stringpiece.h

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// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
// Copyright (C) 2009-2013, International Business Machines
// Corporation and others. All Rights Reserved.
//
// Copyright 2001 and onwards Google Inc.
// Author: Sanjay Ghemawat

// This code is a contribution of Google code, and the style used here is
// a compromise between the original Google code and the ICU coding guidelines.
// For example, data types are ICU-ified (size_t,int->int32_t),
// and API comments doxygen-ified, but function names and behavior are
// as in the original, if possible.
// Assertion-style error handling, not available in ICU, was changed to
// parameter "pinning" similar to UnicodeString.
//
// In addition, this is only a partial port of the original Google code,
// limited to what was needed so far. The (nearly) complete original code
// is in the ICU svn repository at icuhtml/trunk/design/strings/contrib
// (see ICU ticket 6765, r25517).

#ifndef __STRINGPIECE_H__
#define __STRINGPIECE_H__

#include "unicode/utypes.h"

#if U_SHOW_CPLUSPLUS_API

#include <cstddef>
#include <type_traits>

#include "unicode/uobject.h"
#include "unicode/std_string.h"

// Arghh!  I wish C++ literals were "string".

U_NAMESPACE_BEGIN

class U_COMMON_API StringPiece : public UMemory {
 private:
  const char*   ptr_;
  int32_t       length_;

 public:
  StringPiece() : ptr_(nullptr), length_(0) { }

  StringPiece(const char* str);
#if defined(__cpp_char8_t) || defined(U_IN_DOXYGEN)

  StringPiece(const char8_t* str) : StringPiece(reinterpret_cast<const char*>(str)) {}
#endif

  StringPiece(std::nullptr_t p) : ptr_(p), length_(0) {}

  StringPiece(const std::string& str)
    : ptr_(str.data()), length_(static_cast<int32_t>(str.size())) { }
#if defined(__cpp_lib_char8_t) || defined(U_IN_DOXYGEN)

  StringPiece(const std::u8string& str)
    : ptr_(reinterpret_cast<const char*>(str.data())),
      length_(static_cast<int32_t>(str.size())) { }
#endif

  template <typename T,
            typename = typename std::enable_if<
                (std::is_same<decltype(T().data()), const char*>::value
#if defined(__cpp_char8_t)
                    || std::is_same<decltype(T().data()), const char8_t*>::value
#endif
                ) &&
                std::is_same<decltype(T().size()), size_t>::value>::type>
  StringPiece(T str)
      : ptr_(reinterpret_cast<const char*>(str.data())),
        length_(static_cast<int32_t>(str.size())) {}

  StringPiece(const char* offset, int32_t len) : ptr_(offset), length_(len) { }
#if defined(__cpp_char8_t) || defined(U_IN_DOXYGEN)

  StringPiece(const char8_t* str, int32_t len) :
      StringPiece(reinterpret_cast<const char*>(str), len) {}
#endif

  StringPiece(const StringPiece& x, int32_t pos);
  StringPiece(const StringPiece& x, int32_t pos, int32_t len);

  const char* data() const { return ptr_; }
  int32_t size() const { return length_; }
  int32_t length() const { return length_; }
  UBool empty() const { return length_ == 0; }

  void clear() { ptr_ = nullptr; length_ = 0; }

  void set(const char* xdata, int32_t len) { ptr_ = xdata; length_ = len; }

  void set(const char* str);

#if defined(__cpp_char8_t) || defined(U_IN_DOXYGEN)

  inline void set(const char8_t* xdata, int32_t len) {
      set(reinterpret_cast<const char*>(xdata), len);
  }

  inline void set(const char8_t* str) {
      set(reinterpret_cast<const char*>(str));
  }
#endif

  void remove_prefix(int32_t n) {
    if (n >= 0) {
      if (n > length_) {
        n = length_;
      }
      ptr_ += n;
      length_ -= n;
    }
  }

  void remove_suffix(int32_t n) {
    if (n >= 0) {
      if (n <= length_) {
        length_ -= n;
      } else {
        length_ = 0;
      }
    }
  }

  int32_t find(StringPiece needle, int32_t offset);

  int32_t compare(StringPiece other);

  static const int32_t npos; // = 0x7fffffff;

  StringPiece substr(int32_t pos, int32_t len = npos) const {
    return StringPiece(*this, pos, len);
  }
};

U_EXPORT UBool U_EXPORT2 
operator==(const StringPiece& x, const StringPiece& y);

inline bool operator!=(const StringPiece& x, const StringPiece& y) {
  return !(x == y);
}

U_NAMESPACE_END

#endif /* U_SHOW_CPLUSPLUS_API */

#endif  // __STRINGPIECE_H__