libnbtplusplus/include/io/izlibstream.h

/*
 * libnbt++ - A library for the Minecraft Named Binary Tag format.
 * Copyright (C) 2013, 2015  ljfa-ag
 *
 * This file is part of libnbt++.
 *
 * libnbt++ is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * libnbt++ is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with libnbt++.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef IZLIBSTREAM_H_INCLUDED
#define IZLIBSTREAM_H_INCLUDED

#include "io/zlib_streambuf.h"
#include <istream>
#include <zlib.h>

namespace zlib
{

/**
 * @brief Stream buffer used by zlib::izlibstream
 * @sa izlibstream
 */
class NBT_EXPORT inflate_streambuf : public zlib_streambuf
{
public:
    /**
     * @param input the istream to wrap
     * @param bufsize the size of the internal buffers
     * @param window_bits the base two logarithm of the maximum window size that
     * zlib will use.
     * This parameter also determines which type of input to expect.
     * The default argument will autodetect between zlib and gzip data.
     * Refer to the zlib documentation of inflateInit2 for more details.
     *
     * @throw zlib_error if zlib encounters a problem during initialization
     */
    explicit inflate_streambuf(std::istream& input, size_t bufsize = 32768, int window_bits = 32 + 15);
    ~inflate_streambuf() noexcept;

    ///@return the wrapped istream
    std::istream& get_istr() const { return is; }

private:
    std::istream& is;
    bool stream_end;

    int_type underflow() override;
};

/**
 * @brief An istream adapter that decompresses data using zlib
 *
 * This istream wraps another istream. The izlibstream will read compressed
 * data from the wrapped istream and inflate (decompress) it with zlib.
 *
 * @note If you want to read more data from the wrapped istream after the end
 * of the compressed data, then it must allow seeking. It is unavoidable for
 * the izlibstream to consume more data after the compressed data.
 * It will automatically attempt to seek the wrapped istream back to the point
 * after the end of the compressed data.
 * @sa inflate_streambuf
 */
class NBT_EXPORT izlibstream : public std::istream
{
public:
    /**
     * @param input the istream to wrap
     * @param bufsize the size of the internal buffers
     */
    explicit izlibstream(std::istream& input, size_t bufsize = 32768):
        std::istream(&buf), buf(input, bufsize)
    {}
    ///@return the wrapped istream
    std::istream& get_istr() const { return buf.get_istr(); }

private:
    inflate_streambuf buf;
};

}

#endif // IZLIBSTREAM_H_INCLUDED