O Monks, hallowed be your woodiness.

For a variety of reasons, I'm collecting words alongside their date of encounter into a database. Then I group them by their woodiness or tinniness. The database table has three columns and looks like this:

30 Sep (Sun) | woody | pert
30 Sep (Sun) | tinny | newspaper
01 Oct (Mon) | woody | ocelot

[download]

Now, to create a more compact view, I'd like to transform the one-word-per-row raw data into an HTML table grouped by date like this:

   date      | woody words              | tinny words
-------------+--------------------------+-------------
28 Sep (Fri)  caribou                    litterbin
29 Sep (Sat)  wasp, yowling, gorn
30 Sep (Sun)  intercourse, bound, pert   newspaper
01 Oct (Mon)  ocelot, concubine          antelope
02 Oct (Tue)  vole, sausage
03 Oct (Wed)                             recidivist, tit

[download]

However, I'm having quite a bit of trouble with the loop logic. I can manage the grouping to date, but the special cases of days where only one type of words appear don't quite work and either the words go into the wrong column or the column is left without (empty) markup.

(I actually created a nice generic function that was supposed to solve this sort of task, but it ended up lacking in a few ways. Its interface borders on the silly (expects 4+ subrefs.))

Attached is sample data along with an iterator that emulates a database query handle.

sub make_generator {
    my ($day, $type, $word) = @_;
    return sub {
        my $line = <DATA>;
        chomp $line;
        return unless $line;

        ($$day, $$type, $$word) = split(/\s+\|\s+/, $line);
        return 1;
    };
}

my $gen = make_generator(\my ($day, $type, $word));

while ($gen->()) {
    print "$day: encountered '$word', a $type word\n";
}

__DATA__
28 Sep (Fri) | woody | caribou
28 Sep (Fri) | tinny | litterbin
29 Sep (Sat) | woody | wasp
29 Sep (Sat) | woody | yowling
29 Sep (Sat) | woody | gorn
30 Sep (Sun) | woody | intercourse
30 Sep (Sun) | woody | bound
30 Sep (Sun) | woody | pert
30 Sep (Sun) | tinny | newspaper
01 Oct (Mon) | woody | ocelot
01 Oct (Mon) | woody | concubine
01 Oct (Mon) | tinny | antelope
02 Oct (Tue) | woody | vole
02 Oct (Tue) | woody | sausage
03 Oct (Wed) | tinny | recidivist
03 Oct (Wed) | tinny | tit

[download]

In reply to Pivoting parts of a database table into an HTML table by Anonymous Monk

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