2
|
1 |
/*
|
|
2 |
* Copyright 1998-2002 Sun Microsystems, Inc. All Rights Reserved.
|
|
3 |
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
|
|
4 |
*
|
|
5 |
* This code is free software; you can redistribute it and/or modify it
|
|
6 |
* under the terms of the GNU General Public License version 2 only, as
|
|
7 |
* published by the Free Software Foundation. Sun designates this
|
|
8 |
* particular file as subject to the "Classpath" exception as provided
|
|
9 |
* by Sun in the LICENSE file that accompanied this code.
|
|
10 |
*
|
|
11 |
* This code is distributed in the hope that it will be useful, but WITHOUT
|
|
12 |
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
13 |
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
|
14 |
* version 2 for more details (a copy is included in the LICENSE file that
|
|
15 |
* accompanied this code).
|
|
16 |
*
|
|
17 |
* You should have received a copy of the GNU General Public License version
|
|
18 |
* 2 along with this work; if not, write to the Free Software Foundation,
|
|
19 |
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
|
|
20 |
*
|
|
21 |
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
|
|
22 |
* CA 95054 USA or visit www.sun.com if you need additional information or
|
|
23 |
* have any questions.
|
|
24 |
*/
|
|
25 |
|
|
26 |
package javax.swing.text;
|
|
27 |
|
|
28 |
import java.util.Stack;
|
|
29 |
import java.util.Enumeration;
|
|
30 |
|
|
31 |
/**
|
|
32 |
* <p>
|
|
33 |
* ElementIterator, as the name suggests, iteratates over the Element
|
|
34 |
* tree. The constructor can be invoked with either Document or an Element
|
|
35 |
* as an argument. If the constructor is invoked with a Document as an
|
|
36 |
* argument then the root of the iteration is the return value of
|
|
37 |
* document.getDefaultRootElement().
|
|
38 |
*
|
|
39 |
* The iteration happens in a depth-first manner. In terms of how
|
|
40 |
* boundary conditions are handled:
|
|
41 |
* a) if next() is called before first() or current(), the
|
|
42 |
* root will be returned.
|
|
43 |
* b) next() returns null to indicate the end of the list.
|
|
44 |
* c) previous() returns null when the current element is the root
|
|
45 |
* or next() has returned null.
|
|
46 |
*
|
|
47 |
* The ElementIterator does no locking of the Element tree. This means
|
|
48 |
* that it does not track any changes. It is the responsibility of the
|
|
49 |
* user of this class, to ensure that no changes happen during element
|
|
50 |
* iteration.
|
|
51 |
*
|
|
52 |
* Simple usage example:
|
|
53 |
*
|
|
54 |
* public void iterate() {
|
|
55 |
* ElementIterator it = new ElementIterator(root);
|
|
56 |
* Element elem;
|
|
57 |
* while (true) {
|
|
58 |
* if ((elem = next()) != null) {
|
|
59 |
* // process element
|
|
60 |
* System.out.println("elem: " + elem.getName());
|
|
61 |
* } else {
|
|
62 |
* break;
|
|
63 |
* }
|
|
64 |
* }
|
|
65 |
* }
|
|
66 |
*
|
|
67 |
* @author Sunita Mani
|
|
68 |
*
|
|
69 |
*/
|
|
70 |
|
|
71 |
public class ElementIterator implements Cloneable {
|
|
72 |
|
|
73 |
|
|
74 |
private Element root;
|
|
75 |
private Stack elementStack = null;
|
|
76 |
|
|
77 |
/**
|
|
78 |
* The StackItem class stores the element
|
|
79 |
* as well as a child index. If the
|
|
80 |
* index is -1, then the element represented
|
|
81 |
* on the stack is the element itself.
|
|
82 |
* Otherwise, the index functions as as index
|
|
83 |
* into the vector of children of the element.
