text: // Protocol Buffers - Google's data interchange format
  // Copyright 2008 Google Inc.  All rights reserved.
  // https://developers.google.com/protocol-buffers/
  //
  // 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 StringPiece points to part or all of a string, Cord, double-quoted string
  // literal, or other string-like object.  A StringPiece does *not* own the
  // string to which it points.  A StringPiece is not null-terminated.
  //
  // You can use StringPiece as a function or method parameter.  A StringPiece
  // parameter can receive a double-quoted string literal argument, a "const
  // char*" argument, a string argument, or a StringPiece argument with no data
  // copying.  Systematic use of StringPiece for arguments reduces data
  // copies and strlen() calls.
  //
  // Prefer passing StringPieces by value:
  //   void MyFunction(StringPiece arg);
  // If circumstances require, you may also pass by const reference:
  //   void MyFunction(const StringPiece& arg);  // not preferred
  // Both of these have the same lifetime semantics.  Passing by value
  // generates slightly smaller code.  For more discussion, see the thread
  // go/stringpiecebyvalue on c-users.
  //
  // StringPiece is also suitable for local variables if you know that
  // the lifetime of the underlying object is longer than the lifetime
  // of your StringPiece variable.
  //
  // Beware of binding a StringPiece to a temporary:
  //   StringPiece sp = obj.MethodReturningString();  // BAD: lifetime problem
  //
  // This code is okay:
  //   string str = obj.MethodReturningString();  // str owns its contents
  //   StringPiece sp(str);  // GOOD, because str outlives sp
  //
  // StringPiece is sometimes a poor choice for a return value and usually a poor
  // choice for a data member.  If you do use a StringPiece this way, it is your
  // responsibility to ensure that the object pointed to by the StringPiece
  // outlives the StringPiece.
  //
  // A StringPiece may represent just part of a string; thus the name "Piece".
  // For example, when splitting a string, vector<StringPiece> is a natural data
  // type for the output.  For another example, a Cord is a non-contiguous,
  // potentially very long string-like object.  The Cord class has an interface
  // that iteratively provides StringPiece objects that point to the
  // successive pieces of a Cord object.
  //
  // A StringPiece is not null-terminated.  If you write code that scans a
  // StringPiece, you must check its length before reading any characters.
  // Common idioms that work on null-terminated strings do not work on
  // StringPiece objects.
  //
  // There are several ways to create a null StringPiece:
  //   StringPiece()
  //   StringPiece(NULL)
  //   StringPiece(NULL, 0)
  // For all of the above, sp.data() == NULL, sp.length() == 0,
  // and sp.empty() == true.  Also, if you create a StringPiece with
  // a non-NULL pointer then sp.data() != NULL.  Once created,
  // sp.data() will stay either NULL or not-NULL, except if you call
  // sp.clear() or sp.set().
  //
  // Thus, you can use StringPiece(NULL) to signal an out-of-band value
  // that is different from other StringPiece values.  This is similar
  // to the way that const char* p1 = NULL; is different from
  // const char* p2 = "";.
  //
  // There are many ways to create an empty StringPiece:
  //   StringPiece()
  //   StringPiece(NULL)
  //   StringPiece(NULL, 0)
  //   StringPiece("")
  //   StringPiece("", 0)
  //   StringPiece("abcdef", 0)
  //   StringPiece("abcdef"+6, 0)
  // For all of the above, sp.length() will be 0 and sp.empty() will be true.
  // For some empty StringPiece values, sp.data() will be NULL.
  // For some empty StringPiece values, sp.data() will not be NULL.
  //
  // Be careful not to confuse: null StringPiece and empty StringPiece.
  // The set of empty StringPieces properly includes the set of null StringPieces.
  // That is, every null StringPiece is an empty StringPiece,
  // but some non-null StringPieces are empty Stringpieces too.
  //
  // All empty StringPiece values compare equal to each other.
  // Even a null StringPieces compares equal to a non-null empty StringPiece:
  //  StringPiece() == StringPiece("", 0)
  //  StringPiece(NULL) == StringPiece("abc", 0)
  //  StringPiece(NULL, 0) == StringPiece("abcdef"+6, 0)
  //
  // Look carefully at this example:
  //   StringPiece("") == NULL
  // True or false?  TRUE, because StringPiece::operator== converts
  // the right-hand side from NULL to StringPiece(NULL),
  // and then compares two zero-length spans of characters.
  // However, we are working to make this example produce a compile error.
  //
  // Suppose you want to write:
  //   bool TestWhat?(StringPiece sp) { return sp == NULL; }  // BAD
  // Do not do that.  Write one of these instead:
  //   bool TestNull(StringPiece sp) { return sp.data() == NULL; }
  //   bool TestEmpty(StringPiece sp) { return sp.empty(); }
  // The intent of TestWhat? is unclear.  Did you mean TestNull or TestEmpty?
  // Right now, TestWhat? behaves likes TestEmpty.
  // We are working to make TestWhat? produce a compile error.
  // TestNull is good to test for an out-of-band signal.
  // TestEmpty is good to test for an empty StringPiece.
  //
  // Caveats (again):
  // (1) The lifetime of the pointed-to string (or piece of a string)
  //     must be longer than the lifetime of the StringPiece.
  // (2) There may or may not be a '\0' character after the end of
  //     StringPiece data.
  // (3) A null StringPiece is empty.
  //     An empty StringPiece may or may not be a null StringPiece.
  
