org.apache.xpath

Class NodeSetDTM

public class NodeSetDTM extends NodeVector implements DTMIterator, Cloneable

The NodeSetDTM class can act as either a NodeVector, NodeList, or NodeIterator. However, in order for it to act as a NodeVector or NodeList, it's required that setShouldCacheNodes(true) be called before the first nextNode() is called, in order that nodes can be added as they are fetched. Derived classes that implement iterators must override runTo(int index), in order that they may run the iteration to the given index.

Note that we directly implement the DOM's NodeIterator interface. We do not emulate all the behavior of the standard NodeIterator. In particular, we do not guarantee to present a "live view" of the document ... but in XSLT, the source document should never be mutated, so this should never be an issue.

Thought: Should NodeSetDTM really implement NodeList and NodeIterator, or should there be specific subclasses of it which do so? The advantage of doing it all here is that all NodeSetDTMs will respond to the same calls; the disadvantage is that some of them may return less-than-enlightening results when you do so.

UNKNOWN: advanced

Constructor Summary
NodeSetDTM(DTMManager dtmManager)
Create an empty nodelist.
NodeSetDTM(int blocksize, int dummy, DTMManager dtmManager)
Create an empty, using the given block size.
NodeSetDTM(NodeSetDTM nodelist)
Create a NodeSetDTM, and copy the members of the given NodeSetDTM into it.
NodeSetDTM(DTMIterator ni)
Create a NodeSetDTM, and copy the members of the given DTMIterator into it.
NodeSetDTM(NodeIterator iterator, XPathContext xctxt)
Create a NodeSetDTM, and copy the members of the given DTMIterator into it.
NodeSetDTM(NodeList nodeList, XPathContext xctxt)
Create a NodeSetDTM, and copy the members of the given DTMIterator into it.
NodeSetDTM(int node, DTMManager dtmManager)
Create a NodeSetDTM which contains the given Node.
Method Summary
voidaddElement(int value)
Append a Node onto the vector.
voidaddNode(int n)
Add a node to the NodeSetDTM.
intaddNodeInDocOrder(int node, boolean test, XPathContext support)
Add the node into a vector of nodes where it should occur in document order.
intaddNodeInDocOrder(int node, XPathContext support)
Add the node into a vector of nodes where it should occur in document order.
voidaddNodes(DTMIterator iterator)
Copy NodeList members into this nodelist, adding in document order.
voidaddNodesInDocOrder(DTMIterator iterator, XPathContext support)
Copy NodeList members into this nodelist, adding in document order.
voidallowDetachToRelease(boolean allowRelease)
Specify if it's OK for detach to release the iterator for reuse.
voidappendNodes(NodeVector nodes)
Append the nodes to the list.
Objectclone()
Clone this NodeSetDTM.
DTMIteratorcloneWithReset()
Get a cloned Iterator, and reset its state to the beginning of the iteration.
booleancontains(int s)
Tell if the table contains the given node.
voiddetach()
Detaches the iterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state.
intelementAt(int i)
Get the nth element.
intgetAxis()
Returns the axis being iterated, if it is known.
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 object used to screen nodes.
intgetLast()
intgetLength()
The number of nodes in the list.
intgetRoot()
booleangetShouldCacheNodes()
Get whether or not this is a cached node set.
intgetWhatToShow()
This attribute determines which node types are presented via the iterator.
intindexOf(int elem, int index)
Searches for the first occurence of the given argument, beginning the search at index, and testing for equality using the equals method.
intindexOf(int elem)
Searches for the first occurence of the given argument, beginning the search at index, and testing for equality using the equals method.
voidinsertElementAt(int value, int at)
Inserts the specified node in this vector at the specified index.
voidinsertNode(int n, int pos)
Insert a node at a given position.
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.
intitem(int index)
Returns the indexth item in the collection.
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.
voidremoveAllElements()
Inserts the specified node in this vector at the specified index.
booleanremoveElement(int s)
Removes the first occurrence of the argument from this vector.
voidremoveElementAt(int i)
Deletes the component at the specified index.
voidremoveNode(int n)
Remove a node.
voidreset()
Reset the iterator.
voidrunTo(int index)
If an index is requested, NodeSetDTM will call this method to run the iterator to the index.
voidsetCurrentPos(int i)
Set the current position in the node set.
voidsetElementAt(int node, int index)
Sets the component at the specified index of this vector to be the specified object.
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.
voidsetItem(int node, int index)
Same as setElementAt.
voidsetLast(int last)
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 list.

Constructor Detail

NodeSetDTM

public NodeSetDTM(DTMManager dtmManager)
Create an empty nodelist.

NodeSetDTM

public NodeSetDTM(int blocksize, int dummy, DTMManager dtmManager)
Create an empty, using the given block size.

