/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses 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 org.apache.commons.collections4.map;

import java.util.Comparator;
import java.util.SortedMap;

import org.apache.commons.collections4.Factory;
import org.apache.commons.collections4.Transformer;

Decorates another SortedMap to create objects in the map on demand.
 When the LazyMap.get(Object) method is called with a key that does not exist in the map, the factory is used to create the object. The created object will be added to the map using the requested key. 

For instance:
Factory<Date> factory = new Factory<Date>() {
    public Date create() {
        return new Date();
    }
}
SortedMap<String, Date> lazy =
    LazySortedMap.lazySortedMap(new HashMap<String, Date>(), factory);
Date date = lazy.get("NOW");

After the above code is executed, date will refer to
a new Date instance. Furthermore, that Date
instance is mapped to the "NOW" key in the map.

Note that LazySortedMap is not synchronized and is not thread-safe. If you wish to use this map from multiple threads concurrently, you must use appropriate synchronization. The simplest approach is to wrap this map using Collections.synchronizedSortedMap. This class may throw exceptions when accessed by concurrent threads without synchronization. 

This class is Serializable from Commons Collections 3.1.
Type parameters:
<K> – the type of the keys in this map
<V> – the type of the values in this map
Since:
3.0/**
 * Decorates another <code>SortedMap</code> to create objects in the map on demand.
 * <p>
 * When the {@link #get(Object)} method is called with a key that does not
 * exist in the map, the factory is used to create the object. The created
 * object will be added to the map using the requested key.
 * <p>
 * For instance:
 * <pre>
 * Factory&lt;Date&gt; factory = new Factory&lt;Date&gt;() {
 *     public Date create() {
 *         return new Date();
 *     }
 * }
 * SortedMap&lt;String, Date&gt; lazy =
 *     LazySortedMap.lazySortedMap(new HashMap&lt;String, Date&gt;(), factory);
 * Date date = lazy.get("NOW");
 * </pre>
 *
 * After the above code is executed, <code>date</code> will refer to
 * a new <code>Date</code> instance. Furthermore, that <code>Date</code>
 * instance is mapped to the "NOW" key in the map.
 * <p>
 * <strong>Note that LazySortedMap is not synchronized and is not thread-safe.</strong>
 * If you wish to use this map from multiple threads concurrently, you must use
 * appropriate synchronization. The simplest approach is to wrap this map
 * using {@link java.util.Collections#synchronizedSortedMap}. This class may throw
 * exceptions when accessed by concurrent threads without synchronization.
 * <p>
 * This class is Serializable from Commons Collections 3.1.
 *
 * @param <K> the type of the keys in this map
 * @param <V> the type of the values in this map
 * @since 3.0
 */
public class LazySortedMap<K,V> extends LazyMap<K,V> implements SortedMap<K,V> {

    
Serialization version /** Serialization version */
    private static final long serialVersionUID = 2715322183617658933L;

    
Factory method to create a lazily instantiated sorted map.
Params:
map –  the map to decorate, must not be null
factory –  the factory to use, must not be null
Type parameters:
<K> –  the key type
<V> –  the value type
Throws:
NullPointerException – if map or factory is null
Returns:
a new lazy sorted map
Since:
4.0/**
     * Factory method to create a lazily instantiated sorted map.
     *
     * @param <K>  the key type
     * @param <V>  the value type
     * @param map  the map to decorate, must not be null
     * @param factory  the factory to use, must not be null
     * @return a new lazy sorted map
     * @throws NullPointerException if map or factory is null
     * @since 4.0
     */
    public static <K, V> LazySortedMap<K, V> lazySortedMap(final SortedMap<K, V> map,
                                                           final Factory<? extends V> factory) {
        return new LazySortedMap<>(map, factory);
    }

    
Factory method to create a lazily instantiated sorted map.
Params:
map –  the map to decorate, must not be null
factory –  the factory to use, must not be null
Type parameters:
<K> –  the key type
<V> –  the value type
Throws:
NullPointerException – if map or factory is null
Returns:
a new lazy sorted map
Since:
4.0/**
     * Factory method to create a lazily instantiated sorted map.
     *
     * @param <K>  the key type
     * @param <V>  the value type
     * @param map  the map to decorate, must not be null
     * @param factory  the factory to use, must not be null
     * @return a new lazy sorted map
     * @throws NullPointerException if map or factory is null
     * @since 4.0
     */
    public static <K, V> LazySortedMap<K, V> lazySortedMap(final SortedMap<K, V> map,
                                                           final Transformer<? super K, ? extends V> factory) {
        return new LazySortedMap<>(map, factory);
    }

    //-----------------------------------------------------------------------
    
Constructor that wraps (not copies).
Params:
map –  the map to decorate, must not be null
factory –  the factory to use, must not be null
Throws:
NullPointerException – if map or factory is null/**
     * Constructor that wraps (not copies).
     *
     * @param map  the map to decorate, must not be null
     * @param factory  the factory to use, must not be null
     * @throws NullPointerException if map or factory is null
     */
    protected LazySortedMap(final SortedMap<K,V> map, final Factory<? extends V> factory) {
        super(map, factory);
    }

    
Constructor that wraps (not copies).
Params:
map –  the map to decorate, must not be null
factory –  the factory to use, must not be null
Throws:
NullPointerException – if map or factory is null/**
     * Constructor that wraps (not copies).
     *
     * @param map  the map to decorate, must not be null
     * @param factory  the factory to use, must not be null
     * @throws NullPointerException if map or factory is null
     */
    protected LazySortedMap(final SortedMap<K,V> map, final Transformer<? super K, ? extends V> factory) {
        super(map, factory);
    }

    //-----------------------------------------------------------------------
    
Gets the map being decorated.
Returns:
the decorated map/**
     * Gets the map being decorated.
     *
     * @return the decorated map
     */
    protected SortedMap<K,V> getSortedMap() {
        return (SortedMap<K,V>) map;
    }

    //-----------------------------------------------------------------------
    @Override
    public K firstKey() {
        return getSortedMap().firstKey();
    }

    @Override
    public K lastKey() {
        return getSortedMap().lastKey();
    }

    @Override
    public Comparator<? super K> comparator() {
        return getSortedMap().comparator();
    }

    @Override
    public SortedMap<K,V> subMap(final K fromKey, final K toKey) {
        final SortedMap<K,V> map = getSortedMap().subMap(fromKey, toKey);
        return new LazySortedMap<>(map, factory);
    }

    @Override
    public SortedMap<K,V> headMap(final K toKey) {
        final SortedMap<K,V> map = getSortedMap().headMap(toKey);
        return new LazySortedMap<>(map, factory);
    }

    @Override
    public SortedMap<K,V> tailMap(final K fromKey) {
        final SortedMap<K,V> map = getSortedMap().tailMap(fromKey);
        return new LazySortedMap<>(map, factory);
    }

}