base/strings/string_piece.cc

// Copyright (c) 2012 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 "base/strings/string_piece.h"

#include <algorithm>
#include <ostream>

namespace base {

// MSVC doesn't like complex extern templates and DLLs.
#if !defined(COMPILER_MSVC)
namespace internal {
template class StringPieceDetail<std::string>;
template class StringPieceDetail<string16>;
}  // namespace internal

template class BasicStringPiece<string16>;
#endif

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;
}

std::ostream& operator<<(std::ostream& o, const StringPiece& piece) {
  o.write(piece.data(), static_cast<std::streamsize>(piece.size()));
  return o;
}

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

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

StringPiece::size_type copy(const StringPiece& self,
                            char* buf,
                            StringPiece::size_type n,
                            StringPiece::size_type pos) {
  StringPiece::size_type ret = std::min(self.size() - pos, n);
  memcpy(buf, self.data() + pos, ret);
  return ret;
}

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

  StringPiece::const_iterator result =
      std::search(self.begin() + pos, self.end(), s.begin(), s.end());
  const StringPiece::size_type xpos =
    static_cast<size_t>(result - self.begin());
  return xpos + s.size() <= self.size() ? xpos : StringPiece::npos;
}

StringPiece::size_type find(const StringPiece& self,
                            char c,
                            StringPiece::size_type pos) {
  if (pos >= self.size())
    return StringPiece::npos;

  StringPiece::const_iterator result =
      std::find(self.begin() + pos, self.end(), c);
  return result != self.end() ?
      static_cast<size_t>(result - self.begin()) : StringPiece::npos;
}

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

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

  StringPiece::const_iterator last =
      self.begin() + std::min(self.size() - s.size(), pos) + s.size();
  StringPiece::const_iterator result =
      std::find_end(self.begin(), last, s.begin(), s.end());
  return result != last ?
      static_cast<size_t>(result - self.begin()) : StringPiece::npos;
}

StringPiece::size_type rfind(const StringPiece& self,
                             char c,
                             StringPiece::size_type pos) {
  if (self.size() == 0)
    return StringPiece::npos;

  for (StringPiece::size_type i = std::min(pos, self.size() - 1); ; --i) {
    if (self.data()[i] == c)
      return i;
    if (i == 0)
      break;
  }
  return StringPiece::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 StringPiece::size_type length = characters_wanted.length();
  const char* const data = characters_wanted.data();
  for (StringPiece::size_type i = 0; i < length; ++i) {
    table[static_cast<unsigned char>(data[i])] = true;
  }
}

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

  // Avoid the cost of BuildLookupTable() for a single-character search.
  if (s.size() == 1)
    return find(self, s.data()[0], pos);

  bool lookup[UCHAR_MAX + 1] = { false };
  BuildLookupTable(s, lookup);
  for (StringPiece::size_type i = pos; i < self.size(); ++i) {
    if (lookup[static_cast<unsigned char>(self.data()[i])]) {
      return i;
    }
  }
  return StringPiece::npos;
}

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

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

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

  bool lookup[UCHAR_MAX + 1] = { false };
  BuildLookupTable(s, lookup);
  for (StringPiece::size_type i = pos; i < self.size(); ++i) {
    if (!lookup[static_cast<unsigned char>(self.data()[i])]) {
      return i;
    }
  }
  return StringPiece::npos;
}

StringPiece::size_type find_first_not_of(const StringPiece& self,
                                         char c,
                                         StringPiece::size_type pos) {
  if (self.size() == 0)
    return StringPiece::npos;

  for (; pos < self.size(); ++pos) {
    if (self.data()[pos] != c) {
      return pos;
    }
  }
  return StringPiece::npos;
}

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

  // Avoid the cost of BuildLookupTable() for a single-character search.
  if (s.size() == 1)
    return rfind(self, s.data()[0], pos);

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

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

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

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

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

StringPiece::size_type find_last_not_of(const StringPiece& self,
                                        char c,
                                        StringPiece::size_type pos) {
  if (self.size() == 0)
    return StringPiece::npos;

  for (StringPiece::size_type i = std::min(pos, self.size() - 1); ; --i) {
    if (self.data()[i] != c)
      return i;
    if (i == 0)
      break;
  }
  return StringPiece::npos;
}

StringPiece substr(const StringPiece& self,
                   StringPiece::size_type pos,
                   StringPiece::size_type n) {
  if (pos > self.size()) pos = self.size();
  if (n > self.size() - pos) n = self.size() - pos;
  return StringPiece(self.data() + pos, n);
}

}  // namespace internal
}  // namespace base