[scpubgit/stemmatology.git] / lib / Text / Tradition / Parser / Self.pm

package Text::Tradition::Parser::Self;

use strict;
use warnings;
use Text::Tradition::Parser::GraphML qw/ graphml_parse /;
use Text::Tradition::UserStore;
use TryCatch;

=head1 NAME

Text::Tradition::Parser::GraphML

=head1 SYNOPSIS

  use Text::Tradition;
  
  my $t_from_file = Text::Tradition->new( 
    'name' => 'my text',
    'input' => 'Self',
    'file' => '/path/to/tradition.xml'
    );
    
  my $t_from_string = Text::Tradition->new( 
    'name' => 'my text',
    'input' => 'Self',
    'string' => $tradition_xml,
    );

=head1 DESCRIPTION

Parser module for Text::Tradition to read in its own GraphML output format.
GraphML is a relatively simple graph description language; a 'graph' element
can have 'node' and 'edge' elements, and each of these can have simple 'data'
elements for attributes to be saved.

The graph itself has attributes as in the Collation object:

=over

=item * linear 

=item * ac_label

=item * baselabel

=item * wit_list_separator

=back

The node objects have the following attributes:

=over

=item * name

=item * reading

=item * identical

=item * rank

=item * class

=back

The edge objects have the following attributes:

=over

=item * class

=item * witness (for 'path' class edges)

=item * extra   (for 'path' class edges)

=item * relationship    (for 'relationship' class edges)

=item * equal_rank      (for 'relationship' class edges)

=item * non_correctable (for 'relationship' class edges)

=item * non_independent (for 'relationship' class edges)

=back

=head1 METHODS

=head2 B<parse>

parse( $graph, $opts );

Takes an initialized Text::Tradition object and a set of options; creates
the appropriate nodes and edges on the graph.  The options hash should
include either a 'file' argument or a 'string' argument, depending on the
source of the XML to be parsed.

=begin testing

use File::Temp;
use Test::Warn;
use Text::Tradition;
binmode STDOUT, ":utf8";
binmode STDERR, ":utf8";
eval { no warnings; binmode $DB::OUT, ":utf8"; };

my $tradition = 't/data/florilegium_graphml.xml';
my $t = Text::Tradition->new( 
    'name'  => 'inline', 
    'input' => 'Self',
    'file'  => $tradition,
    );

is( ref( $t ), 'Text::Tradition', "Parsed GraphML version 2" );
if( $t ) {
    is( scalar $t->collation->readings, 319, "Collation has all readings" );
    is( scalar $t->collation->paths, 376, "Collation has all paths" );
    is( scalar $t->witnesses, 13, "Collation has all witnesses" );
}

# TODO add a relationship, add a stemma, write graphml, reparse it, check that 
# the new data is there
$t->language('Greek');
$t->add_stemma( 'dotfile' => 't/data/florilegium.dot' );
$t->collation->add_relationship( 'w12', 'w13', 
	{ 'type' => 'grammatical', 'scope' => 'global', 
	  'annotation' => 'This is some note' } );
ok( $t->collation->get_relationship( 'w12', 'w13' ), "Relationship set" );
my $graphml_str = $t->collation->as_graphml;

my $newt = Text::Tradition->new( 'input' => 'Self', 'string' => $graphml_str );
is( ref( $newt ), 'Text::Tradition', "Parsed current GraphML version" );
if( $newt ) {
    is( scalar $newt->collation->readings, 319, "Collation has all readings" );
    is( scalar $newt->collation->paths, 376, "Collation has all paths" );
    is( scalar $newt->witnesses, 13, "Collation has all witnesses" );
    is( scalar $newt->collation->relationships, 1, "Collation has added relationship" );
    is( $newt->language, 'Greek', "Tradition has correct language setting" );
    my $rel = $newt->collation->get_relationship( 'w12', 'w13' );
    ok( $rel, "Found set relationship" );
    is( $rel->annotation, 'This is some note', "Relationship has its properties" );
    is( scalar $newt->stemmata, 1, "Tradition has its stemma" );
    is( $newt->stemma(0)->witnesses, $t->stemma(0)->witnesses, "Stemma has correct length witness list" );
}

