org.apache.xpath.axes

Class LocPathIterator

public abstract class LocPathIterator extends PredicatedNodeTest implements Cloneable, DTMIterator, Serializable, PathComponent

This class extends NodeSetDTM, which implements NodeIterator, and fetches nodes one at a time in document order based on a XPath

UNKNOWN: advanced

Field Summary
intm_lastFetched
The last node that was fetched, usually by nextNode.
Method Summary
voidallowDetachToRelease(boolean allowRelease)
Specify if it's OK for detach to release the iterator for reuse.
DTMIteratorasIterator(XPathContext xctxt, int contextNode)
Given an select expression and a context, evaluate the XPath and return the resulting iterator.
intasNode(XPathContext xctxt)
Return the first node out of the nodeset, if this expression is a nodeset expression.
booleanbool(XPathContext xctxt)
Evaluate this operation directly to a boolean.
voidcallVisitors(ExpressionOwner owner, XPathVisitor visitor)
DTMIteratorcloneWithReset()
Get a cloned Iterator that is reset to the beginning of the query.
voiddetach()
Detaches the iterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state.
XObjectexecute(XPathContext xctxt)
Execute this iterator, meaning create a clone that can store state, and initialize it for fast execution from the current runtime state.
voidexecuteCharsToContentHandler(XPathContext xctxt, ContentHandler handler)
Execute an expression in the XPath runtime context, and return the result of the expression.
intgetAnalysisBits()
Get the analysis bits for this walker, as defined in the WalkerFactory.
intgetAxis()
Returns the axis being iterated, if it is known.
intgetContext()
The node context for the iterator.
intgetCurrentContextNode()
The node context from where the expression is being executed from (i.e. for current() support).
intgetCurrentNode()
Return the last fetched node.
intgetCurrentPos()
Get the current position, 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.
DTMgetDTM(int nodeHandle)
Get an instance of a DTM that "owns" a node handle.
DTMManagergetDTMManager()
Get an instance of the DTMManager.
booleangetExpandEntityReferences()
The value of this flag determines whether the children of entity reference nodes are visible to the iterator.
DTMFiltergetFilter()
The filter used to screen nodes.
booleangetFoundLast()
Tells if we've found the last node yet.
booleangetIsTopLevel()
Get if this is an iterator at the upper level of the XPath.
intgetLastPos(XPathContext xctxt)
intgetLength()
The number of nodes in the list.
PrefixResolvergetPrefixResolver()
Return the saved reference to the prefix resolver that was in effect when this iterator was created.
intgetRoot()
The root node of the Iterator, as specified when it was created.
intgetWhatToShow()
This attribute determines which node types are presented via the iterator.
XPathContextgetXPathContext()
The XPath execution context we are operating on.
voidincrementCurrentPos()
Increment the current position in the node set.
booleanisDocOrdered()
Returns true if all the nodes in the iteration well be returned in document order.
booleanisFresh()
Tells if this NodeSetDTM is "fresh", in other words, if the first nextNode() that is called will return the first node in the set.
booleanisMutable()
Tells if this iterator can have nodes added to it or set via the setItem(int node, int index) method.
booleanisNodesetExpr()
Tell if the expression is a nodeset expression.
intitem(int index)
Returns the index th item in the collection.
abstract intnextNode()
Returns the next node in the set and advances the position of the iterator in the set.
intpreviousNode()
Returns the previous node in the set and moves the position of the iterator backwards in the set.
voidreset()
Reset the iterator.
voidrunTo(int index)
If an index is requested, NodeSetDTM will call this method to run the iterator to the index.
voidsetCurrentContextNode(int n)
Set the current context node for this iterator.
voidsetCurrentPos(int i)
Set the current position in the node set.
voidsetEnvironment(Object environment)
Set 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.
voidsetIsTopLevel(boolean b)
Set if this is an iterator at the upper level of the XPath.
voidsetItem(int node, int index)
Sets the node at the specified index of this vector to be the specified node.
voidsetRoot(int context, Object environment)
Initialize the context values for this expression after it is cloned.
voidsetShouldCacheNodes(boolean b)
If setShouldCacheNodes(true) is called, then nodes will be cached.
intsize()
Get the length of the cached nodes.

