uk.ac.starlink.ttools.jel

Class JELArrayFunction<I,O>

java.lang.Object

uk.ac.starlink.ttools.jel.JELArrayFunction<I,O>

All Implemented Interfaces:

java.util.function.Function<I,O>

public class JELArrayFunction<I,O>
extends Object
implements java.util.function.Function<I,O>

Provides an array->array function in which input elements are mapped to output elements by use of a given JEL expression.

Instances of this class are not threadsafe.

Since:

23 Mar 2021

Author:

Mark Taylor

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	JELArrayFunction.XResolver This public class is an implementation detail, not intended for external use.

Constructor Summary

Constructors

Constructor and Description
JELArrayFunction(String ivarName, String xvarName, String fexpr, Class<I> inClazz, Class<O> outClazz) Constructor.

Method Summary

Modifier and Type	Method and Description
O	apply(I inArray) Does exactly the same as evaluate(I).
O	evaluate(I inArray) Evaluates this expression.
static <I> Object	evaluate(String ivarName, String xvarName, String fexpr, I inArray) Utility method to create and use an array function in one go.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.function.Function

andThen, compose, identity

Constructor Detail

JELArrayFunction

public JELArrayFunction(String ivarName,
                        String xvarName,
                        String fexpr,
                        Class<I> inClazz,
                        Class<O> outClazz)
                 throws gnu.jel.CompilationException

Constructor.

Parameters:

ivarName - name of the array index variable (0-based)

xvarName - name of the array element variable (for instance "x")

fexpr - text of expression giving the function value, in terms of xvarname (for instance "x+1")

inClazz - type of input array; must be an array type of primitive or object elements

outClazz - type of output array; if not known, Object.class may be given, and the output type will be determined from the expression

Throws:

gnu.jel.CompilationException

Method Detail

evaluate

public O evaluate(I inArray)

Evaluates this expression. Elements for which the evaluation failed are given some type-dependent default value, such as NaN, null, or zero.

Parameters:

inArray - input array

Returns:

outArray output array, same length as input

apply

public O apply(I inArray)

Does exactly the same as evaluate(I).

Specified by:

apply in interface java.util.function.Function<I,O>

evaluate

public static <I> Object evaluate(String ivarName,
                                  String xvarName,
                                  String fexpr,
                                  I inArray)
                           throws gnu.jel.CompilationException

Utility method to create and use an array function in one go.

Parameters:

ivarName - name of the array index variable (for instance "i")

xvarName - name of the array element variable (for instance "x")

fexpr - text of expression giving the function value, in terms of xvarname (for instance "x+1")

inArray - input array

Returns:

output array, same length as input

Throws:

gnu.jel.CompilationException