AbstractObjectSet.java 

/*
 * Copyright (c) 2006, Regents of the University of California
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in
 *   the documentation and/or other materials provided with the
 *   distribution.  
 *
 * * Neither the name of the University of California, Berkeley nor
 *   the names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior 
 *   written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package blog;

import java.util.*;
Abstract implementation of the ObjectSet interface. It includes protected methods isEmptyInternal, sizeInternal, and containsInternal that return Boolean and Integer objects rather than primitive data types. Null return values indicate that the corresponding Set interface method should throw an IllegalStateException and the corresponding canDetermine method should return false. 


public abstract class AbstractObjectSet extends AbstractSet 
                                        implements ObjectSet {
    public boolean isEmpty() {
	Boolean isEmpty = isEmptyInternal();
	if (isEmpty == null) {
	    throw new IllegalArgumentException
		("Underlying partial world is not complete enough to "
		 + "determine if set is empty: " + this);
	}
	return isEmpty.booleanValue();
    }

    public boolean canDetermineIsEmpty() {
	return (isEmptyInternal() != null);
    }

    public int size() {
	Integer size = sizeInternal();
	if (size == null) {
	    throw new IllegalArgumentException
		("Underlying partial world is not complete enough to "
		 + "determine size of set: " + this);
	}
	return size.intValue();
    }

    public boolean canDetermineSize() {
	return (sizeInternal() != null);
    }
    
    public boolean contains(Object obj) {
	Boolean result = containsInternal(obj);
	if (result == null) {
	    throw new IllegalArgumentException
		("Underlying partial world is not complete enough to "
		 + "determine whether " + obj + " is in set: " + this);
	}
	return result.booleanValue();
    }

    public boolean canDetermineContains(Object obj) {
	return (containsInternal(obj) != null);
    }
Returns the iterator obtained by calling iterator(Collections.EMPTY_SET): that is, an iterator that recognizes no externally distinguished objects. 


    public Iterator iterator() {
	return iterator(Collections.EMPTY_SET);
    }

    public boolean canDetermineElements() {
	return (getExplicitVersion() != null);
    }
Returns Boolean.TRUE if this set is empty, Boolean.FALSE if it is not empty, and null if the underlying partial world is not complete enough to determine whether the set is empty.

The default implementation just uses the result of sizeInternal. 


    protected Boolean isEmptyInternal() {
	Integer n = sizeInternal();
	if (n == null) {
	    return null;
	}
	return Boolean.valueOf(n.intValue() == 0);
    }
Returns the size of this set, or null if the underlying partial world is not complete enough to determine the size. 


    protected abstract Integer sizeInternal();
Returns Boolean.TRUE if this set contains obj, Boolean.FALSE if this set does not contain obj, and null if the underlying partial world is not complete enough to make the distinction. 


    protected abstract Boolean containsInternal(Object obj);


    public static ObjectSet singleton(Object element) {
	return new SingletonSet(element);
    }

    private static class SingletonSet extends AbstractObjectSet {
	SingletonSet(Object element) {
	    this.element = element;
	}

	protected Integer sizeInternal() {
	    return new Integer(1);
	}

	protected Boolean containsInternal(Object o) {
	    return Boolean.valueOf(element.equals(o));
	}

	public ObjectSet getExplicitVersion() {
	    return this;
	}

	public ObjectIterator iterator(Set externallyDistinguished) {
	    return new DefaultObjectIterator
		(Collections.singleton(element).iterator());
	}

	public Object sample(int n) {
	    if (n == 0) {
		return element;
	    }
	    throw new IllegalArgumentException
		("Can't sample element " + n + " from singleton set.");
	}

	public int indexOf(Object o) {
	    if (element.equals(o)) {
		return 0;
	    }
	    return -1;
	}

	private Object element;
    }
}

This file was generated on Tue Jun 08 17:53:35 PDT 2010 from file AbstractObjectSet.java
by the ilog.language.tools.Hilite Java tool written by Hassan Aït-Kaci