Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
DefaultPrimaryKeyConverter |
|
| 2.125;2.125 |
1 | // Copyright 2005 The Apache Software Foundation | |
2 | // | |
3 | // Licensed under the Apache License, Version 2.0 (the "License"); | |
4 | // you may not use this file except in compliance with the License. | |
5 | // You may obtain a copy of the License at | |
6 | // | |
7 | // http://www.apache.org/licenses/LICENSE-2.0 | |
8 | // | |
9 | // Unless required by applicable law or agreed to in writing, software | |
10 | // distributed under the License is distributed on an "AS IS" BASIS, | |
11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
12 | // See the License for the specific language governing permissions and | |
13 | // limitations under the License. | |
14 | ||
15 | package org.apache.tapestry.util; | |
16 | ||
17 | import java.util.ArrayList; | |
18 | import java.util.Collections; | |
19 | import java.util.HashMap; | |
20 | import java.util.HashSet; | |
21 | import java.util.List; | |
22 | import java.util.Map; | |
23 | import java.util.Set; | |
24 | ||
25 | import org.apache.hivemind.ApplicationRuntimeException; | |
26 | import org.apache.hivemind.util.Defense; | |
27 | import org.apache.tapestry.components.IPrimaryKeyConverter; | |
28 | ||
29 | /** | |
30 | * Companion to the {@link org.apache.tapestry.components.ForBean For component}, this class is an | |
31 | * implementation of {@link org.apache.tapestry.components.IPrimaryKeyConverter} that performs some | |
32 | * additional handling, such as tracking value sets.. | |
33 | * <p> | |
34 | * Value sets are sets of value objects maintained by the converter; the converter will provide a | |
35 | * synthetic read/write boolean property that indicates if the {@link #getLastValue() last value} is | |
36 | * or is not in the set. | |
37 | * <p> | |
38 | * A single built-in value set, {@link #isDeleted()} has a special purpose; it controls whether or | |
39 | * not values are returned from {@link #getValues()}. Subclasses may add additional synthetic | |
40 | * boolean properties and additional sets. | |
41 | * <p> | |
42 | * Why not just store a boolean property in the object itself? Well, deleted is a good example of a | |
43 | * property that is meaningful in the context of an operation, but isn't stored ... once an object | |
44 | * is deleted (from secondary storage, such as a database) there's no place to store such a flag. | |
45 | * The DefaultPrimaryKey converter is used in this context to store transient, operation data ... | |
46 | * such as which values are to be deleted. | |
47 | * <p> | |
48 | * This class can be thought of as a successor to {@link org.apache.tapestry.form.ListEditMap}. | |
49 | * | |
50 | * @author Howard M. Lewis Ship | |
51 | * @since 4.0 | |
52 | */ | |
53 | 0 | public class DefaultPrimaryKeyConverter implements IPrimaryKeyConverter |
54 | { | |
55 | 0 | private final Map _map = new HashMap(); |
56 | ||
57 | 0 | private final List _keys = new ArrayList(); |
58 | ||
59 | // The values added to the Map, in the order they were added. | |
60 | 0 | private final List _values = new ArrayList(); |
61 | ||
62 | // The last value accessed by getPrimaryKey() or getValue(). | |
63 | // Other methods may operate upon this value. | |
64 | ||
65 | private Object _lastValue; | |
66 | ||
67 | private Set _deletedValues; | |
68 | ||
69 | /** | |
70 | * Clears all properties of the converter, returning it to a pristine state. Subclasses should | |
71 | * invoke this implementation in addition to clearing any of their own state. | |
72 | */ | |
73 | public void clear() | |
74 | { | |
75 | 0 | _map.clear(); |
76 | 0 | _keys.clear(); |
77 | 0 | _values.clear(); |
78 | 0 | _lastValue = null; |
79 | 0 | _deletedValues = null; |
80 | 0 | } |
81 | ||
82 | public final void add(Object key, Object value) | |
83 | { | |
84 | 0 | Defense.notNull(key, "key"); |
