regexps are fine on their own for one-off use, but for iterative use they are often better wrapped up into a parser, e.g.:

#untested
use myParser;
my %CSV = ('n' => 'n',
           't' => 't',
           'f' => 'f',
           '\\' => '\\',
          );
$_ = '\\\\\\\\\\';


my ($result,$status) = parse( LEXICON=>\%CSV );

package myParser;

sub new {
    my $self = Interface( @_ );
    my $class = ref( $self ) || $self;
    return (bless $self), $class;
}

sub parse {
    my $self = Interface( @_ );
    my $bufadr = ($self -> { BUFREF } ||= \$_); # default buffer $_
    my $lexicon = $self -> { LEXICON } or die;
    my $return = [];
    my $lexStatus = 1;
    while( length( $$bufadr ) && lexStatus ) {
        Throw( $self );
        my $content;
        ( $content, $lexStatus ) = AntiLex( $self, keys %$lexicon );
        $lexStatus and push @$return, $content;
    }
    return $return, $lexStatus;
}

sub Throw {
    AntiLex( shift(), '\S' );
}

sub AntiLex {
    my $self = shift;
    my $bufadr = $self -> { BUFADR };
    my $status;
    for my $pattern ( @_ || die() ) {
        if ( $$bufadr =~ /^\n*($pattern)(.*)$/m ) {
            $$bufadr = $2;
            return ( $1, 1 );
        }
    }
    return ( undef(), 0 );    
}
sub Interface { return ( ref( $_[0] ) || !$#_ ) ? shift() : { @_ }; }
1;
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