1 | package de.ugoe.cs.eventbench.models;
|
---|
2 |
|
---|
3 | import java.io.Serializable;
|
---|
4 | import java.security.InvalidParameterException;
|
---|
5 | import java.util.Collection;
|
---|
6 | import java.util.LinkedList;
|
---|
7 | import java.util.List;
|
---|
8 |
|
---|
9 | import de.ugoe.cs.eventbench.models.Trie.Edge;
|
---|
10 | import de.ugoe.cs.eventbench.models.Trie.TrieVertex;
|
---|
11 | import de.ugoe.cs.util.StringTools;
|
---|
12 | import edu.uci.ics.jung.graph.DelegateTree;
|
---|
13 | import edu.uci.ics.jung.graph.Tree;
|
---|
14 |
|
---|
15 | /**
|
---|
16 | * <p>
|
---|
17 | * This class implements a node of a trie. Each node is associated with a symbol
|
---|
18 | * and has a counter. The counter marks the number of occurences of the sequence
|
---|
19 | * defined by the path from the root of the trie to this node.
|
---|
20 | * </p>
|
---|
21 | *
|
---|
22 | * @author Steffen Herbold
|
---|
23 | *
|
---|
24 | * @param <T>
|
---|
25 | * Type of the symbols that are stored in the trie.
|
---|
26 | * @see Trie
|
---|
27 | */
|
---|
28 | class TrieNode<T> implements Serializable {
|
---|
29 |
|
---|
30 | /**
|
---|
31 | * <p>
|
---|
32 | * Id for object serialization.
|
---|
33 | * </p>
|
---|
34 | */
|
---|
35 | private static final long serialVersionUID = 1L;
|
---|
36 |
|
---|
37 | /**
|
---|
38 | * <p>
|
---|
39 | * Counter for the number of occurences of the sequence.
|
---|
40 | * </p>
|
---|
41 | */
|
---|
42 | private int count;
|
---|
43 |
|
---|
44 | /**
|
---|
45 | * <p>
|
---|
46 | * Symbol associated with the node.
|
---|
47 | * </p>
|
---|
48 | */
|
---|
49 | private final T symbol;
|
---|
50 |
|
---|
51 | /**
|
---|
52 | * <p>
|
---|
53 | * Child nodes of this node. If the node is a leaf this collection is empty.
|
---|
54 | * </p>
|
---|
55 | */
|
---|
56 | private Collection<TrieNode<T>> children;
|
---|
57 |
|
---|
58 | /**
|
---|
59 | * <p>
|
---|
60 | * Constructor. Creates a new TrieNode without a symbol associated.<br>
|
---|
61 | * <b>This constructor should only be used to create the root node of the
|
---|
62 | * trie!</b>
|
---|
63 | * </p>
|
---|
64 | */
|
---|
65 | TrieNode() {
|
---|
66 | this.symbol = null;
|
---|
67 | count = 0;
|
---|
68 | children = new LinkedList<TrieNode<T>>();
|
---|
69 | }
|
---|
70 |
|
---|
71 | /**
|
---|
72 | * <p>
|
---|
73 | * Constructor. Creates a new TrieNode. The symbol must not be null.
|
---|
74 | * </p>
|
---|
75 | *
|
---|
76 | * @param symbol
|
---|
77 | * symbol associated with the trie node
|
---|
78 | */
|
---|
79 | public TrieNode(T symbol) {
|
---|
80 | if (symbol == null) {
|
---|
81 | throw new InvalidParameterException(
|
---|
82 | "symbol must not be null. null is reserved for root node!");
|
---|
83 | }
|
---|
84 | this.symbol = symbol;
|
---|
85 | count = 0;
|
---|
86 | children = new LinkedList<TrieNode<T>>();
|
---|
87 | }
|
---|
88 |
|
---|
89 | /**
|
---|
90 | * <p>
|
---|
91 | * Adds a given subsequence to the trie and increases the counters
|
---|
92 | * accordingly.