# Test user save / restore
my $fh = File::Temp->new();
my $file = $fh->filename;
$fh->close;
my $dsn = "dbi:SQLite:dbname=$file";
my $userstore = Text::Tradition::UserStore->new( { dsn => $dsn,
	extra_args => { create => 1 } } );
my $scope = $userstore->new_scope();
my $testuser = $userstore->add_user( { url => 'http://example.com' } );
is( ref( $testuser ), 'Text::Tradition::User', "Created test user via userstore" );
$testuser->add_tradition( $newt );
is( $newt->user->id, $testuser->id, "Assigned tradition to test user" );
$graphml_str = $newt->collation->as_graphml;
my $usert;
warning_is {
	$usert = Text::Tradition->new( 'input' => 'Self', 'string' => $graphml_str );
} 'DROPPING user assignment without a specified userstore',
	"Got expected user drop warning on parse";
$usert = Text::Tradition->new( 'input' => 'Self', 'string' => $graphml_str,
	'userstore' => { 'dsn' => $dsn } );
is( $usert->user->id, $testuser->id, "Parsed tradition with userstore points to correct user" );


=end testing

=cut

sub parse {
    my( $tradition, $opts ) = @_;
    
    # Collation data is in the first graph; relationship-specific stuff 
    # is in the second.
    my( $graph_data, $rel_data ) = graphml_parse( $opts );
    
    my $collation = $tradition->collation;
    my %witnesses;
    
    # print STDERR "Setting graph globals\n";
    $tradition->name( $graph_data->{'name'} );
    my $use_version;
    my $tmeta = $tradition->meta;
    my $cmeta = $collation->meta;
    foreach my $gkey ( keys %{$graph_data->{'global'}} ) {
		my $val = $graph_data->{'global'}->{$gkey};
		if( $gkey eq 'version' ) {
			$use_version = $val;
		} elsif( $gkey eq 'stemmata' ) {
			# Parse the stemmata into objects
			foreach my $dotstr ( split( /\n/, $val ) ) {
				$tradition->add_stemma( 'dot' => $dotstr );
			}
		} elsif( $gkey eq 'user' ) {
			# Assign the tradition to the user if we can
			if( exists $opts->{'userstore'} ) {
				my $userdir;
				try {
					$userdir = Text::Tradition::UserStore->new( $opts->{'userstore'} );
				} catch {
					warn( "Could not connect to specified user store; DROPPING user assignment" );
				}
				my $user = $userdir->find_user( { username => $val } );
				if( $user ) {
					$user->add_tradition( $tradition );
				} else {
					warn( "Found no user with ID $val; DROPPING user assignment" );
				}
			} else {
				warn( "DROPPING user assignment without a specified userstore" );
			}
		} elsif( $tmeta->has_attribute( $gkey ) ) {
			$tradition->$gkey( $val );
		} else {
			$collation->$gkey( $val );
		}
	}
		
    # Add the nodes to the graph.
    # Note any reading IDs that were changed in order to comply with XML 
    # name restrictions; we have to hardcode start & end.
    my %namechange = ( '#START#' => '__START__', '#END#' => '__END__' );

    # print STDERR "Adding collation readings\n";
    foreach my $n ( @{$graph_data->{'nodes'}} ) {    	
    	# If it is the start or end node, we already have one, so
    	# grab the rank and go.
    	next if( defined $n->{'is_start'} );
    	if( defined $n->{'is_end'} ) {
    		$collation->end->rank( $n->{'rank'} );
    		next;
    	}
		my $gnode = $collation->add_reading( $n );
		if( $gnode->id ne $n->{'id'} ) {
			$namechange{$n->{'id'}} = $gnode->id;
		}
    }
        
    # Now add the edges.
    # print STDERR "Adding collation path edges\n";
    foreach my $e ( @{$graph_data->{'edges'}} ) {
    	my $sourceid = exists $namechange{$e->{'source'}->{'id'}}
    		? $namechange{$e->{'source'}->{'id'}} : $e->{'source'}->{'id'};
    	my $targetid = exists $namechange{$e->{'target'}->{'id'}}
    		? $namechange{$e->{'target'}->{'id'}} : $e->{'target'}->{'id'};
        my $from = $collation->reading( $sourceid );
        my $to = $collation->reading( $targetid );

		warn "No witness label on path edge!" unless $e->{'witness'};
		my $label = $e->{'witness'} . ( $e->{'extra'} ? $collation->ac_label : '' );
		$collation->add_path( $from, $to, $label );
		
		# Add the witness if we don't have it already.
		unless( $witnesses{$e->{'witness'}} ) {
			$tradition->add_witness( 
				sigil => $e->{'witness'}, 'sourcetype' => 'collation' );
			$witnesses{$e->{'witness'}} = 1;
		}
		$tradition->witness( $e->{'witness'} )->is_layered( 1 ) if $e->{'extra'};
    }
    
