+void *
+var_attach_aux (struct variable *v,
+ void *aux, void (*aux_dtor) (struct variable *))
+{
+ assert (v->aux == NULL);
+ assert (aux != NULL);
+ v->aux = aux;
+ v->aux_dtor = aux_dtor;
+ return aux;
+}
+
+void *
+var_detach_aux (struct variable *v)
+{
+ void *aux = v->aux;
+ assert (aux != NULL);
+ v->aux = NULL;
+ return aux;
+}
+
+void
+var_clear_aux (struct variable *v)
+{
+ assert (v != NULL);
+ if (v->aux != NULL)
+ {
+ if (v->aux_dtor != NULL)
+ v->aux_dtor (v);
+ v->aux = NULL;
+ }
+}
+
+void
+var_dtor_free (struct variable *v)
+{
+ free (v->aux);
+}
+
+/* Compares A and B, which both have the given WIDTH, and returns
+ a strcmp()-type result. */
+int
+compare_values (const union value *a, const union value *b, int width)
+{
+ if (width == 0)
+ return a->f < b->f ? -1 : a->f > b->f;
+ else
+ return memcmp (a->s, b->s, min(MAX_SHORT_STRING, width));
+}
+
+/* Create a hash of v */
+unsigned
+hash_value(const union value *v, int width)
+{
+ unsigned id_hash;
+
+ if ( 0 == width )
+ id_hash = hsh_hash_double (v->f);
+ else
+ id_hash = hsh_hash_bytes (v->s, min(MAX_SHORT_STRING, width));
+
+ return id_hash;
+}
+
+
+