|
|
84 |
* In this case, the item on the stack
|
|
85 |
* represents the "index"th child of the element
|
|
86 |
*
|
|
87 |
*/
|
|
88 |
private class StackItem implements Cloneable {
|
|
89 |
Element item;
|
|
90 |
int childIndex;
|
|
91 |
|
|
92 |
private StackItem(Element elem) {
|
|
93 |
/**
|
|
94 |
* -1 index implies a self reference,
|
|
95 |
* as opposed to an index into its
|
|
96 |
* list of children.
|
|
97 |
*/
|
|
98 |
this.item = elem;
|
|
99 |
this.childIndex = -1;
|
|
100 |
}
|
|
101 |
|
|
102 |
private void incrementIndex() {
|
|
103 |
childIndex++;
|
|
104 |
}
|
|
105 |
|
|
106 |
private Element getElement() {
|
|
107 |
return item;
|
|
108 |
}
|
|
109 |
|
|
110 |
private int getIndex() {
|
|
111 |
return childIndex;
|
|
112 |
}
|
|
113 |
|
|
114 |
protected Object clone() throws java.lang.CloneNotSupportedException {
|
|
115 |
return super.clone();
|
|
116 |
}
|
|
117 |
}
|
|
118 |
|
|
119 |
/**
|
|
120 |
* Creates a new ElementIterator. The
|
|
121 |
* root element is taken to get the
|
|
122 |
* default root element of the document.
|
|
123 |
*
|
|
124 |
* @param document a Document.
|
|
125 |
*/
|
|
126 |
public ElementIterator(Document document) {
|
|
127 |
root = document.getDefaultRootElement();
|
|
128 |
}
|
|
129 |
|
|
130 |
|
|
131 |
/**
|
|
132 |
* Creates a new ElementIterator.
|
|
133 |
*
|
|
134 |
* @param root the root Element.
|
|
135 |
*/
|
|
136 |
public ElementIterator(Element root) {
|
|
137 |
this.root = root;
|
|
138 |
}
|
|
139 |
|
|
140 |
|
|
141 |
/**
|
|
142 |
* Clones the ElementIterator.
|
|
143 |
*
|
|
144 |
* @return a cloned ElementIterator Object.
|
|
145 |
*/
|
|
146 |
public synchronized Object clone() {
|
|
147 |
|
|
148 |
try {
|
|
149 |
ElementIterator it = new ElementIterator(root);
|
|
150 |
if (elementStack != null) {
|
|
151 |
it.elementStack = new Stack();
|
|
152 |
for (int i = 0; i < elementStack.size(); i++) {
|
|
153 |
StackItem item = (StackItem)elementStack.elementAt(i);
|
|
154 |
StackItem clonee = (StackItem)item.clone();
|
|
155 |
it.elementStack.push(clonee);
|
|
156 |
}
|
|
157 |
}
|
|
158 |
return it;
|
|
159 |
} catch (CloneNotSupportedException e) {
|
|
160 |
throw new InternalError();
|
|
161 |
}
|
|
162 |
}
|
|
163 |
|
|
164 |
|
|
165 |
/**
|
|
166 |
* Fetches the first element.
|
|
167 |
*
|
|
168 |
* @return an Element.
|
|
169 |
*/
|
|
170 |
public Element first() {
|
|
171 |
// just in case...
|
|
172 |
if (root == null) {
|
|
173 |
return null;
|
|
174 |
}
|
|
175 |
|
|
176 |
elementStack = new Stack();
|
|
177 |
if (root.getElementCount() != 0) {
|
|
178 |
elementStack.push(new StackItem(root));
|
|
179 |
}
|
|
180 |
return root;
|
|
181 |
}
|
|
182 |
|
|
183 |
/**
|
|
184 |
* Fetches the current depth of element tree.
|
|
185 |
*
|
|
186 |
* @return the depth.
