/* -*-c-*-
*
- * $Id: sym.h,v 1.7 1999/06/01 09:49:33 mdw Exp $
+ * $Id: sym.h,v 1.12 2001/01/20 11:49:37 mdw Exp $
*
* Symbol table management
*
/*----- Revision history --------------------------------------------------*
*
* $Log: sym.h,v $
+ * Revision 1.12 2001/01/20 11:49:37 mdw
+ * Export tuning parameters from header file, for the benefit of other
+ * hashtable implementations. Change the storage of symbol names: store
+ * the name after the allocated symbol block in all cases. This replaces
+ * the previous complicated and slightly wasteful arrangement.
+ *
+ * Revision 1.11 2000/06/17 10:37:39 mdw
+ * Add support for arena management.
+ *
+ * Revision 1.10 1999/12/10 23:42:04 mdw
+ * Change header file guard names.
+ *
+ * Revision 1.9 1999/08/02 16:53:48 mdw
+ * Improve type safety for sym_iter objects.
+ *
+ * Revision 1.8 1999/08/02 14:45:48 mdw
+ * Break low-level hashtable code out from sym.
+ *
* Revision 1.7 1999/06/01 09:49:33 mdw
* Allow things to be looked up by just their caller-supplied hashes. This
* actually needs to be thought through better.
*
*/
-#ifndef SYM_H
-#define SYM_H
+#ifndef MLIB_SYM_H
+#define MLIB_SYM_H
#ifdef __cplusplus
extern "C" {
#include <stddef.h>
-#ifndef BITS_H
+#ifndef MLIB_BITS_H
# include "bits.h"
#endif
+#ifndef MLIB_HASH_H
+# include "hash.h"
+#endif
+
+#ifndef MLIB_SUB_H
+# include "sub.h"
+#endif
+
+/*----- Tuning parameters -------------------------------------------------*/
+
+/* --- Initial hash table size --- *
+ *
+ * This is the initial @mask@ value. It must be of the form %$2^n - 1$%,
+ * so that it can be used to mask of the bottom bits of a hash value.
+ */
+
+#define SYM_INITSZ 32 /* Size of a new hash table */
+
+/* --- Maximum load factor --- *
+ *
+ * This parameter controls how much the table has to be loaded before the
+ * table is extended. The number of elements %$n$%, the number of bins %$b$%
+ * and the limit %$l$% satisfy the relation %$n < bl$%; if a new item is
+ * added to the table and this relation is found to be false, the table is
+ * doubled in size.
+ */
+
+#define SYM_LIMIT(n) ((n) * 2) /* Load factor for growing table */
+
/*----- Type definitions --------------------------------------------------*/
/* --- Symbol table --- *
*/
typedef struct sym_table {
- unsigned long mask; /* Bit mask for hashing purposes */
- size_t c; /* Down counter for growing table */
- struct sym_base **a; /* Array of hash bins */
+ hash_table t;
+ subarena *s;
+ size_t load;
} sym_table;
/* --- A symbol table entry --- *
* sufficient to allow me to manipulate such objects.
*/
-#define SYM_BUFSZ 16 /* Size of local string buffer */
-
typedef struct sym_base {
- struct sym_base *next; /* Next symbol in hash bin */
- uint32 hash; /* Hash value for symbol's name */
- union {
- char *p; /* Pointer to name string */
- char b[SYM_BUFSZ]; /* Buffer containing a short name */
- } name; /* Name of this symbol */
+ hash_base b; /* Base structure */
+ char *name; /* Pointer to name string */
size_t len; /* Length of the symbol's name */
} sym_base;
-/* --- A macro to pick a symbol's name out from the mess --- */
+/* --- Macros for picking out useful information --- *
+ *
+ * Note that @SYM_LEN@ returns the size of the symbol key. For textual keys,
+ * this will include the terminating null.
+ */
-#define SYM_NAME(sy) \
- (((sym_base *)(sy))->len > SYM_BUFSZ ? \
- ((sym_base *)(sy))->name.p : \
- ((sym_base *)(sy))->name.b)
+#define SYM_NAME(sy) ((const char *)(((sym_base *)(sy))->name))
+#define SYM_LEN(sy) (((sym_base *)(sy))->len + 0)
+#define SYM_HASH(sy) (((sym_base *)(sy))->b.hash + 0)
/* --- An iterator block --- */
-typedef struct sym_iter {
- sym_table *t; /* Symbol table being iterated */
- sym_base *n; /* Address of next item to return */
- size_t i; /* Index of next hash bin to use */
-} sym_iter;
+typedef struct { hash_iter i; } sym_iter;
/*----- External functions ------------------------------------------------*/
* may be given, in which case the name may contain arbitrary
* binary data, or it may be given as a negative number, in
* which case the length of the name is calculated as
- * @strlen(n) + 1@. The name pointer @n@ may also be zero; in
- * this case, @l@ is taken to be a raw hash, and any element
- * with a matching hash is taken to be the one wanted.
+ * @strlen(n) + 1@.
*
* The return value is the address of a pointer to a @sym_base@
* block (which may have other things on the end, as above). If
/* --- @sym_remove@ --- *
*
- * Arguments: @sym_table *i@ = pointer to a symbol table object
+ * Arguments: @sym_table *t@ = pointer to a symbol table object
* @void *b@ = pointer to symbol table entry
*
* Returns: ---
* iterate through a symbol table.
*/
+#define SYM_MKITER(i_, t_) HASH_MKITER(&(i_)->i, &(t_)->t)
+
extern void sym_mkiter(sym_iter */*i*/, sym_table */*t*/);
/* --- @sym_next@ --- *
* returned in any particular order.
*/
+#define SYM_NEXT(i_, p) do { \
+ hash_base *_q; \
+ HASH_NEXT(&(i_)->i, _q); \
+ (p) = (void *)_q; \
+} while (0)
+
extern void *sym_next(sym_iter */*i*/);
/*----- That's all, folks -------------------------------------------------*/
~mdw / mLib / blobdiff