Merge PR#362 from perweij/refactor/avoid-recursion

Closes #379.

README.md

@@ -1540,7 +1540,9 @@ other value (the body).
 
 #### -partition-after-pred `(pred list)`
 
-Partition directly after each time `pred` is true on an element of `list`.
+Partition `list` after each element for which `pred` returns non-nil.
+
+This function's anaphoric counterpart is `--partition-after-pred`.
 
 ```el
 (-partition-after-pred #'booleanp ()) ;; => ()

dash.el

@@ -1382,20 +1382,31 @@ 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)
+  "Partition LIST after each element for which FORM evaluates to non-nil.
+Each element of LIST in turn is bound to `it' before evaluating
+FORM.
+
+This is the anaphoric counterpart to `-partition-after-pred'."
+  (let ((l (make-symbol "list"))
+        (r (make-symbol "result"))
+        (s (make-symbol "sublist")))
+    `(let ((,l ,list) ,r ,s)
+       (when ,l
+         (--each ,l
+           (push it ,s)
+           (when ,form
+             (push (nreverse ,s) ,r)
+             (setq ,s ())))
+         (when ,s
+           (push (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 LIST after each element for which PRED returns non-nil.
+
+This function's anaphoric counterpart is `--partition-after-pred'."
+  (--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."

dash.texi

@@ -2197,7 +2197,9 @@ other value (the body).
 
 @anchor{-partition-after-pred}
 @defun -partition-after-pred (pred list)
-Partition directly after each time @var{pred} is true on an element of @var{list}.
+Partition @var{list} after each element for which @var{pred} returns non-nil.
+
+This function's anaphoric counterpart is @code{--partition-after-pred}.
 
 @example
 @group

dev/examples.el

@@ -806,7 +806,25 @@ 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 (= (% it 2) 0) '()) => '()
+    (--partition-after-pred (= (% it 2) 1) '()) => '()
+    (--partition-after-pred (= (% it 2) 0) '(0)) => '((0))
+    (--partition-after-pred (= (% it 2) 1) '(0)) => '((0))
+    (--partition-after-pred (= (% it 2) 0) '(0 1)) => '((0) (1))
+    (--partition-after-pred (= (% it 2) 1) '(0 1)) => '((0 1))
+    (--partition-after-pred (= (% it 2) 0) '(0 1 2)) => '((0) (1 2))
+    (--partition-after-pred (= (% it 2) 1) '(0 1 2)) => '((0 1) (2))
+    (--partition-after-pred (= (% it 2) 0) '(0 1 2 3)) => '((0) (1 2) (3))
+    (--partition-after-pred (= (% it 2) 1) '(0 1 2 3)) => '((0 1) (2 3))
+    (--partition-after-pred t '()) => ()
+    (--partition-after-pred t '(0)) => '((0))
+    (--partition-after-pred t '(0 1)) => '((0) (1))
+    (--partition-after-pred t '(0 1 2)) => '((0) (1) (2))
+    (--partition-after-pred nil '()) => '()
+    (--partition-after-pred nil '(0)) => '((0))
+    (--partition-after-pred nil '(0 1)) => '((0 1))
+    (--partition-after-pred nil '(0 1 2)) => '((0 1 2)))
 
   (defexamples -partition-before-pred
     (-partition-before-pred #'booleanp '()) => '()