org.apache.xpath
Class NodeSet

java.lang.Object
  |
  +--org.apache.xpath.NodeSet

public class NodeSet
extends java.lang.Object
implements NodeList, NodeIterator, java.lang.Cloneable, ContextNodeList

The NodeSet 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 NodeSet 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 NodeSets will respond to the same calls; the disadvantage is that some of them may return less-than-enlightening results when you do so.

Usage:
**For advanced use only**

Constructor Summary
NodeSet()
          Create an empty nodelist.
NodeSet(int blocksize)
          Create an empty, using the given block size.
NodeSet(Node node)
          Create a NodeSet which contains the given Node.
NodeSet(NodeIterator ni)
          Create a NodeSet, and copy the members of the given NodeIterator into it.
NodeSet(NodeList nodelist)
          Create a NodeSet, and copy the members of the given nodelist into it.
NodeSet(NodeSet nodelist)
          Create a NodeSet, and copy the members of the given NodeSet into it.
 
Method Summary
 void addElement(Node value)
          Append a Node onto the vector.
 void addNode(Node n)
          Add a node to the NodeSet.
 int addNodeInDocOrder(Node node, boolean test, XPathContext support)
          Add the node into a vector of nodes where it should occur in document order.
 int addNodeInDocOrder(Node node, XPathContext support)
          Add the node into a vector of nodes where it should occur in document order.
 void addNodes(NodeIterator iterator)
          Copy NodeList members into this nodelist, adding in document order.
 void addNodes(NodeList nodelist)
          Copy NodeList members into this nodelist, adding in document order.
 void addNodes(NodeSet ns)
          Copy NodeList members into this nodelist, adding in document order.
 void addNodesInDocOrder(NodeIterator iterator, XPathContext support)
          Copy NodeList members into this nodelist, adding in document order.
 void addNodesInDocOrder(NodeList nodelist, XPathContext support)
          Copy NodeList members into this nodelist, adding in document order.
 void appendNodes(NodeSet nodes)
          Append the nodes to the list.
 java.lang.Object clone()
          Get a cloned LocPathIterator.
 NodeIterator cloneWithReset()
          Get a cloned Iterator, and reset its state to the beginning of the iteration.
 boolean contains(Node 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.
 Node elementAt(int i)
          Get the nth element.
 Node getCurrentNode()
          Return the last fetched node.
 int getCurrentPos()
          Get the current position, which is one less than the next nextNode() call will retrieve.
 boolean getExpandEntityReferences()
          The value of this flag determines whether the children of entity reference nodes are visible to the iterator.
 NodeFilter getFilter()
          The filter object used to screen nodes.
 int getLast()
           
 int getLength()
          The number of nodes in the list.
 Node 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(Node 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(Node 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(Node value, int at)
          Inserts the specified node in this vector at the specified index.
 void insertNode(Node n, int pos)
          Insert a node at a given position.
 boolean isFresh()
          Tells if this NodeSet is "fresh", in other words, if the first nextNode() that is called will return the first node in the set.
 Node item(int index)
          Returns the indexth item in the collection.
 Node nextNode()
          Returns the next node in the set and advances the position of the iterator in the set.
 Node peepOrNull()
          Return the node at the top of the stack without popping the stack.
 Node peepTail()
          Return the node at the tail of the vector without popping Special purpose method for TransformerImpl, pushElemTemplateElement.
 Node peepTailSub1()
          Return the node one position from the tail without popping.
 Node pop()
          Pop a node from the tail of the vector and return the result.
 Node popAndTop()
          Pop a node from the tail of the vector and return the top of the stack after the pop.
 void popPair()
          Pop a pair of nodes from the tail of the stack.
 void popQuick()
          Pop a node from the tail of the vector.
 Node previousNode()
          Returns the previous node in the set and moves the position of the iterator backwards in the set.
 void push(Node value)
          Append a Node onto the vector.
 void pushPair(Node v1, Node v2)
          Push a pair of nodes into the stack.
 void removeAllElements()
          Inserts the specified node in this vector at the specified index.
 boolean removeElement(Node s)
          Removes the first occurrence of the argument from this vector.
 void removeElementAt(int i)
          Deletes the component at the specified index.
 void removeNode(Node n)
          Remove a node.
 void reset()
          Reset the iterator.
 void runTo(int index)
          If an index is requested, NodeSet 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(Node node, int index)
          Sets the component at the specified index of this vector to be the specified object.
 void setLast(int last)
           
 void setShouldCacheNodes(boolean b)
          If setShouldCacheNodes(true) is called, then nodes will be cached.
 void setTail(Node n)
          Set the tail of the stack to the given node.
 void setTailSub1(Node n)
          Set the given node one position from the tail.
 int size()
          Get the length of the list.
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

NodeSet

public NodeSet()
Create an empty nodelist.

