net.sf.saxon.lib

Interface FunctionAnnotationHandler

All Known Implementing Classes:

SimpleFunctionAnnotationHandler, XQueryFunctionAnnotationHandler

public interface FunctionAnnotationHandler

Interface to a user-supplied class that handles XQuery annotation assertions in a particular namespace. The interface provides a callback method used to determine whether the set of annotations on a given user defined function satisfies a particular annotation assertion defined in a function item test (for example, the required function type for an argument of a higher-order function)

Method Summary

Modifier and Type	Method and Description
void	check(AnnotationList annotations, java.lang.String construct) Test whether a given set of annotations in this namespace is valid.
java.lang.String	getAssertionNamespace() Get the namespace handled by this function annotation handler.
int	relationship(AnnotationList firstList, AnnotationList secondList) Test the relationship of one list of annotation assertions to another list of annotation assertions, all from this namespace.
boolean	satisfiesAssertion(Annotation assertion, AnnotationList annotationList) Test whether a function with a given list of annotations satisfies an annotation assertion present on a function item test.

Method Detail

getAssertionNamespace

java.lang.String getAssertionNamespace()

Get the namespace handled by this function annotation handler. This handler will only be called in respect of annotation assertions that are in this namespace. Use the empty string to refer to the null namespace

Returns:

the namespace handled by this function annotation handler.

check

void check(AnnotationList annotations,
           java.lang.String construct)
    throws XPathException

Test whether a given set of annotations in this namespace is valid.

Parameters:

annotations - the annotation list (filtered by namespace: all the annotations will have names in the namespace for this annotation handler)

construct - the construct on which this list of annotations appears. One of "DF" (declare function), "DV" (declare variable), "IF" (inline function), "FT" (function test)

Throws:

XPathException - if the annotation is invalid, or if it is inconsistent with the annotations in the existing list.

satisfiesAssertion

boolean satisfiesAssertion(Annotation assertion,
                           AnnotationList annotationList)

Test whether a function with a given list of annotations satisfies an annotation assertion present on a function item test.

Parameters:

assertion - the annotation assertion present in the function item test

annotationList - the annotations present on the function being tested, filtered by namespace

Returns:

true if the assertion is satisfied, false if not

relationship

int relationship(AnnotationList firstList,
                 AnnotationList secondList)

Test the relationship of one list of annotation assertions to another list of annotation assertions, all from this namespace.

The lists will always be non-empty, because it is assumed that a test with an empty list of assertions always subsumes a test with a non-empty list.

Parameters:

firstList - the first list of annotation assertions

secondList - the second list of annotation assertions

Returns:

the relationship between the two lists, as one of the values TypeHierarchy.SAME_TYPE, TypeHierarchy.DISJOINT, TypeHierarchy.OVERLAPS, TypeHierarchy.SUBSUMES, TypeHierarchy.SUBSUMED_BY. For example, if the first list is %colour("blue") and the second list is %colour("green"), and no function can be both blue and green, then return DISJOINT. But if a function can have more than one colour, return OVERLAPS because the set of functions conforming to the two assertions has a non-empty intersection. If the first list is %colour("any") and the second list is %colour("blue"), then return SUBSUMES, because the set of functions satisfying the first assertion is a superset of those satisfying the second assertion.

The result of this method must be consistent with the satisfiesAssertion(Annotation, AnnotationList) method. For example, if this method indicates that %big subsumes %huge, then it must indeed be the case that the set of functions that satisfy the assertion %big is a superset of those that satisfy the assertion %huge.

If in doubt, it is always safe to return OVERLAPS: the worst that can happen is that type-checking is deferred until run-time.