Class Unindexed

  • All Implemented Interfaces:
    Callable, FunctionItem, GroundedValue, Item, Sequence

    public class Unindexed
    extends SystemFunction
    The extension function saxon:unindexed returns the value of its argument unchanged. A static call on saxon:unindexed will generally be optimized away; but if the argument is a filter expression, then it disables the use of indexes to optimize that filter expression. This is useful in cases where indexing would achieve no benefit.
    • Constructor Detail

      • Unindexed

        public Unindexed()
    • 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 Sequence call​(XPathContext context,
                             Sequence[] arguments)
                      throws XPathException
        Description copied from interface: Callable
        Call the Callable.
        Parameters:
        context - the dynamic evaluation context
        arguments - the values of the arguments, supplied as Sequences.

        Generally it is advisable, if calling iterate() to process a supplied sequence, to call it only once; if the value is required more than once, it should first be converted to a GroundedValue by calling the utility method SequenceTool.toGroundedValue().

        If the expected value is a single item, the item should be obtained by calling Sequence.head(): it cannot be assumed that the item will be passed as an instance of Item or AtomicValue.

        It is the caller's responsibility to perform any type conversions required to convert arguments to the type expected by the callee. An exception is where this Callable is explicitly an argument-converting wrapper around the original Callable.

        Returns:
        the result of the evaluation, in the form of a Sequence. It is the responsibility of the callee to ensure that the type of result conforms to the expected result type.
        Throws:
        XPathException - if a dynamic error occurs during the evaluation of the expression