| 1 | package org.apache.velocity.anakia; |
| 2 | |
| 3 | /* |
| 4 | * Copyright 2001,2004 The Apache Software Foundation. |
| 5 | * |
| 6 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 7 | * you may not use this file except in compliance with the License. |
| 8 | * You may obtain a copy of the License at |
| 9 | * |
| 10 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 11 | * |
| 12 | * Unless required by applicable law or agreed to in writing, software |
| 13 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 15 | * See the License for the specific language governing permissions and |
| 16 | * limitations under the License. |
| 17 | */ |
| 18 | |
| 19 | import java.io.Writer; |
| 20 | import java.io.IOException; |
| 21 | import java.io.StringWriter; |
| 22 | import java.util.*; |
| 23 | import org.jdom.*; |
| 24 | import org.jdom.output.*; |
| 25 | |
| 26 | /** |
| 27 | * Provides a class for wrapping a list of JDOM objects primarily for use in template |
| 28 | * engines and other kinds of text transformation tools. |
| 29 | * It has a {@link #toString()} method that will output the XML serialized form of the |
| 30 | * nodes it contains - again focusing on template engine usage, as well as the |
| 31 | * {@link #selectNodes(String)} method that helps selecting a different set of nodes |
| 32 | * starting from the nodes in this list. The class also implements the {@link java.util.List} |
| 33 | * interface by simply delegating calls to the contained list (the {@link #subList(int, int)} |
| 34 | * method is implemented by delegating to the contained list and wrapping the returned |
| 35 | * sublist into a <code>NodeList</code>). |
| 36 | * |
| 37 | * @author <a href="mailto:szegedia@freemail.hu">Attila Szegedi</a> |
| 38 | * @version $Id: NodeList.java,v 1.2.4.1 2004/03/03 23:22:04 geirm Exp $ |
| 39 | */ |
| 40 | public class NodeList implements List, Cloneable |
| 41 | { |
| 42 | private static final AttributeXMLOutputter DEFAULT_OUTPUTTER = |
| 43 | new AttributeXMLOutputter(); |
| 44 | |
| 45 | /** The contained nodes */ |
| 46 | private List nodes; |
| 47 | |
| 48 | /** |
| 49 | * Creates an empty node list. |
| 50 | */ |
| 51 | public NodeList() |
| 52 | { |
| 53 | nodes = new ArrayList(); |
| 54 | } |
| 55 | |
| 56 | /** |
| 57 | * Creates a node list that holds a single {@link Document} node. |
| 58 | */ |
| 59 | public NodeList(Document document) |
| 60 | { |
| 61 | this((Object)document); |
| 62 | } |
| 63 | |
| 64 | /** |
| 65 | * Creates a node list that holds a single {@link Element} node. |
| 66 | */ |
| 67 | public NodeList(Element element) |
| 68 | { |
| 69 | this((Object)element); |
| 70 | } |
| 71 | |
| 72 | private NodeList(Object object) |
| 73 | { |
| 74 | if(object == null) |
| 75 | { |
| 76 | throw new IllegalArgumentException( |
| 77 | "Cannot construct NodeList with null."); |
| 78 | } |
| 79 | nodes = new ArrayList(1); |
| 80 | nodes.add(object); |
| 81 | } |
| 82 | |
| 83 | /** |
| 84 | * Creates a node list that holds a list of nodes. |
| 85 | * @param nodes the list of nodes this template should hold. The created |
| 86 | * template will copy the passed nodes list, so changes to the passed list |
| 87 | * will not affect the model. |
| 88 | */ |
| 89 | public NodeList(List nodes) |
| 90 | { |
| 91 | this(nodes, true); |
| 92 | } |
| 93 | |
| 94 | /** |
