bug#15631: 24.3; ido : invert effect of ido-restrict-to-matches with prefix arg

[Nicolas Richard]

Nicolas Richard <theonewiththeevillook@yahoo.fr> writes:
> The function `ido-restrict-to-matches' is used within ido to restrict
> focus on currently matched items. It was asked on #emacs to have a
> function with the opposite effect : restrict focus on unmatched items.
>
> I found it was useful for me and came up with this solution (adding an
> optional argument to the existing function) :

I modified the patch a tiny bit and now use the new library seq.el and
add a NEWS entry. If nobody complains I'll install this patch in the
next few days.

>From c8469c5892c7d01045f81a99a7535b3ed76abd2d Mon Sep 17 00:00:00 2001
From: Nicolas Richard <youngfrog@members.fsf.org>
Date: Tue, 30 Jun 2015 09:18:27 +0200
Subject: [PATCH] Add argument to reverse the meaning of
 ido-restrict-to-matches

* lisp/ido.el (ido-restrict-to-matches): Add an optional argument
to reverse the meaning.

; * etc/NEWS: Mention the change
---
 etc/NEWS    |  3 +++
 lisp/ido.el | 17 +++++++++++++----
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index 1f8cbbc..8ee8364 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -398,6 +398,9 @@ If you need your objects to be named, do it by inheriting 
from `eieio-named'.
 *** New command `ido-bury-buffer-at-head' bound to C-S-b
 Bury the buffer at the head of `ido-matches', analogous to how C-k
 kills the buffer at head.
+*** A prefix argument to `ido-restrict-to-matches' will reverse its
+meaning, and the list is restricted those elements that do not match
+the current input.
 
 ** Minibuffer
 
diff --git a/lisp/ido.el b/lisp/ido.el
index 5995fcd..1f12fbf 100644
--- a/lisp/ido.el
+++ b/lisp/ido.el
@@ -322,6 +322,7 @@
 ;;; Code:
 
 (defvar recentf-list)
+(require 'seq)
 
 ;;;; Options
 
@@ -3180,11 +3181,19 @@ for first matching file."
       (if (> i 0)
          (setq ido-cur-list (ido-chop ido-cur-list (nth i ido-matches)))))))
 
-(defun ido-restrict-to-matches ()
-  "Set current item list to the currently matched items."
-  (interactive)
+(defun ido-restrict-to-matches (&optional removep)
+  "Set current item list to the currently matched items.
+
+When argument REMOVEP is non-nil, the currently matched items are
+instead removed from the current item list."
+  (interactive "P")
   (when ido-matches
-    (setq ido-cur-list ido-matches
+    (setq ido-cur-list (if removep
+                           ;; An important feature is to preserve the
+                           ;; order of the elements.
+                           (seq-difference ido-cur-list ido-matches)
+                         ido-matches)
+          ido-matches ido-cur-list
          ido-text-init ""
          ido-rescan nil
          ido-exit 'keep)
-- 
2.4.5

-- 
Nico.