org.apache.openjpa.util.CollectionChangeTrackerImpl Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.openjpa.util;
import java.util.ArrayList;
import java.util.Collection;
/**
* Default {@link CollectionChangeTracker}.
*
* @author Abe White
* @nojavadoc
*/
public class CollectionChangeTrackerImpl
extends AbstractChangeTracker
implements CollectionChangeTracker {
protected final Collection _coll;
protected final boolean _dups;
protected final boolean _order;
/**
* Constructor.
*
* @param coll the collection to delegate to
* @param dups true if the collection allows duplicates, false otherwise
* @param order true if the collection is ordered, false otherwise
*/
public CollectionChangeTrackerImpl(Collection coll, boolean dups,
boolean order,boolean autoOff) {
_coll = coll;
_dups = dups;
_order = order;
this.setAutoOff(autoOff);
}
/**
* Whether the underlying collection allows duplicates.
*/
public boolean allowsDuplicates() {
return _dups;
}
/**
* Whether the underlying collection is ordered.
*/
public boolean isOrdered() {
return _order;
}
public void added(Object elem) {
super.added(elem);
}
public void removed(Object elem) {
super.removed(elem);
}
protected int initialSequence() {
if (_order)
return _coll.size();
return super.initialSequence();
}
protected void add(Object elem) {
if (rem == null || !rem.remove(elem)) {
// after a point it's inefficient to keep tracking
if (getAutoOff()
&& getAdded().size() + getRemoved().size() >= _coll.size())
stopTracking();
else {
if (add == null) {
if (_dups || _order)
add = new ArrayList();
else
add = newSet();
}
add.add(elem);
}
} else if (_order)
stopTracking();
else {
if (change == null)
change = newSet();
change.add(elem);
}
}
protected void remove(Object elem) {
// if the collection contains multiple copies of the elem, we can't
// use change tracking because some back-ends can't just delete a
// single copy of a elem
if (_dups && getAutoOff() && _coll.contains(elem))
stopTracking();
else if (add == null || !add.remove(elem)) {
// after a point it's inefficient to keep tracking
if (getAutoOff()
&& getRemoved().size() + getAdded().size() >= _coll.size())
stopTracking();
else {
if (rem == null)
rem = newSet();
rem.add(elem);
}
}
}
protected void change(Object elem) {
throw new InternalException();
}
}