string_piece.cc revision c7f5f8508d98d5952d42ed7648c2a8f30a4da156 
1// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4// Copied from strings/stringpiece.cc with modifications
5
6#include <algorithm>
7#include <iostream>
8
9#include "base/string_piece.h"
10
11namespace base {
12
13typedef StringPiece::size_type size_type;
14
15std::ostream& operator<<(std::ostream& o, const StringPiece& piece) {
16  o.write(piece.data(), static_cast<std::streamsize>(piece.size()));
17  return o;
18}
19
20bool operator==(const StringPiece& x, const StringPiece& y) {
21  if (x.size() != y.size())
22    return false;
23
24  return StringPiece::wordmemcmp(x.data(), y.data(), x.size()) == 0;
25}
26
27void StringPiece::CopyToString(std::string* target) const {
28  target->assign(!empty() ? data() : "", size());
29}
30
31void StringPiece::AppendToString(std::string* target) const {
32  if (!empty())
33    target->append(data(), size());
34}
35
36size_type StringPiece::copy(char* buf, size_type n, size_type pos) const {
37  size_type ret = std::min(length_ - pos, n);
38  memcpy(buf, ptr_ + pos, ret);
39  return ret;
40}
41
42size_type StringPiece::find(const StringPiece& s, size_type pos) const {
43  if (pos > length_)
44    return npos;
45
46  const char* result = std::search(ptr_ + pos, ptr_ + length_,
47                                   s.ptr_, s.ptr_ + s.length_);
48  const size_type xpos = result - ptr_;
49  return xpos + s.length_ <= length_ ? xpos : npos;
50}
51
52size_type StringPiece::find(char c, size_type pos) const {
53  if (pos >= length_)
54    return npos;
55
56  const char* result = std::find(ptr_ + pos, ptr_ + length_, c);
57  return result != ptr_ + length_ ? result - ptr_ : npos;
58}
59
60size_type StringPiece::rfind(const StringPiece& s, size_type pos) const {
61  if (length_ < s.length_)
62    return npos;
63
64  if (s.empty())
65    return std::min(length_, pos);
66
67  const char* last = ptr_ + std::min(length_ - s.length_, pos) + s.length_;
68  const char* result = std::find_end(ptr_, last, s.ptr_, s.ptr_ + s.length_);
69  return result != last ? result - ptr_ : npos;
70}
71
72size_type StringPiece::rfind(char c, size_type pos) const {
73  if (length_ == 0)
74    return npos;
75
76  for (size_type i = std::min(pos, length_ - 1); ; --i) {
77    if (ptr_[i] == c)
78      return i;
79    if (i == 0)
80      break;
81  }
82  return npos;
83}
84
85// For each character in characters_wanted, sets the index corresponding
86// to the ASCII code of that character to 1 in table.  This is used by
87// the find_.*_of methods below to tell whether or not a character is in
88// the lookup table in constant time.
89// The argument `table' must be an array that is large enough to hold all
90// the possible values of an unsigned char.  Thus it should be be declared
91// as follows:
92//   bool table[UCHAR_MAX + 1]
93static inline void BuildLookupTable(const StringPiece& characters_wanted,
94                                    bool* table) {
95  const size_type length = characters_wanted.length();
96  const char* const data = characters_wanted.data();
97  for (size_type i = 0; i < length; ++i) {
98    table[static_cast<unsigned char>(data[i])] = true;
99  }
100}
101
102size_type StringPiece::find_first_of(const StringPiece& s,
103                                     size_type pos) const {
104  if (length_ == 0 || s.length_ == 0)
105    return npos;
106
107  // Avoid the cost of BuildLookupTable() for a single-character search.
108  if (s.length_ == 1)
109    return find_first_of(s.ptr_[0], pos);
110
111  bool lookup[UCHAR_MAX + 1] = { false };
112  BuildLookupTable(s, lookup);
113  for (size_type i = pos; i < length_; ++i) {
114    if (lookup[static_cast<unsigned char>(ptr_[i])]) {
115      return i;
116    }
117  }
118  return npos;
119}
120
121size_type StringPiece::find_first_not_of(const StringPiece& s,
122                                         size_type pos) const {
123  if (length_ == 0)
124    return npos;
125
126  if (s.length_ == 0)
127    return 0;
128
129  // Avoid the cost of BuildLookupTable() for a single-character search.
130  if (s.length_ == 1)
131    return find_first_not_of(s.ptr_[0], pos);
132
133  bool lookup[UCHAR_MAX + 1] = { false };
134  BuildLookupTable(s, lookup);
135  for (size_type i = pos; i < length_; ++i) {
136    if (!lookup[static_cast<unsigned char>(ptr_[i])]) {
137      return i;
138    }
139  }
140  return npos;
141}
142
143size_type StringPiece::find_first_not_of(char c, size_type pos) const {
144  if (length_ == 0)
145    return npos;
146
147  for (; pos < length_; ++pos) {
148    if (ptr_[pos] != c) {
149      return pos;
150    }
151  }
152  return npos;
153}
154
155size_type StringPiece::find_last_of(const StringPiece& s, size_type pos) const {
156  if (length_ == 0 || s.length_ == 0)
157    return npos;
158
159  // Avoid the cost of BuildLookupTable() for a single-character search.
160  if (s.length_ == 1)
161    return find_last_of(s.ptr_[0], pos);
162
163  bool lookup[UCHAR_MAX + 1] = { false };
164  BuildLookupTable(s, lookup);
165  for (size_type i = std::min(pos, length_ - 1); ; --i) {
166    if (lookup[static_cast<unsigned char>(ptr_[i])])
167      return i;
168    if (i == 0)
169      break;
170  }
171  return npos;
172}
173
174size_type StringPiece::find_last_not_of(const StringPiece& s,
175                                        size_type pos) const {
176  if (length_ == 0)
177    return npos;
178
179  size_type i = std::min(pos, length_ - 1);
180  if (s.length_ == 0)
181    return i;
182
183  // Avoid the cost of BuildLookupTable() for a single-character search.
184  if (s.length_ == 1)
185    return find_last_not_of(s.ptr_[0], pos);
186
187  bool lookup[UCHAR_MAX + 1] = { false };
188  BuildLookupTable(s, lookup);
189  for (; ; --i) {
190    if (!lookup[static_cast<unsigned char>(ptr_[i])])
191      return i;
192    if (i == 0)
193      break;
194  }
195  return npos;
196}
197
198size_type StringPiece::find_last_not_of(char c, size_type pos) const {
199  if (length_ == 0)
200    return npos;
201
202  for (size_type i = std::min(pos, length_ - 1); ; --i) {
203    if (ptr_[i] != c)
204      return i;
205    if (i == 0)
206      break;
207  }
208  return npos;
209}
210
211StringPiece StringPiece::substr(size_type pos, size_type n) const {
212  if (pos > length_) pos = length_;
213  if (n > length_ - pos) n = length_ - pos;
214  return StringPiece(ptr_ + pos, n);
215}
216
217const StringPiece::size_type StringPiece::npos = size_type(-1);
218
219}  // namespace base
220