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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.io.Serializable;
import java.util.Comparator;

import org.databene.commons.ComparableComparator;
import org.databene.commons.NullSafeComparator;

/**
 * Represents an interval between to endpoints. 
 * The endpoints can be of any class for which a {@link Comparator} can be provided.
 * Using the parameters {@link #minInclusive} and {@link #maxInclusive}, one can 
 * specify whether the interval shall contain the endpoint values themselves.
 * Created: 10.03.2011 15:20:36
 * @param  the type of the bounds that define the interval
 * @since 0.5.8
 * @author Volker Bergmann
 */
public class Interval implements Serializable {

	private static final long serialVersionUID = -5866553873478128132L;
	
	public final E min;
	public final boolean minInclusive;
	
	public final E max;
	public final boolean maxInclusive;
	
	public final Comparator comparator;

	public Interval(E min, boolean minInclusive, E max, boolean maxInclusive,
			Comparator comparator) {
		this.min = min;
		this.minInclusive = minInclusive;
		this.max = max;
		this.maxInclusive = maxInclusive;
		this.comparator = comparator;
	}
	
	public static > Interval createClosedInterval(T min, T max) {
		return new Interval(min, true, max, true, new ComparableComparator());
	}
	
	public E getMin() {
		return min;
	}
	
	public boolean isMinInclusive() {
		return minInclusive;
	}
	
	public E getMax() {
		return max;
	}
	
	public boolean isMaxInclusive() {
		return maxInclusive;
	}
	
	public static  Interval createInfiniteInterval() {
		return new Interval(null, false, null, false, null);
	}

	public boolean contains(E x) {
		if (min != null) {
			int minComp = comparator.compare(min, x);
			if (minComp > 0 || (!minInclusive && minComp == 0))
				return false;
		}
		if (max == null)
			return true;
		int maxComp = comparator.compare(x, max);
		return (maxComp < 0 || (maxInclusive && maxComp == 0));
	}
	
	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + ((max == null) ? 0 : max.hashCode());
		result = prime * result + (maxInclusive ? 1231 : 1237);
		result = prime * result + ((min == null) ? 0 : min.hashCode());
		result = prime * result + (minInclusive ? 1231 : 1237);
		return result;
	}

	@Override
	public boolean equals(Object other) {
		if (this == other)
			return true;
		if (other == null || getClass() != other.getClass())
			return false;
		@SuppressWarnings("rawtypes")
		Interval that = (Interval) other;
		return 
			(NullSafeComparator.equals(this.min, that.min)
			&& this.minInclusive == that.minInclusive 
			&& NullSafeComparator.equals(this.max, that.max) 
			&& this.maxInclusive == that.maxInclusive);
	}

	@Override
	public String toString() {
		if (min != null && max != null && comparator.compare(min, max) == 0)
			return String.valueOf(min);
		else
			return (minInclusive ? '[' : ']') + String.valueOf(min) + ',' + String.valueOf(max) + (maxInclusive ? ']' : '[');
	}

}