org.apache.xpath.axes
Class NodeSequence

java.lang.Object
  extended by org.apache.xpath.Expression
      extended by org.apache.xpath.objects.XObject
          extended by org.apache.xpath.axes.NodeSequence
All Implemented Interfaces:
java.io.Serializable, java.lang.Cloneable, javax.xml.transform.SourceLocator, DTMIterator, PathComponent, ExpressionNode, XPathVisitable
Direct Known Subclasses:
XNodeSet

public class NodeSequence
extends XObject
implements DTMIterator, java.lang.Cloneable, PathComponent

This class is the dynamic wrapper for a Xalan DTMIterator instance, and provides random access capabilities.

See Also:
Serialized Form

Nested Class Summary
private static class NodeSequence.IteratorCache
          Each NodeSequence object has an iterator which is "walked".
 
Field Summary
private  NodeSequence.IteratorCache m_cache
          A cache of a list of nodes obtained from the iterator so far.
protected  DTMManager m_dtmMgr
          The DTMManager to use if we're using a NodeVector only.
protected  DTMIterator m_iter
          The functional iterator that fetches nodes.
protected  int m_last
          The index of the last node in the iteration.
protected  int m_next
          The index of the next node to be fetched.
(package private) static long serialVersionUID
           
 
Fields inherited from class org.apache.xpath.objects.XObject
CLASS_BOOLEAN, CLASS_NODESET, CLASS_NULL, CLASS_NUMBER, CLASS_RTREEFRAG, CLASS_STRING, CLASS_UNKNOWN, CLASS_UNRESOLVEDVARIABLE, m_obj
 
Fields inherited from interface org.apache.xml.dtm.DTMIterator
FILTER_ACCEPT, FILTER_REJECT, FILTER_SKIP
 
Constructor Summary
  NodeSequence()
          Create a new NodeSequence in an invalid (null) state.
private NodeSequence(DTMIterator iter, int context, XPathContext xctxt, boolean shouldCacheNodes)
          Create a new NodeSequence from a (already cloned) iterator.
private NodeSequence(DTMManager dtmMgr)
          Construct an empty XNodeSet object.
  NodeSequence(java.lang.Object nodeVector)
          Create a new NodeSequence from a (already cloned) iterator.
 
Method Summary
protected  int addNodeInDocOrder(int node)
          Add the node into a vector of nodes where it should occur in document order.
 void allowDetachToRelease(boolean allowRelease)
          Calling this with a value of false will cause the nodeset to be cached.
private  boolean cacheComplete()
          If this NodeSequence has a cache, and that cache is fully populated then this method returns true, otherwise if there is no cache or it is not complete it returns false.
 java.lang.Object clone()
          Get a clone of this iterator, but don't reset the iteration in the process, so that it may be used from the current position.
 DTMIterator cloneWithReset()
          Note: Not a deep clone.
 void detach()
          Detaches the DTMIterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state.
 void fixupVariables(java.util.Vector vars, int globalsSize)
          XObjects should not normally need to fix up variables.
 int getAnalysisBits()
          Get the analysis bits for this path component, as defined in the WalkerFactory.
 int getAxis()
          Returns the axis being iterated, if it is known.
private  NodeSequence.IteratorCache getCache()
          Get the cache (if any) of nodes obtained from the iterator so far.
 DTMIterator getContainedIter()
          Get the functional iterator that fetches nodes.
 int getCurrentNode()
          Get the current node in the iterator.
 int getCurrentPos()
          Get the current position within the cached list, 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.
protected  NodeSequence.IteratorCache getIteratorCache()
          Get the cached list of nodes appended with values obtained from the iterator as a NodeSequence is walked when its nextNode() method is called.
 int getLength()
          The number of nodes in the list.
 int getRoot()
          The root node of the DTMIterator, as specified when it was created.
protected  NodeVector getVector()
          If this iterator needs to cache nodes that are fetched, they are stored in the Vector in the generic object.
 int getWhatToShow()
          This attribute determines which node types are presented via the iterator.
 boolean hasCache()
          If the iterator needs to cache nodes as they are fetched, then this method returns true.
 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 node handle of an item in the collection.
private  void markCacheComplete()
          If this NodeSequence has a cache, mark that it is complete.
 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 DTMIterator backwards in the set.
 void reset()
          Reset for fresh reuse.
 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 setItem(int node, int index)
          Sets the node at the specified index of this vector to be the specified node.
 void setIter(DTMIterator iter)
          Set the functional iterator that fetches nodes.
protected  void setObject(java.lang.Object obj)
          It used to be that many locations in the code simply did an assignment to this.m_obj directly, rather than calling the setObject(Object) method.
 void setRoot(int nodeHandle, java.lang.Object environment)
          Reset the root node of the DTMIterator, overriding the value specified when it was created.
 void setShouldCacheNodes(boolean b)
          If setShouldCacheNodes(true) is called, then nodes will be cached, enabling random access, and giving the ability to do sorts and the like.
protected  void SetVector(NodeVector v)
          Set the vector where nodes will be cached.
 
