Class Concat

    • Constructor Detail

      • Concat

        public Concat()
    • Method Detail

      • resultIfEmpty

        protected Sequence resultIfEmpty​(int arg)
        Description copied from class: SystemFunction
        Ask if the function always returns a known result when one of the arguments is an empty sequence
        Overrides:
        resultIfEmpty in class SystemFunction
        Parameters:
        arg - the argument whose value is an empty sequence (counting from zero)
        Returns:
        the value to be returned when this argument is an empty sequence, or null if unknown / not applicable
      • makeOptimizedFunctionCall

        public Expression makeOptimizedFunctionCall​(ExpressionVisitor visitor,
                                                    ContextItemStaticInfo contextInfo,
                                                    Expression... arguments)
                                             throws XPathException
        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 StringValue call​(XPathContext context,
                                Sequence[] arguments)
                         throws XPathException
        Description copied from interface: Callable
        Call the Callable.
        Specified by:
        call in interface 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
      • process

        public void process​(Outputter destination,
                            XPathContext context,
                            Sequence[] arguments)
                     throws XPathException
        Description copied from interface: PushableFunction
        Evaluate the function in "push" mode
        Specified by:
        process in interface PushableFunction
        Parameters:
        destination - the destination for the function result
        context - the dynamic evaluation context
        arguments - the supplied arguments to the function
        Throws:
        XPathException - if a dynamic error occurs during the evaluation
      • getRequiredType

        public SequenceType getRequiredType​(int arg)
        Get the required type of the nth argument
        Overrides:
        getRequiredType in class SystemFunction
        Parameters:
        arg - the number of the argument whose type is requested, zero-based
        Returns:
        the required type of the argument as defined in the function signature
      • getCompilerName

        public java.lang.String getCompilerName()
        Description copied from class: SystemFunction
        Get the (local) name of a class that can be used to generate bytecode for this system function
        Overrides:
        getCompilerName in class SystemFunction
        Returns:
        the name of a bytecode generation class, or null if there is no bytecode support for this function