Parameters: blocksize Size of blocks to allocate dummy pass zero for right now...

NodeSetDTM

public NodeSetDTM(NodeSetDTM nodelist)
Create a NodeSetDTM, and copy the members of the given NodeSetDTM into it.

Parameters: nodelist Set of Nodes to be made members of the new set.

NodeSetDTM

public NodeSetDTM(DTMIterator ni)
Create a NodeSetDTM, and copy the members of the given DTMIterator into it.

Parameters: ni Iterator which yields Nodes to be made members of the new set.

NodeSetDTM

public NodeSetDTM(NodeIterator iterator, XPathContext xctxt)
Create a NodeSetDTM, and copy the members of the given DTMIterator into it.

Parameters: iterator Iterator which yields Nodes to be made members of the new set.

NodeSetDTM

public NodeSetDTM(NodeList nodeList, XPathContext xctxt)
Create a NodeSetDTM, and copy the members of the given DTMIterator into it.

NodeSetDTM

public NodeSetDTM(int node, DTMManager dtmManager)
Create a NodeSetDTM which contains the given Node.

Parameters: node Single node to be added to the new set.

Method Detail

addElement

public void addElement(int value)
Append a Node onto the vector.

Parameters: value The node to be added.

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

addNode

public void addNode(int n)
Add a node to the NodeSetDTM. Not all types of NodeSetDTMs support this operation

Parameters: n Node to be added

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

addNodeInDocOrder

public int addNodeInDocOrder(int node, boolean test, XPathContext support)
Add the node into a vector of nodes where it should occur in document order.

Parameters: node The node to be added. test true if we should test for doc order support The XPath runtime context.

Returns: insertIndex.

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

addNodeInDocOrder

public int addNodeInDocOrder(int node, XPathContext support)
Add the node into a vector of nodes where it should occur in document order.

Parameters: node The node to be added. support The XPath runtime context.

Returns: The index where it was inserted.

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

addNodes

public void addNodes(DTMIterator iterator)
Copy NodeList members into this nodelist, adding in document order. Null references are not added.

Parameters: iterator DTMIterator which yields the nodes to be added.

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

addNodesInDocOrder

public void addNodesInDocOrder(DTMIterator iterator, XPathContext support)
Copy NodeList members into this nodelist, adding in document order. If a node is null, don't add it.

Parameters: iterator DTMIterator which yields the nodes to be added. support The XPath runtime context.

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

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.

appendNodes

public void appendNodes(NodeVector nodes)
Append the nodes to the list.

Parameters: nodes The nodes to be appended to this node set.

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

clone

public Object clone()
Clone this NodeSetDTM. At this time, we only expect this to be used with LocPathIterators; it may not work with other kinds of NodeSetDTMs.

Returns: a new NodeSetDTM of the same type, having the same state... though unless overridden in the subclasses, it may not copy all the state information.

Throws: CloneNotSupportedException if this subclass of NodeSetDTM does not support the clone() operation.

cloneWithReset

public DTMIterator cloneWithReset()
Get a cloned Iterator, and reset its state to the beginning of the iteration.

Returns: a new NodeSetDTM of the same type, having the same state... except that the reset() operation has been called.

Throws: CloneNotSupportedException if this subclass of NodeSetDTM does not support the clone() operation.

contains

public boolean contains(int s)
Tell if the table contains the given node.

Parameters: s Node to look for

Returns: True if the given node was found.

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.

This operation is a no-op in NodeSetDTM, and will not cause INVALID_STATE_ERR to be raised by later operations.

elementAt

public int elementAt(int i)
Get the nth element.

Parameters: i The index of the requested node.

Returns: Node at specified index.

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.

getCurrentNode

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

Returns: the last fetched node.

Throws: RuntimeException thrown if this NodeSetDTM is not of a cached type, and thus doesn't permit indexed access.

getCurrentPos

public 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: The the current position index.

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: true for all iterators based on NodeSetDTM, meaning that the contents of EntityRefrence nodes may be returned (though whatToShow says that the EntityReferences themselves are not shown.)

getFilter

public DTMFilter getFilter()
The filter object used to screen nodes. Filters are applied to further reduce (and restructure) the DTMIterator's view of the document. In our case, we will be using hardcoded filters built into our iterators... but getFilter() is part of the DOM's DTMIterator interface, so we have to support it.

Returns: null, which is slightly misleading. True, there is no user-written filter object, but in fact we are doing some very sophisticated custom filtering. A DOM purist might suggest returning a placeholder object just to indicate that this is not going to return all nodes selected by whatToShow.

getLast

public int getLast()

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 operation requires finding all the matching nodes, which may defeat attempts to defer that work.

