bug#73172: [PATCH] Move to start of current header in diff-{file, hunk}-prev

[Spencer Baugh]

Tags: patch


(The following change is split across two patches; the first one, "move
easy-mmode", fixes an unrelated FIXME, which makes the diff in the
second patch simpler)

If point was after a file or hunk header, the diff-file-prev and
diff-hunk-prev commands would move to the start of that header.
But if point was *within* the header, they would not move, and
would report "No previous file" or "No previous hunk".  This
differs from the behavior of most other movement commands,
e.g. backward-sexp or backward-sentence.

This commit fixes diff-file-prev and diff-hunk-prev, as well as
other easy-mmode-define-navigation BASE-prev commands.  Now
these commands move to the start of the containing "thing" just
like other movement commands.

* lisp/emacs-lisp/easy-mmode.el (easy-mmode--prev): Move to
start of current match first.

Also discussed here:
https://lists.gnu.org/archive/html/help-gnu-emacs/2024-08/msg00367.html

In GNU Emacs 29.2.50 (build 17, x86_64-pc-linux-gnu, X toolkit, cairo
 version 1.15.12, Xaw scroll bars) of 2024-09-06 built on
 igm-qws-u22796a
Repository revision: e6d04c06a7eb6ce932b52a346368d02b7a811a00
Repository branch: emacs-29
Windowing system distributor 'The X.Org Foundation', version 11.0.12011000
System Description: Rocky Linux 8.10 (Green Obsidian)

Configured using:
 'configure --with-x-toolkit=lucid --without-gpm --without-gconf
 --without-selinux --without-imagemagick --with-modules --with-gif=no
 --with-cairo --with-rsvg --without-compress-install
 --with-native-compilation=aot --with-tree-sitter
 PKG_CONFIG_PATH=/usr/local/home/garnish/libtree-sitter/0.22.6-1/lib/pkgconfig/'

>From 93f50388bda9f986a5aa8e51378793031cfdce05 Mon Sep 17 00:00:00 2001
From: Spencer Baugh <sbaugh@janestreet.com>
Date: Tue, 10 Sep 2024 13:46:18 -0400
Subject: [PATCH] Move easy-mmode-define-navigation logic to helper functions

The functions defined by easy-mmode-define-navigation are useful
even if the easy-mmode-define-navigation macro is not used.
Let's take a step towards exposing them by moving them out as
helpers.

This also makes the macro much easier to modify and work on.

* lisp/emacs-lisp/easy-mmode.el (easy-mmode--prev)
(easy-mmode--next): Add.
(easy-mmode-define-navigation): Use easy-mmode--prev and
easy-mmode--next.
---
 lisp/emacs-lisp/easy-mmode.el | 86 ++++++++++++++++++++---------------
 1 file changed, 49 insertions(+), 37 deletions(-)

diff --git a/lisp/emacs-lisp/easy-mmode.el b/lisp/emacs-lisp/easy-mmode.el
index a140027839e..d3dcab899d6 100644
--- a/lisp/emacs-lisp/easy-mmode.el
+++ b/lisp/emacs-lisp/easy-mmode.el
@@ -763,6 +763,48 @@ easy-mmode-defsyntax
 ;;; easy-mmode-define-navigation
 ;;;
 
