com.creativewidgetworks.goldparser.simple2.rulehandlers.IfThenElse Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of goldengine Show documentation

Java implementation of Devin Cook's GOLD Parser engine

There is a newer version: 5.0.5

package com.creativewidgetworks.goldparser.simple2.rulehandlers;

import com.creativewidgetworks.goldparser.engine.ParserException;
import com.creativewidgetworks.goldparser.engine.Reduction;
import com.creativewidgetworks.goldparser.parser.GOLDParser;
import com.creativewidgetworks.goldparser.parser.ProcessRule;
import com.creativewidgetworks.goldparser.simple2.Simple2;

@ProcessRule(rule={
    " ::= if  then  end",
    " ::= if  then  else  end"
})

/**
 * Rule handler for the If-Then-Else rules.
 *
 * if  then 
 *   
 * end
 * 
 * if  then
 *   
 * else
 *   
 * end
 *
 * if  then
 *   
 * else if  then
 *   
 * else if ...
 *   
 * else
 *   
 * end end end ..
 *
 * @author Ralph Iden (http://www.creativewidgetworks.com)
 * @version 5.0.0 
 */
public class IfThenElse extends Reduction {
    private Reduction conditional;
    private Reduction thenStatements;
    private Reduction elseStatements;

    public IfThenElse(GOLDParser parser) {
        Reduction reduction = parser.getCurrentReduction();
        if (reduction != null) {
            if (reduction.size() == 5) {
                // if x then y end
                conditional    = reduction.get(1).asReduction();
                thenStatements = reduction.get(3).asReduction();                
            } else if (reduction.size() == 7) {
                // if x then y else z end
                conditional    = reduction.get(1).asReduction();
                thenStatements = reduction.get(3).asReduction(); 
                elseStatements = reduction.get(5).asReduction();
            } else {
                if (reduction.size() < 5) {
                    // if x then y form
                    parser.raiseParserException(Simple2.formatMessage("error.param_count", "5", String.valueOf(reduction.size())));
                }
                // if x then y else z end form
                parser.raiseParserException(Simple2.formatMessage("error.param_count", "7", String.valueOf(reduction.size())));
            }
        } else {
            parser.raiseParserException(Simple2.formatMessage("error.no_reduction"));
        }        
     }

    @Override
    public void execute() throws ParserException {
       if (conditional.getValue().asBool()) {
           thenStatements.execute();
       } else if (elseStatements != null) {
           elseStatements.execute();
       }
    }

}