85 | 0 | Defense.notNull(value, "value"); |
86 | ||
87 | 0 | if (_map.containsKey(key)) |
88 | 0 | throw new ApplicationRuntimeException(UtilMessages.keyAlreadyExists(key)); |
89 | ||
90 | 0 | _map.put(key, value); |
91 | ||
92 | 0 | _keys.add(key); |
93 | 0 | _values.add(value); |
94 | ||
95 | 0 | _lastValue = value; |
96 | 0 | } |
97 | ||
98 | /** | |
99 | * Returns a unmodifiable list of values stored into the converter, in the order in which they | |
100 | * were stored. | |
101 | * | |
102 | * @return an unmodifiable List | |
103 | * @see #add(Object, Object) | |
104 | */ | |
105 | public final List getAllValues() | |
106 | { | |
107 | 0 | return Collections.unmodifiableList(_values); |
108 | } | |
109 | ||
110 | /** | |
111 | * Returns a list of all values stored into the converter, with deleted values removed. | |
112 | */ | |
113 | ||
114 | public final List getValues() | |
115 | { | |
116 | 0 | if (isDeletedValuesEmpty()) |
117 | 0 | return getAllValues(); |
118 | ||
119 | 0 | List result = new ArrayList(_values); |
120 | ||
121 | 0 | result.removeAll(_deletedValues); |
122 | ||
123 | 0 | return result; |
124 | } | |
125 | ||
126 | /** | |
127 | * Returns true if the deleted values set is empty (or null). | |
128 | */ | |
129 | private boolean isDeletedValuesEmpty() | |
130 | { | |
131 | 0 | return _deletedValues == null || _deletedValues.isEmpty(); |
132 | } | |
133 | ||
134 | /** | |
135 | * Checks to see if the {@link #getLastValue() last value} is, or is not, in the set of deleted | |
136 | * values. | |
137 | */ | |
138 | public final boolean isDeleted() | |
139 | { | |
140 | 0 | return checkValueSetForLastValue(_deletedValues); |
141 | } | |
142 | ||
143 | /** | |
144 | * Checks the set to see if it contains the {@link #getLastValue() last value}. | |
145 | * | |
146 | * @param valueSet | |
147 | * the set to check, which may be null | |
148 | * @return true if the last value is in the set (if non-null) | |
149 | */ | |
150 | protected final boolean checkValueSetForLastValue(Set valueSet) | |
151 | { | |
152 | 0 | return valueSet != null && valueSet.contains(_lastValue); |
153 | } | |
154 | ||
155 | /** | |
156 | * Adds or removes the {@link #getLastValue() last value} from the | |
157 | * {@link #getDeletedValues() deleted values set}. | |
158 | * | |
159 | * @param deleted | |
160 | */ | |
161 | public final void setDeleted(boolean deleted) | |
162 | { | |
163 | 0 | _deletedValues = updateValueSetForLastValue(_deletedValues, deleted); |
164 | 0 | } |
165 | ||
166 | /** | |
167 | * Updates a value set to add or remove the {@link #getLastValue() last value} to the set. The | |
168 | * logic here will create and return a new Set instance if necessary (that is, if inSet is true | |
169 | * and set is null). The point is to defer the creation of the set until its actually needed. | |
170 | * | |
171 | * @param set | |
172 | * the set to update, which may be null | |
173 | * @param inSet | |
174 | * if true, the last value will be added to the set (creating the set as necessary); | |
175 | * if false, the last value will be removed | |
176 | * @return the set passed in, or a new Set instance | |
177 | */ | |
178 | protected final Set updateValueSetForLastValue(Set set, boolean inSet) | |
179 | { | |
180 | 0 | Set updatedSet = set; |
181 | 0 | if (inSet) |
182 | { | |
183 | 0 | if (updatedSet == null) |
184 | 0 | updatedSet = new HashSet(); |
185 | ||
186 | 0 | updatedSet.add(_lastValue); |
187 | ||
188 | 0 | return updatedSet; |
189 | } | |
190 | ||
191 | 0 | if (updatedSet != null) |
192 | 0 | updatedSet.remove(_lastValue); |
193 | ||
194 | 0 | return updatedSet; |
195 | } | |
196 | ||
197 | /** | |
198 | * Returns the last active value; this is the value passed to {@link #getPrimaryKey(Object)} or | |
199 | * the value for the key passed to {@link #getValue(Object)}. | |
200 | * <p> | |