Field Detail

m_lastFetched

public transient int m_lastFetched
The last node that was fetched, usually by nextNode.

Method Detail

allowDetachToRelease

public void allowDetachToRelease(boolean allowRelease)
Specify if it's OK for detach to release the iterator for reuse.

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

asIterator

public DTMIterator asIterator(XPathContext xctxt, int contextNode)
Given an select expression and a context, evaluate the XPath and return the resulting iterator.

Parameters: xctxt The execution context. contextNode The node that "." expresses.

Throws: TransformerException thrown if the active ProblemListener decides the error condition is severe enough to halt processing. javax.xml.transform.TransformerException

UNKNOWN: experimental

asNode

public int asNode(XPathContext xctxt)
Return the first node out of the nodeset, if this expression is a nodeset expression. This is the default implementation for nodesets. Derived classes should try and override this and return a value without having to do a clone operation.

Parameters: xctxt The XPath runtime context.

Returns: the first node out of the nodeset, or DTM.NULL.

bool

public boolean bool(XPathContext xctxt)
Evaluate this operation directly to a boolean.

Parameters: xctxt The runtime execution context.

Returns: The result of the operation as a boolean.

Throws: javax.xml.transform.TransformerException

callVisitors

public void callVisitors(ExpressionOwner owner, XPathVisitor visitor)

See Also: XPathVisitable

cloneWithReset

public DTMIterator cloneWithReset()
Get a cloned Iterator that is reset to the beginning of the query.

Returns: A cloned NodeIterator set of the start of the query.

Throws: CloneNotSupportedException

detach

public void detach()
Detaches the iterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state. Afterdetach has been invoked, calls to nextNode orpreviousNode will raise the exception INVALID_STATE_ERR.

execute

public XObject execute(XPathContext xctxt)
Execute this iterator, meaning create a clone that can store state, and initialize it for fast execution from the current runtime state. When this is called, no actual query from the current context node is performed.

Parameters: xctxt The XPath execution context.

Returns: An XNodeSet reference that holds this iterator.

Throws: javax.xml.transform.TransformerException

executeCharsToContentHandler

public void executeCharsToContentHandler(XPathContext xctxt, ContentHandler handler)
Execute an expression in the XPath runtime context, and return the result of the expression.

Parameters: xctxt The XPath runtime context. handler The target content handler.

Returns: The result of the expression in the form of a XObject.

Throws: javax.xml.transform.TransformerException if a runtime exception occurs. org.xml.sax.SAXException

getAnalysisBits

public int getAnalysisBits()
Get the analysis bits for this walker, as defined in the WalkerFactory.

Returns: One of WalkerFactory#BIT_DESCENDANT, etc.

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.

getContext

public final int getContext()
The node context for the iterator.

Returns: The node context, same as getRoot().

getCurrentContextNode

public final int getCurrentContextNode()
The node context from where the expression is being executed from (i.e. for current() support).

Returns: The top-level node context of the entire expression.

getCurrentNode

public int getCurrentNode()
Return the last fetched node. Needed to support the UnionPathIterator.

Returns: The last fetched node, or null if the last fetch was null.

getCurrentPos

public final int getCurrentPos()
Get the current position, 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.

Returns: A value greater than or equal to zero that indicates the next node position to fetch.

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.

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.

Returns: a non-null DTMManager reference.

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 will be skipped over.
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.

Returns: Always true, since entity reference nodes are not visible in the XPath model.

getFilter

public DTMFilter getFilter()
The filter used to screen nodes. Not used at this time, this is here only to fullfill the DOM NodeIterator interface.

Returns: Always null.

See Also: org.w3c.dom.traversal.NodeIterator

getFoundLast

public final boolean getFoundLast()
Tells if we've found the last node yet.