    ## Done with the main graph, now look at the relationships.
	# Nodes are added via the call to add_reading above.  We only need
	# add the relationships themselves.
	# TODO check that scoping does trt
	$rel_data->{'edges'} ||= []; # so that the next line doesn't break on no rels
	foreach my $e ( sort { _layersort_rel( $a, $b ) } @{$rel_data->{'edges'}} ) {
    	my $sourceid = exists $namechange{$e->{'source'}->{'id'}}
    		? $namechange{$e->{'source'}->{'id'}} : $e->{'source'}->{'id'};
    	my $targetid = exists $namechange{$e->{'target'}->{'id'}}
    		? $namechange{$e->{'target'}->{'id'}} : $e->{'target'}->{'id'};
        my $from = $collation->reading( $sourceid );
        my $to = $collation->reading( $targetid );
		delete $e->{'source'};
		delete $e->{'target'};
		# The remaining keys are relationship attributes.
		# Backward compatibility...
		if( $use_version eq '2.0' || $use_version eq '3.0' ) {
			delete $e->{'class'};
			$e->{'type'} = delete $e->{'relationship'} if exists $e->{'relationship'};
		}
		# Add the specified relationship unless we already have done.
		my $rel_exists;
		if( $e->{'scope'} ne 'local' ) {
			my $relobj = $collation->get_relationship( $from, $to );
			if( $relobj && $relobj->scope eq $e->{'scope'}
				&& $relobj->type eq $e->{'type'} ) {
				$rel_exists = 1;
			}
		}
		try {
			$collation->add_relationship( $from, $to, $e ) unless $rel_exists;
		} catch( Text::Tradition::Error $e ) {
			warn "DROPPING $from -> $to: " . $e->message;
		}
	}
	
    # Save the text for each witness so that we can ensure consistency
    # later on
	$collation->text_from_paths();	
}

## Return the relationship that comes first in priority.
my %LAYERS = (
	'collated' => 1,
	'orthographic' => 2,
	'spelling' => 3,
	);

sub _layersort_rel {
	my( $a, $b ) = @_;
	my $key = exists $a->{'type'} ? 'type' : 'relationship';
	my $at = $LAYERS{$a->{$key}} || 99;
	my $bt = $LAYERS{$b->{$key}} || 99;
	return $at <=> $bt;
}

1;

=head1 BUGS / TODO

=over

=item * Make this into a stream parser with GraphML

=item * Simply field -> attribute correspondence for nodes and edges

=item * Share key name constants with Collation.pm

=back

=head1 LICENSE

This package is free software and is provided "as is" without express
or implied warranty.  You can redistribute it and/or modify it under
the same terms as Perl itself.

