org.databene.commons.collection.CompressedIntSet Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of databene-commons Show documentation
'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.
There is a newer version: 1.0.11
Show newest version
/*
 * 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.collection;

import java.util.Iterator;
import java.util.TreeMap;
import java.util.Map.Entry;

/**
 * Collects int values in a compressed way.
 * Created: 05.10.2010 19:17:30
 * @since 0.5.4
 * @author Volker Bergmann
 */
public class CompressedIntSet {
	
	protected TreeMap numbers;
	protected long size;
	
	public CompressedIntSet() {
	    this.numbers = new TreeMap();
	    this.size = 0;
    }

	public void clear() {
		numbers.clear();
		this.size = 0;
    }
	
	public void addAll(int... numbers) {
		for (int number : numbers)
			add(number);
	}

	public void add(int i) {
		if (numbers.isEmpty()) {
			// if the set is empty, insert the number
			insertNumber(i);
			size = 1;
		} else {
			// search the highest entry which is less or equals to i
			Entry floorEntry = numbers.floorEntry(i);
			IntRange rangeBelow;
			if (floorEntry == null)
				extendRangeAboveOrInsertNumber(i); // no range below found, check above
			else {
				// check found range
				rangeBelow = floorEntry.getValue();
				if (rangeBelow.contains(i))
					return;
				if (rangeBelow.getMax() + 1 == i) {
					// extend found range if applicable
					rangeBelow.setMax(i);
					size++;
					// check if two adjacent ranges can be merged
				    IntRange upperNeighbor = numbers.get(i + 1);
				    if (upperNeighbor != null) {
				    	numbers.remove(i + 1);
				    	rangeBelow.setMax(upperNeighbor.getMax());
				    }
				} else
					extendRangeAboveOrInsertNumber(i);
			}
		}
    }

	private void extendRangeAboveOrInsertNumber(int i) {
	    IntRange rangeAbove = numbers.get(i + 1);
	    if (rangeAbove != null) {
	    	numbers.remove(i + 1);
	    	rangeAbove.setMin(i);
	    	numbers.put(i, rangeAbove);
	    } else
	        insertNumber(i);
	    size++;
    }

	private void insertNumber(int i) {
	    numbers.put(i, new IntRange(i, i));
    }

	public boolean contains(int i) {
		Entry floorEntry = numbers.floorEntry(i);
		return (floorEntry != null && floorEntry.getValue().contains(i));
    }

	public boolean remove(int i) {
		Entry floorEntry = numbers.floorEntry(i);
		if (floorEntry == null || !floorEntry.getValue().contains(i)) 
			return false;
		IntRange range = floorEntry.getValue();
		if (i == range.getMax() && range.getMax() > range.getMin()) {
			range.setMax(i - 1);
		} else if (i == range.getMin()) {
			numbers.remove(i);
			if (range.getMax() > i) {
				range.setMin(i + 1);
				numbers.put(i + 1, range);
			}
		} else {
			int max = range.getMax();
			range.setMax(i - 1);
			IntRange range2 = new IntRange(i + 1, max);
			numbers.put(i + 1, range2);
		}
		return true;
    }

	public boolean isEmpty() {
	    return numbers.isEmpty();
    }
	
	public long size() {
		return size;
	}
	
	public Iterator iterator() {
		return new CompressedSetIterator();
	}
	
	// java.lang.Object overrides --------------------------------------------------------------------------------------

	@Override
    public boolean equals(Object obj) {
	    if (this == obj)
		    return true;
	    if (obj == null || getClass() != obj.getClass())
		    return false;
	    CompressedIntSet that = (CompressedIntSet) obj;
	    return this.equals(that.numbers);
    }
	
    @Override
	public int hashCode() {
		return numbers.hashCode();
	}
    
	@Override
	public String toString() {
	    return numbers.values().toString();
	}
	
	
	
	// Iterator class --------------------------------------------------------------------------------------------------
	
	public class CompressedSetIterator implements Iterator {
    	
    	protected Iterator intRangeIterator;
    	protected IntRange currentIntRange;
    	protected Integer lastInt;
    	
    	protected CompressedSetIterator() {
    		intRangeIterator = numbers.values().iterator();
    		currentIntRange = null;
    		lastInt = null;
    	}

	    @Override
		public boolean hasNext() {
	    	if (currentIntRange == null) {
	    		if (intRangeIterator != null && intRangeIterator.hasNext()) {
	    			currentIntRange = intRangeIterator.next();
	    			lastInt = null;
	    			return true;
	    		} else {
	    			intRangeIterator = null;
	    			return false;
	    		}
	    	}
	    	return (lastInt == null || lastInt < currentIntRange.max);
	    }

	    @Override
		public Integer next() {
	    	if (intRangeIterator != null && currentIntRange == null) {
	    		if (intRangeIterator.hasNext()) {
	    			currentIntRange = intRangeIterator.next();
	    		} else {
	    			intRangeIterator = null;
	    			currentIntRange = null;
	    		}
	    	}
	    	if (intRangeIterator == null || currentIntRange == null)
    			throw new IllegalStateException("No 'next' value available. Check hasNext() before calling next().");
	    	lastInt = (lastInt != null ? ++lastInt : currentIntRange.min);
	    	if (lastInt == currentIntRange.max)
	    		currentIntRange = null;
	    	return lastInt;
	    }

	    @Override
		public void remove() {
	    	CompressedIntSet.this.remove(lastInt);
	    }
    }
	
}