/**
* Copyright 2009 Google Inc.
*
* 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.waveprotocol.wave.model.adt.docbased;
import org.waveprotocol.wave.model.adt.ObservableMonotonicMap;
import org.waveprotocol.wave.model.document.util.DocumentEventRouter;
import org.waveprotocol.wave.model.util.Serializer;
/**
* Provides a map of keys to monotonically increasing values, as a region of a concurrent document.
*
* @param <E> document's element type
* @param <K> map key type
* @param <C> map value type (comparable)
*/
public class DocumentBasedMonotonicMap<E, K, C extends Comparable<C>>
extends AbstractDocumentBasedMap<E, K, C> implements ObservableMonotonicMap<K, C> {
/**
* Monotonicity enforcement. The entry parameter is ignored.
*
* @return true iff the new value is greater than the current value or null.
*/
@Override
protected boolean canReplace(E oldEntry, E newEntry, C currentValue, C value) {
if (currentValue == null || currentValue.compareTo(value) < 0) {
return true;
}
return false;
}
/** Do not alter the map for entries that would be rejected for non-monotonicity. */
@Override
protected boolean isRedundantPut(C currentValue, C newValue) {
if (currentValue == null) {
return newValue == null;
} else if (newValue != null) {
// Reject currentValue >= newValue.
return currentValue.compareTo(newValue) >= 0;
} else {
// This condition (currentValue not null, newValue is null) should only
// occur when the map is being deleted.
return false;
}
}
/**
* Creates a monotonic map.
*
* @param router router for the document holding the map state
* @param entryContainer element in which entry elements should be created
* @param keySerializer converter between strings and keys
* @param valueSerializer converter between strings and values
* @param entryTagName name to use for entry elements
* @param keyAttrName name to use for key attributes
* @param valueAttrName name to use for value attributes
* @param activeCleanUp if true, will delete observed redundant entries
*/
DocumentBasedMonotonicMap(DocumentEventRouter<? super E, E, ?> router,
E entryContainer, Serializer<K> keySerializer, Serializer<C> valueSerializer,
String entryTagName, String keyAttrName, String valueAttrName,
boolean activeCleanUp) {
super(router, entryContainer, keySerializer, valueSerializer, entryTagName, keyAttrName,
valueAttrName, activeCleanUp);
}
/**
* Creates a monotonic map.
*/
public static <E, K, C extends Comparable<C>> DocumentBasedMonotonicMap<E, K, C> create(
DocumentEventRouter<? super E, E, ?> router,
E entryContainer, Serializer<K> keySerializer, Serializer<C> valueSerializer,
String entryTagName, String keyAttrName, String valueAttrName) {
DocumentBasedMonotonicMap<E, K, C> map = new DocumentBasedMonotonicMap<E, K, C>(
router, entryContainer, keySerializer, valueSerializer,
entryTagName, keyAttrName, valueAttrName, true);
map.dispatchAndLoad();
return map;
}
}