+# id3fs - a FUSE-based filesystem for browsing audio metadata
+# Copyright (C) 2010 Ian Beckwith <ianb@erislabs.net>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
package ID3FS::Path;
use strict;
use warnings;
use ID3FS::Path::Node;
-our ($STATE_INVALID, $STATE_ROOT, $STATE_TAG, $STATE_TAGVAL,
- $STATE_BOOLEAN, $STATE_ALBUMS, $STATE_TRACKLIST,
- $STATE_FILE, $STATE_ALL)=(0..8);
+our ($STATE_INVALID, $STATE_ROOT, $STATE_TAG, $STATE_BOOLEAN,
+ $STATE_ALBUMS, $STATE_TRACKLIST, $STATE_FILE, $STATE_ALL)=(0..7);
+# operator precedence
our %priorities=( "OR" => 0, "AND" => 1, "NOT" => 2 );
-our $PATH_ALLTRACKS="TRACKS";
-our $PATH_NOARTIST="NOARTIST";
-our $PATH_NOALBUM="NOALBUM";
+our $PATH_ALLTRACKS= "TRACKS";
+our $PATH_NOARTIST = "NOARTIST";
+our $PATH_NOALBUM = "NOALBUM";
+
+our $ENABLE_FILTER = 0;
sub new
{
$self->{path} =~ s/\/\//\//g; # drop doubled slashes
$self->parse();
-# print "STATE: ", $self->state(), "\n";
return $self;
}
my @dents=();
my @fents=();
my $state=$self->state();
-# print "DIRENTS: STATE: $state\n";
-# print "DIRENTS: FILE: $self->{path}\n";
if($state==$STATE_ALL)
{
- @dents=($PATH_ALLTRACKS, $PATH_NOARTIST, $self->artists());
+ @dents=($self->filter($PATH_ALLTRACKS, $PATH_NOARTIST), $self->artists());
}
- elsif($state==$STATE_TAG || $state==$STATE_TAGVAL)
+ elsif($state==$STATE_TAG)
{
- if($state==$STATE_TAG && $self->at("tag") &&
- $self->{db}->tag_has_values($self->tail()->id()))
+ my $tail=$self->tail();
+ if($self->is($TYPE_TAG, $tail) && $self->{db}->tag_has_values($tail->id()))
{
@dents=$self->tags();
}
{
@dents=qw(AND OR);
}
- push(@dents, $self->filter($PATH_ALLTRACKS, $PATH_NOARTIST));
- push(@dents, $self->artists());
+ push(@dents, $self->filter($PATH_ALLTRACKS, $PATH_NOARTIST), $self->artists());
}
}
elsif($state==$STATE_BOOLEAN)
{
my $parent=$self->tail();
- unless($self->is("boolean", $parent) &&
- $parent->{name} eq "NOT")
+ unless($self->is($TYPE_BOOL, $parent) && $parent->name() eq "NOT")
{
@dents=("NOT");
}
}
elsif($state==$STATE_ALBUMS)
{
- @dents=($self->filter($PATH_ALLTRACKS, $PATH_NOALBUM), $self->albums());
+ @dents=$self->filter($PATH_ALLTRACKS, $PATH_NOALBUM, $self->albums());
}
elsif($state==$STATE_TRACKLIST)
{
}
else
{
- print "DIRENTS: UNHANDLED STATE: $state\n";
+ print "id3fsd: INTERNAL ERROR: DIRENTS: UNHANDLED STATE: $state\n";
}
return(\@dents, \@fents);
}
+# State Machine Of Doom
sub parse
{
my($self)=@_;
- @{$self->{components}}=split(/\//, $self->{path});
- shift @{$self->{components}}; # drop empty field before leading /
-# print "PATH: $self->{path}\n";
$self->state($STATE_ROOT);
return if($self->{path} eq "/");
+ @{$self->{components}}=split(/\//, $self->{path});
+ shift @{$self->{components}}; # drop empty field before leading /
my @parts=@{$self->{components}};
my($tag, $tagval);
$self->{elements}=[];
- $self->{bare_not}=0;
$self->{in_all}=0;
my $root_not=0;
my $tags_seen=0;
while(defined(my $name=shift @parts))
{
-# print "NAME: $name\n";
my $state=$self->state();
if($state==$STATE_INVALID)
{
-# print "SM: INVALID: $name\n";
return;
}
elsif($state==$STATE_ROOT)
{
-# print "SM: ROOT: $name\n";
