| /* |
| * 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.openjpa.persistence.graph; |
| |
| import java.util.HashSet; |
| import java.util.Iterator; |
| import java.util.Set; |
| |
| import javax.persistence.CascadeType; |
| import javax.persistence.Entity; |
| import javax.persistence.OneToMany; |
| |
| /** |
| * RelationGraph is a first-class persistent entity that express its persistent state as a set of |
| * {@link Relation persistent relations}. |
| * |
| * @author Pinaki Poddar |
| * |
| */ |
| |
| @Entity |
| public class RelationGraph<E> extends PersistentGraph<E> { |
| private static final long serialVersionUID = 1L; |
| @OneToMany(cascade={CascadeType.PERSIST,CascadeType.MERGE, CascadeType.DETACH, CascadeType.REFRESH}) |
| private Set<PersistentRelation<E,E>> relations = new HashSet<>(); |
| |
| /* |
| * Links the given vertices, unless they are already connected. |
| * |
| * @param source non-null source vertex |
| * @param target non-null target vertex |
| * |
| * @see org.apache.openjpa.persistence.graph.Graph#link(V1, V2) |
| */ |
| @Override |
| public <V1 extends E,V2 extends E> Relation<V1,V2> link(V1 source, V2 target) { |
| if (source == null) |
| throw new NullPointerException("Can not link from a null source vertex"); |
| if (target == null) |
| throw new NullPointerException("Can not link to a null target vertex"); |
| |
| Relation<V1,V2> r = getRelation(source, target); |
| if (r == null) { |
| r = new PersistentRelation<>(source, target); |
| relations.add((PersistentRelation<E, E>) r); |
| } |
| return r; |
| |
| } |
| |
| /* |
| * Delinks the given vertices, if they are currently connected. |
| * |
| * |
| * @see org.apache.openjpa.persistence.graph.Graph#delink(V1, V2) |
| */ |
| @Override |
| public <V1 extends E,V2 extends E> Relation<V1,V2> delink(V1 source, V2 target) { |
| Relation<V1,V2> r = getRelation(source, target); |
| if (r != null) { |
| relations.remove(r); |
| } |
| return r; |
| |
| } |
| |
| /* |
| * Get the relation between the given vertex. |
| * |
| * @see org.apache.openjpa.persistence.graph2.Graph#getRelation(V1, V2) |
| */ |
| @Override |
| public <V1 extends E,V2 extends E> Relation<V1,V2> getRelation(V1 source, V2 target) { |
| for (Relation<?,?> r : relations) { |
| if (r.getSource().equals(source) && r.getTarget() != null && r.getTarget().equals(target)) { |
| return (Relation<V1,V2>)r; |
| } |
| } |
| return null; |
| } |
| |
| /** |
| * Iterator over the nodes of this graph. |
| */ |
| @Override |
| public Iterator<E> iterator() { |
| return getNodes().iterator(); |
| } |
| |
| @Override |
| public int size() { |
| return 0; |
| } |
| |
| @Override |
| public <V extends E> Set<Relation<V, E>> getRelationsFrom(V source) { |
| Set<Relation<V,E>> rs = new HashSet<>(); |
| for (Relation<E,E> r : relations) { |
| if (r.getSource().equals(source) && r.getTarget() != null) |
| rs.add((Relation<V,E>)r); |
| } |
| return rs; |
| } |
| |
| @Override |
| public <V extends E> Set<Relation<E, V>> getRelationsTo(V target) { |
| Set<Relation<E, V>> rs = new HashSet<>(); |
| for (Relation<?,?> r : relations) { |
| if (r.getTarget() != null && r.getTarget().equals(target)) |
| rs.add((Relation<E, V>)r); |
| } |
| return rs; |
| } |
| |
| @Override |
| public Set<E> getSources(Object target) { |
| Set<E> sources = new HashSet<>(); |
| for (Relation<E,E> r : relations) { |
| if (r.getTarget() != null && r.getTarget().equals(target)) |
| sources.add(r.getSource()); |
| } |
| return sources; |
| } |
| |
| @Override |
| public Set<E> getTargets(Object source) { |
| Set<E> targets = new HashSet<>(); |
| for (Relation<E,E> r : relations) { |
| if (r.getSource().equals(source) && r.getTarget() != null) |
| targets.add(r.getTarget()); |
| } |
| return targets; |
| } |
| |
| public Set<E> getNodes() { |
| Set all = new HashSet(); |
| for (Relation<?,?> r : relations) { |
| all.add(r.getSource()); |
| if (r.getTarget() != null) |
| all.add(r.getTarget()); |
| } |
| return all; |
| } |
| |
| @Override |
| public boolean add(E e) { |
| if (contains(e)) |
| return false; |
| relations.add(new PersistentRelation<>(e, null)); |
| return true; |
| } |
| } |