Package com.saxonica.ee.stream.adjunct

Class StreamingAdjunct

    • Constructor Detail

      • StreamingAdjunct

        public StreamingAdjunct()

    • Method Detail

      • emptyAdjunctMap

        public static java.util.Map<java.lang.String,​java.lang.Class<? extends StreamingAdjunct>> emptyAdjunctMap()

      • makeStreamingAdjunct

        public static StreamingAdjunct makeStreamingAdjunct​(Configuration config,
                                                    Expression exp)
        Make a streaming adjunct for a particular expression.
        Parameters:
        config - the Saxon Configuration
        exp - the expression to be compiled
        Returns:
        the compiler for this kind of expression

      • setConfiguration

        public void setConfiguration​(Configuration config)
        Set the Saxon Configuration
        Parameters:
        config - the Configuration

      • getConfiguration

        public Configuration getConfiguration()
        Get the Saxon Configuration
        Returns:
        the configuration

      • setExpression

        public void setExpression​(Expression expression)
        Set the expression being processed by this StreamingAdjunct
        Parameters:
        expression - the expression being processed

      • getExpression

        public Expression getExpression()
        Get the expression being processed by this StreamingAdjunct
        Returns:
        the expression being processed

      • computeStreamability

        public 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. 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.
        Parameters:
        contextInfo - Information about the context item type and posture
        reasons - 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

      • findConsumingArg

        public static int findConsumingArg​(Expression expression,
                                   int knownConsumingArg)
                            throws XPathException
        Find which operand of an expression is the consuming operand. Helper method for use by subclasses
        Parameters:
        expression - the expression
        knownConsumingArg - index of the consuming operand if known, otherwise -1
        Returns:
        index identifying the consuming operand
        Throws:
        XPathException - if there is no consuming operand

      • 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)
        Parameters:
        config - the Saxon configuration
        Returns:
        the equivalent pattern if conversion succeeds; otherwise null

      • getWatchMaker

        public WatchMaker getWatchMaker​(boolean forGrouping)
                         throws XPathException
        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 value Expression.WATCH_METHOD
        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

      • getFeedMaker

        public FeedMaker getFeedMaker​(int arg)
                       throws XPathException
        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.
        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 method Expression.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

      • getDefaultFeedMaker

        protected FeedMaker getDefaultFeedMaker​(int arg)
        Get a FeedMaker which will generate a feed to handle streamed input of operand "arg".
        Parameters:
        arg - identifies which operand of the expression is the streamed (consuming) input
        Returns:
        a FeedMaker

      • genId

        public static java.lang.String genId​(NodeInfo node)