org.apache.xpath.axes

## Class LocPathIterator

- java.lang.Object
- - org.apache.xpath.Expression
  - - org.apache.xpath.patterns.NodeTest
    - - org.apache.xpath.axes.PredicatedNodeTest
      - - org.apache.xpath.axes.LocPathIterator

- All Implemented Interfaces:
    java.io.Serializable, java.lang.Cloneable, SourceLocator, DTMIterator, PathComponent, SubContextList, ExpressionNode, XPathVisitable
  Direct Known Subclasses:
    BasicTestIterator, ChildIterator, DescendantIterator, FilterExprIteratorSimple, MatchPatternIterator, SelfIteratorNoPredicate, UnionPathIterator, WalkingIterator

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

  This class extends NodeSetDTM, which implements NodeIterator, and fetches nodes one at a time in document order based on a XPath
  See Also:
    Serialized Form
  Usage:
    **For advanced use only**

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `int` | `m_lastFetched` The last node that was fetched, usually by nextNode.

    - ### 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`

    - ### Fields inherited from interface org.apache.xml.dtm.DTMIterator

      `FILTER_ACCEPT, FILTER_REJECT, FILTER_SKIP`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `allowDetachToRelease(boolean allowRelease)` Specify if it's OK for detach to release the iterator for reuse.
    `DTMIterator` | `asIterator(XPathContext xctxt, int contextNode)` Given an select expression and a context, evaluate the XPath and return the resulting iterator.
    `int` | `asNode(XPathContext xctxt)` Return the first node out of the nodeset, if this expression is a nodeset expression.
    `boolean` | `bool(XPathContext xctxt)` Evaluate this operation directly to a boolean.
    `void` | `callVisitors(ExpressionOwner owner, XPathVisitor visitor)` This will traverse the heararchy, calling the visitor for each member.
    `DTMIterator` | `cloneWithReset()` Get a cloned Iterator that is reset to the beginning of the query.
    `void` | `detach()` Detaches the iterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state.
    `XObject` | `execute(XPathContext xctxt)` Execute this iterator, meaning create a clone that can store state, and initialize it for fast execution from the current runtime state.
    `void` | `executeCharsToContentHandler(XPathContext xctxt, ContentHandler handler)` Execute an expression in the XPath runtime context, and return the result of the expression.
    `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` | `getContext()` The node context for the iterator.
    `int` | `getCurrentContextNode()` The node context from where the expression is being executed from (i.e. for current() support).
    `int` | `getCurrentNode()` Return the last fetched node.
    `int` | `getCurrentPos()` Get the current position, which is one less than the next nextNode() call will retrieve.
    `DTM` | `getDTM(int nodeHandle)` Get an instance of a DTM that "owns" a node handle.
    `DTMManager` | `getDTMManager()` Get an instance of the DTMManager.
    `boolean` | `getExpandEntityReferences()` The value of this flag determines whether the children of entity reference nodes are visible to the iterator.
    `DTMFilter` | `getFilter()` The filter used to screen nodes.
    `boolean` | `getFoundLast()` Tells if we've found the last node yet.
    `boolean` | `getIsTopLevel()` Get if this is an iterator at the upper level of the XPath.
    `int` | `getLastPos(XPathContext xctxt)` Get the index of the last node that can be itterated to.
    `int` | `getLength()` The number of nodes in the list.
    `PrefixResolver` | `getPrefixResolver()` Return the saved reference to the prefix resolver that was in effect when this iterator was created.
    `int` | `getRoot()` The root node of the Iterator, as specified when it was created.
    `int` | `getWhatToShow()` This attribute determines which node types are presented via the iterator.
    `XPathContext` | `getXPathContext()` The XPath execution context we are operating on.
    `void` | `incrementCurrentPos()` Increment the current position in the node set.
    `boolean` | `isDocOrdered()` Returns true if all the nodes in the iteration well be returned in document order.
    `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.
    `boolean` | `isMutable()` Tells if this iterator can have nodes added to it or set via the `setItem(int node, int index)` method.
    `boolean` | `isNodesetExpr()` Tell if the expression is a nodeset expression.
    `int` | `item(int index)` Returns the `index` th item in the collection.
    `abstract int` | `nextNode()` Returns the next node in the set and advances the position of the iterator in the set.
    `int` | `previousNode()` Returns the previous node in the set and moves the position of the iterator backwards in the set.
    `void` | `reset()` Reset the iterator.
    `void` | `runTo(int index)` If an index is requested, NodeSetDTM will call this method to run the iterator to the index.
    `void` | `setCurrentContextNode(int n)` Set the current context node for this iterator.
    `void` | `setCurrentPos(int i)` Set the current position in the node set.
    `void` | `setEnvironment(java.lang.Object environment)` Set 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.
    `void` | `setIsTopLevel(boolean b)` Set if this is an iterator at the upper level of the XPath.
    `void` | `setItem(int node, int index)` Sets the node at the specified index of this vector to be the specified node.
    `void` | `setRoot(int context, java.lang.Object environment)` Initialize the context values for this expression after it is cloned.
    `void` | `setShouldCacheNodes(boolean b)` If setShouldCacheNodes(true) is called, then nodes will be cached.
    `int` | `size()` Get the length of the cached nodes.

