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MemoryStream.h

//
// MemoryStream.h
//
// $Id: //poco/1.4/Foundation/include/Poco/MemoryStream.h#1 $
//
// Library: Foundation
// Package: Streams
// Module:  MemoryStream
//
// Definition of MemoryStreamBuf, MemoryInputStream, MemoryOutputStream
//
// Copyright (c) 2009, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


#ifndef Foundation_MemoryStream_INCLUDED
#define Foundation_MemoryStream_INCLUDED


#include "Poco/Foundation.h"
#include "Poco/StreamUtil.h"
#include <streambuf>
#include <iosfwd>
#include <ios>
#include <istream>
#include <ostream>


namespace Poco {


template <typename ch, typename tr> 
00056 class BasicMemoryStreamBuf: public std::basic_streambuf<ch, tr>
      /// BasicMemoryStreamBuf is a simple implementation of a 
      /// stream buffer for reading and writing from a memory area.
      ///
      /// This streambuf only supports unidirectional streams.
      /// In other words, the BasicBufferedStreamBuf can be
      /// used for the implementation of an istream or an
      /// ostream, but not for an iostream.
{
protected:
      typedef std::basic_streambuf<ch, tr> Base;
      typedef std::basic_ios<ch, tr> IOS;
      typedef ch char_type;
      typedef tr char_traits;
      typedef typename Base::int_type int_type;
      typedef typename Base::pos_type pos_type;
      typedef typename Base::off_type off_type;

public:
      BasicMemoryStreamBuf(char_type* pBuffer, std::streamsize bufferSize):
            _pBuffer(pBuffer),
            _bufferSize(bufferSize)
      {
            this->setg(_pBuffer, _pBuffer, _pBuffer + _bufferSize);
            this->setp(_pBuffer, _pBuffer + _bufferSize);
      }

      ~BasicMemoryStreamBuf()
      {
      }

      virtual int_type overflow(int_type c)
      {
            return char_traits::eof();
      }

      virtual int_type underflow()
      {
            return char_traits::eof();
      }

      virtual int sync()
      {
            return 0;
      }
      
      std::streamsize charsWritten() const
      {
            return static_cast<std::streamsize>(this->pptr() - this->pbase());
      }

00107       void reset()
            /// Resets the buffer so that current read and write positions
            /// will be set to the beginning of the buffer.
      {
            this->setg(_pBuffer, _pBuffer, _pBuffer + _bufferSize);
            this->setp(_pBuffer, _pBuffer + _bufferSize);
      }
            
private:
      char_type*      _pBuffer;
      std::streamsize _bufferSize;

      BasicMemoryStreamBuf();
      BasicMemoryStreamBuf(const BasicMemoryStreamBuf&);
      BasicMemoryStreamBuf& operator = (const BasicMemoryStreamBuf&);
};


//
// We provide an instantiation for char
//
typedef BasicMemoryStreamBuf<char, std::char_traits<char> > MemoryStreamBuf;


00131 class Foundation_API MemoryIOS: public virtual std::ios
      /// The base class for MemoryInputStream and MemoryOutputStream.
      ///
      /// This class is needed to ensure the correct initialization
      /// order of the stream buffer and base classes.
{
public:
      MemoryIOS(char* pBuffer, std::streamsize bufferSize);
            /// Creates the basic stream.
            
      ~MemoryIOS();
            /// Destroys the stream.

      MemoryStreamBuf* rdbuf();
            /// Returns a pointer to the underlying streambuf.
            
protected:
00148       MemoryStreamBuf _buf;
};


00152 class Foundation_API MemoryInputStream: public MemoryIOS, public std::istream
      /// An input stream for reading from a memory area.
{
public:
      MemoryInputStream(const char* pBuffer, std::streamsize bufferSize);
            /// Creates a MemoryInputStream for the given memory area,
            /// ready for reading.
      
      ~MemoryInputStream();
            /// Destroys the MemoryInputStream.
};


00165 class Foundation_API MemoryOutputStream: public MemoryIOS, public std::ostream
      /// An input stream for reading from a memory area.
{
public:
      MemoryOutputStream(char* pBuffer, std::streamsize bufferSize);
            /// Creates a MemoryOutputStream for the given memory area,
            /// ready for writing.
      
      ~MemoryOutputStream();
            /// Destroys the MemoryInputStream.

      std::streamsize charsWritten() const;
            /// Returns the number of chars written to the buffer.
};


//
// inlines
//
00184 inline MemoryStreamBuf* MemoryIOS::rdbuf()
{
      return &_buf;
}


00190 inline std::streamsize MemoryOutputStream::charsWritten() const
{
      return _buf.charsWritten();
}


} // namespace Poco


#endif // Foundation_MemoryStream_INCLUDED

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