SolveInfo.java

/*
 * tuProlog - Copyright (C) 2001-2002  aliCE team at deis.unibo.it
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package alice.tuprolog;

import java.util.List;

/**
 * SolveInfo class represents the result of a solve
 * request made to the engine, providing information
 * about the solution.
 * 
 * @author Alex Benini
 */
public class SolveInfo  {
	
	private Engine.State endState;
	private boolean isSuccess;
	
	private Term query;
	private Struct goal;
	private List<Var> bindings;
	
	SolveInfo(Term initGoal) {
		query = initGoal;
		isSuccess = false;
	}
	
	SolveInfo(Term initGoal, Struct resultGoal, Engine.State resultDemo, List<Var> resultVars) {
		query = initGoal;
		goal = resultGoal;
		bindings = resultVars;
		endState = resultDemo;
		isSuccess = endState == Engine.State.TRUE || endState == Engine.State.TRUE_CP;
	}
	
	/**
	 * Checks if the solve request was successful.
	 *
	 * @return true if the solve was successful
	 */
	public boolean isSuccess() {
		return isSuccess;
	}
	
	/**
	 * Checks if the solve request was halted.
	 *
	 * @return true if the solve was successful
	 */
	public boolean isHalted() {
		return endState == Engine.State.HALT;
	}
	
	/**
	 * Checks if the solve request was halted.
	 *
	 * @return true if the solve was successful
	 */
	public boolean hasOpenAlternatives() {
		return endState == Engine.State.TRUE_CP;
	}
	
	/**
	 * Gets the query.
	 * 
	 * @return the query
	 */
	public Term getQuery() {
		return query;
	}
	
	/**
	 * Gets the solution of the request.
	 *
	 * @exception NoSolutionException if the solve request has no solution
	 */
	public Term  getSolution() throws NoSolutionException {
		if (isSuccess)
			return goal;
		else
			throw new NoSolutionException();
	}
		
	/**
	 * Gets the list of the variables in the solution.
	 * 
	 * @return the array of variables.
	 * @throws NoSolutionException if current solve information
	 * does not concern a successful 
	 */
	public List<Var> getBindingVars() throws NoSolutionException {
		if (isSuccess)
			return bindings;
		else
			throw new NoSolutionException();
	}
	
	/**
	 * Gets the value of a variable in the substitution.
	 * @throws NoSolutionException if the solve request has no solution
	 * @throws UnknownVarException if the variable does not appear in the substitution.
	 */
	public Term getTerm(String varName) throws NoSolutionException, UnknownVarException {
		Term t = getVarValue(varName);
		if (t == null)
			throw new UnknownVarException();
		return t;
	}
	
	/**
	 * Gets the value of a variable in the substitution. Returns <code>null</code>
	 * if the variable does not appear in the substitution.
	 */
	public Term getVarValue(String varName) throws NoSolutionException {
		if (isSuccess) {
			for (Var v : bindings)
				if (v != null && v.getName().equals(varName))
					return v.getTerm();
			return null;
		} else
			throw new NoSolutionException();
	}
	
	/**
	 * Returns the string representation of the result of the demonstration.
	 * 
	 * For successful demonstrations, the representation concerns variables
	 * with bindings. For failed demo, the method returns false string.
	 */
	@Override
	public String toString() {
		if (isSuccess) {
			StringBuilder sb = new StringBuilder("yes");
			if (bindings.size() > 0)
				sb.append(".\n");
			else
				sb.append(". ");
			for (Var v : bindings)
				if (v != null && !v.isAnonymous() && v.isBound() &&
						(!(v.getTerm() instanceof Var) || (!((Var) (v.getTerm())).getName().startsWith("_")))) {
					sb.append(v);
					sb.append("  ");
				}
			return sb.toString().trim();
		} else
			return "no.";
	}
	
}