From: Mark Wooding <mdw@distorted.org.uk>
Date: Thu, 1 Jun 2006 15:26:31 +0000 (+0100)
Subject: collect: New functions collect-append and collect-nconc.
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/lisp/commitdiff_plain/9013ada754a1edb12f6157a3a2b9316be7bd987c?hp=84f4b59f93535e938e21a083e05a49a1f20f9c26

collect: New functions collect-append and collect-nconc.
---

diff --git a/collect.lisp b/collect.lisp
index 219f351..359780c 100644
--- a/collect.lisp
+++ b/collect.lisp
@@ -71,4 +71,19 @@ (defmacro collect-tail (x &optional (name *collecting-anon-list-name*))
      (setf (cdar ,name) ,x)
      (setf (car ,name) nil)))
 
+(defmacro collect-append (list &optional (name *collecting-anon-list-name*))
+  "Append LIST to the tail of `collecting' list NAME.  This obviously
+   involves copying LIST."
+  (with-gensyms item
+    `(dolist (,item ,list)
+       (collect ,item ,name))))
+
+(defmacro collect-nconc (list &optional (name *collecting-anon-list-name*))
+  "Attach LIST to the tail of `collecting' list NAME.  This will involve
+   destroying LIST if anything else gets collected afterwards."
+  (let*/gensyms list
+    `(when ,list
+       (setf (cdar ,name) ,list)
+       (setf (car ,name) (last ,list)))))
+
 ;;;----- That's all, folks --------------------------------------------------