jscl.text.PowerParser Maven / Gradle / Ivy

Go to download
package jscl.text;

import jscl.math.Generic;
import jscl.text.msg.Messages;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;

/**
 * User: serso
 * Date: 10/27/11
 * Time: 2:45 PM
 */
class PowerParser implements Parser {

	public static final Parser parser = new PowerParser();

	private PowerParser() {
	}

	@Nullable
	public Void parse(@Nonnull Parameters p, Generic previousSumElement) throws ParseException {
		int pos0 = p.getPosition().intValue();

		ParserUtils.skipWhitespaces(p);

		if (p.getPosition().intValue() < p.getExpression().length() && p.getExpression().charAt(p.getPosition().intValue()) == '^') {
			p.getPosition().increment();
		} else {
			if (isDoubleStar(p.getExpression(), p.getPosition())) {
				p.getPosition().increment();
				p.getPosition().increment();
			} else {
				ParserUtils.throwParseException(p, pos0, Messages.msg_10, '^', "**");
			}
		}

		return null;
	}

	private boolean isDoubleStar(@Nonnull String string, @Nonnull MutableInt position) {
		final int i = position.intValue();
		return i < string.length() && i + 1 < string.length() && string.charAt(i) == '*' && string.charAt(i + 1) == '*';
	}
}