Application: gvSIG desktop

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

import java.util.Objects;

import org.apache.commons.lang3.StringUtils;

import org.gvsig.expressionevaluator.Code;

import org.gvsig.expressionevaluator.Code.Constant;

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

import org.gvsig.expressionevaluator.Function;

import org.gvsig.expressionevaluator.Interpreter;

import org.gvsig.expressionevaluator.Optimizer;

import org.gvsig.expressionevaluator.Optimizer.FunctionOptimizer;

import org.gvsig.expressionevaluator.Code.Callable;

public class ConcatOperator 

        extends AbstractBinaryOperator 

        implements FunctionOptimizer

    {

    public ConcatOperator() {

        super(Function.GROUP_STRING, OPERATOR_CONCAT, true);

    }

    @Override

    public boolean allowConstantFolding() {

        return true;

    }

    @Override

    public Object call(Interpreter interpreter, Object op1, Object op2) {

        if (op1 == null || op2 == null) {

            return null;

        }

        return Objects.toString(op1, "")+Objects.toString(op2, "");

    }

    @Override

    public Code optimize(Optimizer optimizer, Callable caller) {

        Code op1 = optimizer.optimize(caller.parameters().get(0));

        Code op2 = optimizer.optimize(caller.parameters().get(1));

        if ( op1.code() == Code.CONSTANT && op2.code() == Code.CONSTANT) {

            Code newCode = optimizer.getCodeBuilder().constant(

                    call(

                            optimizer.getInterpreter(), 

                            ((Constant)op1).value(), 

                            ((Constant)op2).value()

                    )

            );

            return newCode;

        } else if ( op1.code() == Code.CONSTANT ) {

            String value = Objects.toString(((Constant)op1).value(), "");

            if( StringUtils.isBlank(value) ) {

                return op2;

            }

            Code newCode = optimizer.getCodeBuilder().operator(caller.name(), op1, op2);

            return newCode;

        } else if ( op2.code() == Code.CONSTANT ) {

            String value = Objects.toString(((Constant)op2).value(), "");

            if( StringUtils.isBlank(value) ) {

                return op1;

            }

            Code newCode = optimizer.getCodeBuilder().operator(caller.name(), op1, op2);

            return newCode;

        }

        return caller;

    }

}