Monday, December 28, 2009

Getting all the notes

I hope everyone had lovely holidays! I've spent a bit of time while away fiddling with my idea for a script to determine if a given tune can be played on a D/G button accordion. I've hit on a bit of a snag, as the code to determine what sharps or flats are in a given key signature is more complicated than I was thinking. It will probably take me a few more days to sort that out, but in the meantime, here is my first stab at extracting all the pitches from an ABC tune:
my $match = $abc ~~ m/ <ABC::tune> /;

die "Tune not matched\n" unless $match ~~ Match;

my @notes = gather for $match<ABC::tune><music><line_of_music> -> $line
for $line<bar> -> $bar
for $bar<element>
when .<broken_rhythm> { take .<broken_rhythm><note>[0]; take .<broken_rhythm><note>[1]; }
when .<note> { take .<note>; }

I'm suspecting there is a lovely Perl 6 idiom I don't quite have yet to squish all the for statements into a series of maps, but this works fine for the time being.

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