/**
* Copyright 2008 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.client.common.util;
import org.waveprotocol.wave.model.util.SimpleMap;
/**
* A partial ordered map interface
*
* @author danilatos@google.com (Daniel Danilatos)
*
* @param <K>
* @param <V>
*/
public interface SequenceMap<K, V> extends SimpleMap<K, V> {
/**
* @param key
* @return a SeqElement for the given key, allowing left/right traversal
* thereafter
*/
SequenceElement<V> getElement(K key);
/**
* @return First one, null if empty
*/
SequenceElement<V> getFirst();
/**
* @return Last one, null if empty
*/
SequenceElement<V> getLast();
/**
* SeqElements wrap, so this method is needed to tell if we are at the start
* of a sequence
*
* @param elt
* @return true if first
*/
boolean isFirst(SequenceElement<V> elt);
/**
* SeqElements wrap, so this method is needed to tell if we are at the end of
* a sequence
*
* @param elt
* @return true if last
*/
boolean isLast(SequenceElement<V> elt);
/**
* @param key
* @return node at or just before the key, or null if none before it. Note: if
* none before it, the last node would be its predecessor, but we use
* null to distinguish "before first" as opposed to "after last"
*/
SequenceElement<V> findBefore(K key);
}