Package eu.bandm.tools.ops

Enum Class EBNFModifier

java.lang.Object

java.lang.Enum<EBNFModifier>

eu.bandm.tools.ops.EBNFModifier

All Implemented Interfaces:

Serializable, Comparable<EBNFModifier>, java.lang.constant.Constable

public enum EBNFModifier
extends Enum<EBNFModifier>

Models the four regular-expression operators which are frequently used in extended Bakus-Naur-forms.

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Enum

Enum.EnumDesc<E extends Enum<E>>

Enum Constant Summary

Enum Constants

Enum Constant	Description
none	Neutral case, that no modifier is appended to a sub-expression.
optional	Operator which allows the decorated sub-expression to appear or not to appear.
plus	Operator which allows the decorated sub-expression to appear arbitrary many times, but at least once
star	Operator which allows the decorated sub-expression to appear zero to arbitrary many times.

Method Summary

Modifier and Type	Method	Description
static boolean	addsEpsilon(EBNFModifier arg)	Whether the given modifier allows empty string.
static boolean	addsRepetitions(EBNFModifier arg)	Whether the given modifier allows using a sub-expression ore than once.
static EBNFModifier	compose(EBNFModifier... args)	Calculate the effect of more than one modifier applied to the same sub-expression.
static EBNFModifier	valueOf(String name)	Returns the enum constant of this class with the specified name.
static EBNFModifier[]	values()	Returns an array containing the constants of this enum class, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, describeConstable, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Details

none

public static final EBNFModifier none

Neutral case, that no modifier is appended to a sub-expression.

optional

public static final EBNFModifier optional

Operator which allows the decorated sub-expression to appear or not to appear.

star

public static final EBNFModifier star

Operator which allows the decorated sub-expression to appear zero to arbitrary many times.

plus

public static final EBNFModifier plus

Operator which allows the decorated sub-expression to appear arbitrary many times, but at least once

Method Details

values

public static EBNFModifier[] values()

Returns an array containing the constants of this enum class, in the order they are declared.

Returns:

an array containing the constants of this enum class, in the order they are declared

valueOf

public static EBNFModifier valueOf(String name)

Returns the enum constant of this class with the specified name. The string must match exactly an identifier used to declare an enum constant in this class. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum class has no constant with the specified name

NullPointerException - if the argument is null

compose

public static EBNFModifier compose(EBNFModifier... args)

Calculate the effect of more than one modifier applied to the same sub-expression. The table is

          -  ?  *  + 
      -----------------
       -  -  ?  *  +
       ?  ?  ?  *  *
       *  *  *  *  *
       +  +  *  *  +
  

addsEpsilon

public static boolean addsEpsilon(EBNFModifier arg)

Whether the given modifier allows empty string.

addsRepetitions

public static boolean addsRepetitions(EBNFModifier arg)

Whether the given modifier allows using a sub-expression ore than once.