com.saxonica.functions.hof

Class CoercedFunction

java.lang.Object

net.sf.saxon.om.AbstractItem

net.sf.saxon.functions.AbstractFunction

com.saxonica.functions.hof.CoercedFunction

All Implemented Interfaces:

PullEvent, Callable, Function, GroundedValue, Item, Sequence

public class CoercedFunction
extends AbstractFunction

A function item obtained by coercing a supplied function; this adds a wrapper to perform dynamic type checking of the arguments in any call, and type checking of the result.

Constructor Summary

Constructors

Constructor and Description
CoercedFunction(Function targetFunction, SpecificFunctionType requiredType) Create a CoercedFunction as a wrapper around a target function
CoercedFunction(SpecificFunctionType requiredType) Create a CoercedFunction whose target function is not yet known (happens during package re-loading)

Method Summary

Methods

Modifier and Type	Method and Description
Sequence	call(XPathContext context, Sequence[] args) Invoke the function
static CoercedFunction	coerce(Function suppliedFunction, SpecificFunctionType requiredType, RoleDiagnostic role) Factory method to create a CoercedFunction with a given type, for a given targetFunction.
void	export(ExpressionPresenter out) Output information about this function item to the diagnostic explain() output
int	getArity() Get the arity of the function
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
void	setTargetFunction(Function targetFunction) Set the target function
void	typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) Type check the function (may modify it by adding code for converting the arguments)

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

atomize, deepEquals, effectiveBooleanValue, getOperandRoles, getStringValue, getStringValueCS, isArray, isMap, optimize, simplify

Methods inherited from class net.sf.saxon.om.AbstractItem

getLength, head, itemAt, iterate, reduce, subsequence

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.Function

iterate

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

head

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

getLength, head, itemAt, reduce, subsequence

Constructor Detail

CoercedFunction

public CoercedFunction(Function targetFunction,
               SpecificFunctionType requiredType)
                throws XPathException

Create a CoercedFunction as a wrapper around a target function

Parameters:

targetFunction - the function to be wrapped by a type-checking layer

requiredType - the type of the coerced function, that is the type required by the context in which the target function is being used

Throws:

XPathException - if the arity of the supplied function does not match the arity of the required type

CoercedFunction

public CoercedFunction(SpecificFunctionType requiredType)
                throws XPathException

Create a CoercedFunction whose target function is not yet known (happens during package re-loading)

Parameters:

requiredType - the type of the coerced function, that is the type required by the context in which the target function is being used

Throws:

XPathException

Method Detail

setTargetFunction

public void setTargetFunction(Function targetFunction)
                       throws XPathException

Set the target function

Parameters:

targetFunction - the function to be wrapped by a type-checking layer

Throws:

XPathException - if the arity of the supplied function does not match the arity of the required type

typeCheck

public void typeCheck(ExpressionVisitor visitor,
             ContextItemStaticInfo contextItemType)
               throws XPathException

Type check the function (may modify it by adding code for converting the arguments)

Overrides:

typeCheck in class AbstractFunction

Parameters:

visitor - the expression visitor, supplies context information

contextItemType - the context item type at the point where the function definition appears

Throws:

XPathException

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:

null indicating that this is 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

Returns:

the number of arguments in the function signature

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

coerce

public static CoercedFunction coerce(Function suppliedFunction,
                     SpecificFunctionType requiredType,
                     RoleDiagnostic role)
                              throws XPathException

Factory method to create a CoercedFunction with a given type, for a given targetFunction. It is assumed that we have already established that coercion is needed. Called from Bytecode compiler.

Parameters:

suppliedFunction - the function to be coerced

requiredType - the target type for the coercion

role - diagnostic information about the role of the expression being coerced

Returns:

the function after coercion

Throws:

XPathException - if the function cannot be coerced to the required type (for example, because it has the wrong arity)

export

public void export(ExpressionPresenter out)

Output information about this function item to the diagnostic explain() output

Specified by:

export in interface Function

Overrides:

export in class AbstractFunction

Parameters:

out -