Application: gvSIG desktop

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

import java.math.BigDecimal;

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

import org.gvsig.expressionevaluator.Function;

import org.gvsig.expressionevaluator.Interpreter;

public class NegOperator extends AbstractUnaryOperator {

    public NegOperator() {

        super(Function.GROUP_NUMERIC, OPERATOR_NEGATE, true);   

    }

    @Override

    public boolean allowConstantFolding() {

        return true;

    }

    @Override

    public Object call(Interpreter interpreter, Object arg) {

        if( !(arg instanceof Number) ) {

            throw new IllegalArgumentException("NEGATE function require a number");

        }

        return negate((Number) arg);

    }

    public static Number negate(Number n) {

        if( n instanceof Double ) {

          return -((Double)n);  

        } 

        if( n instanceof Float ) {

          return -((Float)n);  

        } 

        if( n instanceof Long ) {

          return -((Long)n);  

        } 

        if( n instanceof Integer ) {

          return -((Integer)n);  

        } 

        if( n instanceof BigDecimal ) {

          return ((BigDecimal)n).negate();  

        } 

        return -((Number)n).doubleValue();  

    }

}