001 /*
002 * hammurapi-rules @mesopotamia.version@
003 * Hammurapi rules engine.
004 * Copyright (C) 2005 Hammurapi Group
005 *
006 * This program is free software; you can redistribute it and/or
007 * modify it under the terms of the GNU Lesser General Public
008 * License as published by the Free Software Foundation; either
009 * version 2 of the License, or (at your option) any later version.
010 *
011 * This program is distributed in the hope that it will be useful,
012 * but WITHOUT ANY WARRANTY; without even the implied warranty of
013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 * Lesser General Public License for more details.
015 *
016 * You should have received a copy of the GNU Lesser General Public
017 * License along with this library; if not, write to the Free Software
018 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
019 *
020 * URL: http://http://www.hammurapi.biz
021 * e-Mail: support@hammurapi.biz
022 */
023 package biz.hammurapi.rules;
024
025 import java.util.Collection;
026 import java.util.HashSet;
027 import java.util.Iterator;
028 import java.util.Set;
029
030 /**
031 * This class "maximizes knowledge", which means when more specific (superceding)
032 * conclusions are added to the set less specific are removed. Conclusions less specific than present in
033 * the set are not added at all.
034 * @author Pavel Vlasov
035 * @revision $Revision$
036 */
037 public class KnowledgeMaximizingSet implements Set {
038 private Collection master;
039
040 /**
041 * Adds object if collection doesn't contain equal or superceding object.
042 */
043 public boolean add(Object arg) {
044 if (arg instanceof Supercedable) {
045 Supercedable nc=(Supercedable) arg;
046 Iterator it=master.iterator();
047 while (it.hasNext()) {
048 Object o=it.next();
049 if (o instanceof Supercedable) {
050 Supercedable ec=(Supercedable) o;
051 if (ec.equals(nc) || ec.supercedes(nc)) {
052 return false;
053 }
054
055 if (nc.supercedes(ec)) {
056 it.remove();
057 break; // There can be only one existing object in the collection superceded by this one.
058 }
059 }
060 }
061 return master.add(arg);
062 }
063
064 return master.add(arg);
065 }
066
067 public boolean addAll(Collection arg) {
068 boolean ret=false;
069 Iterator it=arg.iterator();
070 while (it.hasNext()) {
071 ret = ret || add(it.next());
072 }
073 return ret;
074 }
075
076 public void clear() {
077 master.clear();
078 }
079
080 public boolean contains(Object arg0) {
081 return master.contains(arg0);
082 }
083
084 public boolean containsAll(Collection arg0) {
085 return master.containsAll(arg0);
086 }
087
088 public boolean equals(Object arg0) {
089 return master.equals(arg0);
090 }
091
092 public int hashCode() {
093 return master.hashCode();
094 }
095
096 public boolean isEmpty() {
097 return master.isEmpty();
098 }
099
100 public Iterator iterator() {
101 return master.iterator();
102 }
103
104 public boolean remove(Object arg0) {
105 return master.remove(arg0);
106 }
107
108 public boolean removeAll(Collection arg0) {
109 return master.removeAll(arg0);
110 }
111
112 public boolean retainAll(Collection arg0) {
113 return master.retainAll(arg0);
114 }
115
116 public int size() {
117 return master.size();
118 }
119
120 public Object[] toArray() {
121 return master.toArray();
122 }
123
124 public Object[] toArray(Object[] arg0) {
125 return master.toArray(arg0);
126 }
127
128 /**
129 * @param master Master collection
130 */
131 public KnowledgeMaximizingSet(Collection master) {
132 this.master=master;
133 }
134
135 /**
136 * Constructs new KnowledgeMaximizingSet with java.util.HashSet as master.
137 */
138 public KnowledgeMaximizingSet() {
139 this(new HashSet());
140 }
141
142 }