1 | /* This file is part of the project "Hilbert II" - http://www.qedeq.org |
2 | * |
3 | * Copyright 2000-2014, Michael Meyling <mime@qedeq.org>. |
4 | * |
5 | * "Hilbert II" is free software; you can redistribute |
6 | * it and/or modify it under the terms of the GNU General Public |
7 | * License as published by the Free Software Foundation; either |
8 | * version 2 of the License, or (at your option) any later version. |
9 | * |
10 | * This program is distributed in the hope that it will be useful, |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
13 | * GNU General Public License for more details. |
14 | */ |
15 | |
16 | package org.qedeq.kernel.se.dto.list; |
17 | |
18 | import java.util.Arrays; |
19 | import java.util.HashSet; |
20 | import java.util.Iterator; |
21 | import java.util.Set; |
22 | |
23 | import org.qedeq.kernel.se.base.list.Element; |
24 | import org.qedeq.kernel.se.base.list.ElementList; |
25 | |
26 | |
27 | /** |
28 | * This class represents a set of {@link org.qedeq.kernel.se.base.list.Element}s. |
29 | * |
30 | * @author Michael Meyling |
31 | */ |
32 | public class ElementSet { |
33 | |
34 | |
35 | /** Here are the elements stored. */ |
36 | private final Set elements; |
37 | |
38 | |
39 | /** |
40 | * Constructs an empty element set. |
41 | */ |
42 | public ElementSet() { |
43 | this.elements = new HashSet(); |
44 | } |
45 | |
46 | |
47 | /** |
48 | * Constructs an element set. |
49 | * |
50 | * @param elements the elements to put into the set |
51 | * @throws IllegalArgumentException if <code>elements</code> was a NullPointer |
52 | */ |
53 | public ElementSet(final Element[] elements) { |
54 | if (elements == null) { |
55 | throw new IllegalArgumentException( |
56 | "NullPointer as element array is not allowed"); |
57 | } |
58 | this.elements = new HashSet(Arrays.asList(elements)); |
59 | } |
60 | |
61 | |
62 | /** |
63 | * Constructs an element set. |
64 | * |
65 | * @param set contains the elements to put into the set |
66 | * @throws IllegalArgumentException if <code>set</code> was a |
67 | * NullPointer |
68 | */ |
69 | public ElementSet(final ElementSet set) { |
70 | if (set == null) { |
71 | throw new IllegalArgumentException( |
72 | "NullPointer as set is not allowed"); |
73 | } |
74 | this.elements = new HashSet(set.elements); |
75 | } |
76 | |
77 | |
78 | /** |
79 | * Constructs an element set from all operands of an element. |
80 | * The element must not be a symbol. |
81 | * |
82 | * @param element contains the elements to put into the set |
83 | * (without the operator) |
84 | * @throws IllegalArgumentException if <code>element</code> was a |
85 | * NullPointer or was an atom. |
86 | */ |
87 | public ElementSet(final ElementList element) { |
88 | if (element == null) { |
89 | throw new IllegalArgumentException( |
90 | "NullPointer as element is not allowed"); |
91 | } |
92 | if (element.isAtom()) { |
93 | throw new IllegalArgumentException( |
94 | "text as element is not allowed"); |
95 | } |
96 | this.elements = new HashSet(element.getElements()); |
97 | } |
98 | |
99 | |
100 | /** |
101 | * Is element in set? |
102 | * |
103 | * @param element Element to check for. |
104 | * @return Is <code>element</code> in this set? |
105 | * @throws IllegalArgumentException if the element was a |
106 | * NullPointer |
107 | */ |
108 | public final boolean contains(final Element element) { |
109 | if (element == null) { |
110 | throw new IllegalArgumentException("NullPointer as element is not allowed"); |
111 | } |
112 | return this.elements.contains(element); |
113 | } |
114 | |
115 | /** |
116 | * Is this set empty? |
117 | * |
118 | * @return Is this set empty? |
119 | */ |
120 | public final boolean isEmpty() { |
121 | return elements.isEmpty(); |
122 | } |
123 | |
124 | |
125 | /** |
126 | * Is <code>set</code> a superset of this set? |
127 | * |
128 | * @param set Set to check for. |
129 | * @return Is this set a subset of <code>set</code>? |
130 | * @throws IllegalArgumentException if the set was a NullPointer |
131 | */ |
132 | public final boolean isSubset(final ElementSet set) { |
133 | if (set == null) { |
134 | throw new IllegalArgumentException("NullPointer as set is not allowed"); |
135 | } |
136 | return set.elements.containsAll(this.elements); |
137 | } |
138 | |
139 | |
140 | /** |
141 | * Add an element to set. This object is after the method the |
142 | * union of this set with {<code>element</code>} |
143 | * |
144 | * @param element element to put into the set |
145 | * @return Possibly changed <code>this</code>. |
146 | * @throws IllegalArgumentException if the element was a |
147 | * NullPointer |
148 | */ |
149 | public final ElementSet add(final Element element) { |
150 | if (element == null) { |
151 | throw new IllegalArgumentException("NullPointer as element is not allowed"); |
152 | } |
153 | elements.add(element); |
154 | return this; |
155 | } |
156 | |
157 | |
158 | /** |
159 | * Add elements from another {@link ElementSet} to this set. |
160 | * After this method this object is the union of the two sets. |
161 | * |
162 | * @param set add all elements that are here |
163 | * @return Possibly changed <code>this</code>. |
