#!/home/jmc/bin/perl
#
#=head1 FILE
#  ABC.pm
#
#=head1 NAME
#  ABC - module for handling music in abc notation.
#
#=head1 SYNOPSIS
#  use ABC;
#  $t = new ABC(<fields>)
#
#=head1 DESCRIPTION
#
#=head1 BUGS
#
#=head1 SEE ALSO
#
#=head1 AUTHOR
#John Chambers <jc@trillian.mit.edu>
#
#=cut

#package ABC;
use Carp;
# A = qw(Exporter DynaLoader);
# use strict;
my $d = 1;
my $o;

#use ABC_Token;

sub ABC_new {
	my $x = shift;
#	my $class = ref($x) || $x;
	my $self = {};
	local($fld, $val);
#	bless $self;
	$self->{src} = '';	# List for the tune's abc source.
	$self->{T}   = [];	# T: header lines.
	$self->{tok} = [];	# Token list.
	while (($fld = shift) && ($val = shift)) {
		print STDERR "ABC_new: fld=\"$fld\" val=\"$val\"\n" if $d>4;
		$self->{$fld} = $val;
	}
	$d = $main::V;
	return ($o = $self);
}

sub URL {
	my $x = shift;
	if (@_) {$x->{URL} = shift}
	return $x->{URL};
}

$ABC_Key    = 'C';
$ABC_Length = '1/8';
$ABC_Meter  = '4/4';

# $obj->hdr('T',1,'First Title')
# $obj->hdr('T',2,'Second Title')
sub ABC_hdr {
	local($x,$h,$n,$v) = @_;
	local($r);
	if (defined($v)) {
		if (!defined($x->{$h})) {
			$x->{$h} = [];		# Make it into a list.
		}
		push @{$x->{$h}}, $v;
		$r = $v;
	} else {
		$r = $x->{$h}[$n];
	}
	   if ($h eq 'L') {$ABC_Length = $v} 
	elsif ($h eq 'M') {$ABC_Meter  = $v} 
	elsif ($h eq 'K') {$ABC_Key    = $v} 
	return $r;
}

# ABC_bar(obj,bar)
sub ABC_bar {
	local($x,$v) = @_;
	local($r,$t);
	$t = {};
	$t->{'type'} = 'bar';
	$t->{'val'}  = $v; 
	push @{$x->{tok}}, $t;
	return $t;
}

# ABC_gchord(obj,gchord)
sub ABC_gchord {
	local($x,$v) = @_;
	local($r,$t);
	$t = {};
	$t->{'type'} = 'gchord';
	$t->{'val'}  = $v; 
	push @{$x->{tok}}, $t;
	return $t;
}

# ABC_note(obj,pitch,length)
sub ABC_note {
	local($x,$p,$l) = @_;
	local($r,$t);
	$t = {};
	$t->{'type'}   = 'note';
	$t->{'pitch'}  = $p; 
	$t->{'len'}    = $l;
	push @{$x->{tok}}, $t;
	return $t;
}

# Parse some abc text, and build a parse tree for it in our ABC object.
sub ABC_Parse {
	local($x) = shift;		# ABC object to hold parsed music.
	local($src,$hdr,$txt);
	for $src (@_) {
		print STDERR "Parse: abc=\"$src\"\n" if $d>4;
		$x->{src} .= $src;	# Accumulate the abc source text.
	}
	$src = $x->{src};		# Parse the entire source.
	while ($src) {			# Each pass should eat at least 1 char.
		print STDERR "Parse: src=\"", substr($src,0,20), "\"\n" if $d>4;
		if ($src =~ s"^\s*\n\s*"") {
			print STDERR "Parse: Newline.\n" if $d>5;
		} elsif ($src =~ s"^([A-Z]):(.*?)(\n|[A-Z]:)"$3") {
			ABC_hdr($x,$1,0,$2);	# Add to object's headers.
		} elsif ($src =~ s"^([\[|:\]]+)"") {	# Bar line.
			ABC_bar($x,$1);
		} elsif ($src =~ s"^([A-Ga-g][,']*)([\d/]*)"") {	# Note
			ABC_note($x,$1,$2);
		} elsif ($src =~ s#^"([^"]*)"##) {	# Guitar chord.
			ABC_gchord($x,$1);
		} else {
			$src =~ s/^(.)//;
			print STDERR "Parse: SKIP '$1'\n" if $d>5;
		}
		print STDERR "Parse: now \"", substr($src,0,20), "\"\n" if $d>6;
	}
	return $x;
}

1;