=head1 AUTHOR

Tara L Andrews E<lt>aurum@cpan.orgE<gt>
Commit	Line	Data
32014ec9	1	package Text::Tradition::Parser::Self;
	2
	3	use strict;
	4	use warnings;
1f7aa795	5	use Text::Tradition::Parser::GraphML qw/ graphml_parse /;
9fef629b	6	use Text::Tradition::UserStore;
00c5bf0b	7	use TryCatch;
32014ec9	8
	9	=head1 NAME
	10
	11	Text::Tradition::Parser::GraphML
	12
e867486f	13	=head1 SYNOPSIS
	14
	15	use Text::Tradition;
	16
	17	my $t_from_file = Text::Tradition->new(
	18	'name' => 'my text',
	19	'input' => 'Self',
	20	'file' => '/path/to/tradition.xml'
	21	);
	22
	23	my $t_from_string = Text::Tradition->new(
	24	'name' => 'my text',
	25	'input' => 'Self',
	26	'string' => $tradition_xml,
	27	);
	28
32014ec9	29	=head1 DESCRIPTION
	30
	31	Parser module for Text::Tradition to read in its own GraphML output format.
e867486f	32	GraphML is a relatively simple graph description language; a 'graph' element
	33	can have 'node' and 'edge' elements, and each of these can have simple 'data'
	34	elements for attributes to be saved.
32014ec9	35
e867486f	36	The graph itself has attributes as in the Collation object:
	37
	38	=over
	39
	40	=item * linear
	41
	42	=item * ac_label
	43
	44	=item * baselabel
	45
	46	=item * wit_list_separator
	47
	48	=back
	49
	50	The node objects have the following attributes:
32014ec9	51
	52	=over
	53
e867486f	54	=item * name
	55
	56	=item * reading
	57
	58	=item * identical
	59
	60	=item * rank
	61
	62	=item * class
	63
	64	=back
	65
	66	The edge objects have the following attributes:
	67
	68	=over
	69
	70	=item * class
	71
	72	=item * witness (for 'path' class edges)
	73
	74	=item * extra (for 'path' class edges)
	75
	76	=item * relationship (for 'relationship' class edges)
	77
	78	=item * equal_rank (for 'relationship' class edges)
32014ec9	79
e867486f	80	=item * non_correctable (for 'relationship' class edges)
32014ec9	81
e867486f	82	=item * non_independent (for 'relationship' class edges)
	83
	84	=back
	85
	86	=head1 METHODS
	87
	88	=head2 B<parse>
	89
	90	parse( $graph, $opts );
	91
	92	Takes an initialized Text::Tradition object and a set of options; creates
	93	the appropriate nodes and edges on the graph. The options hash should
	94	include either a 'file' argument or a 'string' argument, depending on the
	95	source of the XML to be parsed.
	96
	97	=begin testing
	98
9fef629b	99	use File::Temp;
9fef629b	100	use Test::Warn;
e867486f	101	use Text::Tradition;
	102	binmode STDOUT, ":utf8";
	103	binmode STDERR, ":utf8";
	104	eval { no warnings; binmode $DB::OUT, ":utf8"; };
	105
	106	my $tradition = 't/data/florilegium_graphml.xml';
	107	my $t = Text::Tradition->new(
	108	'name' => 'inline',
	109	'input' => 'Self',
	110	'file' => $tradition,
	111	);
	112
bbd064a9	113	is( ref( $t ), 'Text::Tradition', "Parsed GraphML version 2" );
e867486f	114	if( $t ) {
e867486f	115	is( scalar $t->collation->readings, 319, "Collation has all readings" );
255875b8	116	is( scalar $t->collation->paths, 376, "Collation has all paths" );
e867486f	117	is( scalar $t->witnesses, 13, "Collation has all witnesses" );
	118	}
	119
2a812726	120	# TODO add a relationship, add a stemma, write graphml, reparse it, check that
2a812726	121	# the new data is there
bbd064a9	122	$t->language('Greek');
2a812726	123	$t->add_stemma( 'dotfile' => 't/data/florilegium.dot' );
bbd064a9	124	$t->collation->add_relationship( 'w12', 'w13',
	125	{ 'type' => 'grammatical', 'scope' => 'global',
	126	'annotation' => 'This is some note' } );
	127	ok( $t->collation->get_relationship( 'w12', 'w13' ), "Relationship set" );
	128	my $graphml_str = $t->collation->as_graphml;
	129
	130	my $newt = Text::Tradition->new( 'input' => 'Self', 'string' => $graphml_str );
	131	is( ref( $newt ), 'Text::Tradition', "Parsed current GraphML version" );
	132	if( $newt ) {
	133	is( scalar $newt->collation->readings, 319, "Collation has all readings" );
	134	is( scalar $newt->collation->paths, 376, "Collation has all paths" );
	135	is( scalar $newt->witnesses, 13, "Collation has all witnesses" );
	136	is( scalar $newt->collation->relationships, 1, "Collation has added relationship" );