Methods inherited from class org.apache.xpath.objects.XObject
appendToFsb, bool, boolWithSideEffects, callVisitors, castToType, create, create, deepEquals, destruct, dispatchCharactersEvents, equals, error, error, execute, getFresh, getType, getTypeString, greaterThan, greaterThanOrEqual, iter, lessThan, lessThanOrEqual, mutableNodeset, nodelist, nodeset, notEquals, num, numWithSideEffects, object, rtf, rtf, rtree, rtree, str, toString, xstr
 
Methods inherited from class org.apache.xpath.Expression
asIterator, asIteratorRaw, asNode, assertion, bool, canTraverseOutsideSubtree, error, execute, execute, execute, executeCharsToContentHandler, exprAddChild, exprGetChild, exprGetNumChildren, exprGetParent, exprSetParent, getColumnNumber, getExpressionOwner, getLineNumber, getPublicId, getSystemId, isNodesetExpr, isSameClass, isStableNumber, num, warn, xstr
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

serialVersionUID

static final long serialVersionUID
See Also:
Constant Field Values

m_last

protected int m_last
The index of the last node in the iteration.


m_next

protected int m_next
The index of the next node to be fetched. Useful if this is a cached iterator, and is being used as random access NodeList.


m_cache

private NodeSequence.IteratorCache m_cache
A cache of a list of nodes obtained from the iterator so far. This list is appended to until the iterator is exhausted and the cache is complete.

Multiple NodeSequence objects may share the same cache.


m_iter

protected DTMIterator m_iter
The functional iterator that fetches nodes.


m_dtmMgr

protected DTMManager m_dtmMgr
The DTMManager to use if we're using a NodeVector only. We may well want to do away with this, and store it in the NodeVector.

Constructor Detail

NodeSequence

private NodeSequence(DTMIterator iter,
                     int context,
                     XPathContext xctxt,
                     boolean shouldCacheNodes)
Create a new NodeSequence from a (already cloned) iterator.

Parameters:
iter - Cloned (not static) DTMIterator.
context - The initial context node.
xctxt - The execution context.
shouldCacheNodes - True if this sequence can random access.

NodeSequence

public NodeSequence(java.lang.Object nodeVector)
Create a new NodeSequence from a (already cloned) iterator.

Parameters:
nodeVector -

NodeSequence

private NodeSequence(DTMManager dtmMgr)
Construct an empty XNodeSet object. This is used to create a mutable nodeset to which random nodes may be added.


NodeSequence

public NodeSequence()
Create a new NodeSequence in an invalid (null) state.

Method Detail

getVector

protected NodeVector getVector()
If this iterator needs to cache nodes that are fetched, they are stored in the Vector in the generic object.


getCache

private NodeSequence.IteratorCache getCache()
Get the cache (if any) of nodes obtained from the iterator so far. Note that the cache keeps growing until the iterator is walked to exhaustion, at which point the cache is "complete".


SetVector

protected void SetVector(NodeVector v)
Set the vector where nodes will be cached.


hasCache

public boolean hasCache()
If the iterator needs to cache nodes as they are fetched, then this method returns true.


cacheComplete

private boolean cacheComplete()
If this NodeSequence has a cache, and that cache is fully populated then this method returns true, otherwise if there is no cache or it is not complete it returns false.


markCacheComplete

private void markCacheComplete()
If this NodeSequence has a cache, mark that it is complete. This method should be called after the iterator is exhausted.


setIter

public final void setIter(DTMIterator iter)
Set the functional iterator that fetches nodes.

Parameters:
iter - The iterator that is to be contained.

getContainedIter

public final DTMIterator getContainedIter()
Get the functional iterator that fetches nodes.

Returns:
The contained iterator.

getDTM

public DTM getDTM(int nodeHandle)
Description copied from interface: DTMIterator
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.
See Also:
DTMIterator.getDTM(int)

getDTMManager

public DTMManager getDTMManager()
Description copied from interface: DTMIterator
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.
See Also:
DTMIterator.getDTMManager()

getRoot

public int getRoot()
Description copied from interface: DTMIterator
The root node of the DTMIterator, as specified when it was created. Note the root node is not the root node of the document tree, but the context node from where the iteration begins and ends.

