[elpa] externals/dash b540ebb 1/3: Refactor -partition-after-pred to avoid recursion

[ELPA Syncer]

branch: externals/dash
commit b540ebb9d6289a54188649818ffbab9bf4e859d6
Author: Per Weijnitz <per.weijnitz@gmail.com>
Commit: Basil L. Contovounesios <contovob@tcd.ie>

    Refactor -partition-after-pred to avoid recursion
    
    * dash.el (--partition-after-pred): New anaphoric macro.
    (-partition-after-pred): Use it.
    * dev/examples.el (-partition-after-pred): Test it.
---
 dash.el         | 33 +++++++++++++++++++++------------
 dev/examples.el |  4 +++-
 2 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/dash.el b/dash.el
index c483a00..69c474b 100644
--- a/dash.el
+++ b/dash.el
@@ -1382,20 +1382,29 @@ returns the header value, but only after seeing at 
least one
 other value (the body)."
   (--partition-by-header (funcall fn it) list))
 
+(defmacro --partition-after-pred (form list)
+  "Anaphoric form of `-partition-after-pred'."
+  (let ((r (make-symbol "result"))
+        (s (make-symbol "sublist"))
+        (l (make-symbol "list")))
+    `(let ((,l ,list))
+       (when ,l
+         (let* ((,r nil)
+                (,s nil))
+           (while ,l
+             (let* ((it (car ,l)))
+               (!cdr ,l)
+               (!cons it ,s)
+               (when ,form
+                 (!cons (nreverse ,s) ,r)
+                 (setq ,s nil))))
+           (if ,s
+              (!cons (nreverse ,s) ,r))
+           (nreverse ,r))))))
+
 (defun -partition-after-pred (pred list)
   "Partition directly after each time PRED is true on an element of LIST."
-  (when list
-    (let ((rest (-partition-after-pred pred
-                                       (cdr list))))
-      (if (funcall pred (car list))
-          ;;split after (car list)
-          (cons (list (car list))
-                rest)
-
-        ;;don't split after (car list)
-        (cons (cons (car list)
-                    (car rest))
-              (cdr rest))))))
+  (--partition-after-pred (funcall pred it) list))
 
 (defun -partition-before-pred (pred list)
   "Partition directly before each time PRED is true on an element of LIST."
diff --git a/dev/examples.el b/dev/examples.el
index 4382ba4..81d6da9 100644
--- a/dev/examples.el
+++ b/dev/examples.el
@@ -806,7 +806,9 @@ value rather than consuming a list to produce a single 
value."
     (-partition-after-pred #'booleanp '(t t)) => '((t) (t))
     (-partition-after-pred #'booleanp '(0 0 t t 0 t)) => '((0 0 t) (t) (0 t))
     (-partition-after-pred #'booleanp '(t)) => '((t))
-    (-partition-after-pred #'booleanp '(0 t)) => '((0 t)))
+    (-partition-after-pred #'booleanp '(0 t)) => '((0 t))
+    (--partition-after-pred (= 1 (% it 2)) '(0 0 0 1 0 1 1 0 1))
+    => '((0 0 0 1) (0 1) (1) (0 1)))
 
   (defexamples -partition-before-pred
     (-partition-before-pred #'booleanp '()) => '()