-/* 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
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)))
+/* Returns the data structure corresponding to the given NODE, assuming that
+ NODE is embedded as the given MEMBER name in data type STRUCT. NODE must
+ not be a null pointer. */
+#define BT_DATA(NODE, STRUCT, MEMBER) \
+ (CHECK_POINTER_HAS_TYPE (NODE, struct bt_node *), \
+ UP_CAST (NODE, STRUCT, MEMBER))
+
+/* Like BT_DATA, except that a null NODE yields a null pointer result. */
+#define BT_NULLABLE_DATA(NODE, STRUCT, MEMBER) \
+ ((STRUCT *) bt_nullable_data__ (NODE, offsetof (STRUCT, MEMBER)))
/* Node in a balanced binary tree. */
struct bt_node
size_t size; /* Current node count. */
size_t max_size; /* Max size since last complete rebalance. */
};
+#define BT_INITIALIZER(COMPARE, AUX) { .compare = COMPARE, .aux = AUX }
void bt_init (struct bt *, bt_compare_func *, const void *aux);
struct bt_node *bt_changed (struct bt *, struct bt_node *);
void bt_moved (struct bt *, struct bt_node *);
+/* Convenience macros for iteration.
+
+ These macros automatically use BT_DATA to obtain the data elements that
+ encapsulate bt nodes, which often saves typing and can make code easier to
+ read. Refer to the large comment near the top of this file for an example.
+
+ These macros evaluate their arguments many times. */
+#define BT_FIRST(STRUCT, MEMBER, BT) \
+ BT_NULLABLE_DATA (bt_first (BT), STRUCT, MEMBER)
+#define BT_NEXT(DATA, STRUCT, MEMBER, BT) \
+ BT_NULLABLE_DATA (bt_next (BT, &(DATA)->MEMBER), STRUCT, MEMBER)
+#define BT_FOR_EACH(DATA, STRUCT, MEMBER, BT) \
+ for ((DATA) = BT_FIRST (STRUCT, MEMBER, BT); \
+ (DATA) != NULL; \
+ (DATA) = BT_NEXT (DATA, STRUCT, MEMBER, BT))
+#define BT_FOR_EACH_SAFE(DATA, NEXT, STRUCT, MEMBER, BT) \
+ for ((DATA) = BT_FIRST (STRUCT, MEMBER, BT); \
+ ((DATA) != NULL \
+ ? ((NEXT) = BT_NEXT (DATA, STRUCT, MEMBER, BT), 1) \
+ : 0); \
+ (DATA) = (NEXT))
+
/* Returns the number of nodes currently in 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;
+}
+
+/* Helper for BT_NULLABLE_DATA (to avoid evaluating its NODE argument more than
+ once). */
+static inline void *
+bt_nullable_data__ (struct bt_node *node, size_t member_offset)
+{
+ return node != NULL ? (char *) node - member_offset : NULL;
+}
+
#endif /* libpspp/bt.h */