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.util.CheckArg;
029 import org.jboss.dna.graph.GraphI18n;
030 import org.jboss.dna.graph.Location;
031 import org.jboss.dna.graph.connector.RepositoryConnection;
032 import org.jboss.dna.graph.property.Path;
033 import org.jboss.dna.graph.property.Property;
034
035 /**
036 * Instruction to read a block of the children of a node, where the block is dictated by the {@link #startingAfter location of the
037 * child preceding the block} and the {@link #count() maximum number of children} to include in the block. This command is useful
038 * when paging through a large number of children, when the previous block of children was already retrieved and the next block is
039 * to be read.
040 *
041 * @see ReadBlockOfChildrenRequest
042 * @author Randall Hauch
043 */
044 public class ReadNextBlockOfChildrenRequest extends CacheableRequest {
045
046 public static final int INDEX_NOT_USED = -1;
047
048 private static final long serialVersionUID = 1L;
049
050 private final List<Location> children = new LinkedList<Location>();
051 private final Location startingAfter;
052 private final String workspaceName;
053 private final int count;
054 private Location actualStartingAfter;
055
056 /**
057 * Create a request to read those children of a node that are immediately after a supplied sibling node.
058 *
059 * @param startingAfter the location of the previous sibling that was the last child of the previous block of children read
060 * @param workspaceName the name of the workspace containing the node
061 * @param count the maximum number of children that should be included in the block
062 * @throws IllegalArgumentException if the workspace name or <code>startingAfter</code> location is null, or if
063 * <code>count</count> is less than 1.
064 */
065 public ReadNextBlockOfChildrenRequest( Location startingAfter,
066 String workspaceName,
067 int count ) {
068 CheckArg.isNotNull(startingAfter, "startingAfter");
069 CheckArg.isPositive(count, "count");
070 CheckArg.isNotNull(workspaceName, "workspaceName");
071 this.workspaceName = workspaceName;
072 this.startingAfter = startingAfter;
073 this.count = count;
074 }
075
076 /**
077 * {@inheritDoc}
078 *
079 * @see org.jboss.dna.graph.request.Request#isReadOnly()
080 */
081 @Override
082 public boolean isReadOnly() {
083 return true;
084 }
085
086 /**
087 * Get the maximum number of children that may be returned in the block.
088 *
089 * @return the block's maximum count
090 * @see #startingAfter()
091 */
092 public int count() {
093 return this.count;
094 }
095
096 /**
097 * Get the location of the child after which the block begins. This form may be easier to use when paging through blocks, as
098 * the last children retrieved with the previous block can be supplied with the next read request.
099 *
100 * @return the location of the child that is immediately before the start of the block; index at which this block starts;
101 * never negative
102 * @see #count()
103 */
104 public Location startingAfter() {
105 return this.startingAfter;
106 }
107
108 /**
109 * Get the name of the workspace in which the parent and children exist.
110 *
111 * @return the name of the workspace; never null
112 */
113 public String inWorkspace() {
114 return workspaceName;
115 }
116
117 /**
118 * Get the children that were read from the {@link RepositoryConnection} after the request was processed. Each child is
119 * represented by a location.
120 *
121 * @return the children that were read; never null
122 */
123 public List<Location> getChildren() {
124 return children;
125 }
126
127 /**
128 * Add to the list of children that has been read the child with the given path and identification properties. The children
129 * should be added in order.
130 *
131 * @param child the location of the child that was read
132 * @throws IllegalArgumentException if the location is null
133 * @see #addChild(Path, Property)
134 * @see #addChild(Path, Property, Property...)
135 */
136 public void addChild( Location child ) {
137 CheckArg.isNotNull(child, "child");
138 this.children.add(child);
139 }
140
141 /**
142 * Add to the list of children that has been read the child with the given path and identification properties. The children
143 * should be added in order.
144 *
145 * @param pathToChild the path of the child that was just read
146 * @param firstIdProperty the first identification property of the child that was just read
147 * @param remainingIdProperties the remaining identification properties of the child that was just read
148 * @throws IllegalArgumentException if the path or identification properties are null
149 * @see #addChild(Location)
150 * @see #addChild(Path, Property)
151 */
152 public void addChild( Path pathToChild,
153 Property firstIdProperty,
154 Property... remainingIdProperties ) {
155 Location child = Location.create(pathToChild, firstIdProperty, remainingIdProperties);
156 this.children.add(child);
157 }
158
159 /**
160 * Add to the list of children that has been read the child with the given path and identification property. The children
161 * should be added in order.
162 *
163 * @param pathToChild the path of the child that was just read
164 * @param idProperty the identification property of the child that was just read
165 * @throws IllegalArgumentException if the path or identification properties are null
166 * @see #addChild(Location)
167 * @see #addChild(Path, Property, Property...)
168 */
169 public void addChild( Path pathToChild,
170 Property idProperty ) {
171 Location child = Location.create(pathToChild, idProperty);
172 this.children.add(child);
173 }
174
175 /**
176 * Sets the actual and complete location of the node whose children have been read. This method must be called when processing
177 * the request, and the actual location must have a {@link Location#getPath() path}.
178 *
179 * @param actual the actual location of the node being read, or null if the {@link #startingAfter() starting after location}
180 * should be used
181 * @throws IllegalArgumentException if the actual location does not represent the {@link Location#isSame(Location) same
182 * location} as the {@link #startingAfter() starting after location}, or if the actual location does not have a path.
183 */
184 public void setActualLocationOfStartingAfterNode( Location actual ) {
185 if (!startingAfter.isSame(actual)) { // not same if actual is null
186 throw new IllegalArgumentException(GraphI18n.actualLocationIsNotSameAsInputLocation.text(actual, startingAfter));
187 }
188 assert actual != null;
189 if (!actual.hasPath()) {
190 throw new IllegalArgumentException(GraphI18n.actualLocationMustHavePath.text(actual));
191 }
192 this.actualStartingAfter = actual;
193 }
194
195 /**
196 * Get the actual location of the {@link #startingAfter() starting after} sibling.
197 *
198 * @return the actual location, or null if the actual location was not set
199 */
200 public Location getActualLocationOfStartingAfterNode() {
201 return actualStartingAfter;
202 }
203
204 /**
205 * {@inheritDoc}
206 *
207 * @see java.lang.Object#equals(java.lang.Object)
208 */
209 @Override
210 public boolean equals( Object obj ) {
211 if (obj == this) return true;
212 if (this.getClass().isInstance(obj)) {
213 ReadNextBlockOfChildrenRequest that = (ReadNextBlockOfChildrenRequest)obj;
214 if (!this.startingAfter().equals(that.startingAfter())) return false;
215 if (this.count() != that.count()) return false;
216 if (!this.inWorkspace().equals(that.inWorkspace())) return false;
217 return true;
218 }
219 return false;
220 }
221
222 /**
223 * {@inheritDoc}
224 *
225 * @see java.lang.Object#toString()
226 */
227 @Override
228 public String toString() {
229 if (count() == 1) {
230 return "read the next child after " + startingAfter() + " in the \"" + workspaceName + "\" workspace";
231 }
232 return "read the next " + count() + " children after " + startingAfter() + " in the \"" + workspaceName + "\" workspace";
233 }
234
235 }