NodeSet

public NodeSet(int blocksize)
Create an empty, using the given block size.
Parameters:
blocksize - Size of blocks to allocate

NodeSet

public NodeSet(NodeList nodelist)
Create a NodeSet, and copy the members of the given nodelist into it.
Parameters:
nodelist - List of Nodes to be made members of the new set.

NodeSet

public NodeSet(NodeSet nodelist)
Create a NodeSet, and copy the members of the given NodeSet into it.
Parameters:
nodelist - Set of Nodes to be made members of the new set.

NodeSet

public NodeSet(NodeIterator ni)
Create a NodeSet, and copy the members of the given NodeIterator into it.
Parameters:
ni - Iterator which yields Nodes to be made members of the new set.

NodeSet

public NodeSet(Node node)
Create a NodeSet which contains the given Node.
Parameters:
node - Single node to be added to the new set.
Method Detail

getRoot

public Node getRoot()
Specified by:
getRoot in interface NodeIterator
Returns:
The root node of the Iterator, as specified when it was created. For non-Iterator NodeSets, this will be null.

cloneWithReset

public NodeIterator cloneWithReset()
                            throws java.lang.CloneNotSupportedException
Get a cloned Iterator, and reset its state to the beginning of the iteration.
Specified by:
cloneWithReset in interface ContextNodeList
Returns:
a new NodeSet of the same type, having the same state... except that the reset() operation has been called.
Throws:
java.lang.CloneNotSupportedException - if this subclass of NodeSet 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 ContextNodeList

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

getFilter

public NodeFilter getFilter()
The filter object used to screen nodes. Filters are applied to further reduce (and restructure) the NodeIterator'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 NodeIterator interface, so we have to support it.
Specified by:
getFilter in interface NodeIterator
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 NodeIterator
Returns:
true for all iterators based on NodeSet, meaning that the contents of EntityRefrence nodes may be returned (though whatToShow says that the EntityReferences themselves are not shown.)

nextNode

public Node nextNode()
              throws DOMException
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.
Specified by:
nextNode in interface NodeIterator
Returns:
The next Node in the set being iterated over, or 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 Node previousNode()
                  throws DOMException
Returns the previous node in the set and moves the position of the iterator backwards in the set.
Specified by:
previousNode in interface NodeIterator
Returns:
The previous Node in the set being iterated over, ornull 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 NodeSet 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 NodeSet, and will not cause INVALID_STATE_ERR to be raised by later operations.

Specified by:
detach in interface NodeIterator

isFresh

public boolean isFresh()
Tells if this NodeSet 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 ContextNodeList
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, NodeSet 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 ContextNodeList
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 NodeSet is not one of the types which supports indexing/counting.

item

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

addNode

public void addNode(Node n)
Add a node to the NodeSet. Not all types of NodeSets support this operation
Parameters:
n - Node to be added
Throws:
java.lang.RuntimeException - thrown if this NodeSet is not of a mutable type.

insertNode

public void insertNode(Node 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 NodeSet is not of a mutable type.

removeNode

public void removeNode(Node n)
Remove a node.
Parameters:
n - Node to be added
Throws:
java.lang.RuntimeException - thrown if this NodeSet is not of a mutable type.

addNodes

public void addNodes(NodeList nodelist)
Copy NodeList members into this nodelist, adding in document order. If a node is null, don't add it.
Parameters:
nodelist - List of nodes which should now be referenced by this NodeSet.
Throws:
java.lang.RuntimeException - thrown if this NodeSet is not of a mutable type.

addNodes

public void addNodes(NodeSet ns)

Copy NodeList members into this nodelist, adding in document order. Only genuine node references will be copied; nulls appearing in the source NodeSet will not be added to this one.

In case you're wondering why this function is needed: NodeSet implements both NodeIterator and NodeList. If this method isn't provided, Java can't decide which of those to use when addNodes() is invoked. Providing the more-explicit match avoids that ambiguity.)

