NumberExpressionParser.java

package org.jtwig.parser.parboiled.expression;

import org.jtwig.model.expression.ConstantExpression;
import org.jtwig.parser.parboiled.ParserContext;
import org.jtwig.parser.parboiled.base.BasicParser;
import org.jtwig.parser.parboiled.base.PositionTrackerParser;
import org.parboiled.Rule;

import java.math.BigDecimal;

import static org.parboiled.Parboiled.createParser;

public class NumberExpressionParser extends ExpressionParser<ConstantExpression> {
    public NumberExpressionParser(ParserContext context) {
        super(NumberExpressionParser.class, context);

        createParser(NumberParser.class, context);
    }

    @Override
    public Rule ExpressionRule() {
        NumberParser numberParser = parserContext().parser(NumberParser.class);
        PositionTrackerParser positionTrackerParser = parserContext().parser(PositionTrackerParser.class);
        return Sequence(
                positionTrackerParser.PushPosition(),
                numberParser.NumberRule(),
                push(new ConstantExpression(positionTrackerParser.pop(1), numberParser.pop()))
        );
    }

    public static class NumberParser extends BasicParser<BigDecimal> {
        public NumberParser(ParserContext context) {
            super(NumberParser.class, context);
        }

        // [0-9]+(?:\.[0-9]+)?
        public Rule NumberRule() {
            return Sequence(
                    Sequence(
                            OneOrMore(CharRange('0', '9')),
                            Optional(Sequence(
                                    Ch('.'),
                                    OneOrMore(CharRange('0', '9'))
                            ))
                    ),
                    push(new BigDecimal(match()))
            );
        }
    }
}