Package net.sf.saxon.functions.hof

Class CurriedFunction

java.lang.Object

net.sf.saxon.functions.AbstractFunction

net.sf.saxon.functions.hof.CurriedFunction

All Implemented Interfaces:

Callable, FunctionItem, GroundedValue, Item, Sequence

public class CurriedFunction
extends AbstractFunction

A function obtained by currying another function: that is, the result of a partial function application

Constructor Summary

Constructors

Constructor	Description
CurriedFunction(FunctionItem targetFunction, Sequence[] boundValues, int[] unboundArgMap)	Create a curried (or partially applied) function

Method Summary

Modifier and Type	Method	Description
Sequence	call(XPathContext context, Sequence[] args)	Invoke the function
void	export(ExpressionPresenter out)	Output information about this function item
AnnotationList	getAnnotations()	Get the function annotations (as defined in XQuery).
int	getArity()	Get the arity of the function (equal to the number of placeholders)
String	getDescription()	Get a description of this function for use in error messages.
FunctionItemType	getFunctionItemType()	Get the item type of the function item
StructuredQName	getFunctionName()	Get the name of the function, or null if it is anonymous

Methods inherited from class net.sf.saxon.functions.AbstractFunction

atomize, deepEqual40, deepEquals, effectiveBooleanValue, getOperandRoles, getUnicodeStringValue, getUniqueIdentifier, isArray, isMap, isTrustedResultType, makeNewContext, simplify, toShortString, typeCheck

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

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

getGenre, isSequenceVariadic

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

asIterable, concatenate, containsNode, materialize

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

getLabel, getLength, getStringValue, head, isStreamed, itemAt, iterate, reduce, subsequence

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

makeRepeatable

Constructor Details

CurriedFunction

public CurriedFunction(FunctionItem targetFunction,
 Sequence[] boundValues,
 int[] unboundArgMap)

Create a curried (or partially applied) function

Parameters:

targetFunction - the base function to be curried

boundValues - the values to which the arguments are to be bound, representing unbound values (placeholders) by null. So if the arguments are (4, ?, 5) then this array will be [4, null, 5]. If keywords are used in the call then they will have been resolved to argument positions. The values supplied must conform to the required type: coercion is the responsibility of the caller.

unboundArgMap - for unbound arguments (placeholders), mapping from argument positions in the curried function to argument positions in the target function. If the arguments are (4, ?, 5) then this array will be [1], indicating that the first and only argument in the curried function is bound to the second (position==1) argument in the underlying function. If keywords are used in the call then this mapping may be non-trivial; for example if the base function is f(x,y) and the partial function application is f(y:=?, x:=?), then this array will contain [1,0]. The length of this array is equal to the arity of the curried function.

Method Details

getFunctionItemType

public FunctionItemType getFunctionItemType()

Get the item type of the function item

Returns:

the function item's type

getFunctionName

public 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

getDescription

public String getDescription()

Get a description of this function for use in error messages. For named functions, the description is the function name (as a lexical QName). For others, it might be, for example, "inline function", or "partially-applied ends-with function".

Returns:

a description of the function for use in error messages

getArity

public int getArity()

Get the arity of the function (equal to the number of placeholders)

Returns:

the number of arguments in the function signature

getAnnotations

public AnnotationList getAnnotations()

Get the function annotations (as defined in XQuery). Returns an empty list if there are no function annotations. The function annotations on a partially applied function are the same as the annotations on its base function.

Specified by:

getAnnotations in interface FunctionItem

Overrides:

getAnnotations in class AbstractFunction

Returns:

the function annotations

call

public Sequence call(XPathContext context,
 Sequence[] args)
              throws XPathException

Invoke the function

Parameters:

context - the XPath dynamic evaluation context

args - the actual arguments to be supplied

Returns:

the result of invoking the function

Throws:

XPathException - if the function reports a dynamic error

export

public void export(ExpressionPresenter out)
            throws XPathException

Output information about this function item

Specified by:

export in interface FunctionItem

Overrides:

export in class AbstractFunction

Parameters:

out - the destination to write to

Throws:

XPathException - if things go wrong