Returns: true if the last nextNode returned null.

getIsTopLevel

public boolean getIsTopLevel()
Get if this is an iterator at the upper level of the XPath.

Returns: true if this location path is at the top level of the expression.

UNKNOWN: advanced

getLastPos

public int getLastPos(XPathContext xctxt)

See Also: getLastPos

getLength

public int getLength()
The number of nodes in the list. The range of valid child node indices is 0 to length-1 inclusive.

Returns: The number of nodes in the list, always greater or equal to zero.

getPrefixResolver

public final PrefixResolver getPrefixResolver()
Return the saved reference to the prefix resolver that was in effect when this iterator was created.

Returns: The prefix resolver or this iterator, which may be null.

getRoot

public int getRoot()
The root node of the Iterator, as specified when it was created.

Returns: The "root" of this iterator, which, in XPath terms, is the node context for this iterator.

getWhatToShow

public int getWhatToShow()
This attribute determines which node types are presented via the iterator. The available set of constants is defined in the NodeFilter interface.

This is somewhat useless at this time, since it doesn't really return information that tells what this iterator will show. It is here only to fullfill the DOM NodeIterator interface.

Returns: For now, always NodeFilter.SHOW_ALL & ~NodeFilter.SHOW_ENTITY_REFERENCE.

See Also: org.w3c.dom.traversal.NodeIterator

getXPathContext

public final XPathContext getXPathContext()
The XPath execution context we are operating on.

Returns: XPath execution context this iterator is operating on, or null if setRoot has not been called.

incrementCurrentPos

public void incrementCurrentPos()
Increment the current position in the node set.

isDocOrdered

public boolean isDocOrdered()
Returns true if all the nodes in the iteration well be returned in document order.

Returns: true as a default.

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.

Returns: true of nextNode has not been called.

isMutable

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

Returns: True if the nodelist can be mutated.

isNodesetExpr

public boolean isNodesetExpr()
Tell if the expression is a nodeset expression.

Returns: true if the expression can be represented as a nodeset.

item

public int item(int index)
Returns the index th item in the collection. If index is greater than or equal to the number of nodes in the list, this returns null .

Parameters: index Index into the collection.

Returns: The node at the index th position in the NodeList , or null if that is not a valid index.

nextNode

public abstract int nextNode()
Returns the next node in the set and advances the position of the iterator in the set. After a NodeIterator is created, the first call to nextNode() returns the first node in the set.

Returns: The next Node in the set being iterated over, or 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 iterator backwards in the set.

Returns: The previous Node in the set being iterated over, ornull if there are no more members in that set.

reset

public void reset()
Reset the iterator.

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.

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

setCurrentContextNode

public final void setCurrentContextNode(int n)
Set the current context node for this iterator.

Parameters: n Must be a non-null reference to the node context.

setCurrentPos

public void setCurrentPos(int i)
Set the current position in the node set.

Parameters: i Must be a valid index greater than or equal to zero and less than m_cachedNodes.size().

setEnvironment

public void setEnvironment(Object environment)
Set 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.

Parameters: environment The environment object.

setIsTopLevel

public void setIsTopLevel(boolean b)
Set if this is an iterator at the upper level of the XPath.

Parameters: b true if this location path is at the top level of the expression.

UNKNOWN: advanced

setItem

public void setItem(int node, int index)
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.

Parameters: node Node to set index Index of where to set the node

setRoot

public void setRoot(int context, Object environment)
Initialize the context values for this expression after it is cloned.

Parameters: context The XPath runtime context for this transformation.

setShouldCacheNodes

public void setShouldCacheNodes(boolean b)
If setShouldCacheNodes(true) is called, then nodes will be cached. They are not cached by default.

Parameters: b True if this iterator should cache nodes.

size

public int size()
Get the length of the cached nodes.

Note: for the moment at least, this only returns the size of the nodes that have been fetched to date, it doesn't attempt to run to the end to make sure we have found everything. This should be reviewed.

Returns: The size of the current cache list.

Copyright B) 2005 Apache XML Project. All Rights Reserved.