201 | * Maintaining <em>value sets</em> involves adding or removing the active value from a set. | |
202 | * | |
203 | * @return the last active object | |
204 | */ | |
205 | public final Object getLastValue() | |
206 | { | |
207 | 0 | return _lastValue; |
208 | } | |
209 | ||
210 | /** | |
211 | * Returns an unmodifiable set of all values marked as deleted. | |
212 | */ | |
213 | ||
214 | public final Set getDeletedValues() | |
215 | { | |
216 | 0 | return createUnmodifiableSet(_deletedValues); |
217 | } | |
218 | ||
219 | /** | |
220 | * Converts a value set into a returnable value; null is converted to the empty set, and | |
221 | * non-null is wrapped as unmodifiable. | |
222 | * | |
223 | * @param valueSet | |
224 | * the set to convert and return | |
225 | * @return a non-null, non-modifiable Set | |
226 | */ | |
227 | protected final Set createUnmodifiableSet(Set valueSet) | |
228 | { | |
229 | 0 | return valueSet == null ? Collections.EMPTY_SET : Collections.unmodifiableSet(valueSet); |
230 | } | |
231 | ||
232 | /** | |
233 | * Iterates over the keys and values, removing any values (and corresponding keys) that that are | |
234 | * in the deleted set. After invoking this, {@link #getAllValues()} will be the same as | |
235 | * {@link #getValues()}. | |
236 | */ | |
237 | public final void removeDeletedValues() | |
238 | { | |
239 | 0 | _lastValue = null; |
240 | ||
241 | 0 | if (isDeletedValuesEmpty()) |
242 | 0 | return; |
243 | ||
244 | 0 | int count = _keys.size(); |
245 | ||
246 | 0 | for (int i = count - 1; i >= 0; i--) |
247 | { | |
248 | 0 | if (_deletedValues.contains(_values.get(i))) |
249 | { | |
250 | 0 | _values.remove(i); |
251 | 0 | Object key = _keys.remove(i); |
252 | ||
253 | 0 | _map.remove(key); |
254 | } | |
255 | } | |
256 | 0 | } |
257 | ||
258 | /** | |
259 | * Gets the primary key of an object previously stored in this converter. | |
260 | * | |
261 | * @param value | |
262 | * an object previously stored in the converter | |
263 | * @return the corresponding key used to store the object | |
264 | * @throws ApplicationRuntimeException | |
265 | * if the value was not previously stored | |
266 | * @see #add(Object, Object) | |
267 | */ | |
268 | public final Object getPrimaryKey(Object value) | |
269 | { | |
270 | 0 | int index = _values.indexOf(value); |
271 | ||
272 | 0 | if (index < 0) |
273 | 0 | throw new ApplicationRuntimeException(UtilMessages.valueNotFound(value), value, null, |
274 | null); | |
275 | ||
276 | 0 | _lastValue = value; |
277 | ||
278 | 0 | return _keys.get(index); |
279 | } | |
280 | ||
281 | /** | |
282 | * Given a primary key, locates the corresponding object. May invoke | |
283 | * {@link #provideMissingValue(Object)} if no such key has been stored into the converter. | |
284 | * | |
285 | * @return the object if the key is found, or null otherwise. | |
286 | * @see #add(Object, Object) | |
287 | */ | |
288 | public final Object getValue(Object primaryKey) | |
289 | { | |
290 | 0 | Object result = _map.get(primaryKey); |
291 | ||
292 | 0 | if (result == null) |
293 | 0 | result = provideMissingValue(primaryKey); |
294 | ||
295 | 0 | _lastValue = result; |
296 | ||
297 | 0 | return result; |
298 | } | |
299 | ||
300 | /** | |
301 | * Invoked by {@link #getValue(Object)} when the key is not found in the converter's map. | |
302 | * Subclasses may override this method to either obtain the corresponding object from secondary | |
303 | * storage, to throw an exception, or to provide a new object instance. This implementation | |
304 | * returns null. | |
305 | * | |
306 | * @param key | |
307 | * the key for which an object was requested | |
308 | * @return the object for the key, or null if no object may can be provided | |
309 | */ | |
310 | protected Object provideMissingValue(Object key) | |
311 | { | |
312 | 0 | return null; |
313 | } | |
314 | ||
315 | } |