return npos;

  const char* result = std::find(ptr_ + pos, ptr_ + length_, c);
  return result != ptr_ + length_ ? static_cast<size_t>(result - ptr_) : npos;
}

size_type StringPiece::rfind(const StringPiece& s, size_type pos) const {
  if (length_ < s.length_)
    return npos;

  if (s.empty())
    return std::min(length_, pos);

  const char* last = ptr_ + std::min(length_ - s.length_, pos) + s.length_;
  const char* result = std::find_end(ptr_, last, s.ptr_, s.ptr_ + s.length_);
  return result != last ? static_cast<size_t>(result - ptr_) : npos;
}

size_type StringPiece::rfind(char c, size_type pos) const {
  if (length_ == 0)
    return npos;

  for (size_type i = std::min(pos, length_ - 1); ; --i) {
    if (ptr_[i] == c)
      return i;
    if (i == 0)
      break;
  }
  return npos;
}

// For each character in characters_wanted, sets the index corresponding
// to the ASCII code of that character to 1 in table.  This is used by
// the find_.*_of methods below to tell whether or not a character is in
// the lookup table in constant time.
// The argument `table' must be an array that is large enough to hold all
// the possible values of an unsigned char.  Thus it should be be declared
// as follows:
//   bool table[UCHAR_MAX + 1]
static inline void BuildLookupTable(const StringPiece& characters_wanted,
                                    bool* table) {
  const size_type length = characters_wanted.length();
  const char* const data = characters_wanted.data();
  for (size_type i = 0; i < length; ++i) {
    table[static_cast<unsigned char>(data[i])] = true;
  }
}

size_type StringPiece::find_first_of(const StringPiece& s,
                                     size_type pos) const {
  if (length_ == 0 || s.length_ == 0)
    return npos;

  // Avoid the cost of BuildLookupTable() for a single-character search.
  if (s.length_ == 1)
    return find_first_of(s.ptr_[0], pos);

  bool lookup[UCHAR_MAX + 1] = { false };
  BuildLookupTable(s, lookup);
  for (size_type i = pos; i < length_; ++i) {
    if (lookup[static_cast<unsigned char>(ptr_[i])]) {
      return i;
    }
  }
  return npos;
}

size_type StringPiece::find_first_not_of(const StringPiece& s,
                                         size_type pos) const {
  if (length_ == 0)
    return npos;

  if (s.length_ == 0)
    return 0;

  // Avoid the cost of BuildLookupTable() for a single-character search.
  if (s.length_ == 1)
    return find_first_not_of(s.ptr_[0], pos);

  bool lookup[UCHAR_MAX + 1] = { false };
  BuildLookupTable(s, lookup);
  for (size_type i = pos; i < length_; ++i) {
    if (!lookup[static_cast<unsigned char>(ptr_[i])]) {
      return i;
    }
  }
  return npos;
}

size_type StringPiece::find_first_not_of(char c, size_type pos) const {
  if (length_ == 0)
    return npos;

  for (; pos < length_; ++pos) {
    if (ptr_[pos] != c) {
      return pos;
    }
  }
  return npos;
}

size_type StringPiece::find_last_of(const StringPiece& s, size_type pos) const {
  if (length_ == 0 || s.length_ == 0)
    return npos;

  // Avoid the cost of BuildLookupTable() for a single-character search.
  if (s.length_ == 1)
    return find_last_of(s.ptr_[0], pos);

  bool lookup[UCHAR_MAX + 1] = { false };
  BuildLookupTable(s, lookup);
  for (size_type i = std::min(pos, length_ - 1); ; --i) {
    if (lookup[static_cast<unsigned char>(ptr_[i])])
      return i;
    if (i == 0)
      break;
  }
  return npos;
}

size_type StringPiece::find_last_not_of(const StringPiece& s,
                                        size_type pos) const {
  if (length_ == 0)
    return npos;

  size_type i = std::min(pos, length_ - 1);
  if (s.length_ == 0)
    return i;

  // Avoid the cost of BuildLookupTable() for a single-character search.
  if (s.length_ == 1)
    return find_last_not_of(s.ptr_[0], pos);

  bool lookup[UCHAR_MAX + 1] = { false };
  BuildLookupTable(s, lookup);
  for (; ; --i) {
    if (!lookup[static_cast<unsigned char>(ptr_[i])])
      return i;
    if (i == 0)
      break;
  }
  return npos;
}

size_type StringPiece::find_last_not_of(char c, size_type pos) const {
  if (length_ == 0)
    return npos;

  for (size_type i = std::min(pos, length_ - 1); ; --i) {
    if (ptr_[i] != c)
      return i;
    if (i == 0)
      break;
  }
  return npos;
}

StringPiece StringPiece::substr(size_type pos, size_type n) const {
  if (pos > length_) pos = length_;
  if (n > length_ - pos) n = length_ - pos;
  return StringPiece(ptr_ + pos, n);
}

const StringPiece::size_type StringPiece::npos = size_type(-1);

}  // namespace base