Package uk.ac.starlink.ttools.jel

Class JELArrayFunction<I,​O>

  • public class JELArrayFunction<I,​O>
extends java.lang.Object
    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 Description
      static class  JELArrayFunction.XResolver
      This public class is an implementation detail, not intended for external use.

    • Constructor Summary

      Constructors 
      Constructor Description
      JELArrayFunction​(java.lang.String ivarName, java.lang.String xvarName, java.lang.String fexpr, java.lang.Class<I> inClazz, java.lang.Class<O> outClazz)
      Constructor.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      O evaluate​(I inArray)
      Evaluates this expression.
      static <I> java.lang.Object evaluate​(java.lang.String ivarName, java.lang.String xvarName, java.lang.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

    • Constructor Detail

      • JELArrayFunction

        public JELArrayFunction​(java.lang.String ivarName,
                        java.lang.String xvarName,
                        java.lang.String fexpr,
                        java.lang.Class<I> inClazz,
                        java.lang.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

      • evaluate

        public static <I> java.lang.Object evaluate​(java.lang.String ivarName,
                                            java.lang.String xvarName,
                                            java.lang.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