add DEFINE-MORE-FUN, use it for vararg arithmetic functions

[sbcl.git] / src / code / early-extensions.lisp

diff --git a/src/code/early-extensions.lisp b/src/code/early-extensions.lisp
index 8146656..8b657cc 100644 (file)
--- a/src/code/early-extensions.lisp
+++ b/src/code/early-extensions.lisp
@@ -1354,3 +1354,30 @@ to :INTERPRET, an interpreter will be used.")
      (if (eql x 0.0l0)
          (make-unportable-float :long-float-negative-zero)
          0.0l0))))
+
+;;; Like DEFUN, but replaces &REST with &MORE while hiding that from the
+;;; lambda-list.
+(defmacro define-more-fun (name lambda-list &body body)
+  (let* ((p (position '&rest lambda-list))
+         (head (subseq lambda-list 0 p))
+         (tail (subseq lambda-list p))
+         (more-context (gensym "MORE-CONTEXT"))
+         (more-count (gensym "MORE-COUNT")))
+    (aver (= 2 (length tail)))
+    `(progn
+       (macrolet ((more-count ()
+                    `(truly-the index ,',more-count))
+                  (more-p ()
+                    `(not (eql 0 ,',more-count)))
+                  (more-arg (n)
+                    `(sb!c:%more-arg ,',more-context ,n))
+                  (do-more ((arg &optional (start 0)) &body body)
+                    (let ((i (gensym "I")))
+                      `(do ((,i (the index ,start) (truly-the index (1+ ,i))))
+                           ((>= ,i (more-count)))
+                         (declare (index ,i))
+                         (let ((,arg (sb!c:%more-arg ,',more-context ,i)))
+                           ,@body)))))
+         (defun ,name (,@head &more ,more-context ,more-count)
+           ,@body))
+       (setf (%simple-fun-arglist #',name) ',lambda-list))))