1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
|
multi sub partition(Str:D $filename) {
partition($filename.IO.open(:r, :enc<utf8>));
}
multi sub partition(IO::Handle:D $file) {
my $f = $file;
$f.seek(-4096, SeekFromEnd);
my @positions;
my $start_position = 0;
loop {
my @results = (my $piece = $f.read(4096).decode("utf8")).comb(/^^skip\:\d+$$/);
if @results {
$start_position = @results.tail.comb(/\d+/).head.Int;
last;
}
$f.seek(-4096 * 2 + 64, SeekFromCurrent);
}
my $position = $start_position;
while $position > 0 {
@positions.push: $position;
$f.seek($position max 0, SeekFromBeginning);
my $piece = $f.read(64).decode("utf8");
unless $piece.starts-with("skip:") { die "expected piece starting at $position to start with `skip:`, but piece gotten was `$piece`" }
$position = $piece.substr("skip:".chars, $piece.index("\n") - "skip:".chars).Int;
}
return @positions;
}
sub MAIN($filename) {
my @positions = partition($filename);
.say for @positions;
}
|
