Optimize isFirstChild

diff --git a/XMLTree.h b/XMLTree.h
index 351db20..74a71e6 100644 (file)
--- a/XMLTree.h
+++ b/XMLTree.h
@@ -294,10 +294,15 @@ public:
    bool IsChild(treeNode x, treeNode y);
 
    /** IsFirstChild(x): returns whether node x is the first child of its parent. */
-   /* OCAML */
+   /* SLOW 
    bool IsFirstChild(treeNode x) {
           return ((x != NULLT)&&(x==Root() || bp_prev_sibling(Par,x) == (treeNode)-1));
    };
+   */
+
+   bool IsFirstChild(treeNode x) {
+     return (x <= Root()) || (bp_inspect(Par,x-1) == OP);
+   }
 
    /** NumChildren(x): number of children of node x. Constant time with the
     * data structure of Sadakane. */