	137	is( $newt->language, 'Greek', "Tradition has correct language setting" );
	138	my $rel = $newt->collation->get_relationship( 'w12', 'w13' );
	139	ok( $rel, "Found set relationship" );
	140	is( $rel->annotation, 'This is some note', "Relationship has its properties" );
2a812726	141	is( scalar $newt->stemmata, 1, "Tradition has its stemma" );
2a812726	142	is( $newt->stemma(0)->witnesses, $t->stemma(0)->witnesses, "Stemma has correct length witness list" );
bbd064a9	143	}
bbd064a9	144
9fef629b	145	# Test user save / restore
	146	my $fh = File::Temp->new();
	147	my $file = $fh->filename;
	148	$fh->close;
	149	my $dsn = "dbi:SQLite:dbname=$file";
	150	my $userstore = Text::Tradition::UserStore->new( { dsn => $dsn,
	151	extra_args => { create => 1 } } );
	152	my $scope = $userstore->new_scope();
	153	my $testuser = $userstore->add_user( { url => 'http://example.com' } );
	154	is( ref( $testuser ), 'Text::Tradition::User', "Created test user via userstore" );
	155	$testuser->add_tradition( $newt );
	156	is( $newt->user->id, $testuser->id, "Assigned tradition to test user" );
	157	$graphml_str = $newt->collation->as_graphml;
	158	my $usert;
	159	warning_is {
	160	$usert = Text::Tradition->new( 'input' => 'Self', 'string' => $graphml_str );
	161	} 'DROPPING user assignment without a specified userstore',
	162	"Got expected user drop warning on parse";
	163	$usert = Text::Tradition->new( 'input' => 'Self', 'string' => $graphml_str,
	164	'userstore' => { 'dsn' => $dsn } );
	165	is( $usert->user->id, $testuser->id, "Parsed tradition with userstore points to correct user" );
	166
bbd064a9	167
e867486f	168	=end testing
32014ec9	169
	170	=cut
	171
32014ec9	172	sub parse {
dfc37e38	173	my( $tradition, $opts ) = @_;
2626f709	174
	175	# Collation data is in the first graph; relationship-specific stuff
	176	# is in the second.
	177	my( $graph_data, $rel_data ) = graphml_parse( $opts );
94c00c71	178
32014ec9	179	my $collation = $tradition->collation;
32014ec9	180	my %witnesses;
e309421a	181
0068967c	182	# print STDERR "Setting graph globals\n";
e3196b2a	183	$tradition->name( $graph_data->{'name'} );
2626f709	184	my $use_version;
bbd064a9	185	my $tmeta = $tradition->meta;
bbd064a9	186	my $cmeta = $collation->meta;
255875b8	187	foreach my $gkey ( keys %{$graph_data->{'global'}} ) {
	188	my $val = $graph_data->{'global'}->{$gkey};
	189	if( $gkey eq 'version' ) {
	190	$use_version = $val;
9fef629b	191	} elsif( $gkey eq 'stemmata' ) {
9fef629b	192	# Parse the stemmata into objects
2a812726	193	foreach my $dotstr ( split( /\n/, $val ) ) {
	194	$tradition->add_stemma( 'dot' => $dotstr );
	195	}
9fef629b	196	} elsif( $gkey eq 'user' ) {
	197	# Assign the tradition to the user if we can
	198	if( exists $opts->{'userstore'} ) {
	199	my $userdir;
	200	try {
	201	$userdir = Text::Tradition::UserStore->new( $opts->{'userstore'} );
	202	} catch {
	203	warn( "Could not connect to specified user store; DROPPING user assignment" );
	204	}
	205	my $user = $userdir->find_user( { username => $val } );
	206	if( $user ) {
	207	$user->add_tradition( $tradition );
	208	} else {
	209	warn( "Found no user with ID $val; DROPPING user assignment" );
	210	}
	211	} else {
	212	warn( "DROPPING user assignment without a specified userstore" );
	213	}
bbd064a9	214	} elsif( $tmeta->has_attribute( $gkey ) ) {
bbd064a9	215	$tradition->$gkey( $val );
255875b8	216	} else {
	217	$collation->$gkey( $val );
	218	}
	219	}
e309421a	220
10e4b1ac	221	# Add the nodes to the graph.
	222	# Note any reading IDs that were changed in order to comply with XML
	223	# name restrictions; we have to hardcode start & end.
	224	my %namechange = ( '#START#' => '__START__', '#END#' => '__END__' );
32014ec9	225
bbd064a9	226	# print STDERR "Adding collation readings\n";
2626f709	227	foreach my $n ( @{$graph_data->{'nodes'}} ) {
0174d6a9	228	# If it is the start or end node, we already have one, so
0174d6a9	229	# grab the rank and go.
bbd064a9	230	next if( defined $n->{'is_start'} );
	231	if( defined $n->{'is_end'} ) {
	232	$collation->end->rank( $n->{'rank'} );
0174d6a9	233	next;
0174d6a9	234	}