|
|
187 |
*/
|
|
188 |
public int depth() {
|
|
189 |
if (elementStack == null) {
|
|
190 |
return 0;
|
|
191 |
}
|
|
192 |
return elementStack.size();
|
|
193 |
}
|
|
194 |
|
|
195 |
|
|
196 |
/**
|
|
197 |
* Fetches the current Element.
|
|
198 |
*
|
|
199 |
* @return element on top of the stack or
|
|
200 |
* <code>null</code> if the root element is <code>null</code>
|
|
201 |
*/
|
|
202 |
public Element current() {
|
|
203 |
|
|
204 |
if (elementStack == null) {
|
|
205 |
return first();
|
|
206 |
}
|
|
207 |
|
|
208 |
/*
|
|
209 |
get a handle to the element on top of the stack.
|
|
210 |
*/
|
|
211 |
if (! elementStack.empty()) {
|
|
212 |
StackItem item = (StackItem)elementStack.peek();
|
|
213 |
Element elem = item.getElement();
|
|
214 |
int index = item.getIndex();
|
|
215 |
// self reference
|
|
216 |
if (index == -1) {
|
|
217 |
return elem;
|
|
218 |
}
|
|
219 |
// return the child at location "index".
|
|
220 |
return elem.getElement(index);
|
|
221 |
}
|
|
222 |
return null;
|
|
223 |
}
|
|
224 |
|
|
225 |
|
|
226 |
/**
|
|
227 |
* Fetches the next Element. The strategy
|
|
228 |
* used to locate the next element is
|
|
229 |
* a depth-first search.
|
|
230 |
*
|
|
231 |
* @return the next element or <code>null</code>
|
|
232 |
* at the end of the list.
|
|
233 |
*/
|
|
234 |
public Element next() {
|
|
235 |
|
|
236 |
/* if current() has not been invoked
|
|
237 |
and next is invoked, the very first
|
|
238 |
element will be returned. */
|
|
239 |
if (elementStack == null) {
|
|
240 |
return first();
|
|
241 |
}
|
|
242 |
|
|
243 |
// no more elements
|
|
244 |
if (elementStack.isEmpty()) {
|
|
245 |
return null;
|
|
246 |
}
|
|
247 |
|
|
248 |
// get a handle to the element on top of the stack
|
|
249 |
|
|
250 |
StackItem item = (StackItem)elementStack.peek();
|
|
251 |
Element elem = item.getElement();
|
|
252 |
int index = item.getIndex();
|
|
253 |
|
|
254 |
if (index+1 < elem.getElementCount()) {
|
|
255 |
Element child = elem.getElement(index+1);
|
|
256 |
if (child.isLeaf()) {
|
|
257 |
/* In this case we merely want to increment
|
|
258 |
the child index of the item on top of the
|
|
259 |
stack.*/
|
|
260 |
item.incrementIndex();
|
|
261 |
} else {
|
|
262 |
/* In this case we need to push the child(branch)
|
|
263 |
on the stack so that we can iterate over its
|
|
264 |
children. */
|
|
265 |
elementStack.push(new StackItem(child));
|
|
266 |
}
|
|
267 |
return child;
|
|
268 |
} else {
|
|
269 |
/* No more children for the item on top of the
|
|
270 |
stack therefore pop the stack. */
|
|
271 |
elementStack.pop();
|
|
272 |
if (!elementStack.isEmpty()) {
|
|
273 |
/* Increment the child index for the item that
|
|
274 |
is now on top of the stack. */
|
|
275 |
StackItem top = (StackItem)elementStack.peek();
|
|
276 |
top.incrementIndex();
|
|
277 |
/* We now want to return its next child, therefore
|
|
278 |
call next() recursively. */
|
|
279 |
return next();
|
|
280 |
}
|
|
281 |
}
|
|
282 |
return null;
|
|
283 |
}
|
|
284 |
|
|
285 |
|
|
286 |
/**
|
|
287 |
* Fetches the previous Element. If howver the current
|
|
288 |
* element is the last element, or the current element
|
|
289 |
* is null, then null is returned.
