org.apache.xpath.axes
Class AxesWalker

java.lang.Object
  |
  +--org.apache.xpath.Expression
        |
        +--org.apache.xpath.patterns.NodeTest
              |
              +--org.apache.xpath.axes.PredicatedNodeTest
                    |
                    +--org.apache.xpath.axes.AxesWalker

Direct Known Subclasses:

FilterExprWalker, ReverseAxesWalker

public class AxesWalker

extends PredicatedNodeTest

implements java.lang.Cloneable, PathComponent, ExpressionOwner

Serves as common interface for axes Walkers, and stores common state variables.

See Also:

Serialized Form

Fields inherited from class org.apache.xpath.patterns.NodeTest

SCORE_NODETEST, SCORE_NONE, SCORE_NSWILD, SCORE_OTHER, SCORE_QNAME, SHOW_BYFUNCTION, SUPPORTS_PRE_STRIPPING, WILD

Constructor Summary

AxesWalker(LocPathIterator locPathIterator, int axis)
Construct an AxesWalker using a LocPathIterator.

Method Summary

void	callVisitors(ExpressionOwner owner, XPathVisitor visitor) This will traverse the heararchy, calling the visitor for each member.
java.lang.Object	clone() Get a cloned AxesWalker.
boolean	deepEquals(Expression expr)
void	detach() Detaches the walker from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state.
int	getAnalysisBits() Get the analysis bits for this walker, as defined in the WalkerFactory.
int	getAxis() Returns the axis being iterated, if it is known.
int	getCurrentNode() The node at which the TreeWalker is currently positioned.
DTM	getDTM(int node) Get the DTM for this walker.
Expression	getExpression()
int	getLastPos(XPathContext xctxt) Get the index of the last node that can be itterated to.
AxesWalker	getNextWalker() Get the next walker in the location step chain.
AxesWalker	getPrevWalker() Get the previous walker reference in the location step chain.
int	getRoot() The root node of the TreeWalker, as specified in setRoot(int root).
void	init(Compiler compiler, int opPos, int stepType) Initialize an AxesWalker during the parse of the XPath expression.
boolean	isDocOrdered() Returns true if all the nodes in the iteration well be returned in document order.
int	nextNode() Moves the TreeWalker to the next visible node in document order relative to the current node, and returns the new node.
void	setDefaultDTM(DTM dtm) Set the DTM for this walker.
void	setExpression(Expression exp)
void	setNextWalker(AxesWalker walker) Set the next walker in the location step chain.
void	setPrevWalker(AxesWalker walker) Set or clear the previous walker reference in the location step chain.
void	setRoot(int root) Set the root node of the TreeWalker.
WalkingIterator	wi()

Methods inherited from class org.apache.xpath.axes.PredicatedNodeTest

acceptNode, callPredicateVisitors, canTraverseOutsideSubtree, fixupVariables, getLocPathIterator, getPredicate, getPredicateCount, getPredicateIndex, getProximityPosition, getProximityPosition, initProximityPosition, isReverseAxes, resetProximityPositions, setLocPathIterator, setPredicateCount

Methods inherited from class org.apache.xpath.patterns.NodeTest

debugWhatToShow, execute, execute, execute, getDefaultScore, getLocalName, getNamespace, getNodeTypeTest, getStaticScore, getWhatToShow, initNodeTest, initNodeTest, setLocalName, setNamespace, setStaticScore, setWhatToShow

Methods inherited from class org.apache.xpath.Expression

asIterator, asIteratorRaw, asNode, assertion, bool, error, execute, executeCharsToContentHandler, exprAddChild, exprGetChild, exprGetNumChildren, exprGetParent, exprSetParent, getColumnNumber, getExpressionOwner, getLineNumber, getPublicId, getSystemId, isNodesetExpr, isStableNumber, num, warn, xstr

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AxesWalker

public AxesWalker(LocPathIterator locPathIterator,
                  int axis)

Construct an AxesWalker using a LocPathIterator.

Parameters:

locPathIterator - non-null reference to the parent iterator.

Method Detail

wi

public final WalkingIterator wi()

init

public void init(Compiler compiler,
                 int opPos,
                 int stepType)
          throws TransformerException

Initialize an AxesWalker during the parse of the XPath expression.

Parameters:

compiler - The Compiler object that has information about this walker in the op map.

opPos - The op code position of this location step.

stepType - The type of location step.

