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[Emacs-diffs] master 1f052a5: lisp/subr.el (delete-dups): Use a hash tab
From: |
Oleh Krehel |
Subject: |
[Emacs-diffs] master 1f052a5: lisp/subr.el (delete-dups): Use a hash table |
Date: |
Wed, 06 May 2015 13:58:33 +0000 |
branch: master
commit 1f052a5f26250d726618570a816ddb6fd0cc11a0
Author: Oleh Krehel <address@hidden>
Commit: Oleh Krehel <address@hidden>
lisp/subr.el (delete-dups): Use a hash table
* lisp/subr.el (delete-dups): When there are more than 100 candidates,
use a hash table. This can result in ~500 times speed-up for typical
collections of size 5000, like that of `load-library'.
---
lisp/subr.el | 18 +++++++++++++-----
1 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/lisp/subr.el b/lisp/subr.el
index 0fec29c..591980d 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -417,11 +417,19 @@ If N is omitted or nil, remove the last element."
Store the result in LIST and return it. LIST must be a proper list.
Of several `equal' occurrences of an element in LIST, the first
one is kept."
- (let ((tail list))
- (while tail
- (setcdr tail (delete (car tail) (cdr tail)))
- (setq tail (cdr tail))))
- list)
+ (if (> (length list) 100)
+ (let ((hash (make-hash-table :test #'equal))
+ res)
+ (dolist (elt list)
+ (unless (gethash elt hash)
+ (puthash elt elt hash)
+ (push elt res)))
+ (nreverse res))
+ (let ((tail list))
+ (while tail
+ (setcdr tail (delete (car tail) (cdr tail)))
+ (setq tail (cdr tail))))
+ list))
;; See http://lists.gnu.org/archive/html/emacs-devel/2013-05/msg00204.html
(defun delete-consecutive-dups (list &optional circular)
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