branch: externals/dash
commit 677c1561142db89cb151f50ce21f24096ca1a328
Merge: f1ffdf7 016e0de
Author: Matus Goljer <dota.k...@gmail.com>
Commit: GitHub <nore...@github.com>
Merge pull request #290 from leungbk/rotate
Generalize `-rotate` for `|n|` greater than `(length list)`.
---
dash.el | 8 +++++---
dev/examples.el | 4 +++-
2 files changed, 8 insertions(+), 4 deletions(-)
diff --git a/dash.el b/dash.el
index 5822361..fcfe5d2 100644
--- a/dash.el
+++ b/dash.el
@@ -921,9 +921,11 @@ See also: `-drop'"
"Rotate LIST N places to the right. With N negative, rotate to the left.
The time complexity is O(n)."
(declare (pure t) (side-effect-free t))
- (if (> n 0)
- (append (last list n) (butlast list n))
- (append (-drop (- n) list) (-take (- n) list))))
+ (when list
+ (let* ((len (length list))
+ (n-mod-len (mod n len))
+ (new-tail-len (- len n-mod-len)))
+ (append (-drop new-tail-len list) (-take new-tail-len list)))))
(defun -insert-at (n x list)
"Return a list with X inserted into LIST at position N.
diff --git a/dev/examples.el b/dev/examples.el
index a250b34..2c8a94d 100644
--- a/dev/examples.el
+++ b/dev/examples.el
@@ -694,7 +694,9 @@ new list."
(defexamples -rotate
(-rotate 3 '(1 2 3 4 5 6 7)) => '(5 6 7 1 2 3 4)
- (-rotate -3 '(1 2 3 4 5 6 7)) => '(4 5 6 7 1 2 3))
+ (-rotate -3 '(1 2 3 4 5 6 7)) => '(4 5 6 7 1 2 3)
+ (-rotate 16 '(1 2 3 4 5 6 7)) => '(6 7 1 2 3 4 5)
+ (-rotate -16 '(1 2 3 4 5 6 7)) => '(3 4 5 6 7 1 2))
(defexamples -repeat
(-repeat 3 :a) => '(:a :a :a)
