zstream.h

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#ifndef PhysicsTools_MVAComputer_zstream_h
#define PhysicsTools_MVAComputer_zstream_h
// -*- C++ -*-
//
// Package:     MVAComputer
//

//
// Author:  Christophe Saout <christophe.saout@cern.ch>
// Created:     Sat Apr 24 15:18 CEST 2007
//

#include <iostream>
#include <vector>

#include <zlib.h>

namespace ext {

// implements STL stream wrappers around other streams
// to provide transparent gzip compression/decompression
//
// constructors take reference to an existing stream, rest is straightforward

template<typename Item_t, typename Traits_t = std::char_traits<Item_t>,
         typename Allocator_t = std::allocator<Item_t> >
class basic_ozstreambuf : public std::basic_streambuf<Item_t, Traits_t> {
    public:
    typedef std::basic_ostream<Item_t, Traits_t>    OStream_t;
    typedef std::basic_streambuf<Item_t, Traits_t>  StreamBuf_t;

    typedef Item_t                  char_type;
    typedef typename Traits_t::int_type     int_type;
    typedef typename Traits_t::pos_type     pos_type;
    typedef typename Traits_t::off_type     off_type;
    typedef unsigned char               byte_type;
    typedef Traits_t                traits_type;

    basic_ozstreambuf(OStream_t *os, int level);
    ~basic_ozstreambuf() override;

    using StreamBuf_t::pbase;
    using StreamBuf_t::pptr;
    using StreamBuf_t::epptr;

    int sync() override;
    int_type overflow(int_type c) override;
    std::streamsize flush();

    private:
    bool zipToStream(char_type *buf, std::streamsize size);
    size_t fillInputBuffer();

    OStream_t               *os;
    z_stream                zipStream;
    int                 err;
    std::vector<byte_type>          outputBuffer;
    std::vector<char_type, Allocator_t> buffer;
};

template<typename Item_t, typename Traits_t = std::char_traits<Item_t>,
         typename Allocator_t = std::allocator<Item_t> >
class basic_izstreambuf : public std::basic_streambuf<Item_t, Traits_t> {
    public:
    typedef std::basic_istream<Item_t, Traits_t>    IStream_t;
    typedef std::basic_streambuf<Item_t, Traits_t>  StreamBuf_t;

    typedef Item_t                  char_type;
    typedef typename Traits_t::int_type     int_type;
    typedef typename Traits_t::pos_type     pos_type;
    typedef typename Traits_t::off_type     off_type;
    typedef unsigned char               byte_type;
    typedef Traits_t                traits_type;

    basic_izstreambuf(IStream_t *is);
    ~basic_izstreambuf() override;

    using StreamBuf_t::gptr;
    using StreamBuf_t::egptr;
    using StreamBuf_t::eback;

    int_type underflow() override;

    private:
    void putbackFromZStream();
    std::streamsize unzipFromStream(char_type *buf, std::streamsize size);
    size_t fillInputBuffer();

    IStream_t               *is;
    z_stream                zipStream;
    int                 err;
    std::vector<byte_type>          inputBuffer;
    std::vector<char_type, Allocator_t> buffer;
};

template<typename Item_t, typename Traits_t = std::char_traits<Item_t>,
         typename Allocator_t = std::allocator<Item_t> >
class basic_ozstreambase : virtual public std::basic_ios<Item_t, Traits_t> {
    public:
    typedef std::basic_ostream<Item_t, Traits_t> OStream_t;
    typedef basic_ozstreambuf<Item_t, Traits_t, Allocator_t> ZOStreamBuf_t;

    basic_ozstreambase(OStream_t *os, int level) :
        buffer(os, level) { this->init(&buffer); }

    ZOStreamBuf_t *rdbuf() { return &buffer; }

    private:
    ZOStreamBuf_t buffer;
};

template<typename Item_t, typename Traits_t = std::char_traits<Item_t>,
         typename Allocator_t = std::allocator<Item_t> >
class basic_izstreambase : virtual public std::basic_ios<Item_t, Traits_t> {
    public:
    typedef std::basic_istream<Item_t, Traits_t> IStream_t;
    typedef basic_izstreambuf<Item_t, Traits_t, Allocator_t> ZIStreamBuf_t;

    basic_izstreambase(IStream_t *is) : buffer(is) { this->init(&buffer); }

    ZIStreamBuf_t *rdbuf() { return &buffer; }

    private:
    ZIStreamBuf_t buffer;
};

template<typename Item_t, typename Traits_t = std::char_traits<Item_t>,
         typename Allocator_t = std::allocator<Item_t> >
class basic_ozstream : public basic_ozstreambase<Item_t, Traits_t, Allocator_t>,
                       public std::basic_ostream<Item_t, Traits_t> {
    public:
    typedef std::basic_ostream<Item_t, Traits_t> OStream_t;
    typedef basic_ozstreambase<Item_t, Traits_t, Allocator_t> ZOStreamBase_t;

    basic_ozstream(OStream_t *os, int open_mode = std::ios::out,
                   int level = 9) :
        ZOStreamBase_t(os, level),
        OStream_t(ZOStreamBase_t::rdbuf()) {}
    ~basic_ozstream() override {}
};

template<typename Item_t, typename Traits_t = std::char_traits<Item_t>,
         typename Allocator_t = std::allocator<Item_t> >
class basic_izstream : public basic_izstreambase<Item_t, Traits_t, Allocator_t>,
                       public std::basic_istream<Item_t, Traits_t> {
    public:
    typedef std::basic_istream<Item_t, Traits_t> IStream_t;
    typedef basic_izstreambase<Item_t, Traits_t, Allocator_t> ZIStreamBase_t;

    basic_izstream(IStream_t *is, int open_mode = std::ios::in) :
        ZIStreamBase_t(is), IStream_t(ZIStreamBase_t::rdbuf()) {}
    ~basic_izstream() override {}
};

typedef basic_ozstream<char> ozstream;
typedef basic_ozstream<wchar_t> wozstream;
typedef basic_izstream<char> izstream;
typedef basic_izstream<wchar_t> wizstream;

} // namespace ext

#include "PhysicsTools/MVAComputer/interface/zstream.icc"

#endif // PhysicsTools_MVAComputer_zstream_h