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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.fexp;
import java.util.Iterator;
import pddl4j.EvaluationException;
import pddl4j.exp.term.Substitution;
import pddl4j.exp.term.Term;
import pddl4j.exp.term.TermID;
import pddl4j.exp.type.Type;
import pddl4j.exp.type.TypeSet;
/**
* This class implements an arithmetic function.
*
* @author Damien Pellier
* @version 1.0
*/
public abstract class OpExp extends FExp {
/**
* The operator of this arithmetic function.
*/
private Op op;
/**
* Creates a new arithmetic function with a specified operator.
*
* @param op The arithmetic operator of the function.
* @throws NullPointerException if <code>op == null</code>.
*/
protected OpExp(Op op) {
super(TermID.ARITHMETIC_FUNCTION, op.toString(), new TypeSet(Type.NUMBER));
this.setOp(op);
}
/**
* Returns the operator of this arithmetic function.
*
* @return the operator of this arithmetic function.
*/
public final Op getOp() {
return this.op;
}
/**
* Sets a new operator to this arithmetic function.
*
* @param op the new op to set.
* @throws NullPointerException if <code>op == null</code.
*/
protected void setOp(Op op) {
if (op == null)
throw new NullPointerException();
this.op = op;
}
/**
* Returns a deep copy of this arithmetic function.
*
* @return a deep copy of this arithmetic function.
* @see pddl4j.exp.AbstractExp#clone()
*/
public OpExp clone() {
return (OpExp) super.clone();
}
/**
* Substitutes all occurrences of the variables that occur in this term and
* that are bound in the substitution by its binding term. This method
* modify the content of the term on which it is applied.
*
* @param sigma the substitution.
* @return a substituted copy of this expression.
* @throws NullPointerException if <code>sigma == null</code>.
* @throws EvaluationException if this arithmetic function is ground after
* applying the substitution and its evaluation fails.
*/
public Term apply(Substitution sigma) {
OpExp other = (OpExp) super.apply(sigma);
return other.isEvaluable() ? other.evaluate() : other;
}
/**
* Returns <code>true</code> if this arithmetic function is evaluable.
* Specially, an arithmetic function is evaluable if it is gound and its
* arguments are recursively either a number either a aritmetic function.
*
* @return <code>true</code> if this arithmetic function is evaluable;
* <code>false</code> otherwise.
*/
public final boolean isEvaluable() {
boolean evaluable = this.isGround();
Iterator<Term> i = this.iterator();
while (i.hasNext() && evaluable) {
Term arg = i.next();
if (arg.getTermID().equals(TermID.ARITHMETIC_FUNCTION)) {
OpExp func = (OpExp) arg;
evaluable = func.isEvaluable();
} else if (arg.getTermID().equals(TermID.NUMBER)) {
evaluable = true;
} else {
evaluable = false;
}
}
return evaluable;
}
/**
* Evaluates this arithmetic expression.
*
* @return the result of the evaluation.
* @throws EvaluationException if the arithemtic expression is not ground or
* if an numeric error occurs during the evaluation of an
* numeric error.
*/
public abstract Number evaluate() throws EvaluationException;
}
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