Top Description Fields Methods
com.sun.org.apache.xml.internal.dtm

public Interface DTMIterator

Known Direct Implementers
com.sun.org.apache.xpath.internal.NodeSetDTM, com.sun.org.apache.xpath.internal.axes.LocPathIterator, com.sun.org.apache.xpath.internal.axes.NodeSequence, com.sun.org.apache.xpath.internal.axes.UnionPathIterator

DTMIterators are used to step through a (possibly filtered) set of nodes. Their API is modeled largely after the DOM NodeIterator.

A DTMIterator is a somewhat unusual type of iterator, in that it can serve both single node iteration and random access.

The DTMIterator's traversal semantics, i.e. how it walks the tree, are specified when it is created, possibly and probably by an XPath LocationPath or a UnionExpr.

A DTMIterator is meant to be created once as a master static object, and then cloned many times for runtime use. Or the master object itself may be used for simpler use cases.

At this time, we do not expect DTMIterator to emulate NodeIterator's "maintain relative position" semantics under document mutation. It's likely to respond more like the TreeWalker's "current node" semantics. However, since the base DTM is immutable, this issue currently makes no practical difference.

State: In progress!!

Field Summary

Modifier and TypeField and Description
public static final short
FILTER_ACCEPT

Accept the node.

public static final short
FILTER_REJECT

Reject the node.

public static final short
FILTER_SKIP

Skip this single node.

Method Summary

Modifier and TypeMethod and Description
public void
allowDetachToRelease(boolean
true if it is OK for detach to release this iterator for pooling.
allowRelease
)

Specify if it's OK for detach to release the iterator for reuse.

public Object

Returns:

A clone of this 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.

public DTMIterator

Returns:

A clone of this iteration that has been reset.
cloneWithReset
()

Get a cloned Iterator that is reset to the start of the iteration.

public void
detach()

Detaches the DTMIterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state.

public int

Returns:

Axis.CHILD, etc., or -1 if the axis is not known or is of multiple types.
getAxis
()

Returns the axis being iterated, if it is known.

public int

Returns:

The current node handle, or -1.
getCurrentNode
()

Get the current node in the iterator.

public int

Returns:

The position of the iteration.
getCurrentPos
()

Get the current position within the cached list, which is one less than the next nextNode() call will retrieve.

public DTM

Returns:

a non-null DTM reference.
getDTM
(int
the nodeHandle.
nodeHandle
)

Get an instance of a DTM that "owns" a node handle.

public DTMManager

Returns:

a non-null DTMManager reference.
getDTMManager
()

Get an instance of the DTMManager.

public boolean

Returns:

true if entity references will be expanded.
getExpandEntityReferences
()

The value of this flag determines whether the children of entity reference nodes are visible to the iterator.

public int

Returns:

The number of nodes in the list.
getLength
()

The number of nodes in the list.

public int

Returns:

nodeHandle int Handle of the context node.
getRoot
()

The root node of the DTMIterator, as specified when it was created.

public int

Returns:

one of the SHOW_XXX constants, or several ORed together.
getWhatToShow
()

This attribute determines which node types are presented via the iterator.

public boolean

Returns:

true if all the nodes in the iteration well be returned in document order.
isDocOrdered
()

Returns true if all the nodes in the iteration well be returned in document order.

public boolean

Returns:

true if the iteration of this list has not yet begun.
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.

public boolean

Returns:

True if the nodelist can be mutated.
isMutable
()

Tells if this iterator can have nodes added to it or set via the setItem(int node, int index) method.

public int

Returns:

The node handle at the indexth position in the DTMIterator, or -1 if that is not a valid index.
item
(int
of the item.
index
)

Returns the node handle of an item in the collection.

public int

Returns:

The next node handle in the set being iterated over, or DTM.NULL if there are no more members in that set.
nextNode
()

Returns the next node in the set and advances the position of the iterator in the set.

public int

Returns:

The previous node handle in the set being iterated over, or DTM.NULL if there are no more members in that set.
previousNode
()

Returns the previous node in the set and moves the position of the DTMIterator backwards in the set.

public void
reset()

Reset the iterator to the start.

public void
runTo(int
The index to run to, or -1 if the iterator should be run to the end.
index
)

If an index is requested, NodeSetDTM will call this method to run the iterator to the index.

public void
setCurrentPos(int
Must be a valid index.
i
)

Set the current position in the node set.

public void
setItem(int
Node to set
node
,
int
Index of where to set the node
index
)

Sets the node at the specified index of this vector to be the specified node.

public void
setRoot(int
int Handle of the context node.
nodeHandle
,
Object
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.

environment
)

Reset the root node of the DTMIterator, overriding the value specified when it was created.

public void
setShouldCacheNodes(boolean
true if the nodes should be cached.
b
)

If setShouldCacheNodes(true) is called, then nodes will be cached, enabling random access, and giving the ability to do sorts and the like.

