Package org.apache.xpath.axes

Class AxesWalker

java.lang.Object
org.apache.xpath.Expression
org.apache.xpath.patterns.NodeTest
org.apache.xpath.axes.PredicatedNodeTest
org.apache.xpath.axes.AxesWalker
All Implemented Interfaces:
Serializable, Cloneable, SourceLocator, PathComponent, SubContextList, ExpressionNode, ExpressionOwner, XPathVisitable
Direct Known Subclasses:
FilterExprWalker, ReverseAxesWalker
public class AxesWalker
extends PredicatedNodeTest
implements Cloneable, PathComponent, ExpressionOwner
Serves as common interface for axes Walkers, and stores common state variables.
See Also:
Serialized Form

  • Field Details

    • m_nextWalker

      protected AxesWalker m_nextWalker
      The next walker in the location step chain.

    • m_axis

      protected int m_axis
      The traversal axis from where the nodes will be filtered.

    • m_traverser

      protected DTMAxisTraverser m_traverser
      The DTM inner traversal class, that corresponds to the super axis.

  • Constructor Details

    • AxesWalker

      public AxesWalker​(LocPathIterator locPathIterator, int axis)
      Construct an AxesWalker using a LocPathIterator.
      Parameters:
      locPathIterator - non-null reference to the parent iterator.

  • Method Details

    • wi

      public final WalkingIterator wi()

    • init

      public void init​(Compiler compiler, int opPos, int stepType) throws TransformerException
      Initialize an AxesWalker during the parse of the XPath expression.
      Parameters:
      compiler - The Compiler object that has information about this walker in the op map.
      opPos - The op code position of this location step.
      stepType - The type of location step.
      Throws:
      TransformerException

    • clone

      public Object clone() throws CloneNotSupportedException
      Get a cloned AxesWalker.
      Overrides:
      clone in class PredicatedNodeTest
      Returns:
      A new AxesWalker that can be used without mutating this one.
      Throws:
      CloneNotSupportedException

    • detach

      public void detach()
      Detaches the walker from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state.

    • getRoot

      public int getRoot()
      The root node of the TreeWalker, as specified in setRoot(int root). Note that this may actually be below the current node.
      Returns:
      The context node of the step.

    • getAnalysisBits

      public int getAnalysisBits()
      Get the analysis bits for this walker, as defined in the WalkerFactory.
      Specified by:
      getAnalysisBits in interface PathComponent
      Returns:
      One of WalkerFactory#BIT_DESCENDANT, etc.

    • setRoot

      public void setRoot​(int root)
      Set the root node of the TreeWalker. (Not part of the DOM2 TreeWalker interface).
      Parameters:
      root - The context node of this step.

    • getCurrentNode

      public final int getCurrentNode()
      The node at which the TreeWalker is currently positioned.
      The value must not be null. Alterations to the DOM tree may cause the current node to no longer be accepted by the TreeWalker's associated filter. currentNode may also be explicitly set to any node, whether or not it is within the subtree specified by the root node or would be accepted by the filter and whatToShow flags. Further traversal occurs relative to currentNode even if it is not part of the current view by applying the filters in the requested direction (not changing currentNode where no traversal is possible).
      Returns:
      The node at which the TreeWalker is currently positioned, only null if setRoot has not yet been called.

    • setNextWalker

      public void setNextWalker​(AxesWalker walker)
      Set the next walker in the location step chain.
      Parameters:
      walker - Reference to AxesWalker derivative, or may be null.

    • getNextWalker

      public AxesWalker getNextWalker()
      Get the next walker in the location step chain.
      Returns:
      Reference to AxesWalker derivative, or null.

    • setPrevWalker

      public void setPrevWalker​(AxesWalker walker)
      Set or clear the previous walker reference in the location step chain.
      Parameters:
      walker - Reference to previous walker reference in the location step chain, or null.

    • getPrevWalker

      public AxesWalker getPrevWalker()
      Get the previous walker reference in the location step chain.
      Returns:
      Reference to previous walker reference in the location step chain, or null.

    • getNextNode

      protected int getNextNode()
      Get the next node in document order on the axes.
      Returns:
      the next node in document order on the axes, or null.

    • nextNode

      public int nextNode()
      Moves the TreeWalker to the next visible node in document order relative to the current node, and returns the new node. If the current node has no next node, or if the search for nextNode attempts to step upward from the TreeWalker's root node, returns null , and retains the current node.
      Returns:
      The new node, or null if the current node has no next node in the TreeWalker's logical view.

    • getLastPos

      public int getLastPos​(XPathContext xctxt)
      Get the index of the last node that can be itterated to.
      Specified by:
      getLastPos in interface SubContextList
      Specified by:
      getLastPos in class PredicatedNodeTest
      Parameters:
      xctxt - XPath runtime context.
      Returns:
      the index of the last node that can be itterated to.

    • setDefaultDTM

      public void setDefaultDTM​(DTM dtm)
      Set the DTM for this walker.
      Parameters:
      dtm - Non-null reference to a DTM.

    • getDTM

      public DTM getDTM​(int node)
      Get the DTM for this walker.
      Returns:
      Non-null reference to a DTM.

    • isDocOrdered

      public boolean isDocOrdered()
      Returns true if all the nodes in the iteration well be returned in document order. Warning: This can only be called after setRoot has been called!
      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.

    • callVisitors

      public void callVisitors​(ExpressionOwner owner, XPathVisitor visitor)
      This will traverse the heararchy, calling the visitor for each member. If the called visitor method returns false, the subtree should not be called.
      Specified by:
      callVisitors in interface XPathVisitable
      Overrides:
      callVisitors in class NodeTest
      Parameters:
      owner - The owner of the visitor, where that path may be rewritten if needed.
      visitor - The visitor whose appropriate method will be called.
      See Also:
      XPathVisitable.callVisitors(ExpressionOwner, XPathVisitor)

    • getExpression

      public Expression getExpression()
      Description copied from interface: ExpressionOwner
      Get the raw Expression object that this class wraps.
      Specified by:
      getExpression in interface ExpressionOwner
      Returns:
      the raw Expression object, which should not normally be null.
      See Also:
      ExpressionOwner.getExpression()

    • setExpression

      public void setExpression​(Expression exp)
      Description copied from interface: ExpressionOwner
      Set the raw expression object for this object.
      Specified by:
      setExpression in interface ExpressionOwner
      Parameters:
      exp - the raw Expression object, which should not normally be null.
      See Also:
      ExpressionOwner.setExpression(Expression)

    • deepEquals

      public boolean deepEquals​(Expression expr)
      Description copied from class: Expression
      Compare this object with another object and see if they are equal, include the sub heararchy.
      Overrides:
      deepEquals in class PredicatedNodeTest
      Parameters:
      expr - Another expression object.
      Returns:
      true if this objects class and the expr object's class are the same, and the data contained within both objects are considered equal.
      See Also:
      Expression.deepEquals(Expression)