org.apache.xpath.axes
Class NodeSequence

java.lang.Object
  org.apache.xpath.Expression
      org.apache.xpath.objects.XObject
          org.apache.xpath.axes.NodeSequence

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, javax.xml.transform.SourceLocator, DTMIterator, PathComponent, ExpressionNode, XPathVisitable

Direct Known Subclasses:

XNodeSet

public class NodeSequence
extends XObject
implements DTMIterator, java.lang.Cloneable, PathComponent

This class is the dynamic wrapper for a Xalan DTMIterator instance, and provides random access capabilities.

See Also:

Serialized Form

Nested Class Summary

private static class

NodeSequence.IteratorCache Each NodeSequence object has an iterator which is "walked".

Field Summary

private NodeSequence.IteratorCache	m_cache A cache of a list of nodes obtained from the iterator so far.
protected DTMManager	m_dtmMgr The DTMManager to use if we're using a NodeVector only.
protected DTMIterator	m_iter The functional iterator that fetches nodes.
protected int	m_last The index of the last node in the iteration.
protected int	m_next The index of the next node to be fetched.
(package private) static long	serialVersionUID

Fields inherited from class org.apache.xpath.objects.XObject

CLASS_BOOLEAN, CLASS_NODESET, CLASS_NULL, CLASS_NUMBER, CLASS_RTREEFRAG, CLASS_STRING, CLASS_UNKNOWN, CLASS_UNRESOLVEDVARIABLE, m_obj

Fields inherited from interface org.apache.xml.dtm.DTMIterator

FILTER_ACCEPT, FILTER_REJECT, FILTER_SKIP

Constructor Summary

	NodeSequence() Create a new NodeSequence in an invalid (null) state.
private	NodeSequence(DTMIterator iter, int context, XPathContext xctxt, boolean shouldCacheNodes) Create a new NodeSequence from a (already cloned) iterator.
private	NodeSequence(DTMManager dtmMgr) Construct an empty XNodeSet object.
	NodeSequence(java.lang.Object nodeVector) Create a new NodeSequence from a (already cloned) iterator.

Method Summary

protected int	addNodeInDocOrder(int node) Add the node into a vector of nodes where it should occur in document order.
void	allowDetachToRelease(boolean allowRelease) Calling this with a value of false will cause the nodeset to be cached.
private boolean	cacheComplete() If this NodeSequence has a cache, and that cache is fully populated then this method returns true, otherwise if there is no cache or it is not complete it returns false.
java.lang.Object	clone() Get a clone of this iterator, but don't reset the iteration in the process, so that it may be used from the current position.
DTMIterator	cloneWithReset() Note: Not a deep clone.
void	detach() Detaches the DTMIterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state.
void	fixupVariables(java.util.Vector vars, int globalsSize) XObjects should not normally need to fix up variables.
int	getAnalysisBits() Get the analysis bits for this path component, as defined in the WalkerFactory.
int	getAxis() Returns the axis being iterated, if it is known.
private NodeSequence.IteratorCache	getCache() Get the cache (if any) of nodes obtained from the iterator so far.
DTMIterator	getContainedIter() Get the functional iterator that fetches nodes.
int	getCurrentNode() Get the current node in the iterator.
int	getCurrentPos() Get the current position within the cached list, which is one less than the next nextNode() call will retrieve.
DTM	getDTM(int nodeHandle) Get an instance of a DTM that "owns" a node handle.
DTMManager	getDTMManager() Get an instance of the DTMManager.
boolean	getExpandEntityReferences() The value of this flag determines whether the children of entity reference nodes are visible to the iterator.
protected NodeSequence.IteratorCache	getIteratorCache() Get the cached list of nodes appended with values obtained from the iterator as a NodeSequence is walked when its nextNode() method is called.
int	getLength() The number of nodes in the list.
int	getRoot() The root node of the DTMIterator, as specified when it was created.
protected NodeVector	getVector() If this iterator needs to cache nodes that are fetched, they are stored in the Vector in the generic object.
int	getWhatToShow() This attribute determines which node types are presented via the iterator.
boolean	hasCache() If the iterator needs to cache nodes as they are fetched, then this method returns true.
boolean	isDocOrdered() Returns true if all the nodes in the iteration well be returned in document order.
boolean	isFresh() Tells if this NodeSetDTM is "fresh", in other words, if the first nextNode() that is called will return the first node in the set.
boolean	isMutable() Tells if this iterator can have nodes added to it or set via the setItem(int node, int index) method.
int	item(int index) Returns the node handle of an item in the collection.
private void	markCacheComplete() If this NodeSequence has a cache, mark that it is complete.
int	nextNode() Returns the next node in the set and advances the position of the iterator in the set.
int	previousNode() Returns the previous node in the set and moves the position of the DTMIterator backwards in the set.
void	reset() Reset for fresh reuse.
void	runTo(int index) If an index is requested, NodeSetDTM will call this method to run the iterator to the index.
void	setCurrentPos(int i) Set the current position in the node set.
void	setItem(int node, int index) Sets the node at the specified index of this vector to be the specified node.
void	setIter(DTMIterator iter) Set the functional iterator that fetches nodes.
protected void	setObject(java.lang.Object obj) It used to be that many locations in the code simply did an assignment to this.m_obj directly, rather than calling the setObject(Object) method.
void	setRoot(int nodeHandle, java.lang.Object environment) Reset the root node of the DTMIterator, overriding the value specified when it was created.
void	setShouldCacheNodes(boolean b) If setShouldCacheNodes(true) is called, then nodes will be cached, enabling random access, and giving the ability to do sorts and the like.
protected void	SetVector(NodeVector v) Set the vector where nodes will be cached.

