method quant

gistfile1.pl

    method quant($node, $from, $to) {
        my $min := 0 + ($node.min // 0);
        my $max := 0 + ($node.max // -1); # -1 means Inf
        
        # handle only ?,*,+ for now
        return self.fate($node, $from, $to) if $max > 1 || $min > 1;
        if $max == -1 {
            if $min == 0 { # * quantifier
                my $st := self.regex_nfa($node[0], $from, $from);
                $st := self.addedge($from, $to, $EDGE_EPSILON, 0);
                $to := $st if $to < 0 && $st > 0;
            } else { # + quantifier
                my $start := self.addstate();
                self.addedge($from, $start, $EDGE_EPSILON, 0);
                my $looper := self.addstate();
                my $st := self.regex_nfa($node[0], $start, $looper);
                self.addedge($looper, $start, $EDGE_EPSILON, 0);
                self.addedge($looper, $to, $EDGE_EPSILON, 0);
                $to := $st if $to < 0 && $st > 0;
            }
            $to;
        } elsif $min == 0 && $max == 1 { # ? quantifier
            my $st := self.regex_nfa($node[0], $from, $to);
            $to := $st if $to < 0 && $st > 0;
            $st := self.addedge($from, $to, $EDGE_EPSILON, 0);
            $to := $st if $to < 0 && $st > 0;
            $to;
        } else {
            self.fate($node, $from, $to)
        }
    }