org.htmlunit.xpath.axes

Class NodeSequence

java.lang.Object

org.htmlunit.xpath.Expression

org.htmlunit.xpath.objects.XObject

org.htmlunit.xpath.axes.NodeSequence

All Implemented Interfaces:

Cloneable, SourceLocator, PathComponent, ExpressionNode, DTMIterator, XPathVisitable

Direct Known Subclasses:

XNodeSet

public class NodeSequence
extends XObject
implements DTMIterator, Cloneable, PathComponent

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

Field Summary

Fields

Modifier and Type	Field and Description
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.

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

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

Fields inherited from interface org.htmlunit.xpath.xml.dtm.DTMIterator

FILTER_ACCEPT, FILTER_SKIP

Constructor Summary

Constructors

Constructor and Description
NodeSequence() Create a new NodeSequence in an invalid (null) state.
NodeSequence(Object nodeVector) Create a new NodeSequence from a (already cloned) iterator.

Method Summary

Modifier and Type	Method and Description
protected int	addNodeInDocOrder(int node) Add the node into a vector of nodes where it should occur in document order.
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() Get a cloned Iterator that is reset to the start of the iteration.
void	detach() Detaches the DTMIterator 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 path component, as defined in the WalkerFactory.
int	getAxis() Returns the axis being iterated, if it is known.
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 org.htmlunit.xpath.axes.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.
int	item(int index) Returns the node handle of an item in the collection.
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 the iterator to the start.
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	setIter(DTMIterator iter) Set the functional iterator that fetches nodes.
protected void	setObject(Object obj)
void	setRoot(int nodeHandle, 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.htmlunit.xpath.objects.XObject

bool, boolWithSideEffects, callVisitors, deepEquals, equals, error, error, execute, getType, getTypeString, greaterThan, greaterThanOrEqual, iter, lessThan, lessThanOrEqual, mutableNodeset, nodelist, nodeset, notEquals, num, numWithSideEffects, object, str, toString, xstr

Methods inherited from class org.htmlunit.xpath.Expression

asIterator, asNode, assertion, bool, canTraverseOutsideSubtree, error, execute, execute, execute, exprGetParent, exprSetParent, getColumnNumber, getExpressionOwner, getLineNumber, getPublicId, getSystemId, isSameClass, isStableNumber, num

Methods inherited from class java.lang.Object

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

Field Detail

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_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

public NodeSequence(Object nodeVector)

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

Parameters:

nodeVector -

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.

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.

setIter

public final void setIter(DTMIterator iter)

Set the functional iterator that fetches nodes.

Parameters:

iter - The iterator that is to be contained.

getDTM

public DTM getDTM(int nodeHandle)

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.

getDTMManager

public DTMManager getDTMManager()

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.

getRoot

public int getRoot()

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.

setRoot

public void setRoot(int nodeHandle,
                    Object environment)

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.

reset

public void reset()

Reset the iterator to the start. After resetting, the next node returned will be the root node -- or, if that's filtered out, the first node within the root's subtree which is _not_ skipped by the filters.

Specified by:

reset in interface DTMIterator

getWhatToShow

public int getWhatToShow()

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.

getExpandEntityReferences

public boolean getExpandEntityReferences()

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.

nextNode

public int nextNode()

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.

previousNode

public int previousNode()

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.

detach

public void detach()

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

getCurrentNode

public int getCurrentNode()

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.

isFresh

public 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.

Specified by:

isFresh in interface DTMIterator

Returns:

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

setShouldCacheNodes

public 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. 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.

getCurrentPos

public int getCurrentPos()

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.

runTo

public void runTo(int index)

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.

setCurrentPos

public void setCurrentPos(int i)

Set the current position in the node set.

Specified by:

setCurrentPos in interface DTMIterator

Parameters:

i - Must be a valid index.

item

public int item(int index)

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.

getLength

public int getLength()

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.

cloneWithReset

public DTMIterator cloneWithReset()
                           throws CloneNotSupportedException

Get a cloned Iterator that is reset to the start of the iteration.

Specified by:

cloneWithReset in interface DTMIterator

Returns:

A clone of this iteration that has been reset.

Throws:

CloneNotSupportedException - if any

clone

public Object clone()
             throws 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.

Specified by:

clone in interface DTMIterator

Overrides:

clone in class Object

Returns:

A clone of this object.

Throws:

CloneNotSupportedException - if any

isDocOrdered

public boolean isDocOrdered()

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.

getAxis

public int getAxis()

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.

getAnalysisBits

public int getAnalysisBits()

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.

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:

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

setObject

protected void setObject(Object obj)

Overrides:

setObject in class XObject

getIteratorCache

protected org.htmlunit.xpath.axes.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.