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1
21
24 package org.lobobrowser.util;
25
26 import java.util.*;
27
28
31 public class History implements java.io.Serializable  {
32 private static final long serialVersionUID = 2257845000800300100L;
33
34 private transient ArrayList historySequence;
35
36 private final SortedSet historySortedSet = new TreeSet();
37 private final Map historyMap = new HashMap();
38 private final SortedSet historyTimedSet = new TreeSet();
39
40 private int sequenceCapacity;
41 private int commonEntriesCapacity;
42
43 private transient int sequenceIndex;
44
45
49 public History(int sequenceCapacity, int commonEntriesCapacity) {
50 super();
51 this.historySequence = new ArrayList();
52 this.sequenceIndex = -1;
53 this.sequenceCapacity = sequenceCapacity;
54 this.commonEntriesCapacity = commonEntriesCapacity;
55 }
56
57 private void readObject(java.io.ObjectInputStream in) throws ClassNotFoundException , java.io.IOException {
58 this.historySequence = new ArrayList();
59 this.sequenceIndex = -1;
60 in.defaultReadObject();
61 }
62
63
66 public int getCommonEntriesCapacity() {
67 return commonEntriesCapacity;
68 }
69
70
73 public void setCommonEntriesCapacity(int commonEntriesCapacity) {
74 this.commonEntriesCapacity = commonEntriesCapacity;
75 }
76
79 public int getSequenceCapacity() {
80 return sequenceCapacity;
81 }
82
85 public void setSequenceCapacity(int sequenceCapacity) {
86 this.sequenceCapacity = sequenceCapacity;
87 }
88
89 public String getCurrentItem() {
90 if(this.sequenceIndex >= 0) {
91 return (String ) this.historySequence.get(this.sequenceIndex);
92 }
93 else {
94 return null;
95 }
96 }
97
98 public String back() {
99 if(this.sequenceIndex > 0) {
100 this.sequenceIndex--;
101 return this.getCurrentItem();
102 }
103 else {
104 return null;
105 }
106 }
107
108 public String forward() {
109 if(this.sequenceIndex + 1 < this.historySequence.size()) {
110 this.sequenceIndex++;
111 return this.getCurrentItem();
112 }
113 else {
114 return null;
115 }
116 }
117
118 public Collection getRecentItems(int maxNumItems) {
119 Collection items = new LinkedList();
120 Iterator i = this.historyTimedSet.iterator();
121 int count = 0;
122 while(i.hasNext() && count++ < maxNumItems) {
123 TimedEntry entry = (TimedEntry) i.next();
124 items.add(entry.value);
125 }
126 return items;
127 }
128
129 public Collection getHeadMatchItems(String item, int maxNumItems) {
130 Object [] array = this.historySortedSet.toArray();
131 int idx = Arrays.binarySearch(array, item);
132 int startIdx = idx >= 0 ? idx : (-idx - 1);
133 int count = 0;
134 Collection items = new LinkedList();
135 for(int i = startIdx; i < array.length && (count++ < maxNumItems); i++) {
136 String potentialItem = (String ) array[i];
137 if(potentialItem.startsWith(item)) {
138 items.add(potentialItem);
139 }
140 else {
141 break;
142 }
143 }
144 return items;
145 }
146
147 public void addAsRecentOnly(String item) {
148 TimedEntry entry = (TimedEntry) this.historyMap.get(item);
149 if(entry != null) {
150 this.historyTimedSet.remove(entry);
151 entry.touch();
152 this.historyTimedSet.add(entry);
153 }
154 else {
155 entry = new TimedEntry(item);
156 this.historyTimedSet.add(entry);
157 this.historyMap.put(item, entry);
158 this.historySortedSet.add(item);
159 if(this.historyTimedSet.size() > this.commonEntriesCapacity) {
160 TimedEntry entryToRemove = (TimedEntry) this.historyTimedSet.last();
162 this.historyMap.remove(entryToRemove.value);
163 this.historySortedSet.remove(entryToRemove.value);
164 this.historyTimedSet.remove(entryToRemove);
165 }
166 }
167 }
168
169 public void addItem(String item, boolean updateAsRecent) {
170 int newIndex = this.sequenceIndex + 1;
171
172 while(newIndex >= this.historySequence.size()) {
173 this.historySequence.add(null);
174 }
175 this.historySequence.set(newIndex, item);
176 this.sequenceIndex = newIndex;
177
178 int expectedSize = newIndex + 1;
179 while(this.historySequence.size() > expectedSize) {
180 this.historySequence.remove(expectedSize);
181 }
182
183 while(this.historySequence.size() > this.sequenceCapacity) {
184 this.historySequence.remove(0);
185 this.sequenceIndex--;
186 }
187
188 if(updateAsRecent) {
189 this.addAsRecentOnly(item);
190 }
191 }
192
193 private class TimedEntry implements Comparable , java.io.Serializable {
194 private static final long serialVersionUID = 2257845000000000200L;
195 private long timestamp = System.currentTimeMillis();
196 private final String value;
197
198
201 public TimedEntry(String value) {
202 this.value = value;
203 }
204
205 public void touch() {
206 this.timestamp = System.currentTimeMillis();
207 }
208
209 public boolean equals(Object obj) {
210 TimedEntry other = (TimedEntry) obj;
211 return other.value.equals(this.value);
212 }
213
214
217 public int compareTo(Object arg0) {
218 if(this.equals(arg0)) {
219 return 0;
220 }
221 TimedEntry other = (TimedEntry) arg0;
222 long time1 = this.timestamp;
223 long time2 = other.timestamp;
224 if(time1 > time2) {
225 return -1;
227 }
228 else if(time2 > time1){
229 return +1;
230 }
231 else {
232 int diff = System.identityHashCode(this) - System.identityHashCode(other);
233 if(diff == 0) {
234 return +1;
235 }
236 return diff;
237 }
238 }
239 }
240
241 }
242 |
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