//
// NullStream.h
//
// Library: Foundation
// Package: Streams
// Module:  NullStream
//
// Definition of the NullStreamBuf, NullInputStream and NullOutputStream classes.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_NullStream_INCLUDED
#define Foundation_NullStream_INCLUDED


#include <istream>
#include <ostream>
#include "Poco/Foundation.h"
#include "Poco/UnbufferedStreamBuf.h"


namespace Poco
{


class Foundation_API NullStreamBuf : public UnbufferedStreamBuf
/// This stream buffer discards all characters written to it.
/// Any read operation immediately yields EOF.
{
public:
    NullStreamBuf();
    /// Creates a NullStreamBuf.

    ~NullStreamBuf();
    /// Destroys the NullStreamBuf.

protected:
    int readFromDevice();
    int writeToDevice(char c);
};


class Foundation_API NullIOS : public virtual std::ios
/// The base class for NullInputStream and NullOutputStream.
///
/// This class is needed to ensure the correct initialization
/// order of the stream buffer and base classes.
{
public:
    NullIOS();
    ~NullIOS();

protected:
    NullStreamBuf _buf;
};


class Foundation_API NullInputStream : public NullIOS, public std::istream
/// Any read operation from this stream immediately
/// yields EOF.
{
public:
    NullInputStream();
    /// Creates the NullInputStream.

    ~NullInputStream();
    /// Destroys the NullInputStream.
};


class Foundation_API NullOutputStream : public NullIOS, public std::ostream
/// This stream discards all characters written to it.
{
public:
    NullOutputStream();
    /// Creates the NullOutputStream.

    ~NullOutputStream();
    /// Destroys the NullOutputStream.
};


} // namespace Poco


#endif // Foundation_NullStream_INCLUDED