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/**
 * 
 */
package stream.util;

import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.atomic.AtomicLong;

/**
 * @author chris
 * 
 */
public class MultiSet implements Set {

	final Map countMap = new LinkedHashMap();

	/**
	 * @see java.util.Set#add(java.lang.Object)
	 */
	@Override
	public boolean add(T arg0) {
		if (countMap.containsKey(arg0)) {
			countMap.get(arg0).incrementAndGet();
			return true;
		} else {
			countMap.put(arg0, new AtomicLong(1L));
			return false;
		}
	}

	/**
	 * @see java.util.Set#addAll(java.util.Collection)
	 */
	@Override
	public boolean addAll(Collection arg0) {
		boolean added = false;
		for (T obj : arg0) {
			added = add(obj) | added;
		}
		return added;
	}

	/**
	 * @see java.util.Set#clear()
	 */
	@Override
	public void clear() {
		countMap.clear();
	}

	/**
	 * @see java.util.Set#contains(java.lang.Object)
	 */
	@Override
	public boolean contains(Object arg0) {
		return countMap.containsKey(arg0);
	}

	/**
	 * @see java.util.Set#containsAll(java.util.Collection)
	 */
	@Override
	public boolean containsAll(Collection arg0) {

		for (Object o : arg0) {
			if (!countMap.containsKey(o))
				return false;
		}

		return true;
	}

	/**
	 * @see java.util.Set#isEmpty()
	 */
	@Override
	public boolean isEmpty() {
		return countMap.isEmpty();
	}

	/**
	 * @see java.util.Set#iterator()
	 */
	@Override
	public Iterator iterator() {
		return countMap.keySet().iterator();
	}

	/**
	 * @see java.util.Set#remove(java.lang.Object)
	 */
	@Override
	public boolean remove(Object arg0) {

		if (countMap.containsKey(arg0)) {
			long cnt = countMap.get(arg0).decrementAndGet();
			if (cnt < 1)
				countMap.remove(arg0);
			return true;
		}

		return false;
	}

	/**
	 * @see java.util.Set#removeAll(java.util.Collection)
	 */
	@Override
	public boolean removeAll(Collection arg0) {
		boolean removed = false;

		for (Object o : arg0) {
			removed = remove(o) | removed;
		}

		return removed;
	}

	/**
	 * @see java.util.Set#retainAll(java.util.Collection)
	 */
	@Override
	public boolean retainAll(Collection arg0) {
		boolean removed = false;
		Iterator it = countMap.keySet().iterator();
		while (it.hasNext()) {
			T obj = it.next();
			if (!arg0.contains(obj)) {
				it.remove();
				removed = true;
			}
		}

		return removed;
	}

	/**
	 * @see java.util.Set#size()
	 */
	@Override
	public int size() {
		return countMap.size();
	}

	/**
	 * @see java.util.Set#toArray()
	 */
	@Override
	public Object[] toArray() {
		int i = 0;
		Object[] result = new Object[countMap.size()];
		for (Object obj : countMap.keySet()) {
			result[i] = obj;
			i++;
		}

		return result;
	}

	/**
	 * @see java.util.Set#toArray(T[])
	 */
	@SuppressWarnings({ "unchecked", "hiding" })
	@Override
	public  T[] toArray(T[] arg0) {

		Iterator it = countMap.keySet().iterator();
		for (int i = 0; i < arg0.length && i < countMap.size(); i++) {
			T obj = (T) it.next();
			arg0[i] = obj;
		}

		return arg0;
	}
	
	public int count( T arg0 ){
		if( countMap.containsKey( arg0 ) )
			return countMap.get( arg0 ).intValue();
		return 0;
	}
}