net.sf.saxon.om
Interface FunctionItem<T extends FunctionItem>

All Superinterfaces:

Item<T>, PullEvent, ValueRepresentation<T>

All Known Subinterfaces:

MapItem

All Known Implementing Classes:

AbstractFunctionItem, CoercedFunction, CurriedFunction, FirstClassFunction, ImmutableMap, SingletonMap, UserFunctionItem

public interface FunctionItem<T extends FunctionItem>
extends Item<T>, ValueRepresentation<T>

XDM 3.0 introduces a third kind of item, beyond nodes and atomic values: the function item. Function items implement this marker interface. The actual implementation class is in Saxon-PE and Saxon-EE only.

Field Summary

Fields inherited from interface net.sf.saxon.om.ValueRepresentation

EMPTY_VALUE_ARRAY

Method Summary

FunctionItem	curry(ValueRepresentation<? extends Item>[] values) Curry a function by binding one or more (but not all) of its arguments
boolean	deepEquals(FunctionItem other, XPathContext context, GenericAtomicComparer comparer, int flags) Test whether this FunctionItem is deep-equal to another function item, under the rules of the deep-equal function
int	getArity() Get the arity of the function
FunctionItemType	getFunctionItemType(TypeHierarchy th) Get the item type of the function item
StructuredQName	getFunctionName() Get the name of the function, or null if it is anonymous
SequenceIterator<? extends Item>	invoke(SequenceIterator<? extends Item>[] args, XPathContext context) Invoke the function

Methods inherited from interface net.sf.saxon.om.Item

getStringValue, getStringValueCS, getTypedValue

Method Detail

getFunctionItemType

FunctionItemType getFunctionItemType(TypeHierarchy th)

Get the item type of the function item

Parameters:

th - the type hierarchy cache

Returns:

the function item's type

getFunctionName

StructuredQName getFunctionName()

Get the name of the function, or null if it is anonymous

Returns:

the function name, or null for an anonymous inline function

getArity

int getArity()

Get the arity of the function

Returns:

the number of arguments in the function signature

invoke

SequenceIterator<? extends Item> invoke(SequenceIterator<? extends Item>[] args,
                                        XPathContext context)
                                        throws XPathException

Invoke the function

Parameters:

args - the actual arguments to be supplied

context - the XPath dynamic evaluation context

Returns:

the result of invoking the function

Throws:

XPathException - if a dynamic error occurs within the function

curry

FunctionItem curry(ValueRepresentation<? extends Item>[] values)
                   throws XPathException

Curry a function by binding one or more (but not all) of its arguments

Parameters:

values - the values to which the arguments are to be bound, representing an unbound argument (a placeholder) by null

Returns:

a new function item in which the specified arguments of the original function are bound to a value

Throws:

XPathException - if any dynamic error occurs

deepEquals

boolean deepEquals(FunctionItem other,
                   XPathContext context,
                   GenericAtomicComparer comparer,
                   int flags)
                   throws XPathException

Test whether this FunctionItem is deep-equal to another function item, under the rules of the deep-equal function

Parameters:

other - the other function item

context - the dynamic evaluation context

comparer - the object to perform the comparison

flags - options for how the comparison is performed

Returns:

true if the two function items are deep-equal

Throws:

XPathException - if the comparison cannot be performed