Package net.sf.saxon.functions

Class BooleanFn

    • Constructor Detail

      • BooleanFn

        public BooleanFn()

    • Method Detail

      • supplyTypeInformation

        public void supplyTypeInformation​(ExpressionVisitor visitor,
                                  ContextItemStaticInfo contextItemType,
                                  Expression[] arguments)
                           throws XPathException
        Description copied from class: SystemFunction
        Method called during static type checking. This method may be implemented in subclasses so that functions can take advantage of knowledge of the types of the arguments that will be supplied.
        Overrides:
        supplyTypeInformation in class SystemFunction
        Parameters:
        visitor - an expression visitor, providing access to the static context and configuration
        contextItemType - information about whether the context item is set, and what its type is
        arguments - the expressions appearing as arguments in the function call
        Throws:
        XPathException - if an error is detected

      • rewriteEffectiveBooleanValue

        public static Expression rewriteEffectiveBooleanValue​(Expression exp,
                                                      ExpressionVisitor visitor,
                                                      ContextItemStaticInfo contextItemType)
                                               throws XPathException
        Optimize an expression whose effective boolean value is required. It is appropriate to apply this rewrite to any expression whose value will be obtained by calling the Expression.effectiveBooleanValue() method (and not otherwise)
        Parameters:
        exp - the expression whose EBV is to be evaluated
        visitor - an expression visitor
        contextItemType - the type of the context item for this expression
        Returns:
        an expression that returns the EBV of exp, or null if no optimization was possible
        Throws:
        XPathException - if static errors are found

      • call

        public BooleanValue call​(XPathContext c,
                         Sequence[] arguments)
                  throws XPathException
        Description copied from interface: Callable
        Call the Callable.
        Parameters:
        c - 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

      • makeFunctionCall

        public Expression makeFunctionCall​(Expression[] arguments)
        Description copied from class: SystemFunction
        Make an expression that either calls this function, or that is equivalent to a call on this function
        Overrides:
        makeFunctionCall in class SystemFunction
        Parameters:
        arguments - the supplied arguments to the function call
        Returns:
        either a function call on this function, or an expression that delivers the same result

      • 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.