|
---|
93 | * </p>
|
---|
94 | *
|
---|
95 | * @param subsequence
|
---|
96 | * subsequence whose counters are increased
|
---|
97 | * @see Trie#add(List)
|
---|
98 | */
|
---|
99 | public void add(List<T> subsequence) {
|
---|
100 | if (!subsequence.isEmpty()) {
|
---|
101 | if (!symbol.equals(subsequence.get(0))) { // should be guaranteed by
|
---|
102 | // the
|
---|
103 | // recursion/TrieRoot!
|
---|
104 | throw new AssertionError("Invalid trie operation!");
|
---|
105 | }
|
---|
106 | count++;
|
---|
107 | subsequence.remove(0);
|
---|
108 | if (!subsequence.isEmpty()) {
|
---|
109 | T nextSymbol = subsequence.get(0);
|
---|
110 | getChildCreate(nextSymbol).add(subsequence);
|
---|
111 | }
|
---|
112 | }
|
---|
113 | }
|
---|
114 |
|
---|
115 | /**
|
---|
116 | * <p>
|
---|
117 | * Returns the symbol associated with the node.
|
---|
118 | * </p>
|
---|
119 | *
|
---|
120 | * @return symbol associated with the node
|
---|
121 | */
|
---|
122 | public T getSymbol() {
|
---|
123 | return symbol;
|
---|
124 | }
|
---|
125 |
|
---|
126 | /**
|
---|
127 | * <p>
|
---|
128 | * Returns the number of occurences of the sequence represented by the node.
|
---|
129 | * </p>
|
---|
130 | *
|
---|
131 | * @return number of occurences of the sequence represented by the node
|
---|
132 | */
|
---|
133 | public int getCount() {
|
---|
134 | return count;
|
---|
135 | }
|
---|
136 |
|
---|
137 | /**
|
---|
138 | * <p>
|
---|
139 | * Returns the child of the node associated with the given symbol or creates
|
---|
140 | * it if it does not exist yet.
|
---|
141 | * </p>
|
---|
142 | *
|
---|
143 | * @param symbol
|
---|
144 | * symbol whose node is required
|
---|
145 | * @return node associated with the symbol
|
---|
146 | * @see Trie#getChildCreate(Object)
|
---|
147 | */
|
---|
148 | protected TrieNode<T> getChildCreate(T symbol) {
|
---|
149 | TrieNode<T> node = getChild(symbol);
|
---|
150 | if (node == null) {
|
---|
151 | node = new TrieNode<T>(symbol);
|
---|
152 | children.add(node);
|
---|
153 | }
|
---|
154 | return node;
|
---|
155 | }
|
---|
156 |
|
---|
157 | /**
|
---|
158 | * <p>
|
---|
159 | * Returns the child of the node associated with the given symbol or null if
|
---|
160 | * it does not exist.
|
---|
161 | * </p>
|
---|
162 | *
|
---|
163 | * @param symbol
|
---|
164 | * symbol whose node is required
|
---|
165 | * @return node associated with the symbol; null if no such node exists
|
---|
166 | * @see Trie#getChild(Object)
|
---|
167 | */
|
---|
168 | protected TrieNode<T> getChild(T symbol) {
|
---|
169 | for (TrieNode<T> child : children) {
|
---|
170 | if (child.getSymbol().equals(symbol)) {
|
---|
171 | return child;
|
---|
172 | }
|
---|
173 | }
|
---|
174 | return null;
|
---|
175 | }
|
---|
176 |
|
---|
177 | /**
|
---|
178 | * <p>
|
---|
179 | * Searches the sub-trie of this trie node for a given sequence and returns
|
---|
180 | * the node associated with the sequence or null if no such node is found.
|
---|
181 | * </p>
|
---|
182 | *
|
---|
183 | * @param sequence
|
---|
184 | * sequence that is searched for
|
---|
185 | * @return node associated with the sequence
|
---|
186 | * @see Trie#find(List)
|
---|
187 | */
|
---|
188 | public TrieNode<T> find(List<T> subsequence) {
|
---|
189 | TrieNode<T> result = null;
|
---|
190 | if (subsequence.isEmpty()) {
|
---|
191 | result = this;
|
---|
192 | } else {
|
---|
193 | TrieNode<T> node = getChild(subsequence.get(0));
|
---|
194 | if (node != null) {
|
---|
195 | subsequence.remove(0);
|
---|
196 | result = node.find(subsequence);
|
---|
197 | }
|
---|
198 | }
|
---|
199 | return result;
|
---|
200 | }
|
---|
201 |
|
---|
202 | /**
|
---|
203 | * <p>
|
---|
204 | * Returns a collection of all symbols that follow a this node, i.e., the
|
---|
205 | * symbols associated with the children of this node.
