Package org.loboevolution.apache.xpath.axes

Class NodeSequence

java.lang.Object
org.loboevolution.apache.xpath.Expression
org.loboevolution.apache.xpath.objects.XObject
org.loboevolution.apache.xpath.axes.NodeSequence
All Implemented Interfaces:
Cloneable, SourceLocator, DTMIterator, PathComponent, ExpressionNode, XPathVisitable
Direct Known Subclasses:
XNodeSet
public class NodeSequence extends XObject implements DTMIterator, Cloneable, PathComponent
This class is the dynamic wrapper for a Xalan DTMIterator instance, and provides random access capabilities.

  • Field Details

    • 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_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 Details

    • NodeSequence

      public NodeSequence(Object nodeVector)
      Create a new NodeSequence from a (already cloned) iterator.
      Parameters:
      nodeVector - a Object object.

    • NodeSequence

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

  • Method Details

    • getVector

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

    • 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.

    • setIter

      public final void setIter(DTMIterator iter)
      Set the functional iterator that fetches nodes.
      Parameters:
      iter - The iterator that is to be contained.

    • getDTM

      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.
      Specified by:
      getDTM in interface DTMIterator
      Parameters:
      nodeHandle - the nodeHandle.
      Returns:
      a non-null DTM reference.

    • getDTMManager

      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.
      Specified by:
      getDTMManager in interface DTMIterator
      Returns:
      a non-null DTMManager reference.

    • getRoot

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

    • setRoot

      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.
      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.

    • reset

      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.
      Specified by:
      reset in interface DTMIterator

    • getWhatToShow

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

    • 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 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.

    • nextNode

      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.
      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.

    • previousNode

      public int previousNode()
      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.

    • detach

      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.
      Specified by:
      detach in interface DTMIterator
      Overrides:
      detach in class XObject

    • allowDetachToRelease

      public void allowDetachToRelease(boolean allowRelease)
      Specify if it's OK for detach to release the iterator for reuse. This function should be called with a value of false for objects that are stored in variables. Calling this with a value of false on a XNodeSet 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.

    • getCurrentNode

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

    • isFresh

      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.
      Specified by:
      isFresh in interface DTMIterator
      Returns:
      true if the iteration of this list has not yet begun.

    • setShouldCacheNodes

      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?

      Specified by:
      setShouldCacheNodes in interface DTMIterator
      Parameters:
      b - true if the nodes should be cached.

    • getCurrentPos

      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.
      Specified by:
      getCurrentPos in interface DTMIterator
      Returns:
      The position of the iteration.

    • runTo

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

    • setCurrentPos

      public void setCurrentPos(int i)
      Set the current position in the node set.
      Specified by:
      setCurrentPos in interface DTMIterator
      Parameters:
      i - Must be a valid index.

    • item

      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.
      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.

    • 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 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.

    • cloneWithReset

      public DTMIterator cloneWithReset() throws CloneNotSupportedException
      Get a cloned Iterator that is reset to the start of the iteration.
      Specified by:
      cloneWithReset in interface DTMIterator
      Returns:
      A clone of this iteration that has been reset.
      Throws:
      CloneNotSupportedException - if any

    • clone

      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.
      Specified by:
      clone in interface DTMIterator
      Overrides:
      clone in class Object
      Returns:
      A clone of this object.
      Throws:
      CloneNotSupportedException - if any

    • isDocOrdered

      public boolean isDocOrdered()
      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.

    • getAxis

      public int getAxis()
      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.

    • getAnalysisBits

      public int getAnalysisBits()
      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.

    • 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:
      RuntimeException - thrown if this NodeSetDTM is not of a mutable type.

    • setObject

      protected void setObject(Object obj)
      Overrides:
      setObject in class XObject

    • getIteratorCache

      protected org.loboevolution.apache.xpath.axes.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.