From: yamaoka <yamaoka>
Date: Fri, 10 Dec 1999 08:38:55 +0000 (+0000)
Subject: (union): New compiler macro for emulating cl function.
X-Git-Tag: t-gnus-6_14_0-07
X-Git-Url: http://git.chise.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=62fa081706fb82b151527aad0a4edf0e064852bc;p=elisp%2Fgnus.git-

(union): New compiler macro for emulating cl function.
---

diff --git a/lisp/dgnushack.el b/lisp/dgnushack.el
index 8aec2e5..e4cf885 100644
--- a/lisp/dgnushack.el
+++ b/lisp/dgnushack.el
@@ -113,6 +113,24 @@
 	   (setq arg (cdr arg)))
 	 (apply (function nconc) (nreverse res))))))
 
+(define-compiler-macro union (&whole form list1 list2)
+  (if (and (fboundp 'union)
+	   (subrp (symbol-function 'union)))
+      form
+    `(let ((a ,list1)
+	   (b ,list2))
+       (cond ((null a) b)
+	     ((null b) a)
+	     ((equal a b) a)
+	     (t
+	      (or (>= (length a) (length b))
+		  (setq a (prog1 b (setq b a))))
+	      (while b
+		(or (memq (car b) a)
+		    (push (car b) a))
+		(pop b))
+	      a)))))
+
 ;; If we are building w3 in a different directory than the source
 ;; directory, we must read *.el from source directory and write *.elc
 ;; into the building directory.  For that, we define this function