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package org.modelmapper.internal.util;

import java.util.Collection;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;

/**
 * A thread-safe {@link LinkedHashMap} which creates a copy of the underlying map on write
 * operations.
 * 
 * 
 * Read operations, including iteration, do not interfere with writes since the underlying map is
 * never modified.
 * 
 * @author Jonathan Halterman
 */
public class CopyOnWriteLinkedHashMap implements Map {
  private volatile Map map;

  public CopyOnWriteLinkedHashMap() {
    map = new LinkedHashMap();
  }

  public CopyOnWriteLinkedHashMap(Map data) {
    map = new LinkedHashMap(data);
  }

  public synchronized void clear() {
    map = new LinkedHashMap();
  }

  public boolean containsKey(Object key) {
    return map.containsKey(key);
  }

  public boolean containsValue(Object value) {
    return map.containsValue(value);
  }

  public Set> entrySet() {
    return map.entrySet();
  }

  public V get(Object key) {
    return map.get(key);
  }

  public boolean isEmpty() {
    return map.isEmpty();
  }

  public Set keySet() {
    return map.keySet();
  }

  public synchronized V put(K key, V value) {
    Map newMap = new LinkedHashMap(map);
    V previous = newMap.put(key, value);
    map = newMap;
    return previous;
  }

  public synchronized void putAll(Map newData) {
    Map newMap = new LinkedHashMap(map);
    newMap.putAll(newData);
    map = newMap;
  }

  public synchronized V remove(Object key) {
    Map newMap = new LinkedHashMap(map);
    V previous = newMap.remove(key);
    map = newMap;
    return previous;
  }

  public int size() {
    return map.size();
  }

  public Collection values() {
    return map.values();
  }
}