Package com.saxonica.ee.stream.adjunct
Class FilterExpressionAdjunct
- java.lang.Object
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- com.saxonica.ee.stream.adjunct.StreamingAdjunct
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- com.saxonica.ee.stream.adjunct.TransmissionAdjunct
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- com.saxonica.ee.stream.adjunct.FilteringAdjunct
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- com.saxonica.ee.stream.adjunct.FilterExpressionAdjunct
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- All Implemented Interfaces:
FeedMaker
public class FilterExpressionAdjunct extends FilteringAdjunct
Generate streaming code for a filter expression (when not part of a Watch).
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Constructor Summary
Constructors Constructor Description FilterExpressionAdjunct()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description PostureAndSweep
computeStreamability(ContextItemStaticInfoEE contextInfo, java.util.List<java.lang.String> reasons)
Compute the posture and sweep of this expression as defined in the W3C streamability specifications.FeedMaker
getFeedMaker(int arg)
Get a FeedMaker, a factory class that creates a Feed to evaluate this expression in streaming mode.FilteringFeed.Filter
makeFilter(XPathContext context, ItemFeed out)
Make a filter for the event streamvoid
setExpression(Expression expression)
Set the expression being processed by this StreamingAdjunctPattern
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.FilteringAdjunct
makeItemFeed
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Methods inherited from class com.saxonica.ee.stream.adjunct.TransmissionAdjunct
getWatchMaker, makeTransmissionFlow
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Methods inherited from class com.saxonica.ee.stream.adjunct.StreamingAdjunct
emptyAdjunctMap, findConsumingArg, genId, getConfiguration, getDefaultFeedMaker, getExpression, makeStreamingAdjunct, setConfiguration
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Method Detail
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setExpression
public void setExpression(Expression expression)
Set the expression being processed by this StreamingAdjunct- Overrides:
setExpression
in classStreamingAdjunct
- Parameters:
expression
- the expression being processed
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computeStreamability
public PostureAndSweep computeStreamability(ContextItemStaticInfoEE contextInfo, java.util.List<java.lang.String> reasons)
Description copied from class:StreamingAdjunct
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. The implementation should have the side-effect of computing the streamability of all subexpressions, recursively.- 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; the contents are human-readable messages explaining why the expression is not streamable.- Returns:
- the posture and sweep of the expression
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toStreamingPattern
public Pattern toStreamingPattern(Configuration config)
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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makeFilter
public FilteringFeed.Filter makeFilter(XPathContext context, ItemFeed out)
Make a filter for the event stream- Specified by:
makeFilter
in classFilteringAdjunct
- Parameters:
context
- the XPath dynamic contextout
- the next filter in the pipeline- Returns:
- a filter that can be added to the event stream
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getFeedMaker
public FeedMaker getFeedMaker(int arg) throws XPathException
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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