package com.creativewidgetworks.goldparser.simple3.rulehandlers;
import java.math.BigDecimal;
import com.creativewidgetworks.goldparser.engine.ParserException;
import com.creativewidgetworks.goldparser.engine.Reduction;
import com.creativewidgetworks.goldparser.parser.ProcessRule;
import com.creativewidgetworks.goldparser.parser.Variable;
import com.creativewidgetworks.goldparser.parser.GOLDParser;
import com.creativewidgetworks.goldparser.simple3.Simple3;
@ProcessRule(rule="<Negate Exp> ::= - <Value>")
/**
* Rule handler for the negation rule.
*
* @author Ralph Iden (http://www.creativewidgetworks.com)
* @version 5.0.0
*/
public class Negation extends Reduction {
private GOLDParser theParser;
private Reduction valueToNegate;
public Negation(GOLDParser parser) {
theParser = parser;
Reduction reduction = parser.getCurrentReduction();
if (reduction != null) {
if (reduction.size() == 2) {
valueToNegate = reduction.get(1).asReduction();
} else {
parser.raiseParserException(Simple3.formatMessage("error.param_count", "2", String.valueOf(reduction.size())));
}
} else {
parser.raiseParserException(Simple3.formatMessage("error.no_reduction"));
}
}
@Override
public Variable getValue() throws ParserException {
BigDecimal bd = valueToNegate.getValue().asNumber();
if (bd == null) {
theParser.raiseParserException(Simple3.formatMessage("error.negation_number_expected"));
}
return new Variable(bd.negate());
}
}