DecompressString.h

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/*
 * 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) 2009 Soeren Sonnenburg
 * Copyright (C) 2009 Berlin Institute of Technology
 */

#ifndef _CDECOMPRESS_STRING__H__
#define _CDECOMPRESS_STRING__H__

#include "features/Features.h"
#include "features/StringFeatures.h"
#include "lib/common.h"
#include "lib/Compressor.h"
#include "preproc/StringPreProc.h"

namespace shogun
{
template <class ST> class CStringFeatures;
class CCompressor;
enum E_COMPRESSION_TYPE;

template <class ST> class CDecompressString : public CStringPreProc<ST>
{
    public:
        CDecompressString(E_COMPRESSION_TYPE ct)
            : CStringPreProc<ST>("DecompressString", "DECS")
        {
            compressor=new CCompressor(ct);
        }

        virtual ~CDecompressString()
        {
            delete compressor;
        }

        virtual bool init(CFeatures* f)
        {
            ASSERT(f->get_feature_class()==C_STRING);
            return true;
        }

        virtual void cleanup()
        {
        }

        bool load(FILE* f)
        {
            return false;
        }

        bool save(FILE* f)
        {
            return false;
        }

        virtual bool apply_to_string_features(CFeatures* f)
        {
            int32_t i;
            int32_t num_vec=((CStringFeatures<ST>*)f)->get_num_vectors();

            for (i=0; i<num_vec; i++)
            {
                int32_t len=0;
                bool free_vec;
                ST* vec=((CStringFeatures<ST>*)f)->
                    get_feature_vector(i, len, free_vec);

                ST* decompressed=apply_to_string(vec, len);
                ((CStringFeatures<ST>*)f)->
                    free_feature_vector(vec, i, free_vec);
                ((CStringFeatures<ST>*)f)->
                    cleanup_feature_vector(i);
                ((CStringFeatures<ST>*)f)->
                    set_feature_vector(i, decompressed, len);
            }
            return true;
        }

        virtual ST* apply_to_string(ST* f, int32_t &len)
        {
            uint64_t compressed_size=((int32_t*) f)[0];
            uint64_t uncompressed_size=((int32_t*) f)[1];

            int32_t offs=CMath::ceil(2.0*sizeof(int32_t)/sizeof(ST));
            ASSERT(uint64_t(len)==uint64_t(offs)+compressed_size);

            len=uncompressed_size;
            uncompressed_size*=sizeof(ST);
            ST* vec=new ST[len];
            compressor->decompress((uint8_t*) (&f[offs]), compressed_size,
                    (uint8_t*) vec, uncompressed_size);

            ASSERT(uncompressed_size==((uint64_t) len)*sizeof(ST));
            return vec;
        }

    protected:
        CCompressor* compressor;
};
}
#endif