org.apache.xpath

Class NodeSetDTM

Implemented Interfaces:
Cloneable, DTMIterator, Serializable
Known Direct Subclasses:
RTFIterator

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.

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

FILTER_ACCEPT, FILTER_REJECT, FILTER_SKIP

Constructor Summary

NodeSetDTM(int blocksize, int dummy, DTMManager dtmManager)
Create an empty, using the given block size.
NodeSetDTM(int node, DTMManager dtmManager)
Create a NodeSetDTM which contains the given Node.
NodeSetDTM(DTMIterator ni)
Create a NodeSetDTM, and copy the members of the given DTMIterator into it.
NodeSetDTM(DTMManager dtmManager)
Create an empty nodelist.
NodeSetDTM(NodeSetDTM nodelist)
Create a NodeSetDTM, and copy the members of the given NodeSetDTM into it.
NodeSetDTM(NodeList nodeList, XPathContext xctxt)
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.

Method Summary

void
addElement(int value)
Append a Node onto the vector.
void
addNode(int n)
Add a node to the NodeSetDTM.
int
addNodeInDocOrder(int node, boolean test, XPathContext support)
Add the node into a vector of nodes where it should occur in document order.
int
addNodeInDocOrder(int node, XPathContext support)
Add the node into a vector of nodes where it should occur in document order.
void
addNodes(DTMIterator iterator)
Copy NodeList members into this nodelist, adding in document order.
void
addNodesInDocOrder(DTMIterator iterator, XPathContext support)
Copy NodeList members into this nodelist, adding in document order.
void
allowDetachToRelease(boolean allowRelease)
Specify if it's OK for detach to release the iterator for reuse.
void
appendNodes(NodeVector nodes)
Append the nodes to the list.
Object
clone()
Clone this NodeSetDTM.
DTMIterator
cloneWithReset()
Get a cloned Iterator, and reset its state to the beginning of the iteration.
boolean
contains(int s)
Tell if the table contains the given node.
void
detach()
Detaches the iterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state.
int
elementAt(int i)
Get the nth element.
int
getAxis()
Returns the axis being iterated, if it is known.
int
getCurrentNode()
Return the last fetched node.
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.
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.
DTMFilter
getFilter()
The filter object used to screen nodes.
int
getLast()
int
getLength()
The number of nodes in the list.
int
getRoot()
boolean
getShouldCacheNodes()
Get whether or not this is a cached node set.
int
getWhatToShow()
This attribute determines which node types are presented via the iterator.
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.
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.
void
insertElementAt(int value, int at)
Inserts the specified node in this vector at the specified index.
void
insertNode(int n, int pos)
Insert a node at a given position.
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 indexth 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 iterator backwards in the set.
void
removeAllElements()
Inserts the specified node in this vector at the specified index.
boolean
removeElement(int s)
Removes the first occurrence of the argument from this vector.
void
removeElementAt(int i)
Deletes the component at the specified index.
void
removeNode(int n)
Remove a node.
void
reset()
Reset the iterator.
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
setElementAt(int node, int index)
Sets the component at the specified index of this vector to be the specified object.
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.
void
setItem(int node, int index)
Same as setElementAt.
void
setLast(int last)
void
setRoot(int context, Object environment)
Initialize the context values for this expression after it is cloned.
void
setShouldCacheNodes(boolean b)
If setShouldCacheNodes(true) is called, then nodes will be cached.
int
size()
Get the length of the list.

Methods inherited from class org.apache.xml.utils.NodeVector

RemoveAllNoClear, addElement, appendNodes, clone, contains, elementAt, indexOf, indexOf, insertElementAt, insertInOrder, peepOrNull, peepTail, peepTailSub1, pop, popAndTop, popPair, popQuick, push, pushPair, removeAllElements, removeElement, removeElementAt, setElementAt, setTail, setTailSub1, size, sort, sort

Constructor Details

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

Parameters:
node - Single node to be added to 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(DTMManager dtmManager)
Create an empty nodelist.


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

Parameters:


NodeSetDTM

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

Parameters:

Method Details

addElement

public void addElement(int value)
Append a Node onto the vector.
Overrides:
addElement in interface NodeVector

Parameters:
value - The node to be added.


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


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.


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.


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.


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.


allowDetachToRelease

public void allowDetachToRelease(boolean allowRelease)
Specify if it's OK for detach to release the iterator for reuse.
Specified by:
allowDetachToRelease in interface DTMIterator

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.
Overrides:
appendNodes in interface NodeVector

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


clone

public Object clone()
            throws CloneNotSupportedException
Clone this NodeSetDTM. At this time, we only expect this to be used with LocPathIterators; it may not work with other kinds of NodeSetDTMs.
Specified by:
clone in interface DTMIterator
Overrides:
clone in interface NodeVector

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.


cloneWithReset

public DTMIterator cloneWithReset()
            throws CloneNotSupportedException
Get a cloned Iterator, and reset its state to the beginning of the iteration.
Specified by:
cloneWithReset in interface DTMIterator

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


contains

public boolean contains(int s)
Tell if the table contains the given node.
Overrides:
contains in interface NodeVector

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.

Specified by:
detach in interface DTMIterator


elementAt

public int elementAt(int i)
Get the nth element.
Overrides:
elementAt in interface NodeVector

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.
Specified by:
getAxis in interface DTMIterator

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.
Specified by:
getCurrentNode in interface DTMIterator

Returns:
the last fetched node.


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.
Specified by:
getCurrentPos in interface DTMIterator

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.
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.


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.
Specified by:
getExpandEntityReferences in interface DTMIterator

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.
Specified by:
getLength in interface DTMIterator

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


getRoot

public int getRoot()
Specified by:
getRoot in interface DTMIterator

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.
Specified by:
getWhatToShow in interface DTMIterator

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)
Searches for the first occurence of the given argument, beginning the search at index, and testing for equality using the equals method.
Overrides:
indexOf in interface NodeVector

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.


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.
Overrides:
indexOf in interface NodeVector

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.


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.
Overrides:
insertElementAt in interface NodeVector

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


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.


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 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.
Specified by:
isFresh in interface DTMIterator

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.
Specified by:
isMutable in interface DTMIterator

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?
Specified by:
item in interface DTMIterator

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.
Specified by:
nextNode in interface DTMIterator

Returns:
The next Node 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 iterator backwards in the set.
Specified by:
previousNode in interface DTMIterator

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


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.
Overrides:
removeAllElements in interface NodeVector


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.
Overrides:
removeElement in interface NodeVector

Parameters:
s - The node to be removed.

Returns:
True if the node was successfully removed


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.
Overrides:
removeElementAt in interface NodeVector

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


removeNode

public void removeNode(int n)
Remove a node.

Parameters:
n - Node to be added


reset

public void reset()
Reset the iterator. May have no effect on non-iterator Nodesets.
Specified by:
reset in interface DTMIterator


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.
Specified by:
runTo in interface DTMIterator

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.


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.


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.
Overrides:
setElementAt in interface NodeVector

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


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.
Specified by:
setItem in interface DTMIterator

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


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.
Specified by:
setRoot in interface DTMIterator

Parameters:


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.
Specified by:
setShouldCacheNodes in interface DTMIterator

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


size

public int size()
Get the length of the list.
Overrides:
size in interface NodeVector

Returns:
The size of this node set.


Copyright B) 2004 Apache XML Project. All Rights Reserved.