| 95 | * Creates a node list that holds a list of nodes. |
| 96 | * @param nodes the list of nodes this template should hold. |
| 97 | * @param copy if true, the created template will copy the passed nodes |
| 98 | * list, so changes to the passed list will not affect the model. If false, |
| 99 | * the model will reference the passed list and will sense changes in it, |
| 100 | * altough no operations on the list will be synchronized. |
| 101 | */ |
| 102 | public NodeList(List nodes, boolean copy) |
| 103 | { |
| 104 | if(nodes == null) |
| 105 | { |
| 106 | throw new IllegalArgumentException( |
| 107 | "Cannot initialize NodeList with null list"); |
| 108 | } |
| 109 | this.nodes = copy ? new ArrayList(nodes) : nodes; |
| 110 | } |
| 111 | |
| 112 | /** |
| 113 | * Retrieves the underlying list used to store the nodes. Note however, that |
| 114 | * you can fully use the underlying list through the <code>List</code> interface |
| 115 | * of this class itself. You would probably access the underlying list only for |
| 116 | * synchronization purposes. |
| 117 | */ |
| 118 | public List getList() |
| 119 | { |
| 120 | return nodes; |
| 121 | } |
| 122 | |
| 123 | /** |
| 124 | * This method returns the string resulting from concatenation of string |
| 125 | * representations of its nodes. Each node is rendered using its XML |
| 126 | * serialization format. This greatly simplifies creating XML-transformation |
| 127 | * templates, as to output a node contained in variable x as XML fragment, |
| 128 | * you simply write ${x} in the template (or whatever your template engine |
| 129 | * uses as its expression syntax). |
| 130 | */ |
| 131 | public String toString() |
| 132 | { |
| 133 | if(nodes.isEmpty()) |
| 134 | { |
| 135 | return ""; |
| 136 | } |
| 137 | |
| 138 | StringWriter sw = new StringWriter(nodes.size() * 128); |
| 139 | try |
| 140 | { |
| 141 | for(Iterator i = nodes.iterator(); i.hasNext();) |
| 142 | { |
| 143 | Object node = i.next(); |
| 144 | if(node instanceof Element) |
| 145 | { |
| 146 | DEFAULT_OUTPUTTER.output((Element)node, sw); |
| 147 | } |
| 148 | else if(node instanceof Attribute) |
| 149 | { |
| 150 | DEFAULT_OUTPUTTER.output((Attribute)node, sw); |
| 151 | } |
| 152 | else if(node instanceof Text) |
| 153 | { |
| 154 | DEFAULT_OUTPUTTER.output((Text)node, sw); |
| 155 | } |
| 156 | else if(node instanceof Document) |
| 157 | { |
| 158 | DEFAULT_OUTPUTTER.output((Document)node, sw); |
| 159 | } |
| 160 | else if(node instanceof ProcessingInstruction) |
| 161 | { |
| 162 | DEFAULT_OUTPUTTER.output((ProcessingInstruction)node, sw); |
| 163 | } |
| 164 | else if(node instanceof Comment) |
| 165 | { |
| 166 | DEFAULT_OUTPUTTER.output((Comment)node, sw); |
| 167 | } |
| 168 | else if(node instanceof CDATA) |
| 169 | { |
| 170 | DEFAULT_OUTPUTTER.output((CDATA)node, sw); |
| 171 | } |
| 172 | else if(node instanceof DocType) |
| 173 | { |
| 174 | DEFAULT_OUTPUTTER.output((DocType)node, sw); |
| 175 | } |
| 176 | else if(node instanceof EntityRef) |
| 177 | { |
| 178 | DEFAULT_OUTPUTTER.output((EntityRef)node, sw); |
| 179 | } |
| 180 | else |
| 181 | { |
| 182 | throw new IllegalArgumentException( |
| 183 | "Cannot process a " + |
| 184 | (node == null |
| 185 | ? "null node" |
| 186 | : "node of class " + node.getClass().getName())); |
| 187 | } |
| 188 | } |
| 189 | } |
