// 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(nullptr)

//   StringPiece(nullptr, 0)

// For all of the above, sp.data() == nullptr, sp.length() == 0,

// and sp.empty() == true.  Also, if you create a StringPiece with

// a non-null pointer then sp.data() != nullptr.  Once created,

// sp.data() will stay either nullptr or not-nullptr, except if you call

// sp.clear() or sp.set().

//

// Thus, you can use StringPiece(nullptr) to signal an out-of-band value

// that is different from other StringPiece values.  This is similar

// to the way that const char* p1 = nullptr; is different from

// const char* p2 = "";.

//

// There are many ways to create an empty StringPiece:

//   StringPiece()

//   StringPiece(nullptr)

//   StringPiece(nullptr, 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 nullptr.

// For some empty StringPiece values, sp.data() will not be nullptr.

//

// 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(nullptr) == StringPiece("abc", 0)

//  StringPiece(nullptr, 0) == StringPiece("abcdef"+6, 0)

//

// Look carefully at this example:

//   StringPiece("") == nullptr

// True or false?  TRUE, because StringPiece::operator== converts

// the right-hand side from nullptr to StringPiece(nullptr),

// 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 == nullptr; }  // BAD

// Do not do that.  Write one of these instead:

//   bool TestNull(StringPiece sp) { return sp.data() == nullptr; }

//   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>

#if defined(__cpp_lib_string_view)

#include <string_view>

#endif

#include <google/protobuf/stubs/hash.h>

#include <google/protobuf/port_def.inc>

namespace google {

namespace protobuf {

namespace stringpiece_internal {

class PROTOBUF_EXPORT StringPiece {

 public:

  using traits_type = std::char_traits<char>;

  using value_type = char;

  using pointer = char*;

  using const_pointer = const char*;

  using reference = char&;

  using const_reference = const char&;

  using const_iterator = const char*;

  using iterator = const_iterator;

  using const_reverse_iterator = std::reverse_iterator<const_iterator>;

  using reverse_iterator = const_reverse_iterator;

  using size_type = size_t;

  using difference_type = std::ptrdiff_t;

 private:

  const char* ptr_;

  size_type length_;

  static constexpr size_type kMaxSize =

      (std::numeric_limits<difference_type>::max)();

  static size_type CheckSize(size_type size) {

#if !defined(NDEBUG) || defined(_FORTIFY_SOURCE) && _FORTIFY_SOURCE > 0

    if (PROTOBUF_PREDICT_FALSE(size > kMaxSize)) {

      // Some people grep for this message in logs

      // so take care if you ever change it.

      LogFatalSizeTooBig(size, "string length exceeds max size");

    }

#endif

    return size;

  }

  // Out-of-line error path.

  static void LogFatalSizeTooBig(size_type 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_(nullptr), length_(0) {}

  StringPiece(const char* str)  // NOLINT(runtime/explicit)

      : ptr_(str), length_(0) {

    if (str != nullptr) {

      length_ = CheckSize(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_ = CheckSize(str.size());

  }

#if defined(__cpp_lib_string_view)

  StringPiece(  // NOLINT(runtime/explicit)

      std::string_view str)

      : ptr_(str.data()), length_(0) {

    length_ = CheckSize(str.size());

  }

#endif

  StringPiece(const char* offset, size_type len)

      : ptr_(offset), length_(CheckSize(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_pointer data() const { return ptr_; }

  size_type size() const { return length_; }

  size_type length() const { return length_; }

  bool empty() const { return length_ == 0; }

  char operator[](size_type i) const {

    assert(i < length_);

    return ptr_[i];

  }

  void remove_prefix(size_type n) {

    assert(length_ >= n);

    ptr_ += n;

    length_ -= n;

  }

  void remove_suffix(size_type n) {

    assert(length_ >= n);

    length_ -= n;

  }

  // returns {-1, 0, 1}

  int compare(StringPiece x) const {

    size_type min_size = length_ < x.length_ ? length_ : x.length_;

    int r = memcmp(ptr_, x.ptr_, static_cast<size_t>(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;

  }

  std::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.

  std::string ToString() const {

    if (ptr_ == nullptr) return "";

    return std::string(data(), static_cast<size_type>(size()));

  }

  explicit operator std::string() const { return ToString(); }

  void CopyToString(std::string* target) const;

  void AppendToString(std::string* target) const;

  bool starts_with(StringPiece x) const {

    return (length_ >= x.length_) &&

           (memcmp(ptr_, x.ptr_, static_cast<size_t>(x.length_)) == 0);

  }

  bool ends_with(StringPiece x) const {

    return ((length_ >= x.length_) &&

            (memcmp(ptr_ + (length_-x.length_), x.ptr_,

                 static_cast<size_t>(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

  static const size_type npos;

  const_iterator begin() const { return ptr_; }

  const_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 max_size() const { return length_; }

  size_type capacity() const { return length_; }

  // cpplint.py emits a false positive [build/include_what_you_use]

  size_type copy(char* buf, size_type n, size_type pos = 0) const;  // NOLINT

  bool contains(StringPiece s) const;

  size_type find(StringPiece s, size_type pos = 0) const;

  size_type find(char c, size_type pos = 0) const;

  size_type rfind(StringPiece s, size_type pos = npos) const;

  size_type rfind(char c, size_type pos = npos) const;

  size_type find_first_of(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(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(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(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;

};

// 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::size_type len = x.size();

  if (len != y.size()) {

    return false;

  }

  return x.data() == y.data() || len <= 0 ||

      memcmp(x.data(), y.data(), static_cast<size_t>(len)) == 0;

}

inline bool operator!=(StringPiece x, StringPiece y) {

  return !(x == y);

}

inline bool operator<(StringPiece x, StringPiece y) {

  const StringPiece::size_type min_size =

      x.size() < y.size() ? x.size() : y.size();

  const int r = memcmp(x.data(), y.data(), static_cast<size_t>(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 stringpiece_internal

using ::google::protobuf::stringpiece_internal::StringPiece;

}  // namespace protobuf

}  // namespace google

GOOGLE_PROTOBUF_HASH_NAMESPACE_DECLARATION_START

template<> struct hash<StringPiece> {

  size_t operator()(const StringPiece& s) const {

    size_t result = 0;

    for (const char *str = s.data(), *end = str + s.size(); str < end; str++) {

      result = 5 * result + static_cast<size_t>(*str);

    }

    return result;

  }

};

GOOGLE_PROTOBUF_HASH_NAMESPACE_DECLARATION_END

#include <google/protobuf/port_undef.inc>

#endif  // STRINGS_STRINGPIECE_H_