+(defun easy-mmode--prev (re name count &optional endfun narrowfun)
+  "Go to the previous COUNT'th occurence of RE.
+
+If none, error with NAME.
+
+ENDFUN and NARROWFUN are treated like in `easy-mmode-define-navigation'."
+  (unless count (setq count 1))
+  (if (< count 0) (easy-mmode--next re name (- count) endfun narrowfun)
+    (let ((re-narrow (and narrowfun (prog1 (buffer-narrowed-p) (widen)))))
+      (unless (re-search-backward re nil t count)
+        (user-error "No previous %s" name))
+      (when re-narrow (funcall narrowfun)))))
+
+(defun easy-mmode--next (re name count &optional endfun narrowfun)
+  "Go to the next COUNT'th occurence of RE.
+
+If none, error with NAME.
+
+ENDFUN and NARROWFUN are treated like in `easy-mmode-define-navigation'."
+  (unless count (setq count 1))
+  (if (< count 0) (easy-mmode--prev re name (- count) endfun narrowfun)
+    (if (looking-at re) (setq count (1+ count)))
+    (let ((re-narrow (and narrowfun (prog1 (buffer-narrowed-p) (widen)))))
+      (if (not (re-search-forward re nil t count))
+          (if (looking-at re)
+              (goto-char (or (if endfun (funcall endfun)) (point-max)))
+            (user-error "No next %s" name))
+        (goto-char (match-beginning 0))
+        (when (and (eq (current-buffer) (window-buffer))
+                   (called-interactively-p 'interactive))
+          (let ((endpt (or (save-excursion
+                             (if endfun (funcall endfun)
+                               (re-search-forward re nil t 2)))
+                           (point-max))))
+            (unless (pos-visible-in-window-p endpt nil t)
+              (let ((ws (window-start)))
+                (recenter '(0))
+                (if (< (window-start) ws)
+                    ;; recenter scrolled in the wrong direction!
+                    (set-window-start nil ws)))))))
+      (when re-narrow (funcall narrowfun)))))
+
 (defmacro easy-mmode-define-navigation (base re &optional name endfun narrowfun
                                              &rest body)
   "Define BASE-next and BASE-prev to navigate in the buffer.
@@ -780,53 +822,23 @@ easy-mmode-define-navigation
   (let* ((base-name (symbol-name base))
         (prev-sym (intern (concat base-name "-prev")))
         (next-sym (intern (concat base-name "-next")))
-         (when-narrowed
-          (lambda (body)
-            (if (null narrowfun) body
-              `(let ((was-narrowed (prog1 (buffer-narrowed-p) (widen))))
-                 ,body
-                 (when was-narrowed (funcall #',narrowfun)))))))
+         (endfun (when endfun `#',endfun))
+         (narrowfun (when narrowfun `#',narrowfun)))
     (unless name (setq name base-name))
-    ;; FIXME: Move most of those functions's bodies to helper functions!
     `(progn
        (defun ,next-sym (&optional count)
         ,(format "Go to the next COUNT'th %s.
 Interactively, COUNT is the prefix numeric argument, and defaults to 1." name)
         (interactive "p")
-        (unless count (setq count 1))
-        (if (< count 0) (,prev-sym (- count))
-          (if (looking-at ,re) (setq count (1+ count)))
-           ,(funcall when-narrowed
-             `(if (not (re-search-forward ,re nil t count))
-                  (if (looking-at ,re)
-                      (goto-char (or ,(if endfun `(funcall #',endfun)) 
(point-max)))
-                    (user-error "No next %s" ,name))
-                (goto-char (match-beginning 0))
-                (when (and (eq (current-buffer) (window-buffer))
-                           (called-interactively-p 'interactive))
-                  (let ((endpt (or (save-excursion
-                                     ,(if endfun `(funcall #',endfun)
-                                        `(re-search-forward ,re nil t 2)))
-                                   (point-max))))
-                    (unless (pos-visible-in-window-p endpt nil t)
-                      (let ((ws (window-start)))
-                        (recenter '(0))
-                        (if (< (window-start) ws)
-                            ;; recenter scrolled in the wrong direction!
-                            (set-window-start nil ws))))))))
-           ,@body))
+         (easy-mmode--next ,re ,name count ,endfun ,narrowfun)
+         ,@body)
        (put ',next-sym 'definition-name ',base)
        (defun ,prev-sym (&optional count)
         ,(format "Go to the previous COUNT'th %s.
-Interactively, COUNT is the prefix numeric argument, and defaults to 1."
-                  (or name base-name))
+Interactively, COUNT is the prefix numeric argument, and defaults to 1." name)
         (interactive "p")
-        (unless count (setq count 1))
-        (if (< count 0) (,next-sym (- count))
-           ,(funcall when-narrowed
-             `(unless (re-search-backward ,re nil t count)
-                (user-error "No previous %s" ,name)))
-           ,@body))
+         (easy-mmode--prev ,re ,name count ,endfun ,narrowfun)
+         ,@body)
        (put ',prev-sym 'definition-name ',base))))
 
 ;; When deleting these two, also delete them from loaddefs-gen.el.
-- 
2.39.3

0001-Move-to-start-of-current-header-in-diff-file-hunk-pr.patch
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