DTMIterator (HtmlUnit-XPath 4.9.0 API)

All Known Implementing Classes:

AttributeIterator, BasicTestIterator, ChildIterator, ChildTestIterator, DescendantIterator, LocPathIterator, NodeSequence, NodeSetDTM, OneStepIterator, OneStepIteratorForward, SelfIteratorNoPredicate, UnionChildIterator, UnionPathIterator, WalkingIterator, WalkingIteratorSorted, XNodeSet
```
public interface DTMIterator
```
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

Fields
Modifier and Type Field and Description

static short FILTER_ACCEPT
Accept the node.

static short FILTER_SKIP
Skip this single node.

Fields
Modifier and Type	Field and Description
`static short`	`FILTER_ACCEPT` Accept the node.
`static short`	`FILTER_SKIP` Skip this single node.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`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()` Get a cloned Iterator that is reset to the start of the iteration.
`void`	`detach()` Detaches the `DTMIterator` from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state.
`int`	`getAxis()` Returns the axis being iterated, if it is known.
`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. i.e. if you call getCurrentPos() and the return is 0, the next fetch will take place at index 1.
`DTM`	`getDTM(int nodeHandle)` Get an instance of a DTM that "owns" a node handle.
`DTMManager`	`getDTMManager()` Get an instance of the DTMManager.
`boolean`	`getExpandEntityReferences()` The value of this flag determines whether the children of entity reference nodes are visible to the iterator.
`int`	`getLength()` The number of nodes in the list.
`int`	`getRoot()` The root node of the `DTMIterator`, as specified when it was created.
`int`	`getWhatToShow()` This attribute determines which node types are presented via the iterator.
`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.
`int`	`item(int index)` Returns the `node handle` of an 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 `DTMIterator` backwards in the set.
`void`	`reset()` Reset the iterator to the start.
`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`	`setRoot(int nodeHandle, 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.

- Field Detail
  - FILTER_ACCEPT
```
static final short FILTER_ACCEPT
```
    Accept the node.
    
    See Also:
    
    Constant Field Values
  - FILTER_SKIP
```
static final short FILTER_SKIP
```
    Skip this single node.
    
    See Also:
    
    Constant Field Values
- Method Detail
  - getDTM
```
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 - the nodeHandle.
    
    Returns:
    
    a non-null DTM reference.
  - getDTMManager
```
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:
    
    a non-null DTMManager reference.
  - getRoot
```
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:
    
    nodeHandle int Handle of the context node.
  - setRoot
```
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 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.
  - reset
```
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.
  - getWhatToShow
```
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:
    
    one of the SHOW_XXX constants, or several ORed together.
  - getExpandEntityReferences
```
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:
    
    true if entity references will be expanded.
  - nextNode
```
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:
    
    The next node handle in the set being iterated over, or DTM.NULL if there are no more members in that set.
  - previousNode
```
int previousNode()
```
    Returns the previous node in the set and moves the position of the DTMIterator backwards in the set.
    
    Returns:
    
    The previous node handle in the set being iterated over, or DTM.NULL if there are no more members in that set.
  - detach
```
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.
  - getCurrentNode
```
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:
    
    The current node handle, or -1.
  - isFresh
```
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:
    
    true if the iteration of this list has not yet begun.
  - setShouldCacheNodes
```
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 - true if the nodes should be cached.
  - getCurrentPos
```
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:
    
    The position of the iteration.
  - runTo
```
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 - The index to run to, or -1 if the iterator should be run to the end.
  - setCurrentPos
```
void setCurrentPos(int i)
```
    Set the current position in the node set.
    
    Parameters:
    
    i - Must be a valid index.
  - item
```
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 - of the item.
    
    Returns:
    
    The node handle at the indexth position in the DTMIterator, or -1 if that is not a valid index.
  - getLength
```
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:
    
    The number of nodes in the list.
  - cloneWithReset
```
DTMIterator cloneWithReset()
                    throws CloneNotSupportedException
```
    Get a cloned Iterator that is reset to the start of the iteration.
    
    Returns:
    
    A clone of this iteration that has been reset.
    
    Throws:
    
    CloneNotSupportedException - if any
  - clone
```
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:
    
    A clone of this object.
    
    Throws:
    
    CloneNotSupportedException - if any
  - isDocOrdered
```
boolean isDocOrdered()
```
    Returns true if all the nodes in the iteration well be returned in document order.
    
    Returns:
    
    true if all the nodes in the iteration well be returned in document order.
  - getAxis
```
int getAxis()
```
    Returns the axis being iterated, if it is known.
    
    Returns:
    
    Axis.CHILD, etc., or -1 if the axis is not known or is of multiple types.

Interface DTMIterator

Field Summary

Method Summary

Field Detail

FILTER_ACCEPT

FILTER_SKIP

Method Detail

getDTM

getDTMManager

getRoot

setRoot

reset

getWhatToShow

getExpandEntityReferences

nextNode

previousNode

detach

getCurrentNode

isFresh

setShouldCacheNodes

getCurrentPos

runTo

setCurrentPos

item

getLength

cloneWithReset

clone

isDocOrdered

getAxis