if($name eq "ALL")
{
$self->{in_all}=1;
elsif($name eq "NOT")
{
$root_not=1;
- push(@{$self->{elements}}, ID3FS::Path::Node->new($self->{db}, "boolean", $name));
+ push(@{$self->{elements}}, ID3FS::Path::Node->new($self->{db}, $TYPE_BOOL, $name));
$self->state($STATE_BOOLEAN);
}
else
{
- $tag=ID3FS::Path::Node->new($self->{db},"tag", $name);
+ $tag=ID3FS::Path::Node->new($self->{db}, $TYPE_TAG, $name);
if($tag)
{
push(@{$self->{elements}}, $tag);
}
}
}
- elsif($state==$STATE_TAG || $state==$STATE_TAGVAL)
+ elsif($state==$STATE_TAG)
{
my $tag=$self->tail();
-# print "SM: TAG/TAGVAL($state): $name\n";
- if($state==$STATE_TAG && $self->is("tag", $tag) &&
- $self->{db}->tag_has_values($tag->id()))
+ if($self->is($TYPE_TAG, $tag) && $self->{db}->tag_has_values($tag->id()))
{
-# print "Parsing: parent: $tag->id()\n";
- my $tagval=ID3FS::Path::Node->new($self->{db}, "tag", $name, $tag->id());
+ my $tagval=ID3FS::Path::Node->new($self->{db}, $TYPE_TAG, $name, $tag->id());
if(defined($tagval))
{
- $self->state($STATE_TAGVAL);
# stay in tag state
push(@{$self->{elements}}, $tagval);
}
elsif($name eq "AND")
{
$self->state($STATE_BOOLEAN);
- push(@{$self->{elements}}, ID3FS::Path::Node->new($self->{db}, "boolean", $name));
+ push(@{$self->{elements}}, ID3FS::Path::Node->new($self->{db}, $TYPE_BOOL, $name));
}
elsif($name eq "OR")
{
$self->state($STATE_BOOLEAN);
- push(@{$self->{elements}}, ID3FS::Path::Node->new($self->{db}, "boolean", $name));
+ push(@{$self->{elements}}, ID3FS::Path::Node->new($self->{db}, $TYPE_BOOL, $name));
}
else
{
- my $artist=ID3FS::Path::Node->new($self->{db}, "artist", $name);
+ my $artist=ID3FS::Path::Node->new($self->{db}, $TYPE_ARTIST, $name);
if($artist)
{
push(@{$self->{elements}}, $artist);
}
elsif($state==$STATE_BOOLEAN)
{
-# print "SM: BOOLEAN: $name\n";
my $parent=$self->tail();
my $allownot=1;
- if($self->is("boolean", $parent) &&
- $parent->{name} eq "NOT")
+ if($self->is($TYPE_BOOL, $parent) &&
+ $parent->name() eq "NOT")
{
$allownot=0;
}
if($allownot && $name eq "NOT")
{
$self->state($STATE_BOOLEAN);
- push(@{$self->{elements}}, ID3FS::Path::Node->new($self->{db}, "boolean", $name));
+ push(@{$self->{elements}}, ID3FS::Path::Node->new($self->{db}, $TYPE_BOOL, $name));
}
else
{
- my $tag=ID3FS::Path::Node->new($self->{db}, "tag", $name);
+ my $tag=ID3FS::Path::Node->new($self->{db}, $TYPE_TAG, $name);
if($tag)
{
push(@{$self->{elements}}, $tag);
}
elsif($state==$STATE_ALBUMS)
{
-# print "SM: ALBUM: $name\n";
if($name eq $PATH_ALLTRACKS)
{
$self->state($STATE_TRACKLIST);
}
else
{
- my $album=ID3FS::Path::Node->new($self->{db}, "album", $name);
+ my $album=ID3FS::Path::Node->new($self->{db}, $TYPE_ALBUM, $name);
if($album)
{
push(@{$self->{elements}}, $album);
}
elsif($state==$STATE_TRACKLIST)
{
-# print "SM: TRACKLIST: $name\n";
- my $track=ID3FS::Path::Node->new($self->{db}, "file", $name);
+ my $track=ID3FS::Path::Node->new($self->{db}, $TYPE_FILE, $name);
if($track)
{
push(@{$self->{elements}}, $track);
}
elsif($state==$STATE_FILE)
{
-# print "SM: FILE: $name\n";
# Can't have anything after a filename
$self->state($STATE_INVALID);