    - ### Methods inherited from class org.apache.xpath.axes.PredicatedNodeTest

      `acceptNode, callPredicateVisitors, canTraverseOutsideSubtree, clone, deepEquals, fixupVariables, 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`

    - ### Methods inherited from interface org.apache.xml.dtm.DTMIterator

      `clone`

- - ### Field Detail

    - #### m_lastFetched

          public transient int m_lastFetched

      The last node that was fetched, usually by nextNode.

  - ### Method Detail

    - #### 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.

    - #### setEnvironment

          public void setEnvironment(java.lang.Object environment)

      Set 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.

      Parameters:
        `environment` - The environment object.

    - #### 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.

    - #### execute

          public XObject execute(XPathContext xctxt)
                          throws TransformerException

      Execute this iterator, meaning create a clone that can store state, and initialize it for fast execution from the current runtime state. When this is called, no actual query from the current context node is performed.
      Overrides:
        `execute` in class `NodeTest`
      Parameters:
        `xctxt` - The XPath execution context.
      Returns:
        An XNodeSet reference that holds this iterator.
      Throws:
        `TransformerException`

    - #### executeCharsToContentHandler

          public void executeCharsToContentHandler(XPathContext xctxt,
                                          ContentHandler handler)
                                            throws TransformerException,
                                                   SAXException

      Execute an expression in the XPath runtime context, and return the result of the expression.
      Overrides:
        `executeCharsToContentHandler` in class `Expression`
      Parameters:
        `xctxt` - The XPath runtime context.
        `handler` - The target content handler.
      Throws:
        `TransformerException` - if a runtime exception occurs.
        `SAXException`

    - #### asIterator

          public DTMIterator asIterator(XPathContext xctxt,
                               int contextNode)
                                 throws TransformerException

      Given an select expression and a context, evaluate the XPath and return the resulting iterator.
      Overrides:
        `asIterator` in class `Expression`
      Parameters:
        `xctxt` - The execution context.
        `contextNode` - The node that "." expresses.
      Returns:
        A valid DTMIterator.
      Throws:
        `TransformerException` - thrown if the active ProblemListener decides the error condition is severe enough to halt processing.
        `TransformerException`
      Usage:
        **Experimental**

    - #### isNodesetExpr

          public boolean isNodesetExpr()

      Tell if the expression is a nodeset expression.
      Overrides:
        `isNodesetExpr` in class `Expression`
      Returns:
        true if the expression can be represented as a nodeset.

    - #### asNode

          public int asNode(XPathContext xctxt)
                     throws TransformerException

      Return the first node out of the nodeset, if this expression is a nodeset expression. This is the default implementation for nodesets. Derived classes should try and override this and return a value without having to do a clone operation.
      Overrides:
        `asNode` in class `Expression`
      Parameters:
        `xctxt` - The XPath runtime context.
      Returns:
        the first node out of the nodeset, or DTM.NULL.
      Throws:
        `TransformerException`

    - #### bool

          public boolean bool(XPathContext xctxt)
                       throws TransformerException

      Evaluate this operation directly to a boolean.
      Overrides:
        `bool` in class `Expression`
      Parameters:
        `xctxt` - The runtime execution context.
      Returns:
        The result of the operation as a boolean.
      Throws:
        `TransformerException`

    - #### setIsTopLevel

          public void setIsTopLevel(boolean b)

      Set if this is an iterator at the upper level of the XPath.
      Parameters:
        `b` - true if this location path is at the top level of the expression.
      Usage:
        **For advanced use only**

    - #### getIsTopLevel

          public boolean getIsTopLevel()

      Get if this is an iterator at the upper level of the XPath.
      Returns:
        true if this location path is at the top level of the expression.
      Usage:
        **For advanced use only**

    - #### 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:
        `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.

    - #### getCurrentPos

          public final int getCurrentPos()

      Get the current position, 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:
        A value greater than or equal to zero that indicates the next node position to fetch.

    - #### setShouldCacheNodes

          public void setShouldCacheNodes(boolean b)

      If setShouldCacheNodes(true) is called, then nodes will be cached. They are not cached by default.
      Specified by:
        `setShouldCacheNodes` in interface `DTMIterator`
      Parameters:
        `b` - True if this iterator should cache nodes.

    - #### isMutable

          public boolean isMutable()

      Tells if this iterator can have nodes added to it or set via the `setItem(int node, int index)` method.
      Specified by:
        `isMutable` in interface `DTMIterator`
      Returns:
        True if the nodelist can be mutated.

    - #### 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 greater than or equal to zero and less than m_cachedNodes.size().

    - #### incrementCurrentPos

          public void incrementCurrentPos()

      Increment the current position in the node set.

    - #### size

          public int size()

      Get the length of the cached nodes.

      Note: for the moment at least, this only returns the size of the nodes that have been fetched to date, it doesn't attempt to run to the end to make sure we have found everything. This should be reviewed.

      Returns:
        The size of the current cache list.

