VwNativeCacheReader.h

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/*
 * Copyright (c) 2009 Yahoo! Inc.  All rights reserved.  The copyrights
 * embodied in the content of this file are licensed under the BSD
 * (revised) open source license.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * Written (W) 2011 Shashwat Lal Das
 * Adaptation of Vowpal Wabbit v5.1.
 * Copyright (C) 2011 Berlin Institute of Technology and Max-Planck-Society.
 */

#ifndef _VW_NATIVECACHE_READ_H__
#define _VW_NATIVECACHE_READ_H__

#include <shogun/classifier/vw/cache/VwCacheReader.h>

namespace shogun
{

#ifndef DOXYGEN_SHOULD_SKIP_THIS
// Packed structure for efficient storage
struct one_float
{
    // The float to store
    float32_t f;
} __attribute__((packed));

#endif // DOXYGEN_SHOULD_SKIP_THIS

class CVwNativeCacheReader: public CVwCacheReader
{
public:
    CVwNativeCacheReader();

    CVwNativeCacheReader(char * fname, CVwEnvironment* env_to_use);

    CVwNativeCacheReader(int32_t f, CVwEnvironment* env_to_use);

    virtual ~CVwNativeCacheReader();

    virtual void set_file(int32_t f);

    virtual bool read_cached_example(VwExample* const ae);

    void check_cache_metadata();

    virtual const char* get_name() const { return "VwNativeCacheReader"; }

private:
    void init();

    char* run_len_decode(char *p, vw_size_t& i);

    inline int32_t ZigZagDecode(uint32_t n)
    {
        return (n >> 1) ^ -static_cast<int32_t>(n & 1);
    }

    char* bufread_label(VwLabel* const ld, char* c);

    vw_size_t read_cached_label(VwLabel* const ld);

    vw_size_t read_cached_tag(VwExample* const ae);


protected:
    CIOBuffer buf;

private:
    // Used while parsing
    const vw_size_t char_size;
    vw_size_t neg_1;
    vw_size_t general;
};

}
#endif // _VW_NATIVECACHE_READ_H__