001 /**
002 * GRANITE DATA SERVICES
003 * Copyright (C) 2006-2013 GRANITE DATA SERVICES S.A.S.
004 *
005 * This file is part of the Granite Data Services Platform.
006 *
007 * Granite Data Services is free software; you can redistribute it and/or
008 * modify it under the terms of the GNU Lesser General Public
009 * License as published by the Free Software Foundation; either
010 * version 2.1 of the License, or (at your option) any later version.
011 *
012 * Granite Data Services is distributed in the hope that it will be useful,
013 * but WITHOUT ANY WARRANTY; without even the implied warranty of
014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
015 * General Public License for more details.
016 *
017 * You should have received a copy of the GNU Lesser General Public
018 * License along with this library; if not, write to the Free Software
019 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
020 * USA, or see <http://www.gnu.org/licenses/>.
021 */
022 package org.granite.tide.data;
023
024 import java.util.ArrayList;
025 import java.util.HashMap;
026 import java.util.List;
027 import java.util.Map;
028
029 public class DataUtils {
030
031 public static List<Object[]> diffLists(List<?> oldList, List<?> newList) {
032 ListDiff listDiff = new ListDiff(oldList, newList);
033 listDiff.diff();
034 return listDiff.getOps();
035 }
036
037 private static class ListDiff {
038
039 private final List<?> oldList;
040 private final List<?> newList;
041
042 private int oldi = 0, newi = 0;
043
044 private List<Object[]> ops = new ArrayList<Object[]>();
045
046 private List<Integer> skipOld = new ArrayList<Integer>();
047 private Map<Integer, Object[]> delayedNew = new HashMap<Integer, Object[]>();
048
049 public ListDiff(List<?> oldList, List<?> newList) {
050 this.oldList = oldList;
051 this.newList = newList;
052 }
053
054 public List<Object[]> getOps() {
055 return ops;
056 }
057
058 private void moveNew() {
059 newi++;
060 while (delayedNew.containsKey(newi)) {
061 for (Object op : delayedNew.get(newi))
062 ops.add((Object[])op);
063 newi++;
064 }
065 }
066
067 private int nextOld() {
068 int i = oldi+1;
069 while (skipOld.contains(i) && i < oldList.size())
070 i++;
071 return i;
072 }
073
074 private int nextNew() {
075 return newi+1;
076 }
077
078 private int getIndex(int index) {
079 for (Object[] op : ops) {
080 if (op[0].equals(-1) && (Integer)op[1] <= index)
081 index--;
082 else if (op[0].equals(1) && (Integer)op[1] <= index)
083 index++;
084 }
085 return index;
086 }
087
088 public void diff() {
089 for (oldi = 0; oldi < oldList.size(); oldi++) {
090 if (skipOld.contains(oldi))
091 continue;
092
093 // Same value for current indices on old and new : next and reset current offset
094 if (oldi < oldList.size() && newi < newList.size() && oldList.get(oldi).equals(newList.get(newi))) {
095 moveNew();
096 continue;
097 }
098
099 // Lookup same element in new list
100 int foundNext = -1;
101 if (newi < newList.size()-1) {
102 for (int i = newi+1; i < newList.size(); i++) {
103 if (newList.get(i).equals(oldList.get(oldi)) && !delayedNew.containsKey(i)) {
104 foundNext = i;
105 break;
106 }
107 }
108 }
109 if (foundNext == -1) {
110 int oi = nextOld();
111 int ni = nextNew();
112 if (oi < oldList.size() && ni < newList.size() && oldList.get(oi).equals(newList.get(ni))) {
113 // Element not found in new list but next one matches: update
114 ops.add(new Object[] { 0, getIndex(oldi), newList.get(newi) });
115 moveNew();
116 }
117 else {
118 // Element not found in new list: remove
119 ops.add(new Object[] { -1, getIndex(oldi), oldList.get(oldi) });
120 }
121 }
122 // else if (foundNext == newi+1 && oldi+1 < oldList.size() && oldList.get(oldi+1).equals(newList.get(newi))) {
123 // // Immediate permutation
124 // int index = getIndex(oldi);
125 // ops.add(new Object[] { -1, index, oldList.get(oldi) });
126 // ops.add(new Object[] { 1, index+1, oldList.get(oldi) });
127 // nextNew();
128 // nextNew();
129 // oldi++;
130 // }
131 // else if (foundNext > newi+1 && oldi+foundNext-newi < oldList.size() && oldList.get(oldi+foundNext-newi).equals(newList.get(newi))) {
132 // // Distant permutation
133 // int index = getIndex(oldi);
134 // Object p1 = oldList.get(oldi);
135 // Object p2 = newList.get(newi);
136 // ops.add(new Object[] { -1, index, p1 });
137 // ops.add(new Object[] { 1, index, p2 });
138 // skipOld.add(oldi+foundNext-newi);
139 // nextNew();
140 // delayedNew.put(foundNext, new Object[] { new Object[] { -1, foundNext, p2 }, new Object[] { 1, foundNext, p1 } });
141 // }
142 else if (oldi < oldList.size()-1 && oldList.get(oldi+1).equals(newList.get(newi))) {
143 // Move of element to another position, remove here and schedule an add for final position
144 ops.add(new Object[] { -1, getIndex(oldi), oldList.get(oldi) });
145 delayedNew.put(foundNext, new Object[] { new Object[] { 1, foundNext, oldList.get(oldi) } });
146 }
147 else {
148 // Add elements of new list from current index to found index
149 while (newi < foundNext) {
150 int foundOld = -1;
151 // Lookup if the element is present later in the old list
152 if (oldi < oldList.size()-1) {
153 for (int i = oldi+1; i < oldList.size(); i++) {
154 if (newList.get(newi).equals(oldList.get(i)) && !skipOld.contains(i)) {
155 foundOld = i;
156 break;
157 }
158 }
159 }
160 if (foundOld >= 0) {
161 // Found later, push a remove
162 ops.add(new Object[] { -1, getIndex(foundOld), oldList.get(foundOld) });
163 skipOld.add(foundOld);
164 }
165
166 ops.add(new Object[] { 1, newi, newList.get(newi) });
167 moveNew();
168 }
169 oldi--;
170 }
171 }
172 // Add missing elements from new list
173 while (newi < newList.size()) {
174 ops.add(new Object[] { 1, newi, newList.get(newi) });
175 moveNew();
176 }
177 }
178 }
179 }