1 /*
2 * ModeShape (http://www.modeshape.org)
3 * See the COPYRIGHT.txt file distributed with this work for information
4 * regarding copyright ownership. Some portions may be licensed
5 * to Red Hat, Inc. under one or more contributor license agreements.
6 * See the AUTHORS.txt file in the distribution for a full listing of
7 * individual contributors.
8 *
9 * ModeShape is free software. Unless otherwise indicated, all code in ModeShape
10 * is licensed to you under the terms of the GNU Lesser General Public License as
11 * published by the Free Software Foundation; either version 2.1 of
12 * the License, or (at your option) any later version.
13 *
14 * ModeShape is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with this software; if not, write to the Free
21 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
22 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
23 */
24 package org.modeshape.graph.request;
25
26 import java.util.LinkedList;
27 import java.util.List;
28 import org.modeshape.common.text.Inflector;
29 import org.modeshape.common.util.CheckArg;
30 import org.modeshape.common.util.HashCode;
31 import org.modeshape.graph.GraphI18n;
32 import org.modeshape.graph.Location;
33 import org.modeshape.graph.connector.RepositoryConnection;
34 import org.modeshape.graph.property.Path;
35 import org.modeshape.graph.property.Property;
36
37 /**
38 * Instruction to read a block of the children of a node, where the block is dictated by the {@link #startingAtIndex() starting
39 * index} and the {@link #count() maximum number of children} to include in the block. This command is useful when paging through
40 * a large number of children.
41 *
42 * @see ReadNextBlockOfChildrenRequest
43 */
44 public class ReadBlockOfChildrenRequest extends CacheableRequest {
45
46 public static final int INDEX_NOT_USED = -1;
47
48 private static final long serialVersionUID = 1L;
49
50 private final Location of;
51 private final String workspaceName;
52 private final List<Location> children = new LinkedList<Location>();
53 private final int startingAtIndex;
54 private final int count;
55 private Location actualLocation;
56
57 /**
58 * Create a request to read a block of the children of a node at the supplied location. The block is defined by the starting
59 * index of the first child and the number of children to include. Note that this index is <i>not</i> the
60 * {@link Path.Segment#getIndex() same-name-sibiling index}, but rather is the index of the child as if the children were in
61 * an array.
62 *
63 * @param of the location of the node whose children are to be read
64 * @param workspaceName the name of the workspace containing the parent
65 * @param startingIndex the zero-based index of the first child to be included in the block
66 * @param count the maximum number of children that should be included in the block
67 * @throws IllegalArgumentException if the location or workspace name is null, if <code>startingIndex</code> is negative, or
68 * if <code>count</count> is less than 1.
69 */
70 public ReadBlockOfChildrenRequest( Location of,
71 String workspaceName,
72 int startingIndex,
73 int count ) {
74 CheckArg.isNotNull(of, "of");
75 CheckArg.isNonNegative(startingIndex, "startingIndex");
76 CheckArg.isPositive(count, "count");
77 CheckArg.isNotNull(workspaceName, "workspaceName");
78 this.workspaceName = workspaceName;
79 this.of = of;
80 this.startingAtIndex = startingIndex;
81 this.count = count;
82 }
83
84 /**
85 * {@inheritDoc}
86 *
87 * @see org.modeshape.graph.request.Request#isReadOnly()
88 */
89 @Override
90 public boolean isReadOnly() {
91 return true;
92 }
93
94 /**
95 * Get the location defining the node whose children are to be read.
96 *
97 * @return the location of the parent node; never null
98 */
99 public Location of() {
100 return of;
101 }
102
103 /**
104 * Get the name of the workspace in which the parent and children exist.
105 *
106 * @return the name of the workspace; never null
107 */
108 public String inWorkspace() {
109 return workspaceName;
110 }
111
112 /**
113 * Get the maximum number of children that may be returned in the block.
114 *
115 * @return the block's maximum count
116 * @see #startingAtIndex()
117 * @see #endingBefore()
118 */
119 public int count() {
120 return this.count;
121 }
122
123 /**
124 * Get the starting index of the block, which is the index of the first child to include. This index corresponds to the index
125 * of all children in the list, not the {@link Path.Segment#getIndex() same-name-sibiling index}.
126 *
127 * @return the (zero-based) child index at which this block starts; never negative and always less than
128 * {@link #endingBefore()}
129 * @see #endingBefore()
130 * @see #count()
131 */
132 public int startingAtIndex() {
133 return this.startingAtIndex;
134 }
135
136 /**
137 * Get the index past the last child that is to be included in the block. This index corresponds to the index of all children
138 * in the list, not the {@link Path.Segment#getIndex() same-name-sibiling index}.
139 *
140 * @return the index just past the last child included in the block; always positive and always greater than
141 * {@link #startingAtIndex()}.
142 * @see #startingAtIndex()
143 * @see #count()
144 */
145 public int endingBefore() {
146 return this.startingAtIndex + this.count;
147 }
148
149 /**
150 * Get the children that were read from the {@link RepositoryConnection} after the request was processed. Each child is
151 * represented by a location.
152 *
153 * @return the children that were read; never null
154 */
155 public List<Location> getChildren() {
156 return children;
157 }
158
159 /**
160 * Add to the list of children that has been read the supplied children with the given path and identification properties. The
161 * children are added in order.
