org.apache.xpath
Class NodeSetDTM

java.lang.Object
  |
  +--org.apache.xml.utils.NodeVector
        |
        +--org.apache.xpath.NodeSetDTM
Direct Known Subclasses:
RTFIterator

public class NodeSetDTM
extends NodeVector
implements DTMIterator, java.lang.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.

See Also:
Serialized Form
Usage:
**For advanced use only**

Constructor Summary
NodeSetDTM(DTMIterator ni)
          Create a NodeSetDTM, and copy the members of the given DTMIterator into it.
NodeSetDTM(DTMManager dtmManager)
          Create an empty nodelist.
NodeSetDTM(int node, DTMManager dtmManager)
          Create a NodeSetDTM which contains the given Node.
NodeSetDTM(int blocksize, int dummy, DTMManager dtmManager)
          Create an empty, using the given block size.
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(NodeSetDTM nodelist)
          Create a NodeSetDTM, and copy the members of the given NodeSetDTM 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.
 java.lang.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.
 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(java.lang.Object environment)
          Set the environment in which this iterator operates, which should provide: a node (the context node...
 void setItem(int node, int index)
          Same as setElementAt.
 void setLast(int last)
           
 void setRoot(int context, java.lang.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
insertInOrder, peepOrNull, peepTail, peepTailSub1, pop, popAndTop, popPair, popQuick, push, pushPair, RemoveAllNoClear, setTail, setTailSub1, sort, sort
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

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

setEnvironment

public void setEnvironment(java.lang.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.

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.

setRoot

public void setRoot(int context,
                    java.lang.Object environment)
Initialize the context values for this expression after it is cloned.
Specified by:
setRoot in interface DTMIterator
Parameters:
context - The XPath runtime context for this transformation.

clone

public java.lang.Object clone()
                       throws java.lang.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
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:
java.lang.CloneNotSupportedException - if this subclass of NodeSetDTM does not support the clone() operation.
Overrides:
clone in class NodeVector

cloneWithReset

public DTMIterator cloneWithReset()
                           throws java.lang.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.
Throws:
java.lang.CloneNotSupportedException - if this subclass of NodeSetDTM does not support the clone() operation.

reset

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

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.

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.)

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.

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

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

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.

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.

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

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.

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.

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

size

public int size()
Get the length of the list.
Returns:
The size of this node set.
Overrides:
size in class NodeVector

addElement

public void addElement(int value)
Append a Node onto the vector.
Parameters:
value - The node to be added.
Throws:
java.lang.RuntimeException - thrown if this NodeSetDTM is not of a mutable type.
Overrides:
addElement in class NodeVector

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:
java.lang.RuntimeException - thrown if this NodeSetDTM is not of a mutable type.
Overrides:
insertElementAt in class NodeVector

appendNodes

public void appendNodes(NodeVector nodes)
Append the nodes to the list.
Parameters:
nodes - The nodes to be appended to this node set.
Throws:
java.lang.RuntimeException - thrown if this NodeSetDTM is not of a mutable type.
Overrides:
appendNodes in class NodeVector

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:
java.lang.RuntimeException - thrown if this NodeSetDTM is not of a mutable type.
Overrides:
removeAllElements in class 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.
Parameters:
s - The node to be removed.
Returns:
True if the node was successfully removed
Throws:
java.lang.RuntimeException - thrown if this NodeSetDTM is not of a mutable type.
Overrides:
removeElement in class NodeVector

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:
java.lang.RuntimeException - thrown if this NodeSetDTM is not of a mutable type.
Overrides:
removeElementAt in class NodeVector

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:
java.lang.RuntimeException - thrown if this NodeSetDTM is not of a mutable type.
Overrides:
setElementAt in class NodeVector

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

elementAt

public int elementAt(int i)
Get the nth element.
Parameters:
i - The index of the requested node.
Returns:
Node at specified index.
Overrides:
elementAt in class NodeVector

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.
Overrides:
contains in class NodeVector

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.
Overrides:
indexOf in class NodeVector

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.
Overrides:
indexOf in class NodeVector

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.

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

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

getShouldCacheNodes

public boolean getShouldCacheNodes()
Get whether or not this is a cached node set.
Returns:
True if this list is cached.

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

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.

getLast

public int getLast()

setLast

public void setLast(int last)

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.

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.


Copyright 2006 Apache XML Project. All Rights Reserved.