From: Ian Beckwith <ianb@erislabs.net>
Date: Wed, 20 Oct 2010 21:26:25 +0000 (+0100)
Subject: more special-casing joins
X-Git-Tag: debian/1.0-1~13
X-Git-Url: http://erislabs.net/gitweb/?p=id3fs.git;a=commitdiff_plain;h=516b8d78e15c360c27b7043bb4a6690577f91f3c

more special-casing joins
---

diff --git a/lib/ID3FS/Path/Node.pm b/lib/ID3FS/Path/Node.pm
index b71406d..3171dd4 100644
--- a/lib/ID3FS/Path/Node.pm
+++ b/lib/ID3FS/Path/Node.pm
@@ -99,25 +99,26 @@ sub to_sql
     if(defined($op))
     {
 	my $join=undef;
-	# if right child is a NOT, we don't need extra join/brackets
-	# NOT will do the same and we will end up with an extra one
-	unless($right && $right->name() && $right->name() eq "NOT")
+	# if we are ANDing add an inner join
+	# also if we are NOTing, but we are looking for a tag *value*
+	if($op eq "AND")
 	{
-	    # if we are ANDing or ORing, add an inner join
-	    # also if we are NOTing, but we are looking for a tag *value*
-	    if($op eq "AND")
-	    {
-		$join= "INNER";
-	    }
-	    elsif($op eq "NOT")
-	    {
-		$not=1;
-		$join = ($hasvals ? "INNER" : "LEFT");
-	    }
-	    elsif($op eq "OR")
-	    {
-		$join="INNER" unless($left && $left->name() && $left->name() eq "NOT")
-	    }
+	    # if right child is a NOT, we don't need extra join/brackets
+	    # NOT will do the same and we will end up with an extra one
+	    $join= "INNER" unless($right && $right->name() && $right->name() eq "NOT");
+	}
+	elsif($op eq "NOT")
+	{
+	    $not=1;
+	    $join = ($hasvals ? "INNER" : "LEFT");
+	}
+	elsif($op eq "OR")
+	{
+	    # if the rightmost part of the left sub-expression ends in
+	    # NOT, then we need an extra join. This doesn't apply if
+	    # (as above) the righthand expression is a NOT.
+	    $join="INNER" if(($self->right_ends_in_not($left)) &&
+			     !($right && $right->name() && $right->name() eq "NOT"));
 	}
 	if($join)
 	{
@@ -147,4 +148,19 @@ sub used_tags
     return $self->id();
 }
 
+sub right_ends_in_not
+{
+    my($self, $node)=@_;
+    return 0 unless($node);
+    my $right=$node->right();
+    if($right && $right->type() == $TYPE_BOOL)
+    {
+	return $self->right_ends_in_not($right);
+    }
+    my $op=$node->name();
+    return 0 unless($op);
+    return 1 if($op eq "NOT");
+    return 0;
+}
+
 1;