/*
* #!
* Ontopia Engine
* #-
* Copyright (C) 2001 - 2013 The Ontopia Project
* #-
* 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 net.ontopia.utils;
import java.util.HashMap;
import java.util.Map;
/**
* INTERNAL: A lookup index that extends HashMap. It never forgets
* what it is told using put(), but will, if given a fallback object,
* ask the fallback for values it does not have.
*/
public class HashMapIndex<K, E> extends HashMap<K, E> implements LookupIndexIF<K, E> {
protected LookupIndexIF<K, E> fallback;
public HashMapIndex() {
}
public HashMapIndex(Map<K, E> map) {
super(map);
}
public HashMapIndex(LookupIndexIF<K, E> fallback) {
this.fallback = fallback;
}
public HashMapIndex(Map<K, E> map, LookupIndexIF<K, E> fallback) {
super(map);
this.fallback = fallback;
}
public E get(Object key) {
if (containsKey(key))
return super.get(key);
else if (fallback != null)
return fallback.get((K)key);
return null;
}
}