Parameters:
ns - NodeSet whose members should be merged into this NodeSet.
Throws:
java.lang.RuntimeException - thrown if this NodeSet is not of a mutable type.

addNodes

public void addNodes(NodeIterator iterator)
Copy NodeList members into this nodelist, adding in document order. Null references are not added.
Parameters:
iterator - NodeIterator which yields the nodes to be added.
Throws:
java.lang.RuntimeException - thrown if this NodeSet is not of a mutable type.

addNodesInDocOrder

public void addNodesInDocOrder(NodeList nodelist,
                               XPathContext support)
Copy NodeList members into this nodelist, adding in document order. If a node is null, don't add it.
Parameters:
nodelist - List of nodes to be added
support - The XPath runtime context.
Throws:
java.lang.RuntimeException - thrown if this NodeSet is not of a mutable type.

addNodesInDocOrder

public void addNodesInDocOrder(NodeIterator iterator,
                               XPathContext support)
Copy NodeList members into this nodelist, adding in document order. If a node is null, don't add it.
Parameters:
iterator - NodeIterator which yields the nodes to be added.
support - The XPath runtime context.
Throws:
java.lang.RuntimeException - thrown if this NodeSet is not of a mutable type.

addNodeInDocOrder

public int addNodeInDocOrder(Node 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 NodeSet is not of a mutable type.

addNodeInDocOrder

public int addNodeInDocOrder(Node 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 NodeSet is not of a mutable type.

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 ContextNodeList
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 ContextNodeList
Parameters:
i - Must be a valid index.
Throws:
java.lang.RuntimeException - thrown if this NodeSet is not of a cached type, and thus doesn't permit indexed access.

getCurrentNode

public Node getCurrentNode()
Return the last fetched node. Needed to support the UnionPathIterator.
Specified by:
getCurrentNode in interface ContextNodeList
Returns:
the last fetched node.
Throws:
java.lang.RuntimeException - thrown if this NodeSet 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 ContextNodeList
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.

getLast

public int getLast()
Specified by:
getLast in interface ContextNodeList

setLast

public void setLast(int last)
Specified by:
setLast in interface ContextNodeList

clone

public java.lang.Object clone()
                       throws java.lang.CloneNotSupportedException
Get a cloned LocPathIterator.
Specified by:
clone in interface ContextNodeList
Returns:
A clone of this
Throws:
java.lang.CloneNotSupportedException -  

size

public int size()
Get the length of the list.
Specified by:
size in interface ContextNodeList
Returns:
Number of nodes in this NodeVector

addElement

public void addElement(Node value)
Append a Node onto the vector.
Parameters:
value - Node to add to the vector

push

public final void push(Node value)
Append a Node onto the vector.
Parameters:
value - Node to add to the vector

pop

public final Node pop()
Pop a node from the tail of the vector and return the result.
Returns:
the node at the tail of the vector

popAndTop

public final Node popAndTop()
Pop a node from the tail of the vector and return the top of the stack after the pop.
Returns:
The top of the stack after it's been popped

popQuick

public final void popQuick()
Pop a node from the tail of the vector.

peepOrNull

public final Node peepOrNull()
Return the node at the top of the stack without popping the stack. Special purpose method for TransformerImpl, pushElemTemplateElement. Performance critical.
Returns:
Node at the top of the stack or null if stack is empty.

pushPair

public final void pushPair(Node v1,
                           Node v2)
Push a pair of nodes into the stack. Special purpose method for TransformerImpl, pushElemTemplateElement. Performance critical.
Parameters:
v1 - First node to add to vector
v2 - Second node to add to vector

popPair

public final void popPair()
Pop a pair of nodes from the tail of the stack. Special purpose method for TransformerImpl, pushElemTemplateElement. Performance critical.

setTail

public final void setTail(Node n)
Set the tail of the stack to the given node. Special purpose method for TransformerImpl, pushElemTemplateElement. Performance critical.
Parameters:
n - Node to set at the tail of vector

setTailSub1

public final void setTailSub1(Node n)
Set the given node one position from the tail. Special purpose method for TransformerImpl, pushElemTemplateElement. Performance critical.
Parameters:
n - Node to set

peepTail

public final Node peepTail()
Return the node at the tail of the vector without popping Special purpose method for TransformerImpl, pushElemTemplateElement. Performance critical.
Returns:
Node at the tail of the vector

peepTailSub1

public final Node peepTailSub1()
Return the node one position from the tail without popping. Special purpose method for TransformerImpl, pushElemTemplateElement. Performance critical.
Returns:
Node one away from the tail

insertElementAt

public void insertElementAt(Node 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 - Node to insert
at - Position where to insert

appendNodes

public void appendNodes(NodeSet nodes)
Append the nodes to the list.
Parameters:
nodes - NodeVector to append to this list

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.

removeElement

public boolean removeElement(Node 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 - Node to remove from the list
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.
Parameters:
i - Index of node to remove

setElementAt

public void setElementAt(Node 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 - Node to set
index - Index of where to set the node

elementAt

public Node elementAt(int i)
Get the nth element.
Parameters:
i - Index of node to get
Returns:
Node at specified index

contains

public boolean contains(Node s)
Tell if the table contains the given node.
Parameters:
s - Node to look for
Returns:
True if the given node was found.

indexOf

public int indexOf(Node 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(Node 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.


Copyright 2006 Apache XML Project. All Rights Reserved.