Specified by:
getRoot in interface DTMIterator
Returns:
nodeHandle int Handle of the context node.
See Also:
DTMIterator.getRoot()

setRoot

public void setRoot(int nodeHandle,
                    java.lang.Object environment)
Description copied from interface: DTMIterator
Reset the root node of the DTMIterator, overriding the value specified when it was created. Note the root node is not the root node of the document tree, but the context node from where the iteration begins.

Specified by:
setRoot in interface DTMIterator
Parameters:
nodeHandle - int Handle of the context node.
environment - The environment object. 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.

      See Also:
      DTMIterator.setRoot(int, Object)

reset

public void reset()
Description copied from class: XObject
Reset for fresh reuse.

Specified by:
reset in interface DTMIterator
Overrides:
reset in class XObject
See Also:
DTMIterator.reset()

getWhatToShow

public int getWhatToShow()
Description copied from interface: DTMIterator
This attribute determines which node types are presented via the iterator. The available set of constants is defined above. Nodes not accepted by whatToShow will be skipped, but their children may still be considered.

Specified by:
getWhatToShow in interface DTMIterator
Returns:
one of the SHOW_XXX constants, or several ORed together.
See Also:
DTMIterator.getWhatToShow()

getExpandEntityReferences

public boolean getExpandEntityReferences()
Description copied from interface: DTMIterator

The value of this flag determines whether the children of entity reference nodes are visible to the iterator. If false, they and their descendants will be rejected. Note that this rejection takes precedence over whatToShow and the filter.

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.

NOTE: In Xalan's use of DTM we will generally have fully expanded entity references when the document tree was built, and thus this flag will have no effect.

Specified by:
getExpandEntityReferences in interface DTMIterator
Returns:
true if entity references will be expanded.
See Also:
DTMIterator.getExpandEntityReferences()

nextNode

public int nextNode()
Description copied from interface: DTMIterator
Returns the next node in the set and advances the position of the iterator in the set. After a DTMIterator has setRoot called, the first call to nextNode() returns that root or (if it is rejected by the filters) the first node within its subtree which is not filtered out.

Specified by:
nextNode in interface DTMIterator
Returns:
The next node handle in the set being iterated over, or DTM.NULL if there are no more members in that set.
See Also:
DTMIterator.nextNode()

previousNode

public int previousNode()
Description copied from interface: DTMIterator
Returns the previous node in the set and moves the position of the DTMIterator backwards in the set.

Specified by:
previousNode in interface DTMIterator
Returns:
The previous node handle in the set being iterated over, or DTM.NULL if there are no more members in that set.
See Also:
DTMIterator.previousNode()

detach

public void detach()
Description copied from class: XObject
Detaches the DTMIterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state. After detach has been invoked, calls to nextNode or previousNode will raise a runtime exception.

Specified by:
detach in interface DTMIterator
Overrides:
detach in class XObject
See Also:
DTMIterator.detach()

allowDetachToRelease

public void allowDetachToRelease(boolean allowRelease)
Calling this with a value of false will cause the nodeset to be cached.

Specified by:
allowDetachToRelease in interface DTMIterator
Overrides:
allowDetachToRelease in class XObject
Parameters:
allowRelease - true if it is OK for detach to release this iterator for pooling.
See Also:
DTMIterator.allowDetachToRelease(boolean)

getCurrentNode

public int getCurrentNode()
Description copied from interface: DTMIterator
Get the current node in the iterator. Note that this differs from the DOM's NodeIterator, where the current position lies between two nodes (as part of the maintain-relative-position semantic).

Specified by:
getCurrentNode in interface DTMIterator
Returns:
The current node handle, or -1.
See Also:
DTMIterator.getCurrentNode()

isFresh

public boolean isFresh()
Description copied from interface: DTMIterator
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 the iteration of this list has not yet begun.
See Also:
DTMIterator.isFresh()

setShouldCacheNodes

public void setShouldCacheNodes(boolean b)
Description copied from interface: DTMIterator
If setShouldCacheNodes(true) is called, then nodes will be cached, enabling random access, and giving the ability to do sorts and the like. They are not cached by default. %REVIEW% Shouldn't the other random-access methods throw an exception if they're called on a DTMIterator with this flag set false?

Specified by:
setShouldCacheNodes in interface DTMIterator
Parameters:
b - true if the nodes should be cached.
See Also:
DTMIterator.setShouldCacheNodes(boolean)

isMutable

public boolean isMutable()
Description copied from interface: DTMIterator
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.
See Also:
DTMIterator.isMutable()

getCurrentPos

public int getCurrentPos()
Description copied from interface: DTMIterator
Get the current position within the cached list, 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 position of the iteration.
See Also:
DTMIterator.getCurrentPos()

runTo

public void runTo(int index)
Description copied from interface: DTMIterator
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 and completely fill the cache.

