Extractor.hxx

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/*
 * Copyright (c) 2004 MUSIC TECHNOLOGY GROUP (MTG)
 *                         UNIVERSITAT POMPEU FABRA
 *
 *
 * 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 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#ifndef _Extractor_hxx_
#define _Extractor_hxx_

#include <string>
#include "Pool.hxx"

namespace CLAM
{

template <typename AttributeType>
class Hook 
{
public:
        virtual ~Hook(){}
        void Bind(
                        const std::string & scope,
                        const std::string & attribute)
        {
                _scope = scope;
                _attribute = attribute;
        }

        virtual void Next() = 0;
        virtual bool IsInsideScope() const = 0;
        
protected:
        const std::string GetScope() const
        {
                return _scope;
        }
        std::string _attribute;
        std::string _scope;
};

template <typename AttributeType>
class ReadHook : public Hook<AttributeType>
{
public:
        ReadHook()
        {
                _chained=0;
        }
        ~ReadHook()
        {
                if (_chained) delete _chained;
        }
        ReadHook & Bind(
                const std::string & scope, 
                const std::string & attribute)
        {
                Hook<AttributeType>::Bind(scope,attribute);
                return *this;
        }
        ReadHook & Indirect(
                const std::string & scope, 
                const std::string & attribute)
        {
                if (_chained) 
                {
                        _chained->Indirect(scope,attribute);
                }
                else
                {
                        _chained = new ReadHook<unsigned>;
                        _chained->Bind(scope,attribute);
                }
                return *this;
        }

        const AttributeType & GetForReading() const
        {
                return _data [GetCurrent()];
        }

        void Init(const DescriptionDataPool & pool) 
        {
                _current = 0;
                _pool = &pool;
                const std::string & scope = Hook<AttributeType>::_scope;
                const std::string & attribute = Hook<AttributeType>::_attribute;
                _data = _pool->template GetReadPool<AttributeType>(scope,attribute);
                if (_chained) _chained->Init(pool);
        }

        virtual void Next()
        {
                if (_chained) _chained->Next();
                else _current++;
        }

        virtual bool IsInsideScope() const
        {
                if (_chained) return _chained->IsInsideScope();
                const std::string & scope = Hook<AttributeType>::_scope;
                return _current < _pool->GetNumberOfContexts(scope);
        }

protected:
        virtual unsigned GetCurrent() const
        {
                if (!_chained) return _current;

                unsigned indirection = _chained->GetForReading();
                const std::string & scope = Hook<AttributeType>::_scope;
                CLAM_ASSERT(indirection<_pool->GetNumberOfContexts(scope),
                        "Invalid cross-scope reference");
                return indirection;
        }

protected:
        const DescriptionDataPool * _pool;
        const AttributeType * _data;
        ReadHook<unsigned> * _chained;
private:
        unsigned _current;
};

template <typename AttributeType>
class ReadRangedHook : public ReadHook<AttributeType>
{
public:
        void GetRangeForReading(
                const AttributeType*& begin,
                const AttributeType*& end) const
        {
                begin = & (ReadHook<AttributeType>::GetForReading());
                end = begin + _range;
        }

        ReadHook<AttributeType> & Range(unsigned range)
        {
                _range = range;
                return *this;
        }
private:
        unsigned _range;
};

template <typename AttributeType>
class WriteHook : public Hook<AttributeType>
{
public:
        void Init(DescriptionDataPool & pool) 
        {
                _pool = &pool;
                _current = 0;
                const std::string & scope = Hook<AttributeType>::_scope;
                const std::string & attribute = Hook<AttributeType>::_attribute;
                _data = _pool->template GetWritePool<AttributeType>(scope,attribute);
        }

        AttributeType & GetForWriting() const
        {
                return _data [GetCurrent()];
        }

        virtual void Next()
        {
                _current++;
        }

        virtual bool IsInsideScope() const
        {
                const std::string & scope = Hook<AttributeType>::_scope;
                return _current < _pool->GetNumberOfContexts(scope);
        }

protected:
        unsigned GetCurrent() const
        {
                return _current;
        }
private:
        DescriptionDataPool * _pool;
        AttributeType * _data;
        unsigned _current;
};

}





#endif // _Extractor_hxx_