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Diffstat (limited to 'common/plugins/org.eclipse.jpt.common.utility/src/org/eclipse/jpt/common/utility/internal/Bag.java')
| -rw-r--r-- | common/plugins/org.eclipse.jpt.common.utility/src/org/eclipse/jpt/common/utility/internal/Bag.java | 197 |
1 files changed, 0 insertions, 197 deletions
diff --git a/common/plugins/org.eclipse.jpt.common.utility/src/org/eclipse/jpt/common/utility/internal/Bag.java b/common/plugins/org.eclipse.jpt.common.utility/src/org/eclipse/jpt/common/utility/internal/Bag.java deleted file mode 100644 index 0cecf9718c..0000000000 --- a/common/plugins/org.eclipse.jpt.common.utility/src/org/eclipse/jpt/common/utility/internal/Bag.java +++ /dev/null @@ -1,197 +0,0 @@ -/******************************************************************************* - * Copyright (c) 2005, 2010 Oracle. All rights reserved. - * This program and the accompanying materials are made available under the - * terms of the Eclipse Public License v1.0, which accompanies this distribution - * and is available at http://www.eclipse.org/legal/epl-v10.html. - * - * Contributors: - * Oracle - initial API and implementation - ******************************************************************************/ -package org.eclipse.jpt.common.utility.internal; - -import java.io.Serializable; -import java.util.AbstractCollection; -import java.util.Iterator; -import org.eclipse.jpt.common.utility.internal.iterators.EmptyIterator; - -/** - * A collection that allows duplicate elements. - * <p> - * The <code>Bag</code> interface places additional stipulations, - * beyond those inherited from the {@link java.util.Collection} interface, - * on the contracts of the {@link #equals(Object)} and {@link #hashCode()} methods. - * - * @see HashBag - */ - -public interface Bag<E> extends java.util.Collection<E> { - - /** - * Compares the specified object with this bag for equality. Returns - * <code>true</code> if the specified object is also a bag, the two bags - * have the same size, and every member of the specified bag is - * contained in this bag with the same number of occurrences (or equivalently, - * every member of this bag is contained in the specified bag with the same - * number of occurrences). This definition ensures that the - * equals method works properly across different implementations of the - * bag interface. - */ - boolean equals(Object o); - - /** - * Returns the hash code value for this bag. The hash code of a bag is - * defined to be the sum of the hash codes of the elements in the bag, - * where the hashcode of a <code>null</code> element is defined to be zero. - * This ensures that <code>b1.equals(b2)</code> implies that - * <code>b1.hashCode() == b2.hashCode()</code> for any two bags - * <code>b1</code> and <code>b2</code>, as required by the general - * contract of the {@link Object#hashCode()} method. - */ - int hashCode(); - - /** - * Return the number of times the specified object occurs in the bag. - */ - int count(Object o); - - /** - * Add the specified object the specified number of times to the bag. - * Return whether the bag changed. - */ - boolean add(E o, int count); - - /** - * Remove the specified number of occurrences of the specified object - * from the bag. Return whether the bag changed. - */ - boolean remove(Object o, int count); - - /** - * Return an iterator that returns each item in the bag - * once and only once, irrespective of how many times - * the item was added to the bag. - */ - java.util.Iterator<E> uniqueIterator(); - - /** - * Return the number of unique items in the bag. - */ - int uniqueCount(); - - /** - * Return an iterator that returns an entry for each item in the bag - * once and only once, irrespective of how many times - * the item was added to the bag. The entry will indicate the item's - * count. - */ - java.util.Iterator<Entry<E>> entries(); - - - /** - * A bag entry (element-count pair). - * The {@link Bag#entries()} method returns an iterator whose - * elements are of this class. The <em>only</em> way to obtain a reference - * to a bag entry is from the iterator returned by this method. These - * <code>Bag.Entry</code> objects are valid <em>only</em> for the duration - * of the iteration; more formally, the behavior of a bag entry is - * undefined if the backing bag has been modified after the entry was - * returned by the iterator, except through the {@link #setCount(int)} - * operation on the bag entry. - */ - interface Entry<E> { - - /** - * Return the entry's element. - */ - E getElement(); - - /** - * Return entry's count; i.e. the number of times the entry's element - * occurs in the bag. - * @see Bag#count(Object) - */ - int getCount(); - - /** - * Set the entry's count; i.e. the number of times the entry's element - * occurs in the bag. The new count must be a positive number. - * Return the previous count of the entry's element. - * NB: Use {@link Iterator#remove()} to set the - * count to zero. - */ - int setCount(int count); - - /** - * Return whether the entry is equal to the specified object; - * i.e. the specified object is a <code>Bag.Entry</code> and its - * element and count are the same as the entry's. - */ - boolean equals(Object obj); - - /** - * Return the entry's hash code. - */ - int hashCode(); - - } - - - final class Empty<E> extends AbstractCollection<E> implements Bag<E>, Serializable { - @SuppressWarnings("rawtypes") - public static final Bag INSTANCE = new Empty(); - @SuppressWarnings("unchecked") - public static <T> Bag<T> instance() { - return INSTANCE; - } - // ensure single instance - private Empty() { - super(); - } - @Override - public Iterator<E> iterator() { - return EmptyIterator.instance(); - } - @Override - public int size() { - return 0; - } - public Iterator<E> uniqueIterator() { - return EmptyIterator.instance(); - } - public int uniqueCount() { - return 0; - } - public int count(Object o) { - return 0; - } - public Iterator<Bag.Entry<E>> entries() { - return EmptyIterator.instance(); - } - public boolean remove(Object o, int count) { - return false; - } - public boolean add(E o, int count) { - throw new UnsupportedOperationException(); - } - @Override - public boolean equals(Object o) { - if (o == this) { - return true; - } - if ( ! (o instanceof Bag<?>)) { - return false; - } - return ((Bag<?>) o).size() == 0; - } - @Override - public int hashCode() { - return 0; - } - private static final long serialVersionUID = 1L; - private Object readResolve() { - // replace this object with the singleton - return INSTANCE; - } - } - -} |