--- /dev/null
+/* -*-c-*-
+ *
+ * $Id: assoc.c,v 1.1 2001/01/20 11:50:58 mdw Exp $
+ *
+ * Assocation tables
+ *
+ * (c) 2000 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of the mLib utilities library.
+ *
+ * mLib is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Library General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * mLib 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 Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with mLib; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+/*----- Revision history --------------------------------------------------*
+ *
+ * $Log: assoc.c,v $
+ * Revision 1.1 2001/01/20 11:50:58 mdw
+ * Hash tables indexed by atoms, to avoid expense of hashing keys on each
+ * lookup, and to reduce storage used by key texts.
+ *
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include "alloc.h"
+#include "assoc.h"
+#include "atom.h"
+#include "hash.h"
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @assoc_create@ --- *
+ *
+ * Arguments: @assoc_table *t@ = pointer to an association table
+ *
+ * Returns: ---
+ *
+ * Use: Creates a new association table.
+ */
+
+void assoc_create(assoc_table *t)
+{
+ hash_create(&t->t, SYM_INITSZ);
+ t->load = SYM_LIMIT(SYM_INITSZ);
+}
+
+/* --- @assoc_destroy@ --- *
+ *
+ * Arguments: @assoc_table *t@ = pointer to an association table
+ *
+ * Returns: ---
+ *
+ * Use: Destroys an association table.
+ */
+
+void assoc_destroy(assoc_table *t)
+{
+ hash_iter i;
+
+ HASH_MKITER(&i, &t->t);
+ for (;;) {
+ hash_base *p;
+ HASH_NEXT(&i, p);
+ x_free(t->t.a, p);
+ }
+ hash_destroy(&t->t);
+}
+
+/* --- @assoc_find@ --- *
+ *
+ * Arguments: @assoc_table *t@ = pointer to an association table
+ * @atom *a@ = an atom to label the item
+ * @size_t sz@ = size of block to allocate
+ * @unsigned *f@ = pointer to `found' flag
+ *
+ * Returns: A pointer to the item located or null.
+ *
+ * Use: Looks up an atom in an association table. If the atom is
+ * found, the association is returned. If not, and @sz@ is
+ * zero, a null pointer is returned. Otherwise, a block of size
+ * @sz@ is allocated, its @assoc_base@ header is filled in, and
+ * the pointer returned. The flag @*f@ is cleared if the item
+ * couldn't be found, or set if it was.
+ *
+ * All the atoms used in a particular table should
+ */
+
+void *assoc_find(assoc_table *t, atom *a, size_t sz, unsigned *f)
+{
+ hash_base **bin = HASH_BIN(&t->t, a->b.b.hash), **p;
+ assoc_base *q;
+
+ /* --- Try to find the association --- */
+
+ for (p = bin; *p; p = &(*p)->next) {
+ q = (assoc_base *)*p;
+ if (q->a == a) {
+ *p = q->b.next;
+ q->b.next = *bin;
+ *bin = &q->b;
+ if (f) *f = 1;
+ return (q);
+ }
+ }
+
+ /* --- Failed to find a match --- */
+
+ if (f) *f = 0;
+ if (!sz) return (0);
+
+ /* --- Make a new assoication --- */
+
+ q = x_alloc(t->t.a, sz);
+ q->b.next = *bin;
+ q->b.hash = ATOM_HASH(a);
+ *bin = &q->b;
+
+ /* --- Maybe extend the table --- */
+
+ if (t->load)
+ t->load--;
+ if (!t->load && hash_extend(&t->t))
+ t->load = SYM_LIMIT(t->t.mask + 1);
+ return (q);
+}
+
+/* --- @assoc_remove@ --- *
+ *
+ * Arguments: @assoc_table *t@ = pointer to an association table
+ * @void *p@ = pointer to a block to remove
+ *
+ * Returns: ---
+ *
+ * Use: Removes an association from a table.
+ */
+
+void assoc_remove(assoc_table *t, void *p)
+{
+ assoc_base *q = p;
+ hash_remove(&t->t, &q->b);
+ x_free(t->t.a, q);
+ t->load++;
+}
+
+/* --- @assoc_mkiter@, @assoc_next@ --- *
+ *
+ * Arguments: @assoc_iter *i@ = pointer to an iterator
+ * @assoc_table *t@ = pointer to an association table
+ *
+ * Returns: Next association, or null, for @assoc_next@; nothing for
+ * @assoc_mkiter@.
+ *
+ * Use: Iterates over the associations in a table.
+ */
+
+void assoc_mkiter(assoc_iter *i, assoc_table *t) { ASSOC_MKITER(i, t); }
+void *assoc_next(assoc_iter *i) { void *p; ASSOC_NEXT(i, p); return (p); }
+
+/*----- That's all, folks -------------------------------------------------*/
~mdw / mLib / blobdiff