Returns: integer indicating how many nodes are represented by this list.

getRoot

public int getRoot()

Returns: The root node of the Iterator, as specified when it was created. For non-Iterator NodeSetDTMs, this will be null.

getShouldCacheNodes

public boolean getShouldCacheNodes()
Get whether or not this is a cached node set.

Returns: True if this list is cached.

getWhatToShow

public int getWhatToShow()
This attribute determines which node types are presented via the iterator. The available set of constants is defined in the DTMFilter interface. For NodeSetDTMs, the mask has been hardcoded to show all nodes except EntityReference nodes, which have no equivalent in the XPath data model.

Returns: integer used as a bit-array, containing flags defined in the DOM's DTMFilter class. The value will be SHOW_ALL & ~SHOW_ENTITY_REFERENCE, meaning that only entity references are suppressed.

indexOf

public int indexOf(int elem, int index)
Searches for the first occurence of the given argument, beginning the search at index, and testing for equality using the equals method.

Parameters: elem Node to look for index Index of where to start the search

Returns: the index of the first occurrence of the object argument in this vector at position index or later in the vector; returns -1 if the object is not found.

indexOf

public int indexOf(int elem)
Searches for the first occurence of the given argument, beginning the search at index, and testing for equality using the equals method.

Parameters: elem Node to look for

Returns: the index of the first occurrence of the object argument in this vector at position index or later in the vector; returns -1 if the object is not found.

insertElementAt

public void insertElementAt(int value, int at)
Inserts the specified node in this vector at the specified index. Each component in this vector with an index greater or equal to the specified index is shifted upward to have an index one greater than the value it had previously.

Parameters: value The node to be inserted. at The index where the insert should occur.

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

insertNode

public void insertNode(int n, int pos)
Insert a node at a given position.

Parameters: n Node to be added pos Offset at which the node is to be inserted, with 0 being the first position.

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

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 if nextNode() would return the first node in the set, false if it would return a later one.

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.

item

public int item(int index)
Returns the indexth item in the collection. If index is greater than or equal to the number of nodes in the list, this returns null. TODO: What happens if index is out of range?

Parameters: index Index into the collection.

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

nextNode

public int nextNode()
Returns the next node in the set and advances the position of the iterator in the set. After a DTMIterator 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 DTM.NULL if there are no more members in that set.

Throws: DOMException INVALID_STATE_ERR: Raised if this method is called after the detach method was invoked.

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, orDTM.NULL if there are no more members in that set.

Throws: DOMException INVALID_STATE_ERR: Raised if this method is called after the detach method was invoked. RuntimeException thrown if this NodeSetDTM is not of a cached type, and hence doesn't know what the previous node was.

removeAllElements

public void removeAllElements()
Inserts the specified node in this vector at the specified index. Each component in this vector with an index greater or equal to the specified index is shifted upward to have an index one greater than the value it had previously.

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

removeElement

public boolean removeElement(int s)
Removes the first occurrence of the argument from this vector. If the object is found in this vector, each component in the vector with an index greater or equal to the object's index is shifted downward to have an index one smaller than the value it had previously.

Parameters: s The node to be removed.

Returns: True if the node was successfully removed

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

removeElementAt

public void removeElementAt(int i)
Deletes the component at the specified index. Each component in this vector with an index greater or equal to the specified index is shifted downward to have an index one smaller than the value it had previously.

Parameters: i The index of the node to be removed.

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

removeNode

public void removeNode(int n)
Remove a node.

Parameters: n Node to be added

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

reset

public void reset()
Reset the iterator. May have no effect on non-iterator Nodesets.

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 Position to advance (or retreat) to, with 0 requesting the reset ("fresh") position and -1 (or indeed any out-of-bounds value) requesting the final position.

Throws: RuntimeException thrown if this NodeSetDTM is not one of the types which supports indexing/counting.

setCurrentPos

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

Parameters: i Must be a valid index.

Throws: RuntimeException thrown if this NodeSetDTM is not of a cached type, and thus doesn't permit indexed access.

setElementAt

public void setElementAt(int node, int index)
Sets the component at the specified index of this vector to be the specified object. 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.

Parameters: node The node to be set. index The index of the node to be replaced.

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

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.

setItem

public void setItem(int node, int index)
Same as setElementAt.

Parameters: node The node to be set. index The index of the node to be replaced.

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

setLast

public void setLast(int last)

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. This switch must be set before the first call to nextNode is made, to ensure that all nodes are cached.

Parameters: b true if this node set should be cached.

Throws: RuntimeException thrown if an attempt is made to request caching after we've already begun stepping through the nodes in this set.

size

public int size()
Get the length of the list.

Returns: The size of this node set.

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