Throws:

TransformerException -

clone

public java.lang.Object clone()
                       throws java.lang.CloneNotSupportedException

Get a cloned AxesWalker.

Returns:

A new AxesWalker that can be used without mutating this one.

Throws:

java.lang.CloneNotSupportedException -

Overrides:

clone in class PredicatedNodeTest

detach

public void detach()

Detaches the walker from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state.

getRoot

public int getRoot()

The root node of the TreeWalker, as specified in setRoot(int root). Note that this may actually be below the current node.

Returns:

The context node of the step.

getAnalysisBits

public int getAnalysisBits()

Get the analysis bits for this walker, as defined in the WalkerFactory.

Specified by:

getAnalysisBits in interface PathComponent

Returns:

One of WalkerFactory#BIT_DESCENDANT, etc.

setRoot

public void setRoot(int root)

Set the root node of the TreeWalker. (Not part of the DOM2 TreeWalker interface).

Parameters:

root - The context node of this step.

getCurrentNode

public final int getCurrentNode()

The node at which the TreeWalker is currently positioned.
The value must not be null. Alterations to the DOM tree may cause the current node to no longer be accepted by the TreeWalker's associated filter. currentNode may also be explicitly set to any node, whether or not it is within the subtree specified by the root node or would be accepted by the filter and whatToShow flags. Further traversal occurs relative to currentNode even if it is not part of the current view by applying the filters in the requested direction (not changing currentNode where no traversal is possible).

Returns:

The node at which the TreeWalker is currently positioned, only null if setRoot has not yet been called.

setNextWalker

public void setNextWalker(AxesWalker walker)

Set the next walker in the location step chain.

Parameters:

walker - Reference to AxesWalker derivative, or may be null.

getNextWalker

public AxesWalker getNextWalker()

Get the next walker in the location step chain.

Returns:

Reference to AxesWalker derivative, or null.

setPrevWalker

public void setPrevWalker(AxesWalker walker)

Set or clear the previous walker reference in the location step chain.

Parameters:

walker - Reference to previous walker reference in the location step chain, or null.

getPrevWalker

public AxesWalker getPrevWalker()

Get the previous walker reference in the location step chain.

Returns:

Reference to previous walker reference in the location step chain, or null.

nextNode

public int nextNode()

Moves the TreeWalker to the next visible node in document order relative to the current node, and returns the new node. If the current node has no next node, or if the search for nextNode attempts to step upward from the TreeWalker's root node, returns null , and retains the current node.

Returns:

The new node, or null if the current node has no next node in the TreeWalker's logical view.

getLastPos

public int getLastPos(XPathContext xctxt)

Get the index of the last node that can be itterated to.

Parameters:

xctxt - XPath runtime context.

Returns:

the index of the last node that can be itterated to.

Overrides:

getLastPos in class PredicatedNodeTest

setDefaultDTM

public void setDefaultDTM(DTM dtm)

Set the DTM for this walker.

Parameters:

dtm - Non-null reference to a DTM.

getDTM

public DTM getDTM(int node)

Get the DTM for this walker.

Returns:

Non-null reference to a DTM.

isDocOrdered

public boolean isDocOrdered()

Returns true if all the nodes in the iteration well be returned in document order. Warning: This can only be called after setRoot has been called!

Returns:

true as a default.

getAxis

public int getAxis()

Returns the axis being iterated, if it is known.

Returns:

Axis.CHILD, etc., or -1 if the axis is not known or is of multiple types.

callVisitors

public void callVisitors(ExpressionOwner owner,
                         XPathVisitor visitor)

This will traverse the heararchy, calling the visitor for each member. If the called visitor method returns false, the subtree should not be called.

Parameters:

owner - The owner of the visitor, where that path may be rewritten if needed.

visitor - The visitor whose appropriate method will be called.

Overrides:

callVisitors in class NodeTest

getExpression

public Expression getExpression()

Specified by:

getExpression in interface ExpressionOwner

See Also:

ExpressionOwner.getExpression()

setExpression

public void setExpression(Expression exp)

Specified by:

setExpression in interface ExpressionOwner

See Also:

ExpressionOwner.setExpression(Expression)

deepEquals

public boolean deepEquals(Expression expr)

Overrides:

deepEquals in class PredicatedNodeTest

See Also:

Expression.deepEquals(Expression)