X-Git-Url: http://git.nguyen.vg/gitweb/?a=blobdiff_plain;f=src%2FnodeSet.ml;h=944f85c0dfae609a31072e1a6d47f7691abbd204;hb=35b9abd60699383b0cebf25e905049d3d7027271;hp=142476be16f232230f8e0bddf0aecce3baca5f79;hpb=689b47b109dc54a78008f589f2c55f98672ab61d;p=SXSI%2Fxpathcomp.git

diff --git a/src/nodeSet.ml b/src/nodeSet.ml
index 142476b..944f85c 100644
--- a/src/nodeSet.ml
+++ b/src/nodeSet.ml
@@ -100,11 +100,18 @@ module Mat : S with type t = Tree.node mat =
     let conscat4 e l1 l2 l3 l4 = conscat e l1 (concat l2 (concat l3 l4))
 
     let subtree_tags tree node tag =
-      { clist = SubtreeTags(tree, node, tag);
-	length = Tree.subtree_tags tree node tag }
+      let len = Tree.subtree_tags tree node tag in
+      if len == 0 then empty
+      else
+	{ clist = SubtreeTags(tree, node, tag);
+	  length = len }
+
     let subtree_elements tree node =
-      { clist = SubtreeElts(tree, node);
-	length = Tree.subtree_elements tree node }
+      let len = Tree.subtree_elements tree node in
+      if len == 0 then empty
+      else
+	{ clist = SubtreeElts(tree, node);
+	  length = len }
 
     let fst_tagged tree t tag =
       if Tree.tag tree t == tag then t