Methods inherited from class org.apache.xpath.objects.XObject

appendToFsb, bool, boolWithSideEffects, callVisitors, castToType, create, create, deepEquals, destruct, dispatchCharactersEvents, equals, error, error, execute, getFresh, getType, getTypeString, greaterThan, greaterThanOrEqual, iter, lessThan, lessThanOrEqual, mutableNodeset, nodelist, nodeset, notEquals, num, numWithSideEffects, object, rtf, rtf, rtree, rtree, str, toString, xstr

Methods inherited from class org.apache.xpath.Expression

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

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

serialVersionUID

static final long serialVersionUID

See Also:

Constant Field Values

m_last

protected int m_last

The index of the last node in the iteration.

m_next

protected int m_next

The index of the next node to be fetched. Useful if this is a cached iterator, and is being used as random access NodeList.

m_cache

private NodeSequence.IteratorCache m_cache

A cache of a list of nodes obtained from the iterator so far. This list is appended to until the iterator is exhausted and the cache is complete.

Multiple NodeSequence objects may share the same cache.

m_iter

protected DTMIterator m_iter

The functional iterator that fetches nodes.

m_dtmMgr

protected DTMManager m_dtmMgr

The DTMManager to use if we're using a NodeVector only. We may well want to do away with this, and store it in the NodeVector.

Constructor Detail

NodeSequence

private NodeSequence(DTMIterator iter,
                     int context,
                     XPathContext xctxt,
                     boolean shouldCacheNodes)

Create a new NodeSequence from a (already cloned) iterator.

Parameters:

iter - Cloned (not static) DTMIterator.

context - The initial context node.

xctxt - The execution context.

shouldCacheNodes - True if this sequence can random access.

NodeSequence

public NodeSequence(java.lang.Object nodeVector)

Create a new NodeSequence from a (already cloned) iterator.

Parameters:

nodeVector -

NodeSequence

private NodeSequence(DTMManager dtmMgr)

Construct an empty XNodeSet object. This is used to create a mutable nodeset to which random nodes may be added.

NodeSequence

public NodeSequence()

Create a new NodeSequence in an invalid (null) state.

Method Detail

getVector

protected NodeVector getVector()

If this iterator needs to cache nodes that are fetched, they are stored in the Vector in the generic object.

getCache

private NodeSequence.IteratorCache getCache()

Get the cache (if any) of nodes obtained from the iterator so far. Note that the cache keeps growing until the iterator is walked to exhaustion, at which point the cache is "complete".

