From aace904fb85cd440b849892818ff287b3ce62d1f Mon Sep 17 00:00:00 2001
From: Robert Spalek <robert@ucw.cz>
Date: Mon, 10 Jan 2005 16:03:15 +0000
Subject: [PATCH] added TREE_WANT_BOUNDARY for finding the first/last node

---
 lib/redblack.h | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/lib/redblack.h b/lib/redblack.h
index 764ca104..7658f25f 100644
--- a/lib/redblack.h
+++ b/lib/redblack.h
@@ -68,6 +68,8 @@
  *			Implies TREE_DUPLICATES.
  *  TREE_WANT_SEARCH	node *search(key) -- find the node with the specified
  *			or, if it does not exist, the nearest one.
+ *  TREE_WANT_BOUNDARY	node *boundary(uns direction) -- finds smallest
+ *  			(direction==0) or largest (direction==1) node.
  *  TREE_WANT_ADJACENT	node *adjacent(node *, uns direction) -- finds next
  *			(direction==1) or previous (direction==0) node.
  *  TREE_WANT_NEW	node *new(key) -- create new node with given key.
@@ -410,6 +412,22 @@ STATIC P(node) * P(find) (T *t, TREE_KEY_DECL)
 }
 #endif
 
+#ifdef TREE_WANT_BOUNDARY
+STATIC P(node) * P(boundary) (T *t, uns direction)
+{
+	P(bucket) *n = t->root, *ns;
+	if (!n)
+		return NULL;
+	else
+	{
+		uns son = !!direction;
+		while ((ns = P(tree_son) (n, son)))
+			n = ns;
+		return &n->n;
+	}
+}
+#endif
+
 #ifdef TREE_STORE_PARENT
 STATIC P(node) * P(adjacent) (P(node) *start, uns direction)
 {
@@ -966,6 +984,7 @@ do											\
 #undef TREE_WANT_FIND
 #undef TREE_WANT_FIND_NEXT
 #undef TREE_WANT_SEARCH
+#undef TREE_WANT_BOUNDARY
 #undef TREE_WANT_ADJACENT
 #undef TREE_WANT_NEW
 #undef TREE_WANT_LOOKUP
-- 
2.39.2