  #ifndef GOOGLE_PROTOBUF_STUBS_STRINGPIECE_H_
  #define GOOGLE_PROTOBUF_STUBS_STRINGPIECE_H_
  
  #include <assert.h>
  #include <stddef.h>
  #include <string.h>
  #include <iosfwd>
  #include <limits>
  #include <string>
  
  #include <google/protobuf/stubs/common.h>
  
  namespace google {
  namespace protobuf {
  // StringPiece has *two* size types.
  // StringPiece::size_type
  //   is unsigned
  //   is 32 bits in LP32, 64 bits in LP64, 64 bits in LLP64
  //   no future changes intended
  // stringpiece_ssize_type
  //   is signed
  //   is 32 bits in LP32, 64 bits in LP64, 64 bits in LLP64
  //   future changes intended: http://go/64BitStringPiece
  //
  typedef string::difference_type stringpiece_ssize_type;
  
  // STRINGPIECE_CHECK_SIZE protects us from 32-bit overflows.
  // TODO(mec): delete this after stringpiece_ssize_type goes 64 bit.
  #if !defined(NDEBUG)
  #define STRINGPIECE_CHECK_SIZE 1
  #elif defined(_FORTIFY_SOURCE) && _FORTIFY_SOURCE > 0
  #define STRINGPIECE_CHECK_SIZE 1
  #else
  #define STRINGPIECE_CHECK_SIZE 0
  #endif
  
  class LIBPROTOBUF_EXPORT StringPiece {
   private:
    const char* ptr_;
    stringpiece_ssize_type length_;
  
    // Prevent overflow in debug mode or fortified mode.
    // sizeof(stringpiece_ssize_type) may be smaller than sizeof(size_t).
    static stringpiece_ssize_type CheckedSsizeTFromSizeT(size_t size) {
  #if STRINGPIECE_CHECK_SIZE > 0
  #ifdef max
  #undef max
  #endif
      if (size > static_cast<size_t>(
          std::numeric_limits<stringpiece_ssize_type>::max())) {
        // Some people grep for this message in logs
        // so take care if you ever change it.
        LogFatalSizeTooBig(size, "size_t to int conversion");
      }
  #endif
      return static_cast<stringpiece_ssize_type>(size);
    }
  
    // Out-of-line error path.
    static void LogFatalSizeTooBig(size_t size, const char* details);
  
   public:
    // We provide non-explicit singleton constructors so users can pass
    // in a "const char*" or a "string" wherever a "StringPiece" is
    // expected.
    //
    // Style guide exception granted:
    // http://goto/style-guide-exception-20978288
    StringPiece() : ptr_(NULL), length_(0) {}
  
    StringPiece(const char* str)  // NOLINT(runtime/explicit)
        : ptr_(str), length_(0) {
      if (str != NULL) {
        length_ = CheckedSsizeTFromSizeT(strlen(str));
      }
    }
  
    template <class Allocator>
    StringPiece(  // NOLINT(runtime/explicit)
        const std::basic_string<char, std::char_traits<char>, Allocator>& str)
        : ptr_(str.data()), length_(0) {
      length_ = CheckedSsizeTFromSizeT(str.size());
    }
  #if defined(HAS_GLOBAL_STRING)
    template <class Allocator>
    StringPiece(  // NOLINT(runtime/explicit)
        const basic_string<char, std::char_traits<char>, Allocator>& str)
        : ptr_(str.data()), length_(0) {
      length_ = CheckedSsizeTFromSizeT(str.size());
    }
  #endif
  
    StringPiece(const char* offset, stringpiece_ssize_type len)
        : ptr_(offset), length_(len) {
      assert(len >= 0);
    }
  
