ClickHouse/base/poco/Foundation/include/Poco/PipeStream.h

//
// PipeStream.h
//
// Library: Foundation
// Package: Processes
// Module:  PipeStream
//
// Definition of the PipeStream class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_PipeStream_INCLUDED
#define Foundation_PipeStream_INCLUDED


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


namespace Poco
{


class Foundation_API PipeStreamBuf : public BufferedStreamBuf
/// This is the streambuf class used for reading from and writing to a Pipe.
{
public:
    typedef BufferedStreamBuf::openmode openmode;

    PipeStreamBuf(const Pipe & pipe, openmode mode);
    /// Creates a PipeStreamBuf with the given Pipe.

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

    void close();
    /// Closes the pipe.

protected:
    int readFromDevice(char * buffer, std::streamsize length);
    int writeToDevice(const char * buffer, std::streamsize length);

private:
    enum
    {
        STREAM_BUFFER_SIZE = 1024
    };

    Pipe _pipe;
};


class Foundation_API PipeIOS : public virtual std::ios
/// The base class for PipeInputStream and
/// PipeOutputStream.
///
/// This class is needed to ensure the correct initialization
/// order of the stream buffer and base classes.
{
public:
    PipeIOS(const Pipe & pipe, openmode mode);
    /// Creates the PipeIOS with the given Pipe.

    ~PipeIOS();
    /// Destroys the PipeIOS.
    ///
    /// Flushes the buffer, but does not close the pipe.

    PipeStreamBuf * rdbuf();
    /// Returns a pointer to the internal PipeStreamBuf.

    void close();
    /// Flushes the stream and closes the pipe.

protected:
    PipeStreamBuf _buf;
};


class Foundation_API PipeOutputStream : public PipeIOS, public std::ostream
/// An output stream for writing to a Pipe.
{
public:
    PipeOutputStream(const Pipe & pipe);
    /// Creates the PipeOutputStream with the given Pipe.

    ~PipeOutputStream();
    /// Destroys the PipeOutputStream.
    ///
    /// Flushes the buffer, but does not close the pipe.
};


class Foundation_API PipeInputStream : public PipeIOS, public std::istream
/// An input stream for reading from a Pipe.
///
/// Using formatted input from a PipeInputStream
/// is not recommended, due to the read-ahead behavior of
/// istream with formatted reads.
{
public:
    PipeInputStream(const Pipe & pipe);
    /// Creates the PipeInputStream with the given Pipe.

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


} // namespace Poco


#endif // Foundation_PipeStream_INCLUDED