text: // Copyright 2010-2018, Google Inc.
  // All rights reserved.
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  // A string-like object that points to a sized piece of memory.
  
  #ifndef MOZC_BASE_STRING_PIECE_H_
  #define MOZC_BASE_STRING_PIECE_H_
  
  #include <algorithm>
  #include <cstddef>
  #include <cstring>
  #include <iosfwd>
  #include <iterator>
  #include <string>
  
  // Include namespace.h instead of port.h to reduce a dependency.
  #include "base/port_string.h"
  
  namespace mozc {
  
  
  class StringPiece {
   public:
    using size_type = size_t;
  
    // We provide non-explicit singleton constructors so users can pass
    // in a "const char*" or a "string" wherever a "StringPiece" is expected.
    StringPiece() : ptr_(nullptr), length_(0) {}
    StringPiece(const char *str)    // NOLINT
        : ptr_(str), length_((str != nullptr) ? strlen(str) : 0) {}
    StringPiece(const string &str)  // NOLINT
        : ptr_(str.data()), length_(str.size()) {}
    // Constructs a StringPiece from char ptr and length.
    // Caution! There are confusing two constructors which takes 2 arguments.
    // This method's 2nd argument is *length*.
    StringPiece(const char *offset, size_type len)
        : ptr_(offset), length_(len) {}
  
    // data() may return a pointer to a buffer with embedded NULs, and the
    // returned buffer may or may not be null terminated.  Therefore it is
    // typically a mistake to pass data() to a routine that expects a NUL
    // terminated string.
    const char *data() const { return ptr_; }
    size_type size() const { return length_; }
    size_type length() const { return length_; }
    bool empty() const { return length_ == 0; }
  
    void clear() { ptr_ = nullptr; length_ = 0; }
    void set(const char *data, size_type len) { ptr_ = data; length_ = len; }
    void set(const char *str) {
      ptr_ = str;
      length_ = (str != nullptr) ? strlen(str) : 0;
    }
    void set(const void *data, size_type len) {
      ptr_ = reinterpret_cast<const char *>(data);
      length_ = len;
    }
  
    char operator[](size_type i) const { return ptr_[i]; }
  
    void remove_prefix(size_type n) {
      ptr_ += n;
      length_ -= n;
    }
  
    void remove_suffix(size_type n) {
      length_ -= n;
    }
  
    // returns {-1, 0, 1}
    int compare(StringPiece x) const {
      const size_type min_size = length_ < x.length_ ? length_ : x.length_;
      const int r = memcmp(ptr_, x.ptr_, min_size);
      if (r < 0) {
        return -1;
      }
      if (r > 0) {
        return 1;
      }
      if (length_ < x.length_) {
        return -1;
      }
      if (length_ > x.length_) {
        return 1;
      }
      return 0;
    }
  
    string as_string() const {
      // string doesn't like to take a nullptr pointer even with a 0 size.
      return string(!empty() ? data() : "", size());
    }
  
    explicit operator string() const {
      return string(!empty() ? data() : "", size());
    }
  
    void CopyToString(string *target) const;
    void AppendToString(string *target) const;
  
    bool starts_with(StringPiece x) const {
      return (length_ >= x.length_) && (memcmp(ptr_, x.ptr_, x.length_) == 0);
    }
  
    bool ends_with(StringPiece x) const {
      return ((length_ >= x.length_) &&
              (memcmp(ptr_ + (length_ - x.length_), x.ptr_, x.length_) == 0));
    }
  
    // standard STL container boilerplate
    typedef char value_type;
    typedef const char *pointer;
    typedef const char &reference;
    typedef const char &const_reference;
    typedef ptrdiff_t difference_type;
    static const size_type npos;
    typedef const char *const_iterator;
    typedef const char *iterator;
    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
    typedef std::reverse_iterator<iterator> reverse_iterator;
    iterator begin() const { return ptr_; }
    iterator end() const { return ptr_ + length_; }
    const_reverse_iterator rbegin() const {
      return const_reverse_iterator(ptr_ + length_);
    }
    const_reverse_iterator rend() const {
      return const_reverse_iterator(ptr_);
    }
  
    size_type copy(char *buf, size_type n, size_type pos = 0) const;
  
    size_type find(const StringPiece &s, size_type pos = 0) const;
    size_type find(char c, size_type pos = 0) const;
    size_type rfind(const StringPiece &s, size_type pos = npos) const;
    size_type rfind(char c, size_type pos = npos) const;
  
    size_type find_first_of(const StringPiece &s, size_type pos = 0) const;
    size_type find_first_of(char c, size_type pos = 0) const {
      return find(c, pos);
    }
    size_type find_first_not_of(const StringPiece &s, size_type pos = 0) const;
    size_type find_first_not_of(char c, size_type pos = 0) const;
    size_type find_last_of(const StringPiece &s, size_type pos = npos) const;
    size_type find_last_of(char c, size_type pos = npos) const {
      return rfind(c, pos);
    }
    size_type find_last_not_of(const StringPiece &s, size_type pos = npos) const;
    size_type find_last_not_of(char c, size_type pos = npos) const;
  
    StringPiece substr(size_type pos, size_type n = npos) const;
  
    friend bool operator==(const StringPiece &x, const StringPiece &y) {
      if (x.size() != y.size()) {
        return false;
      }
      return memcmp(x.data(), y.data(), x.size()) == 0;
    }
  
    friend bool operator!=(const StringPiece &x, const StringPiece &y) {
      return !(x == y);
    }
  
    friend bool operator<(const StringPiece &x, const StringPiece &y) {
      const size_type min_size = x.size() < y.size() ? x.size() : y.size();
      const int r = memcmp(x.data(), y.data(), min_size);
      return (r < 0) || (r == 0 && x.size() < y.size());
    }
  
    friend bool operator>(const StringPiece &x, const StringPiece &y) {
      return y < x;
    }
  
    friend bool operator<=(const StringPiece &x, const StringPiece &y) {
      return !(x > y);
    }
  
    friend bool operator>=(const StringPiece &x, const StringPiece &y) {
      return !(x < y);
    }
  
   private:
    const char *ptr_;
    size_type length_;
  };
  
  // allow StringPiece to be logged (needed for unit testing).
  extern std::ostream &operator<<(std::ostream &o, const StringPiece &piece);
  
  inline StringPiece ClippedSubstr(StringPiece sp, size_t pos,
                                   size_t n = StringPiece::npos) {
    size_t sp_size = sp.size();
    pos = std::min(pos, sp_size);
    n = std::min(n, sp_size - pos);
    return sp.substr(pos, n);
  }
  
  
  }  // namespace mozc
  
  #endif  // MOZC_BASE_STRING_PIECE_H_
  