jlibs.core.util.ContextMap Maven / Gradle / Ivy
/**
* Copyright 2015 Santhosh Kumar Tekuri
*
* The JLibs authors license 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 jlibs.core.util;
import java.util.*;
/**
* This class supports chaining of maps.
* If the entry is not found in current map, it will
* search in parent map
*
* @author Santhosh Kumar T
*/
public class ContextMap{
public ContextMap(){
this(null);
}
public ContextMap(ContextMap parent){
setParent(parent);
}
private ContextMap parent;
public ContextMap parent(){
return parent;
}
public void setParent(ContextMap parent){
this.parent = parent;
}
private Map map;
public Map map(){
return map;
}
protected Map createMap(){
return new HashMap();
}
@SuppressWarnings({"SuspiciousMethodCalls"})
public V get(Object key){
ContextMap cmap = this;
do{
if(cmap.map!=null){
V value = cmap.map.get(key);
if(value!=null)
return value;
}
cmap = cmap.parent;
}while(cmap!=null);
return null;
}
public void put(K key, V value){
if(map==null)
map = createMap();
map.put(key, value);
}
public void clear(){
if(map!=null)
map.clear();
}
public Iterator keys(){
Set set = new HashSet();
ContextMap cmap = this;
do{
if(cmap.map!=null)
set.addAll(cmap.map.keySet());
cmap = cmap.parent;
}while(cmap!=null);
return set.iterator();
}
}