base/string_piece.cc

   1 // Copyright (c) 2011 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 <ostream>
   8
   9 #include "base/string_piece.h"
  10
  11 namespace base {
  12
  13 typedef StringPiece::size_type size_type;
  14
  15 bool operator==(const StringPiece& x, const StringPiece& y) {
  16   if (x.size() != y.size())
  17     return false;
  18
  19   return StringPiece::wordmemcmp(x.data(), y.data(), x.size()) == 0;
  20 }
  21
  22 void StringPiece::CopyToString(std::string* target) const {
  23   target->assign(!empty() ? data() : "", size());
  24 }
  25
  26 void StringPiece::AppendToString(std::string* target) const {
  27   if (!empty())
  28     target->append(data(), size());
  29 }
  30
  31 size_type StringPiece::copy(char* buf, size_type n, size_type pos) const {
  32   size_type ret = std::min(length_ - pos, n);
  33   memcpy(buf, ptr_ + pos, ret);
  34   return ret;
  35 }
  36
  37 size_type StringPiece::find(const StringPiece& s, size_type pos) const {
  38   if (pos > length_)
  39     return npos;
  40
  41   const char* result = std::search(ptr_ + pos, ptr_ + length_,
  42                                    s.ptr_, s.ptr_ + s.length_);
  43   const size_type xpos = result - ptr_;
  44   return xpos + s.length_ <= length_ ? xpos : npos;
  45 }
  46
  47 size_type StringPiece::find(char c, size_type pos) const {
  48   if (pos >= length_)
  49     return npos;
  50
  51   const char* result = std::find(ptr_ + pos, ptr_ + length_, c);
  52   return result != ptr_ + length_ ? static_cast<size_t>(result - ptr_) : npos;
  53 }
  54
  55 size_type StringPiece::rfind(const StringPiece& s, size_type pos) const {
  56   if (length_ < s.length_)
  57     return npos;
  58
  59   if (s.empty())
  60     return std::min(length_, pos);
  61
  62   const char* last = ptr_ + std::min(length_ - s.length_, pos) + s.length_;
  63   const char* result = std::find_end(ptr_, last, s.ptr_, s.ptr_ + s.length_);
  64   return result != last ? static_cast<size_t>(result - ptr_) : npos;
  65 }
  66
  67 size_type StringPiece::rfind(char c, size_type pos) const {
  68   if (length_ == 0)
  69     return npos;
  70
  71   for (size_type i = std::min(pos, length_ - 1); ; --i) {
  72     if (ptr_[i] == c)
  73       return i;
  74     if (i == 0)
  75       break;
  76   }
  77   return npos;
  78 }
  79
  80 // For each character in characters_wanted, sets the index corresponding
  81 // to the ASCII code of that character to 1 in table.  This is used by
  82 // the find_.*_of methods below to tell whether or not a character is in
  83 // the lookup table in constant time.
  84 // The argument `table' must be an array that is large enough to hold all
  85 // the possible values of an unsigned char.  Thus it should be be declared
  86 // as follows:
  87 //   bool table[UCHAR_MAX + 1]
  88 static inline void BuildLookupTable(const StringPiece& characters_wanted,
  89                                     bool* table) {
  90   const size_type length = characters_wanted.length();
  91   const char* const data = characters_wanted.data();
  92   for (size_type i = 0; i < length; ++i) {
  93     table[static_cast<unsigned char>(data[i])] = true;
  94   }
  95 }
  96
  97 size_type StringPiece::find_first_of(const StringPiece& s,
  98                                      size_type pos) const {
  99   if (length_ == 0 || s.length_ == 0)
 100     return npos;
 101
 102   // Avoid the cost of BuildLookupTable() for a single-character search.
 103   if (s.length_ == 1)
 104     return find_first_of(s.ptr_[0], pos);
 105
 106   bool lookup[UCHAR_MAX + 1] = { false };
 107   BuildLookupTable(s, lookup);
 108   for (size_type i = pos; i < length_; ++i) {
 109     if (lookup[static_cast<unsigned char>(ptr_[i])]) {
 110       return i;
 111     }
 112   }
 113   return npos;
 114 }
 115
 116 size_type StringPiece::find_first_not_of(const StringPiece& s,
 117                                          size_type pos) const {
 118   if (length_ == 0)
 119     return npos;
 120
 121   if (s.length_ == 0)
 122     return 0;
 123
 124   // Avoid the cost of BuildLookupTable() for a single-character search.
 125   if (s.length_ == 1)
 126     return find_first_not_of(s.ptr_[0], pos);
 127
 128   bool lookup[UCHAR_MAX + 1] = { false };
 129   BuildLookupTable(s, lookup);
 130   for (size_type i = pos; i < length_; ++i) {
 131     if (!lookup[static_cast<unsigned char>(ptr_[i])]) {
 132       return i;
 133     }
 134   }
 135   return npos;
 136 }
 137
 138 size_type StringPiece::find_first_not_of(char c, size_type pos) const {
 139   if (length_ == 0)
 140     return npos;
 141
 142   for (; pos < length_; ++pos) {
 143     if (ptr_[pos] != c) {
 144       return pos;
 145     }
 146   }
 147   return npos;
 148 }
 149
 150 size_type StringPiece::find_last_of(const StringPiece& s, size_type pos) const {
 151   if (length_ == 0 || s.length_ == 0)
 152     return npos;
 153
 154   // Avoid the cost of BuildLookupTable() for a single-character search.
 155   if (s.length_ == 1)
 156     return find_last_of(s.ptr_[0], pos);
 157
 158   bool lookup[UCHAR_MAX + 1] = { false };
 159   BuildLookupTable(s, lookup);
 160   for (size_type i = std::min(pos, length_ - 1); ; --i) {
 161     if (lookup[static_cast<unsigned char>(ptr_[i])])
 162       return i;
 163     if (i == 0)
 164       break;
 165   }
 166   return npos;
 167 }
 168
 169 size_type StringPiece::find_last_not_of(const StringPiece& s,
 170                                         size_type pos) const {
 171   if (length_ == 0)
 172     return npos;
 173
 174   size_type i = std::min(pos, length_ - 1);
 175   if (s.length_ == 0)
 176     return i;
 177
 178   // Avoid the cost of BuildLookupTable() for a single-character search.
 179   if (s.length_ == 1)
 180     return find_last_not_of(s.ptr_[0], pos);
 181
 182   bool lookup[UCHAR_MAX + 1] = { false };
 183   BuildLookupTable(s, lookup);
 184   for (; ; --i) {
 185     if (!lookup[static_cast<unsigned char>(ptr_[i])])
 186       return i;
 187     if (i == 0)
 188       break;
 189   }
 190   return npos;
 191 }
 192
 193 size_type StringPiece::find_last_not_of(char c, size_type pos) const {
 194   if (length_ == 0)
 195     return npos;
 196
 197   for (size_type i = std::min(pos, length_ - 1); ; --i) {
 198     if (ptr_[i] != c)
 199       return i;
 200     if (i == 0)
 201       break;
 202   }
 203   return npos;
 204 }
 205
 206 StringPiece StringPiece::substr(size_type pos, size_type n) const {
 207   if (pos > length_) pos = length_;
 208   if (n > length_ - pos) n = length_ - pos;
 209   return StringPiece(ptr_ + pos, n);
 210 }
 211
 212 const StringPiece::size_type StringPiece::npos = size_type(-1);
 213
 214 }  // namespace base