| 190 | catch(IOException e) |
| 191 | { |
| 192 | // Cannot happen as we work with a StringWriter in memory |
| 193 | throw new Error(); |
| 194 | } |
| 195 | return sw.toString(); |
| 196 | } |
| 197 | |
| 198 | /** |
| 199 | * Returns a NodeList that contains the same nodes as this node list. |
| 200 | * @throws CloneNotSupportedException if the contained list's class does |
| 201 | * not have an accessible no-arg constructor. |
| 202 | */ |
| 203 | public Object clone() |
| 204 | throws CloneNotSupportedException |
| 205 | { |
| 206 | NodeList clonedList = (NodeList)super.clone(); |
| 207 | clonedList.cloneNodes(); |
| 208 | return clonedList; |
| 209 | } |
| 210 | |
| 211 | private void cloneNodes() |
| 212 | throws CloneNotSupportedException |
| 213 | { |
| 214 | Class listClass = nodes.getClass(); |
| 215 | try |
| 216 | { |
| 217 | List clonedNodes = (List)listClass.newInstance(); |
| 218 | clonedNodes.addAll(nodes); |
| 219 | nodes = clonedNodes; |
| 220 | } |
| 221 | catch(IllegalAccessException e) |
| 222 | { |
| 223 | throw new CloneNotSupportedException("Cannot clone NodeList since" |
| 224 | + " there is no accessible no-arg constructor on class " |
| 225 | + listClass.getName()); |
| 226 | } |
| 227 | catch(InstantiationException e) |
| 228 | { |
| 229 | // Cannot happen as listClass represents a concrete, non-primitive, |
| 230 | // non-array, non-void class - there's an instance of it in "nodes" |
| 231 | // which proves these assumptions. |
| 232 | throw new Error(); |
| 233 | } |
| 234 | } |
| 235 | |
| 236 | /** |
| 237 | * Returns the hash code of the contained list. |
| 238 | */ |
| 239 | public int hashCode() |
| 240 | { |
| 241 | return nodes.hashCode(); |
| 242 | } |
| 243 | |
| 244 | /** |
| 245 | * Tests for equality with another object. |
| 246 | * @param o the object to test for equality |
| 247 | * @return true if the other object is also a NodeList and their contained |
| 248 | * {@link List} objects evaluate as equals. |
| 249 | */ |
| 250 | public boolean equals(Object o) |
| 251 | { |
| 252 | return o instanceof NodeList |
| 253 | ? ((NodeList)o).nodes.equals(nodes) |
| 254 | : false; |
| 255 | } |
| 256 | |
| 257 | /** |
| 258 | * Applies an XPath expression to the node list and returns the resulting |
| 259 | * node list. In order for this method to work, your application must have |
| 260 | * access to <a href="http://code.werken.com">werken.xpath</a> library |
| 261 | * classes. The implementation does cache the parsed format of XPath |
| 262 | * expressions in a weak hash map, keyed by the string representation of |
| 263 | * the XPath expression. As the string object passed as the argument is |
| 264 | * usually kept in the parsed template, this ensures that each XPath |
| 265 | * expression is parsed only once during the lifetime of the template that |
| 266 | * first invoked it. |
| 267 | * @param xpathExpression the XPath expression you wish to apply |
| 268 | * @return a NodeList representing the nodes that are the result of |
| 269 | * application of the XPath to the current node list. It can be empty. |
| 270 | */ |
| 271 | public NodeList selectNodes(String xpathString) |
| 272 | { |
| 273 | return new NodeList(XPathCache.getXPath(xpathString).applyTo(nodes), false); |
| 274 | } |
| 275 | |
| 276 | // List methods implemented hereafter |
| 277 | |
| 278 | public boolean add(Object o) |