bbd064a9	235	my $gnode = $collation->add_reading( $n );
10e4b1ac	236	if( $gnode->id ne $n->{'id'} ) {
	237	$namechange{$n->{'id'}} = $gnode->id;
	238	}
32014ec9	239	}
910a0a6d	240
32014ec9	241	# Now add the edges.
bbd064a9	242	# print STDERR "Adding collation path edges\n";
32014ec9	243	foreach my $e ( @{$graph_data->{'edges'}} ) {
10e4b1ac	244	my $sourceid = exists $namechange{$e->{'source'}->{'id'}}
	245	? $namechange{$e->{'source'}->{'id'}} : $e->{'source'}->{'id'};
	246	my $targetid = exists $namechange{$e->{'target'}->{'id'}}
	247	? $namechange{$e->{'target'}->{'id'}} : $e->{'target'}->{'id'};
	248	my $from = $collation->reading( $sourceid );
	249	my $to = $collation->reading( $targetid );
bbd064a9	250
	251	warn "No witness label on path edge!" unless $e->{'witness'};
	252	my $label = $e->{'witness'} . ( $e->{'extra'} ? $collation->ac_label : '' );
	253	$collation->add_path( $from, $to, $label );
	254
2626f709	255	# Add the witness if we don't have it already.
bbd064a9	256	unless( $witnesses{$e->{'witness'}} ) {
82fa4d57	257	$tradition->add_witness(
82fa4d57	258	sigil => $e->{'witness'}, 'sourcetype' => 'collation' );
bbd064a9	259	$witnesses{$e->{'witness'}} = 1;
255875b8	260	}
bbd064a9	261	$tradition->witness( $e->{'witness'} )->is_layered( 1 ) if $e->{'extra'};
32014ec9	262	}
2626f709	263
	264	## Done with the main graph, now look at the relationships.
	265	# Nodes are added via the call to add_reading above. We only need
	266	# add the relationships themselves.
	267	# TODO check that scoping does trt
bf6e338d	268	$rel_data->{'edges'} \|\|= []; # so that the next line doesn't break on no rels
bf6e338d	269	foreach my $e ( sort { _layersort_rel( $a, $b ) } @{$rel_data->{'edges'}} ) {
10e4b1ac	270	my $sourceid = exists $namechange{$e->{'source'}->{'id'}}
	271	? $namechange{$e->{'source'}->{'id'}} : $e->{'source'}->{'id'};
	272	my $targetid = exists $namechange{$e->{'target'}->{'id'}}
	273	? $namechange{$e->{'target'}->{'id'}} : $e->{'target'}->{'id'};
	274	my $from = $collation->reading( $sourceid );
	275	my $to = $collation->reading( $targetid );
bbd064a9	276	delete $e->{'source'};
	277	delete $e->{'target'};
	278	# The remaining keys are relationship attributes.
	279	# Backward compatibility...
	280	if( $use_version eq '2.0' \|\| $use_version eq '3.0' ) {
	281	delete $e->{'class'};
	282	$e->{'type'} = delete $e->{'relationship'} if exists $e->{'relationship'};
	283	}
	284	# Add the specified relationship unless we already have done.
fdfa59a7	285	my $rel_exists;
bbd064a9	286	if( $e->{'scope'} ne 'local' ) {
	287	my $relobj = $collation->get_relationship( $from, $to );
	288	if( $relobj && $relobj->scope eq $e->{'scope'}
	289	&& $relobj->type eq $e->{'type'} ) {
fdfa59a7	290	$rel_exists = 1;
	291	}
	292	}
00c5bf0b	293	try {
	294	$collation->add_relationship( $from, $to, $e ) unless $rel_exists;
	295	} catch( Text::Tradition::Error $e ) {
	296	warn "DROPPING $from -> $to: " . $e->message;
	297	}
2626f709	298	}
861c3e27	299
	300	# Save the text for each witness so that we can ensure consistency
	301	# later on
bbd064a9	302	$collation->text_from_paths();
32014ec9	303	}
32014ec9	304
bf6e338d	305	## Return the relationship that comes first in priority.
	306	my %LAYERS = (
	307	'collated' => 1,
	308	'orthographic' => 2,
	309	'spelling' => 3,
	310	);
	311
	312	sub _layersort_rel {
	313	my( $a, $b ) = @_;
	314	my $key = exists $a->{'type'} ? 'type' : 'relationship';
	315	my $at = $LAYERS{$a->{$key}} \|\| 99;
	316	my $bt = $LAYERS{$b->{$key}} \|\| 99;
	317	return $at <=> $bt;
	318	}
	319
e867486f	320	1;
	321
	322	=head1 BUGS / TODO
	323
	324	=over
	325
	326	=item * Make this into a stream parser with GraphML
	327
	328	=item * Simply field -> attribute correspondence for nodes and edges
	329
	330	=item * Share key name constants with Collation.pm
	331
32014ec9	332	=back
	333
	334	=head1 LICENSE
	335
	336	This package is free software and is provided "as is" without express
	337	or implied warranty. You can redistribute it and/or modify it under
	338	the same terms as Perl itself.
	339
	340	=head1 AUTHOR
	341
e867486f	342	Tara L Andrews E<lt>aurum@cpan.orgE<gt>