}
}
else
{
- my $artist=ID3FS::Path::Node->new($self->{db}, "artist", $name);
+ my $artist=ID3FS::Path::Node->new($self->{db}, $TYPE_ARTIST, $name);
if($artist)
{
push(@{$self->{elements}}, $artist);
}
}
- if($root_not && ($tags_seen < 2))
- {
- $self->{bare_not}=1;
- }
-
- # remove trailing boolean
my @elements=@{$self->{elements}};
- while(@elements && $self->is("boolean", $elements[$#elements]))
+ # remove trailing boolean
+ while(@elements && $self->is($TYPE_BOOL, $elements[$#elements]))
{
pop @elements;
}
+
+ # calculate joins and assign table numbers to nodes
+ $self->{joins}=[$self->number_joins(@elements)];
+
+ # always need at least one join
+ $self->{joins}=[qw(INNER)] unless(@{$self->{joins}});
+
# sort elements by precedence
@elements=$self->sort_elements(@elements);
+
+ # convert to binary tree
$self->{tagtree}=$self->elements_to_tree(\@elements);
- if($self->{tagtree})
+}
+
+sub number_joins
+{
+ my($self, @elements)=@_;
+ my @joins=("INNER");
+ my $table=1;
+ my $nextjoin=undef;
+ my $lastop=undef;
+ return (@joins) unless(@elements);
+ while(my $node=shift @elements)
{
-# my ($conditions, @joins)=$self->{tagtree}->to_sql();
-# print "CONDITIONS(", scalar(@joins), "): ", $conditions, "\n";
+ if($node->type() == $TYPE_BOOL)
+ {
+ my $op=$node->name();
+ if($op eq "AND")
+ {
+ $nextjoin="INNER";
+ }
+ elsif($op eq "NOT")
+ {
+ $nextjoin="LEFT";
+ }
+ elsif($op eq "OR")
+ {
+ # NOT/foo/OR needs an extra join
+ $nextjoin="INNER" if($lastop && $lastop eq "NOT");
+ }
+ $lastop=$op;
+ }
+ else
+ {
+ $node->hasvals(0);
+ if(@elements)
+ {
+ # if tag has a value, eat the tag, shifting to the value
+ if($elements[0]->type() == $TYPE_TAG)
+ {
+ $node->hasvals(1);
+ $node=shift(@elements);
+ }
+ }
+ elsif($self->{db}->tag_has_values($node->id()))
+ {
+ # if the expression ends in a tag that has a value
+ # (ie we have the tag and want the value)
+ # use an INNER join even if we were in a NOT
+ $nextjoin="INNER" if($nextjoin);
+ }
+ if($nextjoin)
+ {
+ $table++;
+ push(@joins, $nextjoin);
+ $nextjoin=undef;
+ }
+ $node->table($table);
+ }
}
+ return @joins;
}
sub state
return $self->{state};
}
+# link up precedence-sorted list into a binary tree
sub elements_to_tree
{
my($self, $elements)=@_;
return undef unless(@$elements);
my ($left, $right, $op)=(undef, undef, undef);
- my $thing=pop @$elements;
- if($self->is("boolean", $thing))
+ my $node=pop @$elements;
+ if($self->is($TYPE_BOOL, $node))
{
$right=$self->elements_to_tree($elements);
- if($thing->{name} ne "NOT")
+ if($node->name() ne "NOT")
{
$left=$self->elements_to_tree($elements);
}
- $thing->left($left);
- $thing->right($right);
+ $node->left($left);
+ $node->right($right);
}
- return $thing;
+ return $node;
}
# Dijkstra's shunting-yard algorithm
my ($self, @input)=@_;
my @opstack=();
my @output=();
-# print "INPUT: ", join(', ', map { $_->{name}; } @input), "\n";
- while(my $thing = shift @input)
+ while(my $node = shift @input)
{
- if($self->is("tag", $thing))
+ if($self->is($TYPE_TAG, $node))
{
# Handle tag values by dropping parent
- if(@input && $self->is("tag", $input[0]))
