Package org.apache.xml.dtm.ref

Class DTMAxisIteratorBase

java.lang.Object
org.apache.xml.dtm.ref.DTMAxisIteratorBase
All Implemented Interfaces:
Cloneable, DTMAxisIterator
Direct Known Subclasses:
DTMDefaultBaseIterators.InternalAxisIteratorBase
public abstract class DTMAxisIteratorBase
extends Object
implements DTMAxisIterator
This class serves as a default base for implementations of mutable DTMAxisIterators.

  • Field Details

    • _last

      protected int _last
      The position of the last node within the iteration, as defined by XPath. Note that this is _not_ the node's handle within the DTM. Also, don't confuse it with the current (most recently returned) position.

    • _position

      protected int _position
      The position of the current node within the iteration, as defined by XPath. Note that this is _not_ the node's handle within the DTM!

    • _markedNode

      protected int _markedNode
      The position of the marked node within the iteration; a saved itaration state that we may want to come back to. Note that only one mark is maintained; there is no stack.

    • _startNode

      protected int _startNode
      The handle to the start, or root, of the iteration. Set this to END to construct an empty iterator.

    • _includeSelf

      protected boolean _includeSelf
      True if the start node should be considered part of the iteration. False will cause it to be skipped.

    • _isRestartable

      protected boolean _isRestartable
      True if this iteration can be restarted. False otherwise (eg, if we are iterating over a stream that can not be re-scanned, or if the iterator was produced by cloning another iterator.)

  • Constructor Details

    • DTMAxisIteratorBase

      public DTMAxisIteratorBase()

  • Method Details

    • getStartNode

      public int getStartNode()
      Get start to END should 'close' the iterator, i.e. subsequent call to next() should return END.
      Specified by:
      getStartNode in interface DTMAxisIterator
      Returns:
      The root node of the iteration.

    • reset

      public DTMAxisIterator reset()
      Description copied from interface: DTMAxisIterator
      Resets the iterator to the last start node.
      Specified by:
      reset in interface DTMAxisIterator
      Returns:
      A DTMAxisIterator which has been reset to the start node, which may or may not be the same as this iterator.

    • includeSelf

      public DTMAxisIterator includeSelf()
      Set the flag to include the start node in the iteration.
      Returns:
      This default method returns just returns this DTMAxisIterator, after setting the flag. (Returning "this" permits C++-style chaining of method calls into a single expression.)

    • getLast

      public int getLast()
      Returns the position of the last node within the iteration, as defined by XPath. In a forward iterator, I believe this equals the number of nodes which this iterator will yield. In a reverse iterator, I believe it should return 1 (since the "last" is the first produced.) This may be an expensive operation when called the first time, since it may have to iterate through a large part of the document to produce its answer.
      Specified by:
      getLast in interface DTMAxisIterator
      Returns:
      The number of nodes in this iterator (forward) or 1 (reverse).

    • getPosition

      public int getPosition()
      Specified by:
      getPosition in interface DTMAxisIterator
      Returns:
      The position of the current node within the set, as defined by XPath. Note that this is one-based, not zero-based.

    • isReverse

      public boolean isReverse()
      Specified by:
      isReverse in interface DTMAxisIterator
      Returns:
      true if this iterator has a reversed axis, else false

    • cloneIterator

      public DTMAxisIterator cloneIterator()
      Returns a deep copy of this iterator. Cloned iterators may not be restartable. The iterator being cloned may or may not become non-restartable as a side effect of this operation.
      Specified by:
      cloneIterator in interface DTMAxisIterator
      Returns:
      a deep copy of this iterator.

    • returnNode

      protected final int returnNode​(int node)
      Do any final cleanup that is required before returning the node that was passed in, and then return it. The intended use is
      return returnNode(node); %REVIEW% If we're calling it purely for side effects, should we really be bothering with a return value? Something like
      accept(node); return node;
      would probably optimize just about as well and avoid questions about whether what's returned could ever be different from what's passed in.
      Parameters:
      node - Node handle which iteration is about to yield.
      Returns:
      The node handle passed in.

    • resetPosition

      protected final DTMAxisIterator resetPosition()
      Reset the position to zero. NOTE that this does not change the iteration state, only the position number associated with that state. %REVIEW% Document when this would be used?
      Returns:
      This instance.

    • isDocOrdered

      public boolean isDocOrdered()
      Returns true if all the nodes in the iteration well be returned in document order.
      Returns:
      true as a default.

    • getAxis

      public 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.

    • setRestartable

      public void setRestartable​(boolean isRestartable)
      Description copied from interface: DTMAxisIterator
      Set if restartable.
      Specified by:
      setRestartable in interface DTMAxisIterator

    • getNodeByPosition

      public int getNodeByPosition​(int position)
      Return the node at the given position.
      Specified by:
      getNodeByPosition in interface DTMAxisIterator
      Parameters:
      position - The position
      Returns:
      The node at the given position.