SetVector

protected void SetVector(NodeVector v)

Set the vector where nodes will be cached.

hasCache

public boolean hasCache()

If the iterator needs to cache nodes as they are fetched, then this method returns true.

cacheComplete

private boolean cacheComplete()

If this NodeSequence has a cache, and that cache is fully populated then this method returns true, otherwise if there is no cache or it is not complete it returns false.

markCacheComplete

private void markCacheComplete()

If this NodeSequence has a cache, mark that it is complete. This method should be called after the iterator is exhausted.

setIter

public final void setIter(DTMIterator iter)

Set the functional iterator that fetches nodes.

Parameters:

iter - The iterator that is to be contained.

getContainedIter

public final DTMIterator getContainedIter()

Get the functional iterator that fetches nodes.

Returns:

The contained iterator.

getDTM

public DTM getDTM(int nodeHandle)

Description copied from interface: DTMIterator

Get an instance of a DTM that "owns" a node handle. Since a node iterator may be passed without a DTMManager, this allows the caller to easily get the DTM using just the iterator.

Specified by:

getDTM in interface DTMIterator

Parameters:

nodeHandle - the nodeHandle.

Returns:

a non-null DTM reference.

See Also:

DTMIterator.getDTM(int)

getDTMManager

public DTMManager getDTMManager()

Description copied from interface: DTMIterator

Get an instance of the DTMManager. Since a node iterator may be passed without a DTMManager, this allows the caller to easily get the DTMManager using just the iterator.

Specified by:

getDTMManager in interface DTMIterator

Returns:

a non-null DTMManager reference.

See Also:

DTMIterator.getDTMManager()

getRoot

public int getRoot()

Description copied from interface: DTMIterator

The root node of the DTMIterator, as specified when it was created. Note the root node is not the root node of the document tree, but the context node from where the iteration begins and ends.

Specified by:

getRoot in interface DTMIterator

Returns:

nodeHandle int Handle of the context node.

See Also:

DTMIterator.getRoot()

setRoot

public void setRoot(int nodeHandle,
                    java.lang.Object environment)

Description copied from interface: DTMIterator

Reset the root node of the DTMIterator, overriding the value specified when it was created. Note the root node is not the root node of the document tree, but the context node from where the iteration begins.

Specified by:

setRoot in interface DTMIterator

Parameters:

nodeHandle - int Handle of the context node.

environment - The environment object. The environment in which this iterator operates, which should provide:

• a node (the context node... same value as "root" defined below)
• a pair of non-zero positive integers (the context position and the context size)
• a set of variable bindings
• a function library
• the set of namespace declarations in scope for the expression.

At this time the exact implementation of this environment is application dependent. Probably a proper interface will be created fairly soon.

See Also:
DTMIterator.setRoot(int, Object)

reset

public void reset()

Description copied from class: XObject

Reset for fresh reuse.

Specified by:

reset in interface DTMIterator

Overrides:

reset in class XObject

See Also:

DTMIterator.reset()

getWhatToShow

public int getWhatToShow()

Description copied from interface: DTMIterator

This attribute determines which node types are presented via the iterator. The available set of constants is defined above. Nodes not accepted by whatToShow will be skipped, but their children may still be considered.

Specified by:

getWhatToShow in interface DTMIterator

Returns:

one of the SHOW_XXX constants, or several ORed together.

See Also:

DTMIterator.getWhatToShow()

getExpandEntityReferences

public boolean getExpandEntityReferences()

Description copied from interface: DTMIterator

The value of this flag determines whether the children of entity reference nodes are visible to the iterator. If false, they and their descendants will be rejected. Note that this rejection takes precedence over whatToShow and the filter.

To produce a view of the document that has entity references expanded and does not expose the entity reference node itself, use the whatToShow flags to hide the entity reference node and set expandEntityReferences to true when creating the iterator. To produce a view of the document that has entity reference nodes but no entity expansion, use the whatToShow flags to show the entity reference node and set expandEntityReferences to false.

NOTE: In Xalan's use of DTM we will generally have fully expanded entity references when the document tree was built, and thus this flag will have no effect.

Specified by:

getExpandEntityReferences in interface DTMIterator

Returns:

true if entity references will be expanded.