+ if(@input && $self->is($TYPE_TAG, $input[0]))
{
- $thing=shift @input;
+ $node=shift @input;
}
- push(@output, $thing);
+ push(@output, $node);
}
- elsif($self->is("boolean", $thing))
+ elsif($self->is($TYPE_BOOL, $node))
{
- # bool
while(@opstack &&
- ($priorities{$thing->{name}} <= $priorities{$opstack[$#opstack]->{name}}))
+ ($priorities{$node->name()} <= $priorities{$opstack[$#opstack]->name()}))
{
push(@output, pop(@opstack));
}
- push(@opstack, $thing);
+ push(@opstack, $node);
}
}
while(@opstack)
{
push(@output, pop(@opstack));
}
-# print "STACK: ", join(', ', map { $_->{name}; } @output), "\n";
return @output;
}
{
my($self)=@_;
my $tail=$self->tail();
- if($self->is("tag", $tail))
+ if($self->is($TYPE_TAG, $tail))
{
return($self->{db}->tag_has_values($tail->id()));
}
{
my($self)=@_;
my $tail=$self->tail();
- if($self->is("tag", $tail))
+ if($self->is($TYPE_TAG, $tail))
{
return($tail->id());
}
{
my($self)=@_;
my $tail=$self->tail();
- if($self->is("tag", $tail))
+ if($self->is($TYPE_TAG, $tail))
{
return($tail->{parents_id});
}
return($self->{elements}->[$#{$self->{elements}}]);
}
-sub at
-{
- my($self, $type)=@_;
- return($self->is($type, $self->tail()));
-}
-
sub is
{
- my($self, $type, $thing)=@_;
- return 0 unless($thing);
- return 0 unless($thing->type());
- return 1 if($type eq $thing->type());
+ my($self, $type, $node)=@_;
+ return 0 unless($node);
+ return 0 unless($node->type());
+ return 1 if($type == $node->type());
return 0;
}
my $sql="SELECT DISTINCT name FROM tags WHERE parents_id='';";
return($self->{db}->cmd_firstcol($sql));
}
- my $hasvals=$self->expecting_values();
- my $parent=$self->trailing_tag_parent();
-# print "THASVALS: $hasvals\n";
-# print "TPARENT: ", (defined($parent)? $parent : "NO"), "\n";
- my @ids=();
- my $sql=("SELECT tags.name FROM (\n" .
- $self->tags_subselect() .
- ") AS subselect\n" .
- "INNER JOIN files_x_tags ON subselect.files_id=files_x_tags.files_id\n" .
- "INNER JOIN tags ON files_x_tags.tags_id=tags.id\n");
- my @allused=$self->used_tags();
- my @used=grep { ref($_) ne "ARRAY"; } @allused;
- my @used_with_vals=grep { ref($_) eq "ARRAY"; } @allused;
-# print "tags(): USED: ", join(", ", @used), "\n";
-# print "tags(): USED_WITH_VALS: ", join(", ", map { "[".$_->[0]. ", ".$_->[1]."]";} @used_with_vals), "\n";
- my @orclauses=();
- my @andclauses=();
- my $id=$self->trailing_tag_id();
- if($hasvals)
+ my $sql="SELECT tags.name FROM ";
+ if($self->want_all_tags())
{
-# print "HAS_VALUES\n";
- my @values=map { "'".$_->[1]."'"; } grep { $_->[0] == $id; } @used_with_vals;
- my $clause="(tags.parents_id='$id'";
- if(@values)
- {
- $clause .= " AND tags.id NOT IN (" . join(', ', @values) . ")";
- }
- $clause .= ")";
- push(@andclauses, $clause);
+ $sql .= "files_x_tags\n";
}
else
{
-# print "HASNT VALUES\n";;
- if(@used)
- {
- push(@andclauses, "(NOT (tags.parents_id='' AND tags.id IN (" . join(', ', @used) . ")))");
- }
- for my $pair (@used_with_vals)
- {
- push(@andclauses, "(NOT (tags.parents_id='" . $pair->[0] . "' AND tags.id='" . $pair->[1] . "'))");
- }
+ $sql .= ("(\n" .
+ $self->tags_subselect() .
+ ") AS subselect\n" .
