com.cedarsoftware.util.SealableMap Maven / Gradle / Ivy
package com.cedarsoftware.util;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Supplier;
/**
* SealableMap provides a Map or Map wrapper that can be 'sealed' and 'unsealed.' When sealed, the
* Map is mutable, when unsealed it is immutable (read-only). The view methods iterator(), keySet(),
* values(), and entrySet() return a view that honors the Supplier's sealed state. The sealed state
* can be changed as often as needed.
*
* NOTE: Please do not reformat this code as the current format makes it easy to see the overall structure.
*
* @author John DeRegnaucourt ([email protected])
*
* Copyright (c) Cedar Software LLC
*
* 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
*
* License
*
* 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.
*/
public class SealableMap implements Map {
private final Map map;
private final transient Supplier sealedSupplier;
/**
* Create a SealableMap. Since a Map is not supplied, this will use a ConcurrentHashMap internally. If you
* want a HashMap to be used internally, use the SealableMap constructor that takes a Map and pass it the
* instance you want it to wrap.
* @param sealedSupplier {@code Supplier} that returns 'true' to indicate sealed, 'false' for mutable.
*/
public SealableMap(Supplier sealedSupplier) {
this.sealedSupplier = sealedSupplier;
this.map = new ConcurrentHashMap<>();
}
/**
* Use this constructor to wrap a Map (any kind of Map) and make it a SealableMap. No duplicate of the Map is
* created and the original map is operated on directly if unsealed, or protected from changes if sealed.
* @param map Map instance to protect.
* @param sealedSupplier {@code Supplier} that returns 'true' to indicate sealed, 'false' for mutable.
*/
public SealableMap(Map map, Supplier sealedSupplier) {
this.sealedSupplier = sealedSupplier;
this.map = map;
}
private void throwIfSealed() {
if (sealedSupplier.get()) {
throw new UnsupportedOperationException("This map has been sealed and is now immutable");
}
}
// Immutable
public boolean equals(Object obj) { return map.equals(obj); }
public int hashCode() { return map.hashCode(); }
public String toString() { return map.toString(); }
public int size() { return map.size(); }
public boolean isEmpty() { return map.isEmpty(); }
public boolean containsKey(Object key) { return map.containsKey(key); }
public boolean containsValue(Object value) { return map.containsValue(value); }
public V get(Object key) { return map.get(key); }
public Set keySet() { return new SealableSet<>(map.keySet(), sealedSupplier); }
public Collection values() { return new SealableList<>(new ArrayList<>(map.values()), sealedSupplier); }
public Set> entrySet() { return new SealableSet<>(map.entrySet(), sealedSupplier); }
// Mutable
public V put(K key, V value) { throwIfSealed(); return map.put(key, value); }
public V remove(Object key) { throwIfSealed(); return map.remove(key); }
public void putAll(Map m) { throwIfSealed(); map.putAll(m); }
public void clear() { throwIfSealed(); map.clear(); }
}