2
* Licensed to the Apache Software Foundation (ASF) under one
3
* or more contributor license agreements. See the NOTICE file
4
* distributed with this work for additional information
5
* regarding copyright ownership. The ASF licenses this file
6
* to you 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
10
* http://www.apache.org/licenses/LICENSE-2.0
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.
19
* $Id: DTMAxisIteratorBase.java,v 1.2 2009/12/10 03:18:39 matthewoliver Exp $
21
package org.apache.xml.dtm.ref;
23
import org.apache.xml.dtm.DTMAxisIterator;
26
* This class serves as a default base for implementations of mutable
29
public abstract class DTMAxisIteratorBase implements DTMAxisIterator
32
/** The position of the last node within the iteration, as defined by XPath.
33
* Note that this is _not_ the node's handle within the DTM. Also, don't
34
* confuse it with the current (most recently returned) position.
36
protected int _last = -1;
38
/** The position of the current node within the iteration, as defined by XPath.
39
* Note that this is _not_ the node's handle within the DTM!
41
protected int _position = 0;
43
/** The position of the marked node within the iteration;
44
* a saved itaration state that we may want to come back to.
45
* Note that only one mark is maintained; there is no stack.
47
protected int _markedNode;
49
/** The handle to the start, or root, of the iteration.
50
* Set this to END to construct an empty iterator.
52
protected int _startNode = DTMAxisIterator.END;
54
/** True if the start node should be considered part of the iteration.
55
* False will cause it to be skipped.
57
protected boolean _includeSelf = false;
59
/** True if this iteration can be restarted. False otherwise (eg, if
60
* we are iterating over a stream that can not be re-scanned, or if
61
* the iterator was produced by cloning another iterator.)
63
protected boolean _isRestartable = true;
66
* Get start to END should 'close' the iterator,
67
* i.e. subsequent call to next() should return END.
69
* @return The root node of the iteration.
71
public int getStartNode()
77
* @return A DTMAxisIterator which has been reset to the start node,
78
* which may or may not be the same as this iterator.
80
public DTMAxisIterator reset()
83
final boolean temp = _isRestartable;
85
_isRestartable = true;
87
setStartNode(_startNode);
89
_isRestartable = temp;
95
* Set the flag to include the start node in the iteration.
98
* @return This default method returns just returns this DTMAxisIterator,
99
* after setting the flag.
100
* (Returning "this" permits C++-style chaining of
101
* method calls into a single expression.)
103
public DTMAxisIterator includeSelf()
111
/** Returns the position of the last node within the iteration, as
112
* defined by XPath. In a forward iterator, I believe this equals the number of nodes which this
113
* iterator will yield. In a reverse iterator, I believe it should return
114
* 1 (since the "last" is the first produced.)
116
* This may be an expensive operation when called the first time, since
117
* it may have to iterate through a large part of the document to produce
120
* @return The number of nodes in this iterator (forward) or 1 (reverse).
125
if (_last == -1) // Not previously established
127
// Note that we're doing both setMark() -- which saves _currentChild
128
// -- and explicitly saving our position counter (number of nodes
131
// %REVIEW% Should position also be saved by setMark()?
132
// (It wasn't in the XSLTC version, but I don't understand why not.)
134
final int temp = _position; // Save state
137
reset(); // Count the nodes found by this iterator
142
while (next() != END);
144
gotoMark(); // Restore saved state
152
* @return The position of the current node within the set, as defined by
153
* XPath. Note that this is one-based, not zero-based.
155
public int getPosition()
157
return _position == 0 ? 1 : _position;
161
* @return true if this iterator has a reversed axis, else false
163
public boolean isReverse()
169
* Returns a deep copy of this iterator. Cloned iterators may not be
170
* restartable. The iterator being cloned may or may not become
171
* non-restartable as a side effect of this operation.
173
* @return a deep copy of this iterator.
175
public DTMAxisIterator cloneIterator()
180
final DTMAxisIteratorBase clone = (DTMAxisIteratorBase) super.clone();
182
clone._isRestartable = false;
184
// return clone.reset();
187
catch (CloneNotSupportedException e)
189
throw new org.apache.xml.utils.WrappedRuntimeException(e);
194
* Do any final cleanup that is required before returning the node that was
195
* passed in, and then return it. The intended use is
197
* <code>return returnNode(node);</code>
199
* %REVIEW% If we're calling it purely for side effects, should we really
200
* be bothering with a return value? Something like
202
* <code> accept(node); return node; </code>
204
* would probably optimize just about as well and avoid questions
205
* about whether what's returned could ever be different from what's
208
* @param node Node handle which iteration is about to yield.
210
* @return The node handle passed in. */
211
protected final int returnNode(final int node)
219
* Reset the position to zero. NOTE that this does not change the iteration
220
* state, only the position number associated with that state.
222
* %REVIEW% Document when this would be used?
224
* @return This instance.
226
protected final DTMAxisIterator resetPosition()
235
* Returns true if all the nodes in the iteration well be returned in document
238
* @return true as a default.
240
public boolean isDocOrdered()
246
* Returns the axis being iterated, if it is known.
248
* @return Axis.CHILD, etc., or -1 if the axis is not known or is of multiple
256
public void setRestartable(boolean isRestartable) {
257
_isRestartable = isRestartable;
261
* Return the node at the given position.
263
* @param position The position
264
* @return The node at the given position.
266
public int getNodeByPosition(int position)
269
final int pos = isReverse() ? getLast() - position + 1
272
while ((node = next()) != DTMAxisIterator.END) {
273
if (pos == getPosition()) {