+ "INNER JOIN files_x_tags ON subselect.files_id=files_x_tags.files_id\n");
}
+ $sql .= "INNER JOIN tags ON files_x_tags.tags_id=tags.id\n";
+ my @andclauses=();
+ my $id=$self->trailing_tag_id();
- my $parentclause= "(tags.parents_id='";
- if($hasvals)
- {
- $parentclause .= $id;
- }
- elsif($parent)
- {
- $parentclause .= $parent;
- }
- $parentclause .= "')";
+ my $parentclause= "tags.parents_id='";
+ $parentclause .= $id if($self->expecting_values());
+ $parentclause .= "'";
push(@andclauses, $parentclause);
- if(@orclauses)
+ my @used=$self->used_tags();
+ if(@used)
{
- push(@andclauses, '( ' . join(' OR ', @orclauses) . ' )');
+ push(@andclauses, "tags.id NOT IN (" . join(', ', @used) . ")");
}
if(@andclauses)
{
$sql .= "WHERE " . join(' AND ', @andclauses) . "\n";
}
+
$sql .= "GROUP BY tags.name;";
print "SQL(TAGS): $sql\n" if($self->{verbose});
my @tagnames=$self->{db}->cmd_firstcol($sql);
my $sql="SELECT DISTINCT name FROM artists WHERE name!='';";
return($self->{db}->cmd_firstcol($sql));
}
- my @ids=();
my $sql=$self->sql_start("artists.name");
$sql .= ("INNER JOIN artists ON files.artists_id=artists.id\n" .
"WHERE artists.name != ''\n" .
sub albums
{
my($self)=@_;
- my @ids=();
my $tail=$self->tail();
- if($self->is("artist", $tail))
+ if($self->is($TYPE_ARTIST, $tail))
{
return $self->artist_albums($tail->id());
}
{
my($self)=@_;
my $tail=$self->tail();
- if($self->is("artist", $tail))
+ if($self->is($TYPE_ARTIST, $tail))
{
return $self->artist_tracks($tail->id());
}
- elsif($self->is("album", $tail))
+ elsif($self->is($TYPE_ALBUM, $tail))
{
my $artist_id=0;
my $artist=$self->tail_parent();
- if($self->is("artist", $artist))
+ if($self->is($TYPE_ARTIST, $artist))
{
# should always happen
$artist_id=$artist->id();
{
my($self, $mountpoint)=@_;
my $tail=$self->tail();
- if($self->is("file", $tail))
+ if($self->is($TYPE_FILE, $tail))
{
my $id=$tail->id();
my $sql=("SELECT paths.name, files.name FROM files\n" .
"GROUP BY paths.name, files.name");
print "FILENAME SQL: $sql\n" if($self->{verbose});
my ($path, $name)=$self->{db}->cmd_onerow($sql, $id);
- my $id3fs_path=join('/', map { $_->{name}; } @{$self->{elements}});
- return($self->{db}->relativise($path, $name, $mountpoint));
+ return($self->{db}->relativise($path, $name, $mountpoint, $self->{path}));
}
# should never happen
return "ERROR";
sub tags_subselect
{
my($self)=@_;
- my $hasvals=$self->expecting_values();
- # we need to specially handle a bare /NOT/tag with no other clauses,
- # using a simple WHERE id !='tagid' instead of a LEFT JOIN
- if($self->{bare_not})
- {
- return $self->bare_not_subselect();
- }
- if($self->{in_all})
- {
- return "\tSELECT id FROM files AS files_id\n";
- }
my $tree=$self->{tagtree};
- print "UNDEF!!\n" unless($self->{tagtree});
- my $parent=$self->trailing_tag_parent();
-
-# print "ELEMENTS: ", join('/', map { $_->{name}; } @{$self->{elements}}), "\n";
-# print "TREE: ", $tree->print(), "\n";
- my $tag=undef;
- if($hasvals)
- {
- $tag=$self->trailing_tag_id();
-# print "Trailing id: $tag\n";
- }
- my ($sqlclause, @joins)=(undef, ());
- ($sqlclause, @joins) = $tree->to_sql($hasvals) if($tree);
-# print "SQL(" . scalar(@joins) .": $sqlclause\n";
+ my ($sqlclause, @joins)=$tree->to_sql() if($tree);
my $sql="\tSELECT fxt1.files_id FROM tags t1";
my @crosses=();
my @inners=();
-# $joinsneeded++ if($tag);
+ @joins=@{$self->{joins}};
for(my $i=0; $i <= $#joins; $i++)
{
my $cnt=$i+1;
$sql .= ("\n\t" . join(" ", @crosses)) if(@crosses);
$sql .= ("\n" . join("\n", @inners)) if(@inners);
$sql .= "\n\tWHERE $sqlclause" if($sqlclause);
-# if($tag)
-# {
-# $sql .= " AND t${joinsneeded}.parents_id='$tag'";
-# }
$sql .= "\n\tGROUP BY fxt1.files_id\n";
return $sql;
}
-sub bare_not_subselect
-{
- my($self)=@_;
- my @tags=grep { $self->is("tag", $_); } @{$self->{elements}};
- my $sql=("\tSELECT f1.id AS files_id FROM files f1 WHERE f1.id NOT IN (\n" .
