Package com.saxonica.ee.stream.feed

Class AbsorptionFeed

java.lang.Object
net.sf.saxon.event.Outputter
net.sf.saxon.event.ProxyOutputter
com.saxonica.ee.stream.feed.ItemFeed
com.saxonica.ee.stream.feed.GroundedItemFeed
com.saxonica.ee.stream.feed.AbsorptionFeed
All Implemented Interfaces:
Result, Receiver
Direct Known Subclasses:
CopyOfFeed, SimpleContentFeed, SnapshotFeed, StringValueFeed, TypedValueFeed
public abstract class AbsorptionFeed extends GroundedItemFeed
This class is used as an abstract superclass for expressions where the consuming operand is absorbed by the expression: for example, data(), string(), or copy-of(). It handles the fact that the input can be crawling, which means that selected nodes can be nested. We therefore need to be collecting the result values of multiple nodes during the same pass of the input. Hence we maintain a stack of values-under-construction. Moreover, an inner value will be available before the outer value, but it follows the outer value in document order, so it needs to be held pending until the outer value is available. Hence we maintain a list of values that are ready to be output.

  • Constructor Details

  • Method Details

    • startSelectedParentNode

      public final Receiver startSelectedParentNode(FleetingParentNode node, Location locationId) throws XPathException
      Signal that an element has been found that matches the selection that this Watch is looking for.
      Overrides:
      startSelectedParentNode in class ItemFeed
      Parameters:
      node - the node that matches the selection
      locationId - the location of the instruction
      Returns:
      a receiver that collects the contents of the selected node
      Throws:
      XPathException - if a dynamic error occurs

    • makePendingItem

      protected abstract AbsorptionFeed.PendingItem makePendingItem(int sequenceNr, FleetingParentNode node) throws XPathException
      Create a pending item (appropriate to the subclass) containing the data needed to compute the result value for one node in the streamed input sequence
      Parameters:
      sequenceNr - the sequence number of this node within a set of nested nodes
      node - the streamed input node
      Returns:
      the data needed to process this node
      Throws:
      XPathException - if a dynamic error is detected at this stage

    • endSelectedParentNode

      public final void endSelectedParentNode(Location locationId) throws XPathException
      Signal that the endElement event has occurred for the element whose startElement event caused the Watch to be activated.
      Overrides:
      endSelectedParentNode in class ItemFeed
      Parameters:
      locationId - the location of the node in the source, or of the instruction that created it
      Throws:
      XPathException - if a dynamic error occurs

    • append

      public void append(Item item) throws XPathException
      Signal that a node (other than an element) that matches the selection has been found. This may be a leaf node in the streamed input, or it may be a grounded node or atomic value (of any kind) that has been mixed into the input sequence for example using a comma operator.
      Specified by:
      append in interface Receiver
      Specified by:
      append in class ItemFeed
      Parameters:
      item - the node or other item that was matched.
      Throws:
      XPathException - if the operation fails

    • processGroundedItem

      protected abstract Sequence processGroundedItem(Item item) throws XPathException
      Process a grounded item in the input sequence: either a streamed leaf node such as an attribute or text node, or an atomic value, or a non-streamed element or document node injected into the sequence for example by use of the comma operator.
      Parameters:
      item - the grounded item
      Returns:
      the result of processing the grounded item
      Throws:
      XPathException - if a dynamic error occurs

    • setHasFailed

      public void setHasFailed()
      Description copied from class: ItemFeed
      Mark this feed as having failed (that is, as having detected and reported a dynamic error). Once the feed is marked as having failed, it should not attempt to process any further input.
      Overrides:
      setHasFailed in class ItemFeed