Class Exists

    • Constructor Detail

      • Exists

        public Exists()
    • Method Detail

      • makeOptimizedFunctionCall

        public Expression makeOptimizedFunctionCall​(ExpressionVisitor visitor,
                                                    ContextItemStaticInfo contextInfo,
                                                    Expression... arguments)
                                             throws XPathException
        Description copied from class: SystemFunction
        Allow the function to create an optimized call based on the values of the actual arguments
        Overrides:
        makeOptimizedFunctionCall in class SystemFunction
        Parameters:
        visitor - the expression visitor
        contextInfo - information about the context item
        arguments - the supplied arguments to the function call. Note: modifying the contents of this array should not be attempted, it is likely to have no effect.
        Returns:
        either a function call on this function, or an expression that delivers the same result, or null indicating that no optimization has taken place
        Throws:
        XPathException - if an error is detected
      • call

        public BooleanValue call​(XPathContext context,
                                 Sequence[] arguments)
                          throws XPathException
        Evaluate the expression
        Parameters:
        context - the dynamic evaluation context
        arguments - the values of the arguments, supplied as SequenceIterators
        Returns:
        the result of the evaluation, in the form of a SequenceIterator
        Throws:
        XPathException - if a dynamic error occurs during the evaluation of the expression
      • getStreamerName

        public java.lang.String getStreamerName()
        Description copied from class: SystemFunction
        Get a name that identifies the class that can be used to evaluate this function in streaming mode, that is, supplying one item or event at a time as it is delivered by the parser. Special streaming support is generally available in Saxon-EE for all system functions that take a sequence as their argument.
        Overrides:
        getStreamerName in class SystemFunction
        Returns:
        a name that identifies a class that supports streamed evaluation of this system function, or null if no such class is available. The mapping of names to classes is defined in the Saxon-EE class StreamerMap. In non-streaming Saxon editions (HE and PE) the method always returns null.
      • getElaborator

        public Elaborator getElaborator()
        Make an elaborator for a system function call on this function
        Overrides:
        getElaborator in class SystemFunction
        Returns:
        a suitable elaborator; or null if no custom elaborator is available