Application: gvSIG desktop

package org.gvsig.expressionevaluator.impl.function.operator;

import static org.gvsig.expressionevaluator.ExpressionBuilder.OPERATOR_NOT;

import org.gvsig.expressionevaluator.Function;

import org.gvsig.expressionevaluator.Interpreter;

public class NotOperator extends AbstractUnaryOperator {

    public NotOperator() {

        super(Function.GROUP_BOOLEAN, OPERATOR_NOT, true);

        this.addAlias("!");        

    }

    @Override

    public boolean allowConstantFolding() {

        return true;

    }

    @Override

    public Object call(Interpreter interpreter, Object arg) {

        if (arg==null) {

            return null;

        }

        if( ! (arg instanceof Boolean) ) {

            throw new IllegalArgumentException("NOT operator require a boolean");

        }

        return !getBoolean(arg,1);

    }

}