164 | * @throws IllegalArgumentException if the set was a |
165 | * NullPointer |
166 | */ |
167 | public final ElementSet union(final ElementSet set) { |
168 | if (set == null) { |
169 | throw new IllegalArgumentException( |
170 | "NullPointer as set is not allowed"); |
171 | } |
172 | elements.addAll(set.elements); |
173 | return this; |
174 | } |
175 | |
176 | |
177 | /** |
178 | * Remove an element from this set. |
179 | * |
180 | * @param element Element to remove from the set. Must not be <code>null</code>. |
181 | * @return Possibly changed <code>this</code>. |
182 | * @throws IllegalArgumentException if the element was a |
183 | * NullPointer |
184 | */ |
185 | public final ElementSet remove(final Element element) { |
186 | if (element == null) { |
187 | throw new IllegalArgumentException( |
188 | "NullPointer as element is not allowed"); |
189 | } |
190 | elements.remove(element); |
191 | return this; |
192 | } |
193 | |
194 | |
195 | /** |
196 | * Remove elements from another {@link ElementSet} from this set. |
197 | * After this method this object is the asymmetric set difference of the |
198 | * two sets: <code>this</code> \ <code>set</code>. |
199 | * |
200 | * @param set Remove all elements that are in this set from |
201 | * <code>this</code>. |
202 | * @return Possibly changed <code>this</code>. |
203 | * @throws IllegalArgumentException if the set was a |
204 | * NullPointer |
205 | */ |
206 | public final ElementSet minus(final ElementSet set) { |
207 | if (set == null) { |
208 | throw new IllegalArgumentException( |
209 | "NullPointer as set is not allowed"); |
210 | } |
211 | this.elements.removeAll(set.elements); |
212 | return this; |
213 | } |
214 | |
215 | |
216 | /** |
217 | * Build the intersection. |
218 | * |
219 | * @param set Check for these elements. |
220 | * @return Possibly changed <code>this</code>. |
221 | * @throws IllegalArgumentException if the set was a |
222 | * NullPointer |
223 | */ |
224 | public final ElementSet intersection(final ElementSet set) { |
225 | if (set == null) { |
226 | throw new IllegalArgumentException( |
227 | "NullPointer as set is not allowed"); |
228 | } |
229 | this.elements.retainAll(set.elements); |
230 | return this; |
231 | } |
232 | |
233 | |
234 | /** |
235 | * Build a new intersection. |
236 | * |
237 | * @param set check for these elements |
238 | * @return New instance that contains all elements that were in <code>this</code> |
239 | * and <code>set</code>. |
240 | * @throws IllegalArgumentException if the set was a |
241 | * NullPointer |
242 | */ |
243 | public final ElementSet newIntersection(final ElementSet set) { |
244 | if (set == null) { |
245 | throw new IllegalArgumentException( |
246 | "NullPointer as set is not allowed"); |
247 | } |
248 | final ElementSet result = new ElementSet(this); |
249 | result.elements.retainAll(set.elements); |
250 | return result; |
251 | } |
252 | |
253 | |
254 | /** |
255 | * Return all elements that are only in one of both sets. |
256 | * This method returns a new instance that holds the symmetric set difference of the |
257 | * two sets. The original set is not modified. |
258 | * |
259 | * @param set Build the symmetric difference with this set. |
260 | * <code>this</code> |
261 | * @return Symmetric difference. |
262 | * @throws IllegalArgumentException if the set was a |
263 | * NullPointer |
264 | */ |
265 | public final ElementSet newDelta(final ElementSet set) { |
266 | if (set == null) { |
267 | throw new IllegalArgumentException( |
268 | "NullPointer as set is not allowed"); |
269 | } |
270 | final ElementSet union = new ElementSet(this); |
271 | union.union(set); |
272 | final ElementSet intersection = new ElementSet(this); |
273 | intersection.intersection(set); |
274 | union.minus(intersection); |
275 | return union; |
276 | } |
277 | |
278 | /** |
279 | * Get number of elements. |
280 | * |
281 | * @return Number of elements in this set. |
282 | */ |
283 | public final int size() { |
284 | return this.elements.size(); |
285 | } |
286 | |
287 | /** |
288 | * Returns an iterator over the elements in this set. The elements are |
289 | * returned in no particular order (unless this set is an instance of some |
290 | * class that provides a guarantee). |
291 | * |
292 | * @return Iterator over the elements in this set. |
293 | */ |
294 | public Iterator iterator() { |
295 | return this.elements.iterator(); |
296 | } |
297 | |
298 | public final boolean equals(final Object obj) { |
299 | if (obj == null) { |
300 | return false; |
301 | } |
302 | if (obj.getClass() == ElementSet.class) { |
303 | return this.elements.equals(((ElementSet) obj).elements); |
304 | } |
305 | return false; |
306 | } |
307 | |
308 | public final int hashCode() { |
309 | return elements.hashCode(); |
310 | } |
311 | |
312 | public final String toString() { |
313 | final StringBuffer result = new StringBuffer(); |
314 | result.append("{"); |
315 | final Iterator iterator = elements.iterator(); |
316 | while (iterator.hasNext()) { |
317 | result.append(iterator.next()); |
318 | if (iterator.hasNext()) { |
319 | result.append(", "); |
320 | } |
321 | } |
322 | result.append("}"); |
323 | return result.toString(); |
324 | } |
325 | |
326 | } |