Specified by:
runTo in interface DTMIterator
Parameters:
index - The index to run to, or -1 if the iterator should be run to the end.
See Also:
DTMIterator.runTo(int)

setCurrentPos

public void setCurrentPos(int i)
Description copied from interface: DTMIterator
Set the current position in the node set.

Specified by:
setCurrentPos in interface DTMIterator
Parameters:
i - Must be a valid index.
See Also:
DTMIterator.setCurrentPos(int)

item

public int item(int index)
Description copied from interface: DTMIterator
Returns the node handle of an item in the collection. If index is greater than or equal to the number of nodes in the list, this returns null.

Specified by:
item in interface DTMIterator
Parameters:
index - of the item.
Returns:
The node handle at the indexth position in the DTMIterator, or -1 if that is not a valid index.
See Also:
DTMIterator.item(int)

setItem

public void setItem(int node,
                    int index)
Description copied from interface: DTMIterator
Sets the node at the specified index of this vector to be the specified node. The previous component at that position is discarded.

The index must be a value greater than or equal to 0 and less than the current size of the vector. The iterator must be in cached mode.

Meant to be used for sorted iterators.

Specified by:
setItem in interface DTMIterator
Parameters:
node - Node to set
index - Index of where to set the node
See Also:
DTMIterator.setItem(int, int)

getLength

public int getLength()
Description copied from interface: DTMIterator
The number of nodes in the list. The range of valid child node indices is 0 to length-1 inclusive. Note that this requires running the iterator to completion, and presumably filling the cache.

Specified by:
getLength in interface DTMIterator
Returns:
The number of nodes in the list.
See Also:
DTMIterator.getLength()

cloneWithReset

public DTMIterator cloneWithReset()
                           throws java.lang.CloneNotSupportedException
Note: Not a deep clone.

Specified by:
cloneWithReset in interface DTMIterator
Returns:
A clone of this iteration that has been reset.
Throws:
java.lang.CloneNotSupportedException
See Also:
DTMIterator.cloneWithReset()

clone

public java.lang.Object clone()
                       throws java.lang.CloneNotSupportedException
Get a clone of this iterator, but don't reset the iteration in the process, so that it may be used from the current position. Note: Not a deep clone.

Specified by:
clone in interface DTMIterator
Overrides:
clone in class java.lang.Object
Returns:
A clone of this object.
Throws:
java.lang.CloneNotSupportedException

isDocOrdered

public boolean isDocOrdered()
Description copied from interface: DTMIterator
Returns true if all the nodes in the iteration well be returned in document order.

Specified by:
isDocOrdered in interface DTMIterator
Returns:
true if all the nodes in the iteration well be returned in document order.
See Also:
DTMIterator.isDocOrdered()

getAxis

public int getAxis()
Description copied from interface: DTMIterator
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.
See Also:
DTMIterator.getAxis()

getAnalysisBits

public int getAnalysisBits()
Description copied from interface: PathComponent
Get the analysis bits for this path component, as defined in the WalkerFactory.

Specified by:
getAnalysisBits in interface PathComponent
Returns:
One of WalkerFactory#BIT_DESCENDANT, etc.
See Also:
PathComponent.getAnalysisBits()

fixupVariables

public void fixupVariables(java.util.Vector vars,
                           int globalsSize)
Description copied from class: XObject
XObjects should not normally need to fix up variables.

Overrides:
fixupVariables in class XObject
Parameters:
vars - List of QNames that correspond to variables. This list should be searched backwards for the first qualified name that corresponds to the variable reference qname. The position of the QName in the vector from the start of the vector will be its position in the stack frame (but variables above the globalsTop value will need to be offset to the current stack frame). NEEDSDOC @param globalsSize
See Also:
Expression.fixupVariables(Vector, int)

addNodeInDocOrder

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

Parameters:
node - The node to be added.
Returns:
insertIndex.
Throws:
java.lang.RuntimeException - thrown if this NodeSetDTM is not of a mutable type.

setObject

protected void setObject(java.lang.Object obj)
It used to be that many locations in the code simply did an assignment to this.m_obj directly, rather than calling the setObject(Object) method. The problem is that our super-class would be updated on what the cache associated with this NodeSequence, but we wouldn't know ourselves.

All setting of m_obj is done through setObject() now, and this method over-rides the super-class method. So now we are in the loop have an opportunity to update some caching information.

Overrides:
setObject in class XObject

getIteratorCache

protected NodeSequence.IteratorCache getIteratorCache()
Get the cached list of nodes appended with values obtained from the iterator as a NodeSequence is walked when its nextNode() method is called.