Application: gvSIG desktop

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

import java.lang.reflect.Field;

import org.apache.commons.lang3.Range;

import org.gvsig.expressionevaluator.AttributeHandler;

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

import org.gvsig.expressionevaluator.Function;

import org.gvsig.expressionevaluator.Interpreter;

import org.gvsig.expressionevaluator.spi.AbstractFunction;

import org.gvsig.tools.dynobject.DynObject;

public class GetattrFunction extends AbstractFunction {

    public GetattrFunction() {

        super(

                Function.GROUP_PROGRAMMING, 

                FUNCTION_GETATTR, 

                Range.is(2),

                null,

                null,

                null,

                null,

                true

        );

    }

    @Override

    public boolean allowConstantFolding() {

        return false;

    }

    @Override

    public Object call(Interpreter interpreter, Object[] args) throws Exception {

        Object obj = getObject(args, 0);

        String attrname = getStr(args,1);

        if( attrname == null ) {

            throw new NullPointerException("A attribute name was expected and a null was received");

        }

        if( obj==null ) {

            throw new NullPointerException("An object pointer was expected to access attribute "+attrname+" and a null was received");

        }

        Object value;

        if( obj instanceof DynObject ) {

            value = ((DynObject) obj).getDynValue(attrname);

        } else if( obj instanceof AttributeHandler ) {

            value = ((AttributeHandler) obj).get(attrname);

        } else {

            Class<?> theClass = obj.getClass();

            Field field = theClass.getField(attrname);

            value = field.get(obj);

        }

        return value;

    }

}