Hash table iterators exposed, with new macro.

* eval.c (eval_init): Register hash-begin and hash-next intrinsics.

* lisplib.c (hash_set_entries, hash_instantiate): New static functions.
(lisplib_init): Register new tables in dl_table.

* share/txr/stdlib/hash.tl: New file.

* txr.1: Document with-hash-iter macro.

1 files changed, 41 insertions, 0 deletions

diff --git a/share/txr/stdlib/hash.tl b/share/txr/stdlib/hash.tl
new file mode 100644
index 00000000..17d0afa2
--- /dev/null
+++ b/share/txr/stdlib/hash.tl
@@ -0,0 +1,41 @@
+;; Copyright 2015
+;; Kaz Kylheku <kaz@kylheku.com>
+;; Vancouver, Canada
+;; All rights reserved.
+;;
+;; Redistribution of this software in source and binary forms, with or without
+;; modification, is permitted provided that the following two conditions are met.
+;;
+;; Use of this software in any manner constitutes agreement with the disclaimer
+;; which follows the two conditions.
+;;
+;; 1. Redistributions of source code must retain the above copyright
+;;    notice, this list of conditions and the following disclaimer.
+;; 2. Redistributions in binary form must reproduce the above copyright
+;;    notice, this list of conditions and the following disclaimer in
+;;    the documentation and/or other materials provided with the
+;;    distribution.
+;;
+;; THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
+;; WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
+;; MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL THE
+;; COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DAMAGES, HOWEVER CAUSED,
+;; AND UNDER ANY THEORY OF LIABILITY, ARISING IN ANY WAY OUT OF THE USE OF THIS
+;; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+(defmacro with-hash-iter ((name hash-form : key val) . body)
+  (let ((hash (gensym))
+        (iter (gensym))
+        (next (gensym)))
+    ^(let* ((,hash ,hash-form)
+            (,iter (hash-begin ,hash))
+            ,*(if key ^((,key)))
+            ,*(if val ^((,val))))
+       (flet ((,name ()
+                ,(if (not (or key val))
+                   ^(hash-next ,iter)
+                   ^(let ((,next (hash-next ,iter)))
+                      ,*(if key ^((set ,key (car ,next))))
+                      ,*(if val ^((set ,val (cdr ,next)))))
+                   ,next)))
+         ,*body))))