001 /*
002 * JBoss DNA (http://www.jboss.org/dna)
003 * See the COPYRIGHT.txt file distributed with this work for information
004 * regarding copyright ownership. Some portions may be licensed
005 * to Red Hat, Inc. under one or more contributor license agreements.
006 * See the AUTHORS.txt file in the distribution for a full listing of
007 * individual contributors.
008 *
009 * JBoss DNA is free software. Unless otherwise indicated, all code in JBoss DNA
010 * is licensed to you under the terms of the GNU Lesser General Public License as
011 * published by the Free Software Foundation; either version 2.1 of
012 * the License, or (at your option) any later version.
013 *
014 * JBoss DNA is distributed in the hope that it will be useful,
015 * but WITHOUT ANY WARRANTY; without even the implied warranty of
016 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
017 * Lesser General Public License for more details.
018 *
019 * You should have received a copy of the GNU Lesser General Public
020 * License along with this software; if not, write to the Free
021 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
022 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
023 */
024 package org.jboss.dna.graph.request;
025
026 import java.util.LinkedList;
027 import java.util.List;
028 import org.jboss.dna.common.text.Inflector;
029 import org.jboss.dna.common.util.CheckArg;
030 import org.jboss.dna.graph.GraphI18n;
031 import org.jboss.dna.graph.Location;
032 import org.jboss.dna.graph.connector.RepositoryConnection;
033 import org.jboss.dna.graph.property.Path;
034 import org.jboss.dna.graph.property.Property;
035
036 /**
037 * Instruction to read a block of the children of a node, where the block is dictated by the {@link #startingAtIndex() starting
038 * index} and the {@link #count() maximum number of children} to include in the block. This command is useful when paging through
039 * a large number of children.
040 *
041 * @see ReadNextBlockOfChildrenRequest
042 * @author Randall Hauch
043 */
044 public class ReadBlockOfChildrenRequest extends CacheableRequest {
045
046 public static final int INDEX_NOT_USED = -1;
047
048 private static final long serialVersionUID = 1L;
049
050 private final Location of;
051 private final String workspaceName;
052 private final List<Location> children = new LinkedList<Location>();
053 private final int startingAtIndex;
054 private final int count;
055 private Location actualLocation;
056
057 /**
058 * Create a request to read a block of the children of a node at the supplied location. The block is defined by the starting
059 * index of the first child and the number of children to include. Note that this index is <i>not</i> the
060 * {@link Path.Segment#getIndex() same-name-sibiling index}, but rather is the index of the child as if the children were in
061 * an array.
062 *
063 * @param of the location of the node whose children are to be read
064 * @param workspaceName the name of the workspace containing the parent
065 * @param startingIndex the zero-based index of the first child to be included in the block
066 * @param count the maximum number of children that should be included in the block
067 * @throws IllegalArgumentException if the location or workspace name is null, if <code>startingIndex</code> is negative, or
068 * if <code>count</count> is less than 1.
069 */
070 public ReadBlockOfChildrenRequest( Location of,
071 String workspaceName,
072 int startingIndex,
073 int count ) {
074 CheckArg.isNotNull(of, "of");
075 CheckArg.isNonNegative(startingIndex, "startingIndex");
076 CheckArg.isPositive(count, "count");
077 CheckArg.isNotNull(workspaceName, "workspaceName");
078 this.workspaceName = workspaceName;
079 this.of = of;
080 this.startingAtIndex = startingIndex;
081 this.count = count;
082 }
083
084 /**
085 * {@inheritDoc}
086 *
087 * @see org.jboss.dna.graph.request.Request#isReadOnly()
088 */
089 @Override
090 public boolean isReadOnly() {
091 return true;
092 }
093
094 /**
095 * Get the location defining the node whose children are to be read.
096 *
097 * @return the location of the parent node; never null
098 */
099 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 child with the given path and identification properties. The children
161 * should be added in order.
