Package org.apache.xpath.axes

Class UnionPathIterator

java.lang.Object
org.apache.xpath.Expression
org.apache.xpath.patterns.NodeTest
org.apache.xpath.axes.PredicatedNodeTest
org.apache.xpath.axes.LocPathIterator
org.apache.xpath.axes.UnionPathIterator
All Implemented Interfaces:
Serializable, Cloneable, SourceLocator, DTMIterator, PathComponent, SubContextList, ExpressionNode, XPathVisitable
public class UnionPathIterator
extends LocPathIterator
implements Cloneable, DTMIterator, Serializable, PathComponent
This class extends NodeSetDTM, which implements DTMIterator, and fetches nodes one at a time in document order based on a XPath UnionExpr. As each node is iterated via nextNode(), the node is also stored in the NodeVector, so that previousNode() can easily be done.
See Also:
Serialized Form

  • Field Details

    • m_exprs

      protected LocPathIterator[] m_exprs
      The location path iterators, one for each location path contained in the union expression.

    • m_iterators

      protected DTMIterator[] m_iterators
      The location path iterators, one for each location path contained in the union expression.

  • Constructor Details

    • UnionPathIterator

      public UnionPathIterator()
      Constructor to create an instance which you can add location paths to.

    • UnionPathIterator

      public UnionPathIterator​(Compiler compiler, int opPos) throws TransformerException
      Create a UnionPathIterator object, including creation of location path iterators from the opcode list, and call back into the Compiler to create predicate expressions.
      Parameters:
      compiler - The Compiler which is creating this expression.
      opPos - The position of this iterator in the opcode list from the compiler.
      Throws:
      TransformerException

  • Method Details

    • setRoot

      public void setRoot​(int context, Object environment)
      Initialize the context values for this expression after it is cloned.
      Specified by:
      setRoot in interface DTMIterator
      Overrides:
      setRoot in class LocPathIterator
      Parameters:
      context - The XPath runtime context for this transformation.
      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.

    • addIterator

      public void addIterator​(DTMIterator expr)
      Add an iterator to the union list.
      Parameters:
      expr - non-null reference to a location path iterator.

    • detach

      public void detach()
      Detaches the iterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state. Afterdetach has been invoked, calls to nextNode orpreviousNode will raise the exception INVALID_STATE_ERR.
      Specified by:
      detach in interface DTMIterator
      Overrides:
      detach in class LocPathIterator

    • createUnionIterator

      public static LocPathIterator createUnionIterator​(Compiler compiler, int opPos) throws TransformerException
      This will return an iterator capable of handling the union of paths given.
      Parameters:
      compiler - The Compiler which is creating this expression.
      opPos - The position of this iterator in the opcode list from the compiler.
      Returns:
      Object that is derived from LocPathIterator.
      Throws:
      TransformerException

    • getAnalysisBits

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

    • clone

      public Object clone() throws CloneNotSupportedException
      Get a cloned LocPathIterator that holds the same position as this iterator.
      Specified by:
      clone in interface DTMIterator
      Overrides:
      clone in class PredicatedNodeTest
      Returns:
      A clone of this iterator that holds the same node position.
      Throws:
      CloneNotSupportedException

    • createDTMIterator

      protected LocPathIterator createDTMIterator​(Compiler compiler, int opPos) throws TransformerException
      Create a new location path iterator.
      Parameters:
      compiler - The Compiler which is creating this expression.
      opPos - The position of this iterator in the
      Returns:
      New location path iterator.
      Throws:
      TransformerException

    • loadLocationPaths

      protected void loadLocationPaths​(Compiler compiler, int opPos, int count) throws TransformerException
      Initialize the location path iterators. Recursive.
      Parameters:
      compiler - The Compiler which is creating this expression.
      opPos - The position of this iterator in the opcode list from the compiler.
      count - The insert position of the iterator.
      Throws:
      TransformerException

    • nextNode

      public int nextNode()
      Returns the next node in the set and advances the position of the iterator in the set. After a DTMIterator is created, the first call to nextNode() returns the first node in the set.
      Specified by:
      nextNode in interface DTMIterator
      Specified by:
      nextNode in class LocPathIterator
      Returns:
      The next Node in the set being iterated over, or null if there are no more members in that set.

    • fixupVariables

      public void fixupVariables​(Vector vars, int globalsSize)
      This function is used to fixup variables from QNames to stack frame indexes at stylesheet build time.
      Overrides:
      fixupVariables in class PredicatedNodeTest
      Parameters:
      vars - List of QNames that correspond to variables. This list should be searched backwards for the first qualified name that corresponds to the variable reference qname. The position of the QName in the vector from the start of the vector will be its position in the stack frame (but variables above the globalsTop value will need to be offset to the current stack frame).

    • getAxis

      public int getAxis()
      Returns the axis being iterated, if it is known.
      Specified by:
      getAxis in interface DTMIterator
      Overrides:
      getAxis in class LocPathIterator
      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)
      Description copied from interface: XPathVisitable
      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 LocPathIterator
      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)

    • 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)