    // Substring of another StringPiece.
    // pos must be non-negative and <= x.length().
    StringPiece(StringPiece x, stringpiece_ssize_type pos);
    // Substring of another StringPiece.
    // pos must be non-negative and <= x.length().
    // len must be non-negative and will be pinned to at most x.length() - pos.
    StringPiece(StringPiece x,
                stringpiece_ssize_type pos,
                stringpiece_ssize_type 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_; }
    stringpiece_ssize_type size() const { return length_; }
    stringpiece_ssize_type length() const { return length_; }
    bool empty() const { return length_ == 0; }
  
    void clear() {
      ptr_ = NULL;
      length_ = 0;
    }
  
    void set(const char* data, stringpiece_ssize_type len) {
      assert(len >= 0);
      ptr_ = data;
      length_ = len;
    }
  
    void set(const char* str) {
      ptr_ = str;
      if (str != NULL)
        length_ = CheckedSsizeTFromSizeT(strlen(str));
      else
        length_ = 0;
    }
  
    void set(const void* data, stringpiece_ssize_type len) {
      ptr_ = reinterpret_cast<const char*>(data);
      length_ = len;
    }
  
    char operator[](stringpiece_ssize_type i) const {
      assert(0 <= i);
      assert(i < length_);
      return ptr_[i];
    }
  
    void remove_prefix(stringpiece_ssize_type n) {
      assert(length_ >= n);
      ptr_ += n;
      length_ -= n;
    }
  
    void remove_suffix(stringpiece_ssize_type n) {
      assert(length_ >= n);
      length_ -= n;
    }
  
    // returns {-1, 0, 1}
    int compare(StringPiece x) const {
      const stringpiece_ssize_type min_size =
          length_ < x.length_ ? length_ : x.length_;
      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 {
      return ToString();
    }
    // We also define ToString() here, since many other string-like
    // interfaces name the routine that converts to a C++ string
    // "ToString", and it's confusing to have the method that does that
    // for a StringPiece be called "as_string()".  We also leave the
    // "as_string()" method defined here for existing code.
    string ToString() const {
      if (ptr_ == NULL) return string();
      return string(data(), size());
    }
  
    operator string() const {
      return ToString();
    }
  
    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));
    }
  
    // Checks whether StringPiece starts with x and if so advances the beginning
    // of it to past the match.  It's basically a shortcut for starts_with
    // followed by remove_prefix.
    bool Consume(StringPiece x);
    // Like above but for the end of the string.
    bool ConsumeFromEnd(StringPiece x);
  
    // standard STL container boilerplate
    typedef char value_type;
    typedef const char* pointer;
    typedef const char& reference;
    typedef const char& const_reference;
    typedef size_t size_type;
    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_);
    }
    stringpiece_ssize_type max_size() const { return length_; }
    stringpiece_ssize_type capacity() const { return length_; }
  
    // cpplint.py emits a false positive [build/include_what_you_use]
    stringpiece_ssize_type copy(char* buf, size_type n, size_type pos = 0) const;  // NOLINT
  
    bool contains(StringPiece s) const;
  
    stringpiece_ssize_type find(StringPiece s, size_type pos = 0) const;
    stringpiece_ssize_type find(char c, size_type pos = 0) const;
    stringpiece_ssize_type rfind(StringPiece s, size_type pos = npos) const;
    stringpiece_ssize_type rfind(char c, size_type pos = npos) const;
  
    stringpiece_ssize_type find_first_of(StringPiece s, size_type pos = 0) const;
    stringpiece_ssize_type find_first_of(char c, size_type pos = 0) const {
      return find(c, pos);
    }
    stringpiece_ssize_type find_first_not_of(StringPiece s,
                                             size_type pos = 0) const;
    stringpiece_ssize_type find_first_not_of(char c, size_type pos = 0) const;
    stringpiece_ssize_type find_last_of(StringPiece s,
                                        size_type pos = npos) const;
    stringpiece_ssize_type find_last_of(char c, size_type pos = npos) const {
      return rfind(c, pos);
    }
    stringpiece_ssize_type find_last_not_of(StringPiece s,
                                            size_type pos = npos) const;
    stringpiece_ssize_type find_last_not_of(char c, size_type pos = npos) const;
  
    StringPiece substr(size_type pos, size_type n = npos) const;
  };
  
  // This large function is defined inline so that in a fairly common case where
  // one of the arguments is a literal, the compiler can elide a lot of the
  // following comparisons.
  inline bool operator==(StringPiece x, StringPiece y) {
    stringpiece_ssize_type len = x.size();
    if (len != y.size()) {
      return false;
    }
  
    return x.data() == y.data() || len <= 0 ||
        memcmp(x.data(), y.data(), len) == 0;
  }
  
  inline bool operator!=(StringPiece x, StringPiece y) {
    return !(x == y);
  }
  
  inline bool operator<(StringPiece x, StringPiece y) {
    const stringpiece_ssize_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());
  }
  
  inline bool operator>(StringPiece x, StringPiece y) {
    return y < x;
  }
  
  inline bool operator<=(StringPiece x, StringPiece y) {
    return !(x > y);
  }
  
  inline bool operator>=(StringPiece x, StringPiece y) {
    return !(x < y);
  }
  
  // allow StringPiece to be logged
  extern std::ostream& operator<<(std::ostream& o, StringPiece piece);
  
  }  // namespace protobuf
  }  // namespace google
  
  #endif  // STRINGS_STRINGPIECE_H_
  