Fix a bug in TaggedFoll

[SXSI/XMLTree.git] / XMLTree.cpp

diff --git a/XMLTree.cpp b/XMLTree.cpp
index f155d3e..bb861a9 100644 (file)
--- a/XMLTree.cpp
+++ b/XMLTree.cpp
@@ -539,6 +539,9 @@ treeNode XMLTree::TaggedFoll(treeNode x, TagType tag)
     }\r
 \r
     int r, s;\r
+    if (x == Root() || (next_sibling(Par,x) == -1 ))\r
+      return NULLT;\r
+    \r
     r = (int) Tags->rank(tag, node2tagpos(next_sibling(Par, x))-1);\r
     s = (int) Tags->select(tag, r+1);  // select returns -1 in case that there is no r+1-th tag.\r
     if (s==-1) return NULLT;\r