abc2jp.pl

#! /usr/bin/env -S perl -p
# -*- perl -*- 
# @Author: Tong SUN, (c)2023, all right reserved

# ABC unit note length
# http://abcnotation.com/wiki/abc:standard:v2.1#lunit_note_length
my $abcL = 4;

## == Headers
## http://abcnotation.com/wiki/abc:standard:v2.1#tune_header_definition

if (/^[XCR]:/) { $_ = '' }
elsif (/^(T:)/) { $repl=$1; s/$repl/title=/; }
elsif (/^(M:)/) { $repl=$1; s/$repl//; }
elsif (/^(K:)/) { $repl=$1; s/$repl/1=/; }
elsif (/^(C:)/) { $repl=$1; s/$repl/composer=/; }
elsif (/^(Q:.*?\/)/) { $repl=$1; s/$repl/%% tempo: /; }
elsif (/^(L:.*?\/)(\d+)/) { $abcL=$2; $_ = ''; print "] abcL=$abcL\n" if 0; }
# body lyrics
elsif (/^(w: *)/) { $repl=$1; s/$repl/L: /; }
else {
    ## == ABC Bodies
    ## http://abcnotation.com/wiki/abc:standard:v2.1#tune_body_definition

    # guitar chords, skip them all
    s/".*?"//g;

    # ABC notes
    # http://abcnotation.com/wiki/abc:standard:v2.1#the_tune_body

    my %abc_notes = (
	C => 1, D => 2, E => 3, F => 4, G => 5, A => 6, B => 7, 
	c => "1'", d => "2'", e => "3'", f => "4'", g => "5'", a => "6'", b => "7'", 
	"c'" => "1''", "d'" => "2''", "e'" => "3''", "f'" => "4''",
	"g'" => "5''", "a'" => "6''", "b'" => "7''", 
	"C," => "1,", "D," => "2,", "E," => "3,", "F," => "4,",
	"G," => "5,", "A," => "6,", "B," => "7,", 
	);

    # notes lengths (1/n)
    my %notes_lengths = (
	4 => 'XZM', 8 => 'q', 16 => 's', 32 => 'd', 64 => 'h',
	);

    # notes extend
    my %notes_extend = (
	1 => '', 2 => ' -', 3 => '. -', 4 => ' - -', 
	);

    # https://www.debuggex.com/r/LrK7RxK0D8LVvQY5
    # https://regex101.com/r/hEpgR3/5
    while (/([a-g][,']*)(((\/+)(\d*))|(\d*))/gi) {
	# org, note, dividing, dividing_n, multiplier
	$o=$&; $n=$1; $d=$4; $dn=$5; $m=$6;
	#print "'$o' note, dividing (n), multiplier: '$n' '$d($dn)' '$m'\n";
	my ($jpn, $jpo) = ($abc_notes{$n}, ''); # jp note, output
	my ($jpl, $jpln) = (1, ''); # note_length, length_name
	if (length($d)>0) {
	    # Shorter notes
	    if (length($dn)>0) {
		# Shorter notes, dividing with number
		$jpl = $abcL * $dn
	    } else {
		# shorthands: A/ = A/2, A// = A/4
		$jpl = $abcL * 2 * length($d)
	    }
	    $jpln = $notes_lengths{$jpl};
	    $jpo = "$jpln$jpn";
	} else {
	    # with a multiplier
	    if ($m == 0) { $m = 1; }
	    $jpln = $notes_lengths{$abcL};
	    $jpo = "$jpln$jpn$notes_extend{$m}";
	}
	#print "'$o' ($jpl) => $jpo\n";
	s/$o/$jpo /;
    }

    s{\|\]}{}g;
}