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 // Copyright (c) 2006-2008 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"

 typedef StringPiece::size_type size_type;

 std::ostream& operator<<(std::ostream& o, const StringPiece& piece) {

   o.write(piece.data(), static_cast<std::streamsize>(piece.size()));

   return o;

 }

 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_ ? 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 ? 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);