See Also:

DTMIterator.getExpandEntityReferences()

nextNode

public int nextNode()

Description copied from interface: DTMIterator

Returns the next node in the set and advances the position of the iterator in the set. After a DTMIterator has setRoot called, the first call to nextNode() returns that root or (if it is rejected by the filters) the first node within its subtree which is not filtered out.

Specified by:

nextNode in interface DTMIterator

Returns:

The next node handle in the set being iterated over, or DTM.NULL if there are no more members in that set.

See Also:

DTMIterator.nextNode()

previousNode

public int previousNode()

Description copied from interface: DTMIterator

Returns the previous node in the set and moves the position of the DTMIterator backwards in the set.

Specified by:

previousNode in interface DTMIterator

Returns:

The previous node handle in the set being iterated over, or DTM.NULL if there are no more members in that set.

See Also:

DTMIterator.previousNode()

detach

public void detach()

Description copied from class: XObject

Detaches the DTMIterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state. After detach has been invoked, calls to nextNode or previousNode will raise a runtime exception.

Specified by:

detach in interface DTMIterator

Overrides:

detach in class XObject

See Also:

DTMIterator.detach()

allowDetachToRelease

public void allowDetachToRelease(boolean allowRelease)

Calling this with a value of false will cause the nodeset to be cached.

Specified by:

allowDetachToRelease in interface DTMIterator

Overrides:

allowDetachToRelease in class XObject

Parameters:

allowRelease - true if it is OK for detach to release this iterator for pooling.

See Also:

DTMIterator.allowDetachToRelease(boolean)

getCurrentNode

public int getCurrentNode()

Description copied from interface: DTMIterator

Get the current node in the iterator. Note that this differs from the DOM's NodeIterator, where the current position lies between two nodes (as part of the maintain-relative-position semantic).

Specified by:

getCurrentNode in interface DTMIterator

Returns:

The current node handle, or -1.

See Also:

DTMIterator.getCurrentNode()

isFresh

public boolean isFresh()

Description copied from interface: DTMIterator

Tells if this NodeSetDTM is "fresh", in other words, if the first nextNode() that is called will return the first node in the set.

Specified by:

isFresh in interface DTMIterator

Returns:

true if the iteration of this list has not yet begun.

See Also:

DTMIterator.isFresh()

setShouldCacheNodes

public void setShouldCacheNodes(boolean b)

Description copied from interface: DTMIterator

If setShouldCacheNodes(true) is called, then nodes will be cached, enabling random access, and giving the ability to do sorts and the like. They are not cached by default. %REVIEW% Shouldn't the other random-access methods throw an exception if they're called on a DTMIterator with this flag set false?

Specified by:

setShouldCacheNodes in interface DTMIterator

Parameters:

b - true if the nodes should be cached.

See Also:

DTMIterator.setShouldCacheNodes(boolean)

isMutable

public boolean isMutable()

Description copied from interface: DTMIterator

Tells if this iterator can have nodes added to it or set via the setItem(int node, int index) method.

Specified by:

isMutable in interface DTMIterator

Returns:

True if the nodelist can be mutated.

See Also:

DTMIterator.isMutable()

getCurrentPos

public int getCurrentPos()

Description copied from interface: DTMIterator

Get the current position within the cached list, which is one less than the next nextNode() call will retrieve. i.e. if you call getCurrentPos() and the return is 0, the next fetch will take place at index 1.

Specified by:

getCurrentPos in interface DTMIterator

Returns:

The position of the iteration.

See Also:

DTMIterator.getCurrentPos()

runTo

public void runTo(int index)

Description copied from interface: DTMIterator

If an index is requested, NodeSetDTM will call this method to run the iterator to the index. By default this sets m_next to the index. If the index argument is -1, this signals that the iterator should be run to the end and completely fill the cache.

Specified by:

runTo in interface DTMIterator

Parameters:

index - The index to run to, or -1 if the iterator should be run to the end.

See Also:

DTMIterator.runTo(int)

setCurrentPos

public void setCurrentPos(int i)

Description copied from interface: DTMIterator

Set the current position in the node set.

Specified by:

setCurrentPos in interface DTMIterator

Parameters:

i - Must be a valid index.

