bytestream.h

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// Copyright (C) 2009-2012, International Business Machines
// Corporation and others. All Rights Reserved.
//
// Copyright 2007 Google Inc. All Rights Reserved.
// Author: sanjay@google.com (Sanjay Ghemawat)
//
// Abstract interface that consumes a sequence of bytes (ByteSink).
//
// Used so that we can write a single piece of code that can operate
// on a variety of output string types.
//
// Various implementations of this interface are provided:
//   ByteSink:
//      CheckedArrayByteSink    Write to a flat array, with bounds checking
//      StringByteSink          Write to an STL string
 
// 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 __BYTESTREAM_H__
#define __BYTESTREAM_H__
 
#include "unicode/utypes.h"
#include "unicode/uobject.h"
#include "unicode/std_string.h"
 
U_NAMESPACE_BEGIN
 
class U_COMMON_API ByteSink : public UMemory {
public:
  ByteSink() { }
  virtual ~ByteSink();
 
  virtual void Append(const char* bytes, int32_t n) = 0;
 
  virtual char* GetAppendBuffer(int32_t min_capacity,
                                int32_t desired_capacity_hint,
                                char* scratch, int32_t scratch_capacity,
                                int32_t* result_capacity);
 
  virtual void Flush();
 
private:
  ByteSink(const ByteSink &); // copy constructor not implemented
  ByteSink &operator=(const ByteSink &); // assignment operator not implemented
};
 
// -------------------------------------------------------------
// Some standard implementations
 
class U_COMMON_API CheckedArrayByteSink : public ByteSink {
public:
  CheckedArrayByteSink(char* outbuf, int32_t capacity);
  virtual ~CheckedArrayByteSink();
  virtual CheckedArrayByteSink& Reset();
  virtual void Append(const char* bytes, int32_t n);
  virtual char* GetAppendBuffer(int32_t min_capacity,
                                int32_t desired_capacity_hint,
                                char* scratch, int32_t scratch_capacity,
                                int32_t* result_capacity);
  int32_t NumberOfBytesWritten() const { return size_; }
  UBool Overflowed() const { return overflowed_; }
  int32_t NumberOfBytesAppended() const { return appended_; }
private:
  char* outbuf_;
  const int32_t capacity_;
  int32_t size_;
  int32_t appended_;
  UBool overflowed_;
  CheckedArrayByteSink(); 
  CheckedArrayByteSink(const CheckedArrayByteSink &); 
  CheckedArrayByteSink &operator=(const CheckedArrayByteSink &); 
};
 
#if U_HAVE_STD_STRING
 
template<typename StringClass>
class StringByteSink : public ByteSink {
 public:
  StringByteSink(StringClass* dest) : dest_(dest) { }
  virtual void Append(const char* data, int32_t n) { dest_->append(data, n); }
 private:
  StringClass* dest_;
  StringByteSink(); 
  StringByteSink(const StringByteSink &); 
  StringByteSink &operator=(const StringByteSink &); 
};
 
#endif
 
U_NAMESPACE_END
 
#endif  // __BYTESTREAM_H__