1/* 2 * Copyright (C) 2013 The Guava Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package com.google.common.collect; 18 19import static com.google.common.collect.CollectPreconditions.checkEntryNotNull; 20 21import com.google.common.annotations.GwtIncompatible; 22 23import javax.annotation.Nullable; 24 25/** 26 * Implementation of {@code Map.Entry} for {@link ImmutableMap} that adds extra methods to traverse 27 * hash buckets for the key and the value. This allows reuse in {@link RegularImmutableMap} and 28 * {@link RegularImmutableBiMap}, which don't have to recopy the entries created by their 29 * {@code Builder} implementations. 30 * 31 * @author Louis Wasserman 32 */ 33@GwtIncompatible("unnecessary") 34abstract class ImmutableMapEntry<K, V> extends ImmutableEntry<K, V> { 35 ImmutableMapEntry(K key, V value) { 36 super(key, value); 37 checkEntryNotNull(key, value); 38 } 39 40 ImmutableMapEntry(ImmutableMapEntry<K, V> contents) { 41 super(contents.getKey(), contents.getValue()); 42 // null check would be redundant 43 } 44 45 @Nullable 46 abstract ImmutableMapEntry<K, V> getNextInKeyBucket(); 47 48 @Nullable 49 abstract ImmutableMapEntry<K, V> getNextInValueBucket(); 50 51 static final class TerminalEntry<K, V> extends ImmutableMapEntry<K, V> { 52 TerminalEntry(ImmutableMapEntry<K, V> contents) { 53 super(contents); 54 } 55 56 TerminalEntry(K key, V value) { 57 super(key, value); 58 } 59 60 @Override 61 @Nullable 62 ImmutableMapEntry<K, V> getNextInKeyBucket() { 63 return null; 64 } 65 66 @Override 67 @Nullable 68 ImmutableMapEntry<K, V> getNextInValueBucket() { 69 return null; 70 } 71 } 72} 73