Package com.saxonica.ee.stream.adjunct
Class DocumentSorterAdjunct
java.lang.Object
com.saxonica.ee.stream.adjunct.StreamingAdjunct
com.saxonica.ee.stream.adjunct.TransmissionAdjunct
com.saxonica.ee.stream.adjunct.DocumentSorterAdjunct
- All Implemented Interfaces:
FeedMaker
Generate streaming code for a document sorting expression node. This will only be used
to support streaming of a path expression of the form child::* / ancestor::*, where the
only operation needed is filtering to remove duplicate ancestors (and returning of ancestors
in document order).
In addition, if the expression a mixture of striding and grounded nodes, then
we can sort it because the streamed nodes retain their order (bug 29507)
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptioncomputeStreamability
(ContextItemStaticInfoEE contextInfo, List<String> reasons) Compute the posture and sweep of this expression as defined in the W3C streamability specifications.getFeedMaker
(int arg) Get a FeedMaker, a factory class that creates a Feed to evaluate this expression in streaming mode.getWatchMaker
(boolean forGrouping) Get a WatchMaker, a factory class that creates a Watch to evaluate this expression in streaming mode.makeItemFeed
(WatchManager watchManager, ItemFeed out, XPathContext context) toStreamingPattern
(Configuration config) Convert this expression to a streaming pattern (a pattern used internally to match nodes during push processing of an event stream)Methods inherited from class com.saxonica.ee.stream.adjunct.TransmissionAdjunct
makeTransmissionFlow
Methods inherited from class com.saxonica.ee.stream.adjunct.StreamingAdjunct
emptyAdjunctMap, findConsumingArg, genId, getConfiguration, getDefaultFeedMaker, getExpression, makeStreamingAdjunct, setConfiguration, setExpression
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Constructor Details
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DocumentSorterAdjunct
public DocumentSorterAdjunct()
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Method Details
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computeStreamability
public PostureAndSweep computeStreamability(ContextItemStaticInfoEE contextInfo, List<String> reasons) Compute the posture and sweep of this expression as defined in the W3C streamability specifications. This must be implemented in all subclasses that don't use the general streamability rules.- Overrides:
computeStreamability
in classStreamingAdjunct
- Parameters:
contextInfo
- Information about the context item type and posturereasons
- the caller may supply a list, in which case the implementation may add to this- Returns:
- the posture and sweep of the expression
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toStreamingPattern
Convert this expression to a streaming pattern (a pattern used internally to match nodes during push processing of an event stream)- Overrides:
toStreamingPattern
in classStreamingAdjunct
- Parameters:
config
- the Saxon configuration- Returns:
- the equivalent pattern if conversion succeeds; otherwise null
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getWatchMaker
Description copied from class:StreamingAdjunct
Get a WatchMaker, a factory class that creates a Watch to evaluate this expression in streaming mode. This method will only be called if the getImplementationMethod() method of the expression includes the valueExpression.WATCH_METHOD
- Overrides:
getWatchMaker
in classTransmissionAdjunct
- Parameters:
forGrouping
- true if the selected items are being grouped- Returns:
- a Watchmaker to evaluate the expression, or null if it is not streamable with respect to the specificed argument.
- Throws:
XPathException
- in the event of a failure
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makeItemFeed
public ItemFeed makeItemFeed(WatchManager watchManager, ItemFeed out, XPathContext context) throws XPathException - Specified by:
makeItemFeed
in interfaceFeedMaker
- Throws:
XPathException
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getFeedMaker
Description copied from class:StreamingAdjunct
Get a FeedMaker, a factory class that creates a Feed to evaluate this expression in streaming mode. In many cases the StreamingAdjunct is itself a FeedMaker, in which case it returns itself. But where an expression has several operands, it will typically create different feeds depending on which argument is the streamed input, and in such cases the individual StreamingAdjunct makes the decision which feed to use, by returning an appropriate FeedMaker.- Overrides:
getFeedMaker
in classStreamingAdjunct
- Parameters:
arg
- identifies the argument with respect to which the expression is to be inverted: usually 0 to indicate the first argument is the value that is streamed. Argument numbering is the same as the sequence of arguments/operands returned by the methodExpression.operands()
- Returns:
- a FeedMaker to evaluate the expression, or null if it is not streamable with respect to the specificed argument.
- Throws:
XPathException
- in the event of a failure
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