X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Flibpspp%2Fbt.h;h=0ee29898e8263eeb434d8987192157c771fbb19a;hb=aaf7e27cbda4b400b6a98360fa7bab08e26c8696;hp=058a64dbab2b8baa7e45b5cab383fbd4fba1538f;hpb=f5c108becd49d78f4898cab11352291f5689d24e;p=pspp

diff --git a/src/libpspp/bt.h b/src/libpspp/bt.h
index 058a64dbab..0ee29898e8 100644
--- a/src/libpspp/bt.h
+++ b/src/libpspp/bt.h
@@ -1,20 +1,18 @@
-/* PSPP - computes sample statistics.
-   Copyright (C) 2007 Free Software Foundation, Inc.
+/* PSPP - a program for statistical analysis.
+   Copyright (C) 2007, 2009, 2010 Free Software Foundation, Inc.
 
-   This program is free software; you can redistribute it and/or
-   modify it under the terms of the GNU General Public License as
-   published by the Free Software Foundation; either version 2 of the
-   License, or (at your option) any later version.
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
 
-   This program is distributed in the hope that it will be useful, but
-   WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   General Public License for more details.
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software
-   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
-   02110-1301, USA. */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>. */
 
 #ifndef LIBPSPP_BT_H
 #define LIBPSPP_BT_H 1
@@ -25,13 +23,16 @@
    balancing applied to the balanced tree, as its operation is
    fully encapsulated. */
 
+#include <stdbool.h>
 #include <stddef.h>
+#include <libpspp/cast.h>
 
 /* Returns the data structure corresponding to the given NODE,
    assuming that NODE is embedded as the given MEMBER name in
    data type STRUCT. */
-#define bt_data(NODE, STRUCT, MEMBER)                                  \
-        ((STRUCT *) ((char *) (NODE) - offsetof (STRUCT, MEMBER)))
+#define bt_data(NODE, STRUCT, MEMBER)                           \
+        (CHECK_POINTER_HAS_TYPE (NODE, struct bt_node *),       \
+         UP_CAST (NODE, STRUCT, MEMBER))
 
 /* Node in a balanced binary tree. */
 struct bt_node
@@ -80,4 +81,11 @@ static inline size_t bt_count (const struct bt *bt)
   return bt->size;
 }
 
+/* Return true if BT contains no nodes,
+   false if BT contains at least one node. */
+static inline bool bt_is_empty (const struct bt *bt)
+{
+  return bt->size == 0;
+}
+
 #endif /* libpspp/bt.h */