1 files changed, 83 insertions, 0 deletions
diff --git a/share/txr/stdlib/conv.tl b/share/txr/stdlib/conv.tl
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+;; Copyright 2016
+;; 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.
+
+(defun sys:conv-let (. body)
+  ^(flet ((i (arg : radix)
+            (toint arg radix))
+          (o (arg)
+            (toint arg 8))
+          (x (arg)
+            (toint arg 16))
+          (b (arg)
+            (toint arg 2))
+          (r (arg)
+            (tofloat arg)))
+     ,*body))
+
+(defun sys:do-conv (lfl mfl tfl nm list)
+  (while (and list lfl)
+    (set (car list) (call (car lfl) (car list)))
+    (set list (cdr list))
+    (set lfl (cdr lfl)))
+  (dotimes (i nm)
+    (unless list
+      (return))
+    (when mfl
+      (set (car list) (call (car mfl) (car list)))
+      (set mfl (cdr mfl)))
+    (set list (cdr list)))
+  (while (and list tfl)
+    (set (car list) (call (car tfl) (car list)))
+    (set list (cdr list))
+    (set tfl (cdr tfl))))
+
+(defun sys:conv-expand (form specs list-sym)
+  (mac-param-bind form (lead : mid trail)
+                       (split* (mapcar [iff (op eq :)
+                                            identity
+                                            [iff (op eq '-)
+                                                 (retf '(fun identity)) 
+                                                 (ret ^[identity ,@1])]]
+                                       specs)
+                               (op where (op eq :)))
+    (let ((nl (length lead))
+          (nt (length trail)))
+      (with-gensyms (i nm lfl mfl tfl)
+        (sys:conv-let
+          ^(let* ((,nm (- (length ,list-sym) ,(+ nl nt)))
+                  (,lfl (list ,*lead))
+                  (,mfl (if (plusp ,nm) (repeat (list ,*mid))))
+                  (,tfl (list ,*trail)))
+             (sys:do-conv ,lfl ,mfl ,tfl ,nm ,list-sym)))))))
+
+(defmacro sys:conv (:form form (. specs) list-expr)
+  (cond
+    ((null specs) list-expr)
+    ((atom specs)
+     (throwf 'eval-error "sys:conv: invalid conversion list: ~s" specs))
+    (t (with-gensyms (list-sym)
+         ^(let ((,list-sym ,list-expr))
+            ,(sys:conv-expand form specs list-sym)
+            ,list-sym)))))