## com.saxonica.validate
Class FieldWatch

    java.lang.Object
      com.saxonica.validate.AbstractWatch
          com.saxonica.validate.FieldWatch

All Implemented Interfaces:
  Watch

    public class FieldWatch

extends AbstractWatch
implements Watch

A FieldWatch is a class that is looking for nodes that match a field selector within a uniqueness or key constraint.

Constructor Summary
`FieldWatch(SelectorWatch parentWatch, Pattern selection, Value[] currentRow, int column)` Create a new FieldWatch

Method Summary
`void` `endSelectedParentNode(int locationId)` Signal that the endElement event has occurred for the element whose startElement event caused the Watch to be activated.
`void` `notifySelectedLeafNode(FleetingNode node, int locationId)` Signal that a node (other than an element) that matches the selection has been found.
`Receiver` `startSelectedParentNode(FleetingNode node, int locationId)` Signal that an element has been found that matches the selection that this Watch is looking for.

Methods inherited from class com.saxonica.validate.AbstractWatch
`close, getAnchorNode, getNamespaceResolver, getPipelineConfiguration, getSelection, open, setAnchorNode, setNamespaceResolver, setPipelineConfiguration, setSelection`

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

Methods inherited from interface com.saxonica.stream.watch.Watch
`close, getAnchorNode, getNamespaceResolver, getPipelineConfiguration, getSelection, open, setAnchorNode, setNamespaceResolver, setPipelineConfiguration, setSelection`

Constructor Detail

### FieldWatch

    public FieldWatch(SelectorWatch parentWatch,
                      Pattern selection,
                      Value[] currentRow,
                      int column)

  Create a new FieldWatch

  Parameters:
    `parentWatch` - The SelectorWatch to which field values should be notified
    `selection` - The selection (that is, the restricted XPath expression) used in this field of the constraint
    `currentRow` - represents the selected node whose fields are being evaluated
    `column` - sequence number for this field within the constraint being evaluated

Method Detail

### startSelectedParentNode

    public Receiver startSelectedParentNode(FleetingNode node,
                                            int locationId)
                                     throws XPathException

  Signal that an element has been found that matches the selection that this Watch is looking for. This method is called by the ConstraintChecker while processing the startElement event that matches the selection. For this purpose, any attributes selected by the last step in the selection are ignored

  Specified by:
    `startSelectedParentNode` in interface `Watch`
  Parameters:
    `node` - the element or document node whose start event has been matched
    `locationId` - the location associated with the element or document node (may be the location of the instruction that created it)
  Returns:
    a Receiver to be notified of all events starting with the startElement/startDocument event for the matched element, and ending with the endElement event for that element.
  Throws:
    `ValidationException` - May be raised if the constraint implemented by this Watch is violated @param locationId
    `XPathException`

### endSelectedParentNode

    public void endSelectedParentNode(int locationId)
                               throws ValidationException

  Signal that the endElement event has occurred for the element whose startElement event caused the Watch to be activated.

  Specified by:
    `endSelectedParentNode` in interface `Watch`
  Parameters:
    `locationId` - the location of the element
  Throws:
    `ValidationException` - May be raised if the constraint implemented by this Watch is violated @param locationId

### notifySelectedLeafNode

    public void notifySelectedLeafNode(FleetingNode node,
                                       int locationId)
                                throws XPathException

  Signal that a node (other than an element) that matches the selection has been found.

  Specified by:
    `notifySelectedLeafNode` in interface `Watch`
  Overrides:
    `notifySelectedLeafNode` in class `AbstractWatch`
  Parameters:
    `node` - the node that was matched.
    `locationId` -
  Throws:
    `XPathException`

Copyright (c) 2004-2010 Saxonica Limited. All rights reserved.