|
---|
206 | * </p>
|
---|
207 | *
|
---|
208 | * @return symbols follow this node
|
---|
209 | * @see TrieNode#getFollowingSymbols()
|
---|
210 | */
|
---|
211 | public Collection<T> getFollowingSymbols() {
|
---|
212 | Collection<T> followingSymbols = new LinkedList<T>();
|
---|
213 | for (TrieNode<T> child : children) {
|
---|
214 | followingSymbols.add(child.getSymbol());
|
---|
215 | }
|
---|
216 | return followingSymbols;
|
---|
217 | }
|
---|
218 |
|
---|
219 | /**
|
---|
220 | * <p>
|
---|
221 | * The string representation of a node is {@code symbol.toString()#count}
|
---|
222 | * </p>
|
---|
223 | *
|
---|
224 | * @see java.lang.Object#toString()
|
---|
225 | */
|
---|
226 | @Override
|
---|
227 | public String toString() {
|
---|
228 | String str = symbol.toString() + " #" + count;
|
---|
229 | if (!children.isEmpty()) {
|
---|
230 | str += StringTools.ENDLINE + children.toString();
|
---|
231 | }
|
---|
232 | return str;
|
---|
233 | }
|
---|
234 |
|
---|
235 | /**
|
---|
236 | * <p>
|
---|
237 | * Generates a {@link Tree} represenation of the trie.
|
---|
238 | * </p>
|
---|
239 | *
|
---|
240 | * @param parent
|
---|
241 | * parent vertex in the generated tree
|
---|
242 | * @param graph
|
---|
243 | * complete tree
|
---|
244 | */
|
---|
245 | void getGraph(TrieVertex parent, DelegateTree<TrieVertex, Edge> graph) {
|
---|
246 | TrieVertex currentVertex;
|
---|
247 | if (symbol == null) {
|
---|
248 | currentVertex = new TrieVertex("root");
|
---|
249 | graph.addVertex(currentVertex);
|
---|
250 | } else {
|
---|
251 | currentVertex = new TrieVertex(getSymbol().toString() + "#"
|
---|
252 | + getCount());
|
---|
253 | graph.addChild(new Edge(), parent, currentVertex);
|
---|
254 | }
|
---|
255 | for (TrieNode<T> node : children) {
|
---|
256 | node.getGraph(currentVertex, graph);
|
---|
257 | }
|
---|
258 | }
|
---|
259 |
|
---|
260 | /**
|
---|
261 | * <p>
|
---|
262 | * Appends the current node to the dot representation of the trie.
|
---|
263 | * </p>
|
---|
264 | *
|
---|
265 | * @param stringBuilder
|
---|
266 | * {@link StringBuilder} to which the dot representation is
|
---|
267 | * appended
|
---|
268 | */
|
---|
269 | void appendDotRepresentation(StringBuilder stringBuilder) {
|
---|
270 | String thisSaneId;
|
---|
271 | if (symbol == null) {
|
---|
272 | thisSaneId = "root";
|
---|
273 | } else {
|
---|
274 | thisSaneId = symbol.toString().replace("\"", "\\\"")
|
---|
275 | .replaceAll("[\r\n]", "")
|
---|
276 | + "#" + count;
|
---|
277 | }
|
---|
278 | stringBuilder.append(" " + hashCode() + " [label=\"" + thisSaneId
|
---|
279 | + "\"];" + StringTools.ENDLINE);
|
---|
280 | for (TrieNode<T> childNode : children) {
|
---|
281 | stringBuilder.append(" " + hashCode() + " -> "
|
---|
282 | + childNode.hashCode() + ";" + StringTools.ENDLINE);
|
---|
283 | }
|
---|
284 | for (TrieNode<T> childNode : children) {
|
---|
285 | childNode.appendDotRepresentation(stringBuilder);
|
---|
286 | }
|
---|
287 | }
|
---|
288 | }
|
---|