Package net.sf.saxon.expr

Class CallableDelegate

java.lang.Object

net.sf.saxon.expr.CallableDelegate

All Implemented Interfaces:

Callable

public class CallableDelegate
extends java.lang.Object
implements Callable

An implementation of Callable that allows the logic to be supplied as a lambda expression.

On Java, it's possible to assign a lambda expression directly to a Callable. But on C#, a Callable isn't a delegate, so lambda expressions can't be used directly; instead, this class is provided as a proxy.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	CallableDelegate.Lambda

Constructor Summary

Constructors

Constructor	Description
CallableDelegate(CallableDelegate.Lambda expression)	Construct a Callable by supplying an implementation in the form of a lambda expression

Method Summary

Modifier and Type	Method	Description
Sequence	call(XPathContext context, Sequence[] arguments)	Call the Callable.

Methods inherited from class java.lang.Object

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

Constructor Detail

CallableDelegate

public CallableDelegate(CallableDelegate.Lambda expression)

Construct a Callable by supplying an implementation in the form of a lambda expression

Parameters:

expression - a lambda expression (typically) that is invoked to evaluate the Callable

Method Detail

call

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

Description copied from interface: Callable

Call the Callable.

Specified by:

call in interface Callable

Parameters:

context - 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