| 279 | { |
| 280 | return nodes.add(o); |
| 281 | } |
| 282 | |
| 283 | public void add(int index, Object o) |
| 284 | { |
| 285 | nodes.add(index, o); |
| 286 | } |
| 287 | |
| 288 | public boolean addAll(Collection c) |
| 289 | { |
| 290 | return nodes.addAll(c); |
| 291 | } |
| 292 | |
| 293 | public boolean addAll(int index, Collection c) |
| 294 | { |
| 295 | return nodes.addAll(index, c); |
| 296 | } |
| 297 | |
| 298 | public void clear() |
| 299 | { |
| 300 | nodes.clear(); |
| 301 | } |
| 302 | |
| 303 | public boolean contains(Object o) |
| 304 | { |
| 305 | return nodes.contains(o); |
| 306 | } |
| 307 | |
| 308 | public boolean containsAll(Collection c) |
| 309 | { |
| 310 | return nodes.containsAll(c); |
| 311 | } |
| 312 | |
| 313 | public Object get(int index) |
| 314 | { |
| 315 | return nodes.get(index); |
| 316 | } |
| 317 | |
| 318 | public int indexOf(Object o) |
| 319 | { |
| 320 | return nodes.indexOf(o); |
| 321 | } |
| 322 | |
| 323 | public boolean isEmpty() |
| 324 | { |
| 325 | return nodes.isEmpty(); |
| 326 | } |
| 327 | |
| 328 | public Iterator iterator() |
| 329 | { |
| 330 | return nodes.iterator(); |
| 331 | } |
| 332 | |
| 333 | public int lastIndexOf(Object o) |
| 334 | { |
| 335 | return nodes.lastIndexOf(o); |
| 336 | } |
| 337 | |
| 338 | public ListIterator listIterator() |
| 339 | { |
| 340 | return nodes.listIterator(); |
| 341 | } |
| 342 | |
| 343 | public ListIterator listIterator(int index) |
| 344 | { |
| 345 | return nodes.listIterator(index); |
| 346 | } |
| 347 | |
| 348 | public Object remove(int index) |
| 349 | { |
| 350 | return nodes.remove(index); |
| 351 | } |
| 352 | |
| 353 | public boolean remove(Object o) |
| 354 | { |
| 355 | return nodes.remove(o); |
| 356 | } |
| 357 | |
| 358 | public boolean removeAll(Collection c) |
| 359 | { |
| 360 | return nodes.removeAll(c); |
| 361 | } |
| 362 | |
| 363 | public boolean retainAll(Collection c) |
| 364 | { |
| 365 | return nodes.retainAll(c); |
| 366 | } |
| 367 | |
| 368 | public Object set(int index, Object o) |
| 369 | { |
| 370 | return nodes.set(index, o); |
| 371 | } |
| 372 | |
| 373 | public int size() |
| 374 | { |
| 375 | return nodes.size(); |
| 376 | } |
| 377 | |
| 378 | public List subList(int fromIndex, int toIndex) |
| 379 | { |
| 380 | return new NodeList(nodes.subList(fromIndex, toIndex)); |
| 381 | } |
| 382 | |
| 383 | public Object[] toArray() |
| 384 | { |
| 385 | return nodes.toArray(); |
| 386 | } |
| 387 | |
| 388 | public Object[] toArray(Object[] a) |
| 389 | { |
| 390 | return nodes.toArray(a); |
| 391 | } |
| 392 | |
| 393 | /** |
| 394 | * A special subclass of XMLOutputter that will be used to output |
| 395 | * Attribute nodes. As a subclass of XMLOutputter it can use its protected |
| 396 | * method escapeAttributeEntities() to serialize the attribute |
| 397 | * appropriately. |
| 398 | */ |
| 399 | private static final class AttributeXMLOutputter extends XMLOutputter |
| 400 | { |
| 401 | public void output(Attribute attribute, Writer out) |
| 402 | throws IOException |
| 403 | { |
| 404 | out.write(" "); |
| 405 | out.write(attribute.getQualifiedName()); |
| 406 | out.write("="); |
| 407 | |
| 408 | out.write("\""); |
| 409 | out.write(escapeAttributeEntities(attribute.getValue())); |
| 410 | out.write("\""); |
| 411 | } |
| 412 | } |
| 413 | } |