    - #### item

          public int item(int index)

      Returns the `index` th 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` - Index into the collection.
      Returns:
        The node at the `index` th position in the `NodeList` , or `null` if that is not a valid index.

    - #### setItem

          public void setItem(int node,
                     int index)

      Sets the node at the specified index of this vector to be the specified node. The previous component at that position is discarded.

      The index must be a value greater than or equal to 0 and less than the current size of the vector. The iterator must be in cached mode.

      Meant to be used for sorted iterators.

      Specified by:
        `setItem` in interface `DTMIterator`
      Parameters:
        `node` - Node to set
        `index` - Index of where to set the node

    - #### getLength

          public int getLength()

      The number of nodes in the list. The range of valid child node indices is 0 to `length-1` inclusive.
      Specified by:
        `getLength` in interface `DTMIterator`
      Returns:
        The number of nodes in the list, always greater or equal to zero.

    - #### 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 of nextNode has not been called.

    - #### previousNode

          public int previousNode()

      Returns the previous node in the set and moves the position of the iterator backwards in the set.
      Specified by:
        `previousNode` in interface `DTMIterator`
      Returns:
        The previous `Node` in the set being iterated over, or`null` if there are no more members in that set.

    - #### getWhatToShow

          public int getWhatToShow()

      This attribute determines which node types are presented via the iterator. The available set of constants is defined in the `NodeFilter` interface.

      This is somewhat useless at this time, since it doesn't really return information that tells what this iterator will show. It is here only to fullfill the DOM NodeIterator interface.

      Specified by:
        `getWhatToShow` in interface `DTMIterator`
      Overrides:
        `getWhatToShow` in class `NodeTest`
      Returns:
        For now, always NodeFilter.SHOW_ALL & ~NodeFilter.SHOW_ENTITY_REFERENCE.
      See Also:
        `NodeIterator`

    - #### getFilter

          public DTMFilter getFilter()

      The filter used to screen nodes. Not used at this time, this is here only to fullfill the DOM NodeIterator interface.
      Returns:
        Always null.
      See Also:
        `NodeIterator`

    - #### getRoot

          public int getRoot()

      The root node of the Iterator, as specified when it was created.
      Specified by:
        `getRoot` in interface `DTMIterator`
      Returns:
        The "root" of this iterator, which, in XPath terms, is the node context for this iterator.

    - #### 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 will be skipped over.
      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.
      Specified by:
        `getExpandEntityReferences` in interface `DTMIterator`
      Returns:
        Always true, since entity reference nodes are not visible in the XPath model.

    - #### allowDetachToRelease

          public void allowDetachToRelease(boolean allowRelease)

      Specify if it's OK for detach to release the iterator for reuse.
      Specified by:
        `allowDetachToRelease` in interface `DTMIterator`
      Parameters:
        `allowRelease` - true if it is OK for detach to release this iterator for pooling.

    - #### 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`

    - #### reset

          public void reset()

      Reset the iterator.
      Specified by:
        `reset` in interface `DTMIterator`

    - #### cloneWithReset

          public DTMIterator cloneWithReset()
                                     throws java.lang.CloneNotSupportedException

      Get a cloned Iterator that is reset to the beginning of the query.
      Specified by:
        `cloneWithReset` in interface `DTMIterator`
      Returns:
        A cloned NodeIterator set of the start of the query.
      Throws:
        `java.lang.CloneNotSupportedException`

    - #### nextNode

          public abstract int nextNode()

      Returns the next node in the set and advances the position of the iterator in the set. After a NodeIterator 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.

    - #### getCurrentNode

          public int getCurrentNode()

      Return the last fetched node. Needed to support the UnionPathIterator.
      Specified by:
        `getCurrentNode` in interface `DTMIterator`
      Returns:
        The last fetched node, or null if the last fetch was null.

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

    - #### getFoundLast

          public final boolean getFoundLast()

      Tells if we've found the last node yet.
      Returns:
        true if the last nextNode returned null.

    - #### getXPathContext

          public final XPathContext getXPathContext()

      The XPath execution context we are operating on.
      Returns:
        XPath execution context this iterator is operating on, or null if setRoot has not been called.

    - #### getContext

          public final int getContext()

      The node context for the iterator.
      Returns:
        The node context, same as getRoot().

    - #### getCurrentContextNode

          public final int getCurrentContextNode()

      The node context from where the expression is being executed from (i.e. for current() support).
      Returns:
        The top-level node context of the entire expression.

    - #### setCurrentContextNode

          public final void setCurrentContextNode(int n)

      Set the current context node for this iterator.
      Parameters:
        `n` - Must be a non-null reference to the node context.

    - #### getPrefixResolver

          public final PrefixResolver getPrefixResolver()

      Return the saved reference to the prefix resolver that was in effect when this iterator was created.
      Returns:
        The prefix resolver or this iterator, which may be null.

    - #### 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 `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)`

    - #### 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 as a default.

    - #### 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.

    - #### getLastPos

          public int getLastPos(XPathContext xctxt)

      Description copied from class: `PredicatedNodeTest`
      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.
      See Also:
        `PredicatedNodeTest.getLastPos(XPathContext)`

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