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## 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

public class UnionPathIterator
extends LocPathIterator
implements java.lang.Cloneable, DTMIterator, java.io.Serializable, PathComponent

**For advanced use only** 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

Fields inherited from class org.apache.xpath.axes.LocPathIterator
`m_lastFetched`

Fields inherited from class org.apache.xpath.patterns.NodeTest
`SCORE_NODETEST, SCORE_NONE, SCORE_NSWILD, SCORE_OTHER, SCORE_QNAME, SHOW_BYFUNCTION, SUPPORTS_PRE_STRIPPING, WILD`

Constructor Summary
`UnionPathIterator()` Constructor to create an instance which you can add location paths to.
`UnionPathIterator(Compiler compiler, int opPos)` Create a UnionPathIterator object, including creation of location path iterators from the opcode list, and call back into the Compiler to create predicate expressions.

Method Summary
`void` | `addIterator(DTMIterator expr)` Add an iterator to the union list.
`void` | `callVisitors(ExpressionOwner owner, XPathVisitor visitor)`
`java.lang.Object` | `clone()` Get a cloned LocPathIterator that holds the same position as this iterator.
`static LocPathIterator` | `createUnionIterator(Compiler compiler, int opPos)` This will return an iterator capable of handling the union of paths given.
`boolean` | `deepEquals(Expression expr)`
`void` | `detach()` Detaches the iterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state.
`void` | `fixupVariables(java.util.Vector vars, int globalsSize)` This function is used to fixup variables from QNames to stack frame indexes at stylesheet build time.
`int` | `getAnalysisBits()` Get the analysis bits for this walker, as defined in the WalkerFactory.
`int` | `getAxis()` Returns the axis being iterated, if it is known.
`int` | `nextNode()` Returns the next node in the set and advances the position of the iterator in the set.
`void` | `setRoot(int context, java.lang.Object environment)` Initialize the context values for this expression after it is cloned.

Methods inherited from class org.apache.xpath.axes.LocPathIterator
`allowDetachToRelease, asIterator, asNode, bool, cloneWithReset, execute, executeCharsToContentHandler, getContext, getCurrentContextNode, getCurrentNode, getCurrentPos, getDTM, getDTMManager, getExpandEntityReferences, getFilter, getFoundLast, getIsTopLevel, getLastPos, getLength, getPrefixResolver, getRoot, getWhatToShow, getXPathContext, incrementCurrentPos, isDocOrdered, isFresh, isMutable, isNodesetExpr, item, previousNode, reset, runTo, setCurrentContextNode, setCurrentPos, setEnvironment, setIsTopLevel, setItem, setShouldCacheNodes, size`

Methods inherited from class org.apache.xpath.axes.PredicatedNodeTest
`acceptNode, callPredicateVisitors, canTraverseOutsideSubtree, getLocPathIterator, getPredicate, getPredicateCount, getPredicateIndex, getProximityPosition, getProximityPosition, initProximityPosition, isReverseAxes, resetProximityPositions, setLocPathIterator, setPredicateCount`

Methods inherited from class org.apache.xpath.patterns.NodeTest
`debugWhatToShow, execute, execute, getDefaultScore, getLocalName, getNamespace, getNodeTypeTest, getStaticScore, initNodeTest, initNodeTest, setLocalName, setNamespace, setStaticScore, setWhatToShow`

Methods inherited from class org.apache.xpath.Expression
`asIteratorRaw, assertion, error, execute, exprAddChild, exprGetChild, exprGetNumChildren, exprGetParent, exprSetParent, getColumnNumber, getExpressionOwner, getLineNumber, getPublicId, getSystemId, isStableNumber, num, warn, xstr`

Methods inherited from class java.lang.Object
`equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### 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 Detail

### setRoot

    public void setRoot(int context,
                        java.lang.Object environment)

  Initialize the context values for this expression after it is cloned.
  Specified by:
    setRoot in interface DTMIterator
  Parameters:
    `execContext` - The XPath runtime context for this transformation.
  Overrides:
    setRoot in class LocPathIterator

### addIterator

    public void addIterator(DTMIterator expr)

  Add an iterator to the union list.
  Parameters:
    `iter` - 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. After`detach` has been invoked, calls to `nextNode` or`previousNode` 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
  Returns:
    One of WalkerFactory#BIT_DESCENDANT, etc.
  Overrides:
    getAnalysisBits in class LocPathIterator

### clone

    public java.lang.Object clone()
                           throws java.lang.CloneNotSupportedException

  Get a cloned LocPathIterator that holds the same position as this iterator.
  Specified by:
    clone in interface DTMIterator
  Returns:
    A clone of this iterator that holds the same node position.
  Throws:
    java.lang.CloneNotSupportedException -
  Overrides:
    clone in class PredicatedNodeTest

### 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
  Returns:
    The next `Node` in the set being iterated over, or `null` if there are no more members in that set.
  Overrides:
    nextNode in class LocPathIterator

### fixupVariables

    public void fixupVariables(java.util.Vector vars,
                               int globalsSize)

  This function is used to fixup variables from QNames to stack frame indexes at stylesheet build time.
  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).
  Overrides:
    fixupVariables in class PredicatedNodeTest

### 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.
  Overrides:
    getAxis in class LocPathIterator

### callVisitors

    public void callVisitors(ExpressionOwner owner,
                             XPathVisitor visitor)

  Overrides:
    callVisitors in class LocPathIterator
  See Also:
    `XPathVisitable#callVisitors(ExpressionOwner, XPathVisitor)`

### deepEquals

    public boolean deepEquals(Expression expr)

  Overrides:
    deepEquals in class PredicatedNodeTest
  See Also:
    `Expression.deepEquals(Expression)`

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