LanguageModel.h

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// LanguageModel.h
//
//
// Copyright (c) 2001-2002 David Ward
//

// Abstract language model class
// See PPMModel for an example implementation

// Contexts are indentified by a unique unsigned integer

#ifndef __LanguageModel_h__
#define __LanguageModel_h__

#include "MSVC_Unannoy.h"
#include <vector>
#include <string>

#include "Alphabet.h"
#include "Context.h"

namespace Dasher {class CLanguageModel;}
class Dasher::CLanguageModel
{
public:
        CLanguageModel(CAlphabet* Alphabet, int Normalization);

        // Interface for the Dasher code
        // --------------------------------------------------------------------------
        class CNodeContext {
        public:
                CNodeContext() {};
                virtual ~CNodeContext() {};
        };
        
        // return the model's normalization - what the probabilities sum to
        const int normalization() const { return m_iNorm;}
        
        CNodeContext* GetRootNodeContext();
        CNodeContext* CloneNodeContext(CNodeContext* NodeContext);
        void ReleaseNodeContext(CNodeContext* NodeContext);
        void EnterNodeSymbol(CNodeContext* NodeContext, symbol Symbol);
        void LearnNodeSymbol(CNodeContext* NodeContext, symbol Symbol);
        void EnterText(CNodeContext* NodeContext, std::string TheText);
        void LearnText(CNodeContext* NodeContext, std::string* TheText, bool IsMore);
        bool GetNodeProbs(CNodeContext* Context, std::vector<symbol> &NewSymbols,
                std::vector<unsigned int> &Groups, std::vector<unsigned int> &Probs, double AddProb);
        
        // Alphabet pass-through functions for widely needed information
        symbol GetSpaceSymbol() {return m_Alphabet->GetSpaceSymbol();}
        
        int GetColour(int character);

protected:
        int GetNumberModelChars() {return m_Alphabet->GetNumberSymbols();}
        
        // Generic language model functions to be implemented 
        // --------------------------------------------------------------------------
        typedef unsigned int modelchar;
        
        // return the id for the root context:
        virtual CContext* GetRootContext()=0;
        // clone a context and return the new id:
        virtual CContext* CloneContext(CContext*)=0;
        // delete a context:
        virtual void ReleaseContext(CContext*)=0;
        // diagnostic info:
        virtual void dump()=0;
        // add character to the language model:
        virtual void LearnSymbol(CContext* Context, modelchar Symbol)=0;
        // update context with a character:
        virtual void EnterSymbol(CContext* context, modelchar Symbol)=0;
        // get the probability distrubution at the given context:
        virtual bool GetProbs(CContext* Context, std::vector<unsigned int> &Probs, double AddProb)=0;
        
private:
        CAlphabet *m_Alphabet;
        int m_iModelChars; // number of charater in the model 1...ModelChars
        int m_iNorm;       // normalization of probabilities
};

using namespace Dasher;


inline CLanguageModel::CNodeContext* CLanguageModel::GetRootNodeContext()
{
        return (CNodeContext*) GetRootContext();
}


inline CLanguageModel::CNodeContext* CLanguageModel::CloneNodeContext(CNodeContext* NodeContext)
{
        return (CNodeContext*) CloneContext((CContext*) NodeContext);
}


inline void CLanguageModel::ReleaseNodeContext(CNodeContext* NodeContext)
{
        ReleaseContext((CContext*) NodeContext);
}


inline void CLanguageModel::EnterNodeSymbol(CNodeContext* NodeContext, symbol Symbol)
{
        EnterSymbol((CContext*) NodeContext, (modelchar) Symbol);
}


inline void CLanguageModel::LearnNodeSymbol(CNodeContext* NodeContext, symbol Symbol)
{
        LearnSymbol((CContext*) NodeContext, (modelchar) Symbol);
}



#endif /* #ifndef __LanguageModel_h__ */

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