FLAT::Legacy::FA::RE 0.1

FLAT::Legacy::FA::RE is a regular expression base class.

SYNOPSIS

use FLAT::Legacy::FA::RE;
use FLAT::Legacy::FA::NFA;
my $re = RE->new();
$re->set_re(a|b|(hi)*);
my $nfa = $re->to_nfa();
print $nfa->info(); # see stuff on NFA
my $dfa = $nfa->to_dfa();
print $dfa->info(); # see stuff on DFA
my @removed = $dfa->minimize();
print $dfa->info(); # see stuff on minimized DFA
print "Removed ".($#removed+1)." statesn";

This module implements a regular expression parser, and supports the conversion of a RE to a deterministic finite automata. A homegrown recursive descent parser is used to build the parse tree, and the method used to conver the regular expression to a DFA uses no intermediate NFA.
Recursive Descent-safe Regex Grammar:

R -> O

O -> CO

O -> | CO | epsilon

C -> SC

C -> .SC | epsilon

S -> LS

S -> *S | epsilon

L -> a | b | c |..| 0 | 1 | 2 |..| (R) | epsilon

Terminal symbols: a,b,c,..,z,0,1,2,..,9,|,*,(,)

NOTE: Concatenation operator, ., is not a terminal symbol and should not be included in the regex

FAQ: Q: Does this support Perl regular expressions?
A: No, just the regular expression using the terminal symbols listed above.