dRegAut
Class RegExp

java.lang.Object
  dRegAut.RegExp

public class RegExp
extends Object

Regular expression. [Martin, Def. 3.1]

We use the following special notation for regular expressions:

• #: the empty language (usually written as Ø)
• %: the empty string (usually written as )
• a (where a): the singleton string a
• r₁+r₂: union
• r₁r₂: concatenation
• r*: Kleene star

Constructor Summary

RegExp(String string, Alphabet alphabet)
Constructs a regular expression from a string.

Method Summary

void	simplify() Simplifies this regular expression (using some very simple rewrite rules).
NFA	toNFA() Converts this regular expression to an NFA.
String	toString() Returns a string representation of this regular expression.

Methods inherited from class java.lang.Object

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

Constructor Detail

RegExp

public RegExp(String string,
              Alphabet alphabet)
       throws IllegalArgumentException

Constructs a regular expression from a string. [Martin, Def. 3.1]

Parameters:

string - string representation of regular expression

alphabet - the alphabet

Throws:

IllegalArgumentException - if an alphabet symbol in the string is not in the alphabet or the string is not a syntactically correct regular expression

Method Detail

simplify

public void simplify()

Simplifies this regular expression (using some very simple rewrite rules).

toNFA

public NFA toNFA()

Converts this regular expression to an NFA. [Martin, Th. 3.25]

toString

public String toString()

Returns a string representation of this regular expression. The resulting string may contain superfluous parentheses.

Overrides:

toString in class Object