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

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


#ifndef Foundation_DeflatingStream_INCLUDED
#define Foundation_DeflatingStream_INCLUDED


#include <istream>
#include <ostream>
#include "Poco/BufferedStreamBuf.h"
#include "Poco/Foundation.h"
#if defined(POCO_UNBUNDLED_ZLIB)
#    include <zlib.h>
#else
#    include "Poco/zlib.h"
#endif


namespace Poco
{


class Foundation_API DeflatingStreamBuf : public BufferedStreamBuf
/// This is the streambuf class used by DeflatingInputStream and DeflatingOutputStream.
/// The actual work is delegated to zlib (see http://zlib.net).
/// Both zlib (deflate) streams and gzip streams are supported.
/// Output streams should always call close() to ensure
/// proper completion of compression.
/// A compression level (0 to 9) can be specified in the constructor.
{
public:
    enum StreamType
    {
        STREAM_ZLIB, /// Create a zlib header, use Adler-32 checksum.
        STREAM_GZIP /// Create a gzip header, use CRC-32 checksum.
    };

    DeflatingStreamBuf(std::istream & istr, StreamType type, int level);
    /// Creates a DeflatingStreamBuf for compressing data read
    /// from the given input stream.

    DeflatingStreamBuf(std::istream & istr, int windowBits, int level);
    /// Creates a DeflatingStreamBuf for compressing data read
    /// from the given input stream.
    ///
    /// Please refer to the zlib documentation of deflateInit2() for a description
    /// of the windowBits parameter.

    DeflatingStreamBuf(std::ostream & ostr, StreamType type, int level);
    /// Creates a DeflatingStreamBuf for compressing data passed
    /// through and forwarding it to the given output stream.

    DeflatingStreamBuf(std::ostream & ostr, int windowBits, int level);
    /// Creates a DeflatingStreamBuf for compressing data passed
    /// through and forwarding it to the given output stream.
    ///
    /// Please refer to the zlib documentation of deflateInit2() for a description
    /// of the windowBits parameter.

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

    int close();
    /// Finishes up the stream.
    ///
    /// Must be called when deflating to an output stream.

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

private:
    enum
    {
        STREAM_BUFFER_SIZE = 1024,
        DEFLATE_BUFFER_SIZE = 32768
    };

    std::istream * _pIstr;
    std::ostream * _pOstr;
    char * _buffer;
    z_stream _zstr;
    bool _eof;
};


class Foundation_API DeflatingIOS : public virtual std::ios
/// The base class for DeflatingOutputStream and DeflatingInputStream.
///
/// This class is needed to ensure the correct initialization
/// order of the stream buffer and base classes.
{
public:
    DeflatingIOS(
        std::ostream & ostr, DeflatingStreamBuf::StreamType type = DeflatingStreamBuf::STREAM_ZLIB, int level = Z_DEFAULT_COMPRESSION);
    /// Creates a DeflatingIOS for compressing data passed
    /// through and forwarding it to the given output stream.

    DeflatingIOS(std::ostream & ostr, int windowBits, int level);
    /// Creates a DeflatingIOS for compressing data passed
    /// through and forwarding it to the given output stream.
    ///
    /// Please refer to the zlib documentation of deflateInit2() for a description
    /// of the windowBits parameter.

    DeflatingIOS(
        std::istream & istr, DeflatingStreamBuf::StreamType type = DeflatingStreamBuf::STREAM_ZLIB, int level = Z_DEFAULT_COMPRESSION);
    /// Creates a DeflatingIOS for compressing data read
    /// from the given input stream.

    DeflatingIOS(std::istream & istr, int windowBits, int level);
    /// Creates a DeflatingIOS for compressing data read
    /// from the given input stream.
    ///
    /// Please refer to the zlib documentation of deflateInit2() for a description
    /// of the windowBits parameter.

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

    DeflatingStreamBuf * rdbuf();
    /// Returns a pointer to the underlying stream buffer.

protected:
    DeflatingStreamBuf _buf;
};


class Foundation_API DeflatingOutputStream : public std::ostream, public DeflatingIOS
/// This stream compresses all data passing through it
/// using zlib's deflate algorithm.
/// After all data has been written to the stream, close()
/// must be called to ensure completion of compression.
/// Example:
///     std::ofstream ostr("data.gz", std::ios::binary);
///     DeflatingOutputStream deflater(ostr, DeflatingStreamBuf::STREAM_GZIP);
///     deflater << "Hello, world!" << std::endl;
///     deflater.close();
///     ostr.close();
{
public:
    DeflatingOutputStream(
        std::ostream & ostr, DeflatingStreamBuf::StreamType type = DeflatingStreamBuf::STREAM_ZLIB, int level = Z_DEFAULT_COMPRESSION);
    /// Creates a DeflatingOutputStream for compressing data passed
    /// through and forwarding it to the given output stream.

    DeflatingOutputStream(std::ostream & ostr, int windowBits, int level);
    /// Creates a DeflatingOutputStream for compressing data passed
    /// through and forwarding it to the given output stream.
    ///
    /// Please refer to the zlib documentation of deflateInit2() for a description
    /// of the windowBits parameter.

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

    int close();
    /// Finishes up the stream.
    ///
    /// Must be called when deflating to an output stream.

protected:
    virtual int sync();
};


class Foundation_API DeflatingInputStream : public std::istream, public DeflatingIOS
/// This stream compresses all data passing through it
/// using zlib's deflate algorithm.
{
public:
    DeflatingInputStream(
        std::istream & istr, DeflatingStreamBuf::StreamType type = DeflatingStreamBuf::STREAM_ZLIB, int level = Z_DEFAULT_COMPRESSION);
    /// Creates a DeflatingIOS for compressing data read
    /// from the given input stream.

    DeflatingInputStream(std::istream & istr, int windowBits, int level);
    /// Creates a DeflatingIOS for compressing data read
    /// from the given input stream.
    ///
    /// Please refer to the zlib documentation of deflateInit2() for a description
    /// of the windowBits parameter.

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


} // namespace Poco


#endif // Foundation_DeflatingStream_INCLUDED