use strict;
use warnings;

use Data::Dump;


{
    my %state;

    sub till {
        my @phases=@_;
        my ($file,$line)= (caller)[1..2];
        my $state = \$state{$file,$line};
        $$state //= 0;
        $phases[1+$$state]->($_);
        if ($phases[$$state]) {
            $$state += 2;
            $$state %= @phases;
        }
    }
}

sub doStage1            { print "1: ",shift }
sub doStage2            { print "2: ",shift }
sub doStage3            { print "3: ",shift }
sub doOtherProcessing   { print "*: ",shift }



while (<DATA>){
    till (
        - /for/   => \&doOtherProcessing, 
        - /their/ => \&doStage1,
        - /fruit/ => \&doStage2,
        - /lazy/  => \&doStage3,
       );
}

__DATA__
now is the time
for all good men to
come to the aid of
their party.
Time flies like an arrow
fruit flies like a  banana.
The quick red fox
jumps over the lazy
brown dog.
Etaoinshrdlu.
[download]

output:

*: now is the time
*: for all good men to
1: come to the aid of
1: their party.
2: Time flies like an arrow
2: fruit flies like a  banana.
3: The quick red fox
3: jumps over the lazy
*: brown dog.
*: Etaoinshrdlu.
[download]