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/*
* Copyright Dept. of Mathematics & Computer Science Univ. Paris-Descartes
*
* This software is governed by the CeCILL license under French law and
* abiding by the rules of distribution of free software. You can use,
* modify and/ or redistribute the software under the terms of the CeCILL
* license as circulated by CEA, CNRS and INRIA at the following URL
* "http://www.cecill.info".
*
* As a counterpart to the access to the source code and rights to copy,
* modify and redistribute granted by the license, users are provided only
* with a limited warranty and the software's author, the holder of the
* economic rights, and the successive licensors have only limited
* liability.
*
* In this respect, the user's attention is drawn to the risks associated
* with loading, using, modifying and/or developing or reproducing the
* software by the user in light of its specific status of free software,
* that may mean that it is complicated to manipulate, and that also
* therefore means that it is reserved for developers and experienced
* professionals having in-depth computer knowledge. Users are therefore
* encouraged to load and test the software's suitability as regards their
* requirements in conditions enabling the security of their systems and/or
* data to be ensured and, more generally, to use and operate it in the
* same conditions as regards security.
*
* The fact that you are presently reading this means that you have had
* knowledge of the CeCILL license and that you accept its terms.
*/
package pddl4j.exp.fcomp;
import java.util.Map;
import java.util.LinkedHashMap;
import pddl4j.EvaluationException;
import pddl4j.exp.InitEl;
import pddl4j.exp.fexp.Number;
import pddl4j.exp.fexp.OpExp;
import pddl4j.exp.term.Constant;
import pddl4j.exp.term.Substitution;
import pddl4j.exp.term.Term;
import pddl4j.exp.term.TermID;
/**
* This class implements the equality comparaison function add of the pddl
* language.
*
* @author Damien Pellier
* @version 1.0
*/
public class EqualComp extends FCompExp implements InitEl {
/**
* The serial version id of the class.
*/
private static final long serialVersionUID = -8369304517135857251L;
/**
* Creates a new empty equality compared function with two arguments.
*
* @param arg1 the first argument of the equality compared function.
* @param arg2 the second argument of the equality compared function.
* @throws NullPointerException if <code>arg1 == null</code> or
* <code>arg2 == null</code>.
*/
public EqualComp(Term arg1, Term arg2) {
super(Comp.EQUAL, arg1, arg2);
}
/**
* Substitutes all occurrences of the variables that occur in this
* expression and that are mapped in the substitution by its binding term.
*
* @param sigma the substitution.
* @return a substituted copy of this expression.
* @throws NullPointerException if <code>sigma == null</code>.
*/
public EqualComp apply(Substitution sigma) {
return (EqualComp) super.apply(sigma);
}
/**
* Standardizes all occurrences of the variables that occur in this
* expression. Remember that free variables are existentially quantified.
*
* @return a standardized copy of this expression.
*/
public EqualComp standardize() {
return this.standardize(new LinkedHashMap<String, String>());
}
/**
* Standardizes all occurrences of the variables that occur in this
* expression. The map argument is used to store the variable already
* standardized. The bound argument is used to store the bound variables. a
* standardized copy of this expression. Remember that free variables are
* existentially quantified.
*
* @param images the object that maps old variable images to the standardize
* image.
* @return a standardized copy of this expression.
* @throws NullPointerException if
* <code>images == null || bound == null</code>.
*/
public EqualComp standardize(Map<String, String> images) {
return (EqualComp) super.standardize(images);
}
/**
* Creates and returns a copy of this expression.
*
* @return a clone of this expression instance.
* @see pddl4j.exp.Exp#clone()
*/
public EqualComp clone() {
return (EqualComp) super.clone();
}
/**
* Returns <code>true</code> if this compared expression is evaluable.
* In the general case, an compared expression is evaluable if it is
* ground and its arguments are recursively either a number either a
* aritmetic function. In the case of the equality, a compared expression
* is also evaluable if the arguments of the expression are constant
* terms.
*
* @return <code>true</code> if this compared expression is evaluable;
* <code>false</code> otherwise.
*/
public boolean isEvaluable() {
return super.isEvaluable() ? true :
this.getArg1().getTermID().equals(TermID.CONSTANT)
&& this.getArg2().getTermID().equals(TermID.CONSTANT);
}
/**
* Evaluates this compared expression.
*
* @return the result of the evaluation.
* @throws EvaluationException if the compared expression is not ground or
* if an numeric error occurs during the evaluation of an
* numeric error.
* @see pddl4j.exp.fcomp.FCompExp#isEvaluable()
*/
public boolean evaluate() throws EvaluationException {
if (super.isEvaluable()) {
Number op1 = null;
if (this.getArg1().equals(TermID.ARITHMETIC_FUNCTION)) {
OpExp func = (OpExp) this.getArg1();
op1 = func.evaluate();
} else {
op1 = (Number) this.getArg1();
}
Number op2 = null;
if (this.getArg2().equals(TermID.ARITHMETIC_FUNCTION)) {
OpExp func = (OpExp) this.getArg2();
op2 = func.evaluate();
} else {
op2 = (Number) this.getArg1();
}
return op1.equals(op2);
} else if (this.getArg1().getTermID().equals(TermID.CONSTANT)
&& this.getArg2().getTermID().equals(TermID.CONSTANT)) {
Constant op1 = (Constant) this.getArg1();
Constant op2 = (Constant) this.getArg2();
return op1.equals(op2);
} else {
throw new EvaluationException("comparaison function "
+ this.toString() + ": is not evaluable");
}
}
}
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