See Also:

DTMIterator.setCurrentPos(int)

item

public int item(int index)

Description copied from interface: DTMIterator

Returns the node handle of an item in the collection. If index is greater than or equal to the number of nodes in the list, this returns null.

Specified by:

item in interface DTMIterator

Parameters:

index - of the item.

Returns:

The node handle at the indexth position in the DTMIterator, or -1 if that is not a valid index.

See Also:

DTMIterator.item(int)

setItem

public void setItem(int node,
                    int index)

Description copied from interface: DTMIterator

Sets the node at the specified index of this vector to be the specified node. The previous component at that position is discarded.

The index must be a value greater than or equal to 0 and less than the current size of the vector. The iterator must be in cached mode.

Meant to be used for sorted iterators.

Specified by:

setItem in interface DTMIterator

Parameters:

node - Node to set

index - Index of where to set the node

See Also:

DTMIterator.setItem(int, int)

getLength

public int getLength()

Description copied from interface: DTMIterator

The number of nodes in the list. The range of valid child node indices is 0 to length-1 inclusive. Note that this requires running the iterator to completion, and presumably filling the cache.

Specified by:

getLength in interface DTMIterator

Returns:

The number of nodes in the list.

See Also:

DTMIterator.getLength()

cloneWithReset

public DTMIterator cloneWithReset()
                           throws java.lang.CloneNotSupportedException

Note: Not a deep clone.

Specified by:

cloneWithReset in interface DTMIterator

Returns:

A clone of this iteration that has been reset.

Throws:

java.lang.CloneNotSupportedException

See Also:

DTMIterator.cloneWithReset()

clone

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

Get a clone of this iterator, but don't reset the iteration in the process, so that it may be used from the current position. Note: Not a deep clone.

Specified by:

clone in interface DTMIterator

Overrides:

clone in class java.lang.Object

Returns:

A clone of this object.

Throws:

java.lang.CloneNotSupportedException

isDocOrdered

public boolean isDocOrdered()

Description copied from interface: DTMIterator

Returns true if all the nodes in the iteration well be returned in document order.

Specified by:

isDocOrdered in interface DTMIterator

Returns:

true if all the nodes in the iteration well be returned in document order.

See Also:

DTMIterator.isDocOrdered()

getAxis

public int getAxis()

Description copied from interface: DTMIterator

Returns the axis being iterated, if it is known.

Specified by:

getAxis in interface DTMIterator

Returns:

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

See Also:

DTMIterator.getAxis()

getAnalysisBits

public int getAnalysisBits()

Description copied from interface: PathComponent

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

Specified by:

getAnalysisBits in interface PathComponent

Returns:

One of WalkerFactory#BIT_DESCENDANT, etc.

See Also:

PathComponent.getAnalysisBits()

fixupVariables

public void fixupVariables(java.util.Vector vars,
                           int globalsSize)

Description copied from class: XObject

XObjects should not normally need to fix up variables.

Overrides:

fixupVariables in class XObject

Parameters:

vars - List of QNames that correspond to variables. This list should be searched backwards for the first qualified name that corresponds to the variable reference qname. The position of the QName in the vector from the start of the vector will be its position in the stack frame (but variables above the globalsTop value will need to be offset to the current stack frame). NEEDSDOC @param globalsSize

See Also:

Expression.fixupVariables(Vector, int)

addNodeInDocOrder

protected int addNodeInDocOrder(int node)

Add the node into a vector of nodes where it should occur in document order.

Parameters:

node - The node to be added.

Returns:

insertIndex.

Throws:

java.lang.RuntimeException - thrown if this NodeSetDTM is not of a mutable type.

setObject

protected void setObject(java.lang.Object obj)

It used to be that many locations in the code simply did an assignment to this.m_obj directly, rather than calling the setObject(Object) method. The problem is that our super-class would be updated on what the cache associated with this NodeSequence, but we wouldn't know ourselves.

All setting of m_obj is done through setObject() now, and this method over-rides the super-class method. So now we are in the loop have an opportunity to update some caching information.

Overrides:

setObject in class XObject

getIteratorCache

protected NodeSequence.IteratorCache getIteratorCache()

Get the cached list of nodes appended with values obtained from the iterator as a NodeSequence is walked when its nextNode() method is called.