162 *
163 * @param child the location of the child that was read
164 * @throws IllegalArgumentException if the location is null
165 * @see #addChild(Path, Property)
166 * @see #addChild(Path, Property, Property...)
167 */
168 public void addChild( Location child ) {
169 CheckArg.isNotNull(child, "child");
170 this.children.add(child);
171 }
172
173 /**
174 * Add to the list of children that has been read the child with the given path and identification properties. The children
175 * should be added in order.
176 *
177 * @param pathToChild the path of the child that was just read
178 * @param firstIdProperty the first identification property of the child that was just read
179 * @param remainingIdProperties the remaining identification properties of the child that was just read
180 * @throws IllegalArgumentException if the path or identification properties are null
181 * @see #addChild(Location)
182 * @see #addChild(Path, Property)
183 */
184 public void addChild( Path pathToChild,
185 Property firstIdProperty,
186 Property... remainingIdProperties ) {
187 Location child = Location.create(pathToChild, firstIdProperty, remainingIdProperties);
188 this.children.add(child);
189 }
190
191 /**
192 * Add to the list of children that has been read the child with the given path and identification property. The children
193 * should be added in order.
194 *
195 * @param pathToChild the path of the child that was just read
196 * @param idProperty the identification property of the child that was just read
197 * @throws IllegalArgumentException if the path or identification properties are null
198 * @see #addChild(Location)
199 * @see #addChild(Path, Property, Property...)
200 */
201 public void addChild( Path pathToChild,
202 Property idProperty ) {
203 Location child = Location.create(pathToChild, idProperty);
204 this.children.add(child);
205 }
206
207 /**
208 * Sets the actual and complete location of the node whose children have been read. This method must be called when processing
209 * the request, and the actual location must have a {@link Location#getPath() path}.
210 *
211 * @param actual the actual location of the node being read, or null if the {@link #of() current location} should be used
212 * @throws IllegalArgumentException if the actual location does not represent the {@link Location#isSame(Location) same
213 * location} as the {@link #of() current location}, or if the actual location does not have a path.
214 */
215 public void setActualLocationOfNode( Location actual ) {
216 if (!of.isSame(actual)) { // not same if actual is null
217 throw new IllegalArgumentException(GraphI18n.actualLocationIsNotSameAsInputLocation.text(actual, of));
218 }
219 assert actual != null;
220 if (!actual.hasPath()) {
221 throw new IllegalArgumentException(GraphI18n.actualLocationMustHavePath.text(actual));
222 }
223 this.actualLocation = actual;
224 }
225
226 /**
227 * Get the actual location of the node whose children were read.
228 *
229 * @return the actual location, or null if the actual location was not set
230 */
231 public Location getActualLocationOfNode() {
232 return actualLocation;
233 }
234
235 /**
236 * {@inheritDoc}
237 *
238 * @see java.lang.Object#equals(java.lang.Object)
239 */
240 @Override
241 public boolean equals( Object obj ) {
242 if (obj == this) return true;
243 if (this.getClass().isInstance(obj)) {
244 ReadBlockOfChildrenRequest that = (ReadBlockOfChildrenRequest)obj;
245 if (!this.of().equals(that.of())) return false;
246 if (this.startingAtIndex() != that.startingAtIndex()) return false;
247 if (this.count() != that.count()) return false;
248 if (!this.inWorkspace().equals(that.inWorkspace())) return false;
249 return true;
250 }
251 return false;
252 }
253
254 /**
255 * {@inheritDoc}
256 *
257 * @see java.lang.Object#toString()
258 */
259 @Override
260 public String toString() {
261 Inflector inflector = Inflector.getInstance();
262 if (count() == 1) {
263 return "read " + inflector.ordinalize(startingAtIndex()) + " thru " + inflector.ordinalize(endingBefore() - 1)
264 + " children of " + of() + " in the \"" + workspaceName + "\" workspace";
265 }
266 return "read " + inflector.ordinalize(startingAtIndex()) + " child of " + of() + " in the \"" + workspaceName
267 + "\" workspace";
268 }
269
270 }