|
|
290 |
*
|
|
291 |
* @return previous <code>Element</code> if available
|
|
292 |
*
|
|
293 |
*/
|
|
294 |
public Element previous() {
|
|
295 |
|
|
296 |
int stackSize;
|
|
297 |
if (elementStack == null || (stackSize = elementStack.size()) == 0) {
|
|
298 |
return null;
|
|
299 |
}
|
|
300 |
|
|
301 |
// get a handle to the element on top of the stack
|
|
302 |
//
|
|
303 |
StackItem item = (StackItem)elementStack.peek();
|
|
304 |
Element elem = item.getElement();
|
|
305 |
int index = item.getIndex();
|
|
306 |
|
|
307 |
if (index > 0) {
|
|
308 |
/* return child at previous index. */
|
|
309 |
return getDeepestLeaf(elem.getElement(--index));
|
|
310 |
} else if (index == 0) {
|
|
311 |
/* this implies that current is the element's
|
|
312 |
first child, therefore previous is the
|
|
313 |
element itself. */
|
|
314 |
return elem;
|
|
315 |
} else if (index == -1) {
|
|
316 |
if (stackSize == 1) {
|
|
317 |
// current is the root, nothing before it.
|
|
318 |
return null;
|
|
319 |
}
|
|
320 |
/* We need to return either the item
|
|
321 |
below the top item or one of the
|
|
322 |
former's children. */
|
|
323 |
Object top = elementStack.pop();
|
|
324 |
item = (StackItem)elementStack.peek();
|
|
325 |
|
|
326 |
// restore the top item.
|
|
327 |
elementStack.push(top);
|
|
328 |
elem = item.getElement();
|
|
329 |
index = item.getIndex();
|
|
330 |
return ((index == -1) ? elem : getDeepestLeaf(elem.getElement
|
|
331 |
(index)));
|
|
332 |
}
|
|
333 |
// should never get here.
|
|
334 |
return null;
|
|
335 |
}
|
|
336 |
|
|
337 |
/**
|
|
338 |
* Returns the last child of <code>parent</code> that is a leaf. If the
|
|
339 |
* last child is a not a leaf, this method is called with the last child.
|
|
340 |
*/
|
|
341 |
private Element getDeepestLeaf(Element parent) {
|
|
342 |
if (parent.isLeaf()) {
|
|
343 |
return parent;
|
|
344 |
}
|
|
345 |
int childCount = parent.getElementCount();
|
|
346 |
if (childCount == 0) {
|
|
347 |
return parent;
|
|
348 |
}
|
|
349 |
return getDeepestLeaf(parent.getElement(childCount - 1));
|
|
350 |
}
|
|
351 |
|
|
352 |
/*
|
|
353 |
Iterates through the element tree and prints
|
|
354 |
out each element and its attributes.
|
|
355 |
*/
|
|
356 |
private void dumpTree() {
|
|
357 |
|
|
358 |
Element elem;
|
|
359 |
while (true) {
|
|
360 |
if ((elem = next()) != null) {
|
|
361 |
System.out.println("elem: " + elem.getName());
|
|
362 |
AttributeSet attr = elem.getAttributes();
|
|
363 |
String s = "";
|
|
364 |
Enumeration names = attr.getAttributeNames();
|
|
365 |
while (names.hasMoreElements()) {
|
|
366 |
Object key = names.nextElement();
|
|
367 |
Object value = attr.getAttribute(key);
|
|
368 |
if (value instanceof AttributeSet) {
|
|
369 |
// don't go recursive
|
|
370 |
s = s + key + "=**AttributeSet** ";
|
|
371 |
} else {
|
|
372 |
s = s + key + "=" + value + " ";
|
|
373 |
}
|
|
374 |
}
|
|
375 |
System.out.println("attributes: " + s);
|
|
376 |
} else {
|
|
377 |
break;
|
|
378 |
}
|
|
379 |
}
|
|
380 |
}
|
|
381 |
}
|