/*
 * Copyright 2010 NCHOVY
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.krakenapps.bnf;

import java.text.ParseException;

public class UnsignedIntegerPlaceholder implements Placeholder {
	@Override
	public Result eval(String text, int position, ParserContext ctx) throws ParseException {
		int begin = StringUtil.skipSpaces(text, position);
		int i = begin;

		while (i < text.length() && isNumber(text.charAt(i)))
			i++;

		if (begin == i)
			throw new ParseException("empty literal", i);

		String token = text.substring(begin, i);
		return new Result(new Binding(this, Integer.valueOf(token)), i);
	}

	private boolean isNumber(char c) {
		return c >= '0' && c <= '9';
	}

	@Override
	public String toString() {
		return "intvar";
	}

}