- "\t\tSELECT fxt1.files_id FROM tags t1\n" .
- "\t\tINNER JOIN files_x_tags fxt1 ON t1.id=fxt1.tags_id\n" .
- "\t\tWHERE ");
- if(scalar(@tags) > 1)
- {
- $sql .= ("(t1.parents_id='" . $tags[0]->id() . "' AND t1.id='" .
- $tags[1]->id() . "')");
- }
- else
- {
- $sql .= ("(t1.parents_id='' AND t1.id='" . $tags[0]->id() . "')");
- }
- $sql .= "\n\t\tGROUP BY fxt1.files_id\n\t)\n";
- return($sql);
-}
-
sub sql_start
{
my($self, $tables)=@_;
return $sql;
}
-
-sub constraints_tag_list
-{
- my($self, @constraints)=@_;
- my $lasttag=undef;
- my @tags=();
- my @tags_vals=();
- for my $constraint (@constraints)
- {
-# print ref($constraint), ": ", $constraint->{name}, "\n";
- if($self->is("tag", $constraint))
- {
- if(defined($lasttag))
- {
-# print "TAGVAL\n";
- push(@tags_vals, [$lasttag, $constraint->id()]) if defined($constraint->id());
- $lasttag=undef;
- }
- elsif($self->tag_has_values($constraint->id()))
- {
-# print "HASVALUES\n";
- $lasttag=$constraint->id() if defined($constraint->id());
- }
- else
- {
-# print "NOVALUES\n";
- push(@tags, $constraint->id()) if(defined($constraint->id()));
- }
- }
- }
- @tags=map{ "\"$_\""; } @tags;
- @tags_vals=map( { [ map({ "\"$_\""; } @$_ ) ] } @tags_vals);
- $lasttag="\"$lasttag\"" if defined($lasttag);
- return(\@tags, \@tags_vals, $lasttag);
-}
-
# we just filter $ALLTRACKS, $NOARTIST and $NOALBUM
# filtering tags properly requires up to four levels of recursion
# (tag/tagval/AND/NOT) and is too slow
sub filter
{
my($self, @dirs)=@_;
+ return(@dirs) unless($ENABLE_FILTER);
my $base=$self->{path};
my @outdirs=();
for my $dir (@dirs)
{
-# print "\nFILTER (",$self->state(), "): $base / $dir\n";
- if($self->empty("$base/$dir"))
- {
-# print "empty: $base / $dir\n";
- }
- else
- {
-# print "non-empty, accepting: $base / $dir\n";
- push(@outdirs, $dir);
- }
+ push(@outdirs, $dir) unless($self->empty("$base/$dir"));
}
return(@outdirs);
}
return 1;
}
+# if path is .../OR/ or .../OR/NOT or .../AND/NOT
+sub want_all_tags
+{
+ my($self)=@_;
+ my $tail=$self->tail();
+ return 0 unless($tail);
+ my $parent=$self->tail_parent();
+ my $parent_valid = ($parent && $parent->type() == $TYPE_BOOL);
+ if($tail->type() == $TYPE_BOOL)
+ {
+ return 1 if($tail->name() eq "OR");
+ return 0 unless($tail->name() eq "NOT");
+ return 0 unless($parent_valid);
+ return 1 if($parent->name() eq "OR");
+ return 1 if($parent->name() eq "AND");
+ }
+ elsif($tail->type() == $TYPE_TAG)
+ {
+ return 0 unless($parent_valid);
+ return 1 if($parent->name() eq "NOT");
+ }
+ return 0;
+}
+
1;