X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Flibpspp%2Fbt.h;h=41fc5d44b0a3bc27ee23277ea2fc5abb27764398;hb=81579d9e9f994fb2908f50af41c3eb033d216e58;hp=2a014aaf96f7eabbaefae9d9edc3a33b1a98f506;hpb=48baf40c86d10eac3525d4199c9bb0ecc94c9d4d;p=pspp-builds.git

diff --git a/src/libpspp/bt.h b/src/libpspp/bt.h
index 2a014aaf..41fc5d44 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, 2011 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
@@ -25,16 +23,19 @@
    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 
+struct bt_node
   {
     struct bt_node *up;        /* Parent (NULL for root). */
     struct bt_node *down[2];   /* Left child, right child. */
@@ -47,7 +48,7 @@ typedef int bt_compare_func (const struct bt_node *a,
                              const void *aux);
 
 /* A balanced binary tree. */
-struct bt 
+struct bt
   {
     struct bt_node *root;       /* Tree's root, NULL if empty. */
     bt_compare_func *compare;   /* To compare nodes. */
@@ -75,9 +76,16 @@ struct bt_node *bt_changed (struct bt *, struct bt_node *);
 void bt_moved (struct bt *, struct bt_node *);
 
 /* Returns the number of nodes currently in BT. */
-static inline size_t bt_count (const struct bt *bt) 
+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 */