/*
 * OAASolver.java
 *
 *
 * Copyright (c) 2004 David Hjelm <dhjelm@ling.gu.se>.
 * 					  	 
 *
 * Project homepage: <http://sourceforge.net/projects/trindikit>.
 *
 * 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.
 */
package se.gu.ling.trindikit.oaa.common;

import com.sri.oaa2.icl.*;

import java.util.*;

/**
   Abstract base class which can be extended to create <em>solvers</em>, 
   classes that encapsulate the functionality to solve a OAA query and can be 
   added to an OAAAgent with the <code>addSolver</code> method. Each instance o
   an OAASolver has a corresponding solvable. 
    @author David Hjelm
    @version February 2003
*/

public abstract class OAASolver{

    private IclTerm solvable;
   
    /**
       Called from the constructor of the implementing class.
       @param solvable the solvable for this solver. Internally represented as an IclTerm. 
     */
    public OAASolver(String solvable){
	this.solvable=IclUtils.fromString(false,solvable);
    }

    /**
       Called from the constructor of the implementing class.
       @param solvable the solvable for this solver. 
    */
    public OAASolver(IclTerm solvable){
	this.solvable = solvable;
    }

    /**
       Abstract method for solving OAA queries. This method is called from
       the OAAAgent when it receives an incoming OAA query. Implement this
       for every solver.
       @param goal The OAA query.
       @param params List of additional parameters passed with the query
       @param answers Answers to query.
       If <code>solve</code> does not have any answers to <code>goal</code>,
       i.e. <code>goal</code> is false according to this solver, return 
       <code>false</code>.
       Otherwise, add the answer(s), which should be IclTerms unifiable with 
       <code>goal</code>, to <code>answers</code> and return <code>true</code>.
       If exceptions occur, they can be encapsulated using SolveException and
       propagated to the caller of the method.
    */
    public abstract boolean solve(IclTerm goal,IclList params,IclList answers)
    throws SolveException;

    /**
       returns the solvable associated with this solver
    */
    public IclTerm getSolvable(){
	return (IclTerm)solvable.clone();
    }
    

    /**
       returns the solvable associated with this solver represented as a String
    */    
    public String getSolvableString(){
	return solvable.toIdentifyingString();
    }  
    


    
}