001/* 002 * Copyright (C) 2008 The Guava Authors 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * http://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package com.google.common.collect.testing.features; 018 019import com.google.common.annotations.GwtCompatible; 020import com.google.common.collect.testing.Helpers; 021import java.lang.annotation.Inherited; 022import java.lang.annotation.Retention; 023import java.lang.annotation.RetentionPolicy; 024import java.util.Collection; 025import java.util.LinkedHashSet; 026import java.util.Set; 027import java.util.SortedSet; 028 029/** 030 * Optional features of classes derived from {@code Collection}. 031 * 032 * @author George van den Driessche 033 */ 034// Enum values use constructors with generic varargs. 035@SuppressWarnings("unchecked") 036@GwtCompatible 037public enum CollectionFeature implements Feature<Collection> { 038 /** 039 * The collection must not throw {@code NullPointerException} on calls such as {@code 040 * contains(null)} or {@code remove(null)}, but instead must return a simple {@code false}. 041 */ 042 ALLOWS_NULL_QUERIES, 043 ALLOWS_NULL_VALUES(ALLOWS_NULL_QUERIES), 044 045 /** 046 * Indicates that a collection disallows certain elements (other than {@code null}, whose validity 047 * as an element is indicated by the presence or absence of {@link #ALLOWS_NULL_VALUES}). From the 048 * documentation for {@link Collection}: 049 * 050 * <blockquote> 051 * 052 * "Some collection implementations have restrictions on the elements that they may contain. For 053 * example, some implementations prohibit null elements, and some have restrictions on the types 054 * of their elements." 055 * 056 * </blockquote> 057 */ 058 RESTRICTS_ELEMENTS, 059 060 /** 061 * Indicates that a collection has a well-defined ordering of its elements. The ordering may 062 * depend on the element values, such as a {@link SortedSet}, or on the insertion ordering, such 063 * as a {@link LinkedHashSet}. All list tests and sorted-collection tests automatically specify 064 * this feature. 065 */ 066 KNOWN_ORDER, 067 068 /** 069 * Indicates that a collection has a different {@link Object#toString} representation than most 070 * collections. If not specified, the collection tests will examine the value returned by {@link 071 * Object#toString}. 072 */ 073 NON_STANDARD_TOSTRING, 074 075 /** 076 * Indicates that the constructor or factory method of a collection, usually an immutable set, 077 * throws an {@link IllegalArgumentException} when presented with duplicate elements instead of 078 * collapsing them to a single element or including duplicate instances in the collection. 079 */ 080 REJECTS_DUPLICATES_AT_CREATION, 081 082 SUPPORTS_ADD, 083 SUPPORTS_REMOVE, 084 SUPPORTS_ITERATOR_REMOVE, 085 FAILS_FAST_ON_CONCURRENT_MODIFICATION, 086 087 /** 088 * Features supported by general-purpose collections - everything but {@link #RESTRICTS_ELEMENTS}. 089 * 090 * @see java.util.Collection the definition of general-purpose collections. 091 */ 092 GENERAL_PURPOSE(SUPPORTS_ADD, SUPPORTS_REMOVE, SUPPORTS_ITERATOR_REMOVE), 093 094 /** Features supported by collections where only removal is allowed. */ 095 REMOVE_OPERATIONS(SUPPORTS_REMOVE, SUPPORTS_ITERATOR_REMOVE), 096 097 SERIALIZABLE, 098 SERIALIZABLE_INCLUDING_VIEWS(SERIALIZABLE), 099 100 SUBSET_VIEW, 101 DESCENDING_VIEW, 102 103 /** 104 * For documenting collections that support no optional features, such as {@link 105 * java.util.Collections#emptySet} 106 */ 107 NONE; 108 109 private final Set<Feature<? super Collection>> implied; 110 111 CollectionFeature(Feature<? super Collection>... implied) { 112 this.implied = Helpers.copyToSet(implied); 113 } 114 115 @Override 116 public Set<Feature<? super Collection>> getImpliedFeatures() { 117 return implied; 118 } 119 120 @Retention(RetentionPolicy.RUNTIME) 121 @Inherited 122 @TesterAnnotation 123 public @interface Require { 124 CollectionFeature[] value() default {}; 125 126 CollectionFeature[] absent() default {}; 127 } 128}