/*
 * Copyright (c) 2008 Harold Cooper. All rights reserved.
 * Licensed under the MIT License.
 * See LICENSE file in the project root for full license information.
 */

package org.pcollections;

import java.util.Map;
import java.util.Map.Entry;

A static convenience class for creating efficient persistent maps.
This class simply creates HashPMaps backed by IntTreePMaps.
Author:
harold/**
 * A static convenience class for creating efficient persistent maps.
 *
 * <p>This class simply creates HashPMaps backed by IntTreePMaps.
 *
 * @author harold
 */
public final class HashTreePMap {
  // not instantiable (or subclassable):
  private HashTreePMap() {}

  private static final HashPMap<Object, Object> EMPTY =
      HashPMap.empty(IntTreePMap.<PSequence<Entry<Object, Object>>>empty());

  
Type parameters:
<K> – 
<V> – 
Returns:
an empty map/**
   * @param <K>
   * @param <V>
   * @return an empty map
   */
  @SuppressWarnings("unchecked")
  public static <K, V> HashPMap<K, V> empty() {
    return (HashPMap<K, V>) EMPTY;
  }

  
Params:
key – 
value – 
Type parameters:
<K> – 
<V> – 
Returns:
empty().plus(key, value)/**
   * @param <K>
   * @param <V>
   * @param key
   * @param value
   * @return empty().plus(key, value)
   */
  public static <K, V> HashPMap<K, V> singleton(final K key, final V value) {
    return HashTreePMap.<K, V>empty().plus(key, value);
  }

  
Params:
map – 
Type parameters:
<K> – 
<V> – 
Returns:
empty().plusAll(map)/**
   * @param <K>
   * @param <V>
   * @param map
   * @return empty().plusAll(map)
   */
  public static <K, V> HashPMap<K, V> from(final Map<? extends K, ? extends V> map) {
    return HashTreePMap.<K, V>empty().plusAll(map);
  }
}