string_data_template.h

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// Copyright 2016 The PDFium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
// Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
#ifndef CORE_FXCRT_STRING_DATA_TEMPLATE_H_
#define CORE_FXCRT_STRING_DATA_TEMPLATE_H_
 
#include <stddef.h>
#include <stdint.h>
 
namespace fxcrt {
 
template <typename CharType>
class StringDataTemplate {
 public:
  static StringDataTemplate* Create(size_t nLen);
  static StringDataTemplate* Create(const CharType* pStr, size_t nLen);
 
  void Retain() { ++m_nRefs; }
  void Release();
 
  bool CanOperateInPlace(size_t nTotalLen) const {
    return m_nRefs <= 1 && nTotalLen <= m_nAllocLength;
  }
 
  void CopyContents(const StringDataTemplate& other);
  void CopyContents(const CharType* pStr, size_t nLen);
  void CopyContentsAt(size_t offset, const CharType* pStr, size_t nLen);
 
  // To ensure ref counts do not overflow, consider the worst possible case:
  // the entire address space contains nothing but pointers to this object.
  // Since the count increments with each new pointer, the largest value is
  // the number of pointers that can fit into the address space. The size of
  // the address space itself is a good upper bound on it.
  intptr_t m_nRefs = 0;
 
  // These lengths are in terms of number of characters, not bytes, and do not
  // include the terminating NUL character, but the underlying buffer is sized
  // to be capable of holding it.
  size_t m_nDataLength;
  const size_t m_nAllocLength;
 
  // Not really 1, variable size.
  CharType m_String[1];
 
 private:
  StringDataTemplate(size_t dataLen, size_t allocLen);
  ~StringDataTemplate() = delete;
};
 
extern template class StringDataTemplate<char>;
extern template class StringDataTemplate<wchar_t>;
 
}  // namespace fxcrt
 
using fxcrt::StringDataTemplate;
 
#endif  // CORE_FXCRT_STRING_DATA_TEMPLATE_H_