001/*
002 * Copyright 2002-2018 the original author or 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 *      https://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 org.springframework.beans.factory.support;
018
019import java.util.LinkedHashSet;
020import java.util.Set;
021
022import org.springframework.beans.BeanMetadataElement;
023import org.springframework.beans.Mergeable;
024import org.springframework.lang.Nullable;
025
026/**
027 * Tag collection class used to hold managed Set values, which may
028 * include runtime bean references (to be resolved into bean objects).
029 *
030 * @author Juergen Hoeller
031 * @author Rob Harrop
032 * @since 21.01.2004
033 * @param <E> the element type
034 */
035@SuppressWarnings("serial")
036public class ManagedSet<E> extends LinkedHashSet<E> implements Mergeable, BeanMetadataElement {
037
038        @Nullable
039        private Object source;
040
041        @Nullable
042        private String elementTypeName;
043
044        private boolean mergeEnabled;
045
046
047        public ManagedSet() {
048        }
049
050        public ManagedSet(int initialCapacity) {
051                super(initialCapacity);
052        }
053
054
055        /**
056         * Set the configuration source {@code Object} for this metadata element.
057         * <p>The exact type of the object will depend on the configuration mechanism used.
058         */
059        public void setSource(@Nullable Object source) {
060                this.source = source;
061        }
062
063        @Override
064        @Nullable
065        public Object getSource() {
066                return this.source;
067        }
068
069        /**
070         * Set the default element type name (class name) to be used for this set.
071         */
072        public void setElementTypeName(@Nullable String elementTypeName) {
073                this.elementTypeName = elementTypeName;
074        }
075
076        /**
077         * Return the default element type name (class name) to be used for this set.
078         */
079        @Nullable
080        public String getElementTypeName() {
081                return this.elementTypeName;
082        }
083
084        /**
085         * Set whether merging should be enabled for this collection,
086         * in case of a 'parent' collection value being present.
087         */
088        public void setMergeEnabled(boolean mergeEnabled) {
089                this.mergeEnabled = mergeEnabled;
090        }
091
092        @Override
093        public boolean isMergeEnabled() {
094                return this.mergeEnabled;
095        }
096
097        @Override
098        @SuppressWarnings("unchecked")
099        public Set<E> merge(@Nullable Object parent) {
100                if (!this.mergeEnabled) {
101                        throw new IllegalStateException("Not allowed to merge when the 'mergeEnabled' property is set to 'false'");
102                }
103                if (parent == null) {
104                        return this;
105                }
106                if (!(parent instanceof Set)) {
107                        throw new IllegalArgumentException("Cannot merge with object of type [" + parent.getClass() + "]");
108                }
109                Set<E> merged = new ManagedSet<>();
110                merged.addAll((Set<E>) parent);
111                merged.addAll(this);
112                return merged;
113        }
114
115}