use 5.012;
use warnings;

my $text = <<EOF;
source '/foo/bar'
hollareiduljoeh
peng '/zack/bumm' source oder so
oans 'zwoa' dreie
EOF

my @lines;
my $pos = 0;
my $len = length $text;
while ($pos < $len) {
  my $sep = index $text, "\n", $pos;
  if ($sep >= 0) {
    push @lines, substr $text, $pos, $sep - $pos;
    $pos = $sep + 1;
  } else {
    push @lines, substr $text, $pos;
    $pos = $len;
  }
}

my @sources =
  map {
    my $start = index $_, "'";
    my $stop = index $_, "'", $start + 1;
    if (index($_, 'source') >= 0 and $start >= 0 and $stop >= 0) {
      (substr $_, ++$start, $stop - $start)
    } else {
      ()
    }
  }
  @lines;

say for @sources;