001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
003// * distributed with this work for additional information regarding copyright ownership.  The ASF licenses this file        *
004// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
005// * with the License.  You may obtain a copy of the License at                                                              *
006// *                                                                                                                         *
007// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
008// *                                                                                                                         *
009// * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an  *
010// * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the License for the        *
011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.internal;
014
015import static org.apache.juneau.internal.ArrayUtils.*;
016import static org.apache.juneau.internal.ThrowableUtils.*;
017
018import java.lang.reflect.*;
019import java.util.*;
020
021import org.apache.juneau.*;
022
023/**
024 * An instance of a <c>Map</c> where the keys and values are simple arrays.
025 *
026 * <p>
027 * Typically more efficient than <c>HashMaps</c> for small maps (e.g. &lt;10 entries).
028 *
029 * <p>
030 * Does not support adding or removing entries.
031 *
032 * <p>
033 * Setting values overwrites the value on the underlying value array.
034 *
035 * @param <K> The key type.
036 * @param <V> The value type.
037 */
038public final class SimpleMap<K,V> extends AbstractMap<K,V> {
039
040   final K[] keys;
041   final V[] values;
042   final SimpleMapEntry[] entries;
043
044   /**
045    * Constructor.
046    *
047    * @param keys The map keys.  Must not be <jk>null</jk>.
048    * @param values The map values.  Must not be <jk>null</jk>.
049    */
050   @SuppressWarnings("unchecked")
051   public SimpleMap(K[] keys, V[] values) {
052      assertFieldNotNull(keys, "keys");
053      assertFieldNotNull(values, "values");
054      if (keys.length != values.length)
055         illegalArg("keys ''{0}'' and values ''{1}'' array lengths differ", keys.length, values.length);
056
057      this.keys = keys;
058      this.values = values;
059      entries = (SimpleMapEntry[]) Array.newInstance(SimpleMapEntry.class, keys.length);
060      for (int i = 0; i < keys.length; i++) {
061         if (keys[i] == null)
062            illegalArg("Keys array cannot contain a null value.");
063         entries[i] = new SimpleMapEntry(i);
064   }
065   }
066
067   @Override /* Map */
068   public Set<Map.Entry<K,V>> entrySet() {
069      return asSet(entries);
070   }
071
072   @Override /* Map */
073   public V get(Object key) {
074      for (int i = 0; i < keys.length; i++)
075         if (keys[i].equals(key))
076            return values[i];
077      return null;
078   }
079
080   @Override /* Map */
081   public Set<K> keySet() {
082      return asSet(keys);
083   }
084
085   @Override /* Map */
086   public V put(K key, V value) {
087      for (int i = 0; i < keys.length; i++) {
088         if (keys[i].equals(key)) {
089            V v = values[i];
090            values[i] = value;
091            return v;
092         }
093      }
094      throw new BasicIllegalArgumentException("No key ''{0}'' defined in map", key);
095   }
096
097   final class SimpleMapEntry implements Map.Entry<K,V> {
098
099      private int index;
100
101      SimpleMapEntry(int index) {
102         this.index = index;
103      }
104
105      @Override /* Map.Entry */
106      public K getKey() {
107         return keys[index];
108      }
109
110      @Override /* Map.Entry */
111      public V getValue() {
112         return values[index];
113      }
114
115      @Override /* Map.Entry */
116      public V setValue(V val) {
117         V v = values[index];
118         values[index] = val;
119         return v;
120      }
121   }
122}