Field Detail

FILTER_ACCEPTback to summary
public static final short FILTER_ACCEPT

Accept the node.

FILTER_REJECTback to summary
public static final short FILTER_REJECT

Reject the node. Same behavior as FILTER_SKIP. (In the DOM these differ when applied to a TreeWalker but have the same result when applied to a NodeIterator).

FILTER_SKIPback to summary
public static final short FILTER_SKIP

Skip this single node.

Method Detail

allowDetachToReleaseback to summary
public void allowDetachToRelease(boolean allowRelease)

Specify if it's OK for detach to release the iterator for reuse.

Parameters
allowRelease:boolean

true if it is OK for detach to release this iterator for pooling.

cloneback to summary
public Object clone() throws 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.

Returns:Object

A clone of this object.

cloneWithResetback to summary
public DTMIterator cloneWithReset() throws CloneNotSupportedException

Get a cloned Iterator that is reset to the start of the iteration.

Returns:DTMIterator

A clone of this iteration that has been reset.

detachback to summary
public void detach()

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.

getAxisback to summary
public int getAxis()

Returns the axis being iterated, if it is known.

Returns:int

Axis.CHILD, etc., or -1 if the axis is not known or is of multiple types.

getCurrentNodeback to summary
public int getCurrentNode()

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).

Returns:int

The current node handle, or -1.

getCurrentPosback to summary
public int getCurrentPos()

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.

Returns:int

The position of the iteration.

getDTMback to summary
public DTM getDTM(int nodeHandle)

Get an instance of a DTM that "owns" a node handle. Since a node iterator may be passed without a DTMManager, this allows the caller to easily get the DTM using just the iterator.

Parameters
nodeHandle:int

the nodeHandle.

Returns:DTM

a non-null DTM reference.

getDTMManagerback to summary
public DTMManager getDTMManager()

Get an instance of the DTMManager. Since a node iterator may be passed without a DTMManager, this allows the caller to easily get the DTMManager using just the iterator.

Returns:DTMManager

a non-null DTMManager reference.

getExpandEntityReferencesback to summary
public boolean getExpandEntityReferences()

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.

Returns:boolean

true if entity references will be expanded.

getLengthback to summary
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 requires running the iterator to completion, and presumably filling the cache.

Returns:int

The number of nodes in the list.

getRootback to summary
public int getRoot()

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.

Returns:int

nodeHandle int Handle of the context node.

getWhatToShowback to summary
public int getWhatToShow()

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.

Returns:int

one of the SHOW_XXX constants, or several ORed together.

isDocOrderedback to summary
public boolean isDocOrdered()

Returns true if all the nodes in the iteration well be returned in document order.

Returns:boolean

true if all the nodes in the iteration well be returned in document order.

isFreshback to summary
public boolean isFresh()

Tells if this NodeSetDTM is "fresh", in other words, if the first nextNode() that is called will return the first node in the set.

Returns:boolean

true if the iteration of this list has not yet begun.

isMutableback to summary
public boolean isMutable()

Tells if this iterator can have nodes added to it or set via the setItem(int node, int index) method.

Returns:boolean

True if the nodelist can be mutated.

itemback to summary
public int item(int index)

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.

Parameters
index:int

of the item.

Returns:int

The node handle at the indexth position in the DTMIterator, or -1 if that is not a valid index.

nextNodeback to summary
public int nextNode()

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.

Returns:int

The next node handle in the set being iterated over, or DTM.NULL if there are no more members in that set.

previousNodeback to summary
public int previousNode()

Returns the previous node in the set and moves the position of the DTMIterator backwards in the set.

Returns:int

The previous node handle in the set being iterated over, or DTM.NULL if there are no more members in that set.

resetback to summary
public void reset()

Reset the iterator to the start. After resetting, the next node returned will be the root node -- or, if that's filtered out, the first node within the root's subtree which is _not_ skipped by the filters.

runToback to summary
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 and completely fill the cache.

Parameters
index:int

The index to run to, or -1 if the iterator should be run to the end.

setCurrentPosback to summary
public void setCurrentPos(int i)

Set the current position in the node set.

Parameters
i:int

Must be a valid index.

setItemback to summary
public void setItem(int node, int index)

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.

Parameters
node:int

Node to set

index:int

Index of where to set the node

setRootback to summary
public void setRoot(int nodeHandle, Object environment)

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.

Parameters
nodeHandle:int

int Handle of the context node.

environment:Object

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.

setShouldCacheNodesback to summary
public 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. 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?

Parameters
b:boolean

true if the nodes should be cached.