gather_tags

#!/usr/bin/env perl

# Author: Alexander Batischev <eual.jp@gmail.com>
# License: Public Domain
#
# This tiny piece of Perl git-greps existing posts for tags and prints them out
# in a nice comma-separated list. I use it to pre-populate metadata of the new
# post when the editor is being fired up (by `start_writing.sh`).

use strict;
use warnings;

my %tags = ();

foreach my $line ( `git grep --no-line-number 'tags: ' -- '*.markdown'` ) {
  chomp $line;
  # git-grep prints out the filename and the match divided by a colon
  $line =~ s/^.*\.markdown:tags: //;
  # tags in posts are comma-separated lists. We split the line by comma here
  # and then trim whitespace in case the list was ', '-separated
  foreach my $tag ( split(',', $line) ) {
    $tag =~ s/^\s+//;
    $tag =~ s/\s+$//;
    $tags{$tag}++;
  }
}

print join (', ', sort (keys %tags)), "\n";