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'databene commons' is an open source Java library by Volker Bergmann. It provides extensions to the Java core library by utility classes, abstract concepts and concrete implementations.

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/*
 * Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
 * All rights reserved.
 *
 * 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.databene.commons.math;

import java.text.ParsePosition;
import java.util.Comparator;

import org.databene.commons.ParseException;
import static org.databene.commons.ParseUtil.skipWhiteSpace;
import org.databene.commons.Parser;

/**
 * Parses an {@link Interval} generically using an endpoint parser and an endpoint comparator.
 * The endpoint parser has to be able to parse the interval endpoint values.
 * Created: 10.03.2011 15:33:01
 * @param  the type of the bounds that define the interval
 * @since 0.5.8
 * @author Volker Bergmann
 */
public class IntervalParser extends Parser> {

	private Parser endpointParser;
	private Comparator endpointComparator;

	public static  Interval parse(String text, Parser endpointParser, Comparator endpointComparator) {
		return new IntervalParser(endpointParser, endpointComparator).parseObject(text, new ParsePosition(0));
	}
	
	public IntervalParser(Parser endPointParser, Comparator endpointComparator) {
		this.endpointParser = endPointParser;
		this.endpointComparator = endpointComparator;
	}

	@Override
	public Interval parseObject(String text, ParsePosition pos) throws ParseException {
		skipWhiteSpace(text, pos);

		// parse left bracket
		boolean minInclusive;
		char c = text.charAt(pos.getIndex());
		switch (c) {
			case '[' : minInclusive = true; break;
			case ']' : minInclusive = false; break;
			default  : throw new ParseException("Expected '[' or ']', found: " + c, text);
		}
		pos.setIndex(pos.getIndex() + 1);
		skipWhiteSpace(text, pos);
		
		// parse lower endpoint
		E min = endpointParser.parseObject(text, pos);
		skipWhiteSpace(text, pos);

		// parse comma
		c = text.charAt(pos.getIndex());
		if (c != ',')
			throw new ParseException("Expected ',', found '" + c + "'", text);
		pos.setIndex(pos.getIndex() + 1);
		skipWhiteSpace(text, pos);
		
		// parse upper endpoint
		E max = endpointParser.parseObject(text, pos);
		skipWhiteSpace(text, pos);
		
		// parse right bracket
		boolean maxInclusive;
		c = text.charAt(pos.getIndex());
		switch (c) {
			case ']' : maxInclusive = true; break;
			case '[' : maxInclusive = false; break;
			default  : throw new ParseException("Expected '[' or ']', found: " + c, text);
		}
		pos.setIndex(pos.getIndex() + 1);
		skipWhiteSpace(text, pos);
		
		return new Interval(min, minInclusive, max, maxInclusive, endpointComparator);
	}

}