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/**
* Copyright (c) 2011, University of Konstanz, Distributed Systems Group
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the University of Konstanz nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.treetank.axis;
import java.util.Stack;
import org.treetank.api.INodeReadTrx;
import org.treetank.data.IConstants;
import org.treetank.data.interfaces.ITreeStructData;
/**
* PrecedingAxis
*
*
* Iterate over all preceding nodes of kind ELEMENT or TEXT starting at a given node. Self is not included.
*
*/
public class PrecedingAxis extends AbsAxis {
private boolean mIsFirst;
private Stack mStack;
/**
* Constructor initializing internal state.
*
* @param rtx
* Exclusive (immutable) trx to iterate with.
*/
public PrecedingAxis(final INodeReadTrx rtx) {
super(rtx);
mIsFirst = true;
mStack = new Stack();
}
/**
* {@inheritDoc}
*/
@Override
public final void reset(final long mNodeKey) {
super.reset(mNodeKey);
mIsFirst = true;
mStack = new Stack();
}
/**
* {@inheritDoc}
*/
@Override
public final boolean hasNext() {
// assure, that preceding is not evaluated on an attribute or a
// namespace
if (mIsFirst) {
mIsFirst = false;
if (getNode().getKind() == IConstants.ATTRIBUTE
// || getTransaction().isNamespaceKind()
) {
resetToStartKey();
return false;
}
}
resetToLastKey();
if (!mStack.empty()) {
// return all nodes of the current subtree in reverse document order
moveTo(mStack.pop());
return true;
}
if (((ITreeStructData)getNode()).hasLeftSibling()) {
moveTo(((ITreeStructData)getNode()).getLeftSiblingKey());
// because this axis return the precedings in reverse document
// order, we
// need to travel to the node in the subtree, that comes last in
// document
// order.
getLastChild();
return true;
}
while (getNode().hasParent()) {
// ancestors are not part of the preceding set
moveTo(getNode().getParentKey());
if (((ITreeStructData)getNode()).hasLeftSibling()) {
moveTo(((ITreeStructData)getNode()).getLeftSiblingKey());
// move to last node in the subtree
getLastChild();
return true;
}
}
resetToStartKey();
return false;
}
/**
* Moves the transaction to the node in the current subtree, that is last in
* document order and pushes all other node key on a stack. At the end the
* stack contains all node keys except for the last one in reverse document
* order.
*/
private void getLastChild() {
// nodekey of the root of the current subtree
final long parent = getNode().getDataKey();
// traverse tree in pre order to the leftmost leaf of the subtree and
// push
// all nodes to the stack
if (((ITreeStructData)getNode()).hasFirstChild()) {
while (((ITreeStructData)getNode()).hasFirstChild()) {
mStack.push(getNode().getDataKey());
moveTo(((ITreeStructData)getNode()).getFirstChildKey());
}
// traverse all the siblings of the leftmost leave and all their
// descendants and push all of them to the stack
while (((ITreeStructData)getNode()).hasRightSibling()) {
mStack.push(getNode().getDataKey());
moveTo(((ITreeStructData)getNode()).getRightSiblingKey());
getLastChild();
}
// step up the path till the root of the current subtree and process
// all
// right siblings and their descendants on each step
if (getNode().hasParent() && (getNode().getParentKey() != parent)) {
mStack.push(getNode().getDataKey());
while (getNode().hasParent() && (getNode().getParentKey() != parent)) {
moveTo(getNode().getParentKey());
// traverse all the siblings of the leftmost leave and all
// their
// descendants and push all of them to the stack
while (((ITreeStructData)getNode()).hasRightSibling()) {
moveTo(((ITreeStructData)getNode()).getRightSiblingKey());
getLastChild();
mStack.push(getNode().getDataKey());
}
}
// set transaction to the node in the subtree that is last in
// document
// order
moveTo(mStack.pop());
}
}
}
}