162 *
163 * @param children the locations of the children that were read
164 * @throws IllegalArgumentException if the parameter is null
165 * @throws IllegalStateException if the request is frozen
166 * @see #addChild(Location)
167 * @see #addChild(Path, Property)
168 * @see #addChild(Path, Property, Property...)
169 */
170 public void addChildren( Iterable<Location> children ) {
171 checkNotFrozen();
172 CheckArg.isNotNull(children, "children");
173 for (Location child : children) {
174 if (child != null) this.children.add(child);
175 }
176 }
177
178 /**
179 * Add to the list of children that has been read the child with the given path and identification properties. The children
180 * should be added in order.
181 *
182 * @param child the location of the child that was read
183 * @throws IllegalArgumentException if the location is null
184 * @throws IllegalStateException if the request is frozen
185 * @see #addChild(Path, Property)
186 * @see #addChild(Path, Property, Property...)
187 */
188 public void addChild( Location child ) {
189 checkNotFrozen();
190 CheckArg.isNotNull(child, "child");
191 this.children.add(child);
192 }
193
194 /**
195 * Add to the list of children that has been read the child with the given path and identification properties. The children
196 * should be added in order.
197 *
198 * @param pathToChild the path of the child that was just read
199 * @param firstIdProperty the first identification property of the child that was just read
200 * @param remainingIdProperties the remaining identification properties of the child that was just read
201 * @throws IllegalArgumentException if the path or identification properties are null
202 * @throws IllegalStateException if the request is frozen
203 * @see #addChild(Location)
204 * @see #addChild(Path, Property)
205 */
206 public void addChild( Path pathToChild,
207 Property firstIdProperty,
208 Property... remainingIdProperties ) {
209 checkNotFrozen();
210 Location child = Location.create(pathToChild, firstIdProperty, remainingIdProperties);
211 this.children.add(child);
212 }
213
214 /**
215 * Add to the list of children that has been read the child with the given path and identification property. The children
216 * should be added in order.
217 *
218 * @param pathToChild the path of the child that was just read
219 * @param idProperty the identification property of the child that was just read
220 * @throws IllegalArgumentException if the path or identification properties are null
221 * @throws IllegalStateException if the request is frozen
222 * @see #addChild(Location)
223 * @see #addChild(Path, Property, Property...)
224 */
225 public void addChild( Path pathToChild,
226 Property idProperty ) {
227 checkNotFrozen();
228 Location child = Location.create(pathToChild, idProperty);
229 this.children.add(child);
230 }
231
232 /**
233 * Sets the actual and complete location of the node whose children have been read. This method must be called when processing
234 * the request, and the actual location must have a {@link Location#getPath() path}.
235 *
236 * @param actual the actual location of the node being read, or null if the {@link #of() current location} should be used
237 * @throws IllegalArgumentException if the actual location is null or does not have a path.
238 * @throws IllegalStateException if the request is frozen
239 */
240 public void setActualLocationOfNode( Location actual ) {
241 checkNotFrozen();
242 CheckArg.isNotNull(actual, "actual");
243 if (!actual.hasPath()) {
244 throw new IllegalArgumentException(GraphI18n.actualLocationMustHavePath.text(actual));
245 }
246 this.actualLocation = actual;
247 }
248
249 /**
250 * Get the actual location of the node whose children were read.
251 *
252 * @return the actual location, or null if the actual location was not set
253 */
254 public Location getActualLocationOfNode() {
255 return actualLocation;
256 }
257
258 /**
259 * {@inheritDoc}
260 *
261 * @see org.modeshape.graph.request.Request#cancel()
262 */
263 @Override
264 public void cancel() {
265 super.cancel();
266 this.actualLocation = null;
267 this.children.clear();
268 }
269
270 /**
271 * {@inheritDoc}
272 *
273 * @see java.lang.Object#hashCode()
274 */
275 @Override
276 public int hashCode() {
277 return HashCode.compute(of, workspaceName);
278 }
279
280 /**
281 * {@inheritDoc}
282 *
283 * @see java.lang.Object#equals(java.lang.Object)
284 */
285 @Override
286 public boolean equals( Object obj ) {
287 if (obj == this) return true;
288 if (this.getClass().isInstance(obj)) {
289 ReadBlockOfChildrenRequest that = (ReadBlockOfChildrenRequest)obj;
290 if (!this.of().isSame(that.of())) return false;
291 if (this.startingAtIndex() != that.startingAtIndex()) return false;
292 if (this.count() != that.count()) return false;
293 if (!this.inWorkspace().equals(that.inWorkspace())) return false;
294 return true;
295 }
296 return false;
297 }
298
299 /**
300 * {@inheritDoc}
301 *
302 * @see java.lang.Object#toString()
303 */
304 @Override
305 public String toString() {
306 Inflector inflector = Inflector.getInstance();
307 if (count() == 1) {
308 return "read " + inflector.ordinalize(startingAtIndex()) + " thru " + inflector.ordinalize(endingBefore() - 1)
309 + " children of " + of() + " in the \"" + workspaceName + "\" workspace";
310 }
311 return "read " + inflector.ordinalize(startingAtIndex()) + " child of " + of() + " in the \"" + workspaceName
312 + "\" workspace";
313 }
314
315 @Override
316 public RequestType getType() {
317 return RequestType.READ_BLOCK_OF_CHILDREN;
318 }
319 }