master 0a094fb65c: Rewrite hl-line-mode

[Lars Ingebrigtsen]

branch: master
commit 0a094fb65ca1392231ef8176f89f936e39f3296e
Author: dickmao <dick.r.chiang@gmail.com>
Commit: Lars Ingebrigtsen <larsi@gnus.org>

    Rewrite hl-line-mode
    
    The fashion of dual global and minor modes, each managing a replica of
    state, has long been outmoded by globalized minor modes (nee
    easy-mmode-define-global-mode) around the turn of the century.
    
    * lisp/calendar/todo-mode.el (todo-toggle-item-highlighting,
    todo-hl-line-range, todo-modes-set-2): Adapt to new
    hl-line-highlight-hook.
    * lisp/hl-line.el (hl-line-overlay): Rename hl-line--overlay.
    (global-hl-line-overlay, global-hl-line-overlays,
    global-hl-line-sticky-flag, hl-line-overlay-buffer,
    hl-line-range-function): Obsolesce.
    (hl-line--overlay): Erstwhile hl-line-overlay.
    (hl-line, hl-line-face): Consolidate.
    (hl-line-sticky-flag): Say less (Gen Z Hospital).
    (hl-line-overlay-priority): Make this a custom.
    (hl-line-highlight-hook): Prefer hook over specialized
    hl-line-range-function.
    (hl-line-mode): Say less (Gen Z Hospital).
    (hl-line-make-overlay): Remove
    (hl-line-highlight, hl-line-unhighlight): Rewrite.
    (hl-line-maybe-unhighlight): Remove.
    (hl-line-turn-on): Necessary for globalized minor mode.
    (global-hl-line-mode, global-hl-line-highlight,
    global-hl-line-highlight-all, global-hl-line-unhighlight,
    global-hl-line-maybe-unhighlight, global-hl-line-unhighlight-all):
    Prefer globalized minor mode.
    (hl-line-move, hl-line-unload-function): Remove.
    * test/lisp/calendar/todo-mode-tests.el (todo-test-item-highlighting,
    todo-test-done-items-separator06-bol,
    todo-test-done-items-separator06-eol,
    todo-test-done-items-separator07): Adapt to consolidated face.
---
 lisp/calendar/todo-mode.el            |  11 +-
 lisp/hl-line.el                       | 297 ++++++++--------------------------
 test/lisp/calendar/todo-mode-tests.el |  10 +-
 test/lisp/hl-line-tests.el            |  51 ++++++
 4 files changed, 123 insertions(+), 246 deletions(-)

diff --git a/lisp/calendar/todo-mode.el b/lisp/calendar/todo-mode.el
index 57fcd1b17e..eed597a033 100644
--- a/lisp/calendar/todo-mode.el
+++ b/lisp/calendar/todo-mode.el
@@ -1040,9 +1040,7 @@ empty line above the done items separator."
   (eval-and-compile (require 'hl-line))
   (when (memq major-mode
              '(todo-mode todo-archive-mode todo-filtered-items-mode))
-    (if hl-line-mode
-       (hl-line-mode -1)
-      (hl-line-mode 1))))
+    (hl-line-mode 'toggle)))
 
 (defvar todo--item-headers-hidden nil
   "Non-nil if item date-time headers in current buffer are hidden.")
@@ -6676,9 +6674,8 @@ Added to `window-configuration-change-hook' in Todo mode."
 (defun todo-hl-line-range ()
   "Make `todo-toggle-item-highlighting' highlight entire item."
   (save-excursion
-    (when (todo-item-end)
-      (cons (todo-item-start)
-            (todo-item-end)))))
+    (when (and (todo-item-end) hl-line--overlay)
+      (move-overlay hl-line--overlay (todo-item-start) (todo-item-end)))))
 
 (defun todo-modes-set-2 ()
   "Make some settings that apply to multiple Todo modes."
@@ -6686,7 +6683,7 @@ Added to `window-configuration-change-hook' in Todo mode."
   (setq buffer-read-only t)
   (setq-local todo--item-headers-hidden nil)
   (setq-local desktop-save-buffer 'todo-desktop-save-buffer)
-  (setq-local hl-line-range-function #'todo-hl-line-range))
+  (add-hook 'hl-line-highlight-hook #'todo-hl-line-range nil t))
 
 (defun todo-modes-set-3 ()
   "Make some settings that apply to multiple Todo modes."
diff --git a/lisp/hl-line.el b/lisp/hl-line.el
index 8e60ddf6b0..daa24c4fbf 100644
--- a/lisp/hl-line.el
+++ b/lisp/hl-line.el
@@ -24,274 +24,103 @@
 
 ;;; Commentary:
 
-;; Provides a local minor mode (toggled by M-x hl-line-mode) and
-;; a global minor mode (toggled by M-x global-hl-line-mode) to
-;; highlight, on a suitable terminal, the line on which point is.  The
-;; global mode highlights the current line in the selected window only
-;; (except when the minibuffer window is selected).  This was
-;; implemented to satisfy a request for a feature of Lesser Editors.
-;; The local mode is sticky: it highlights the line about the buffer's
-;; point even if the buffer's window is not selected.  Caveat: the
-;; buffer's point might be different from the point of a non-selected
-;; window.  Set the variable `hl-line-sticky-flag' to nil to make the
-;; local mode behave like the global mode.
-
-;; You probably don't really want to use the global mode; if the
-;; cursor is difficult to spot, try changing its color, relying on
-;; `blink-cursor-mode' or both.  The hookery used might affect
-;; response noticeably on a slow machine.  The local mode may be
-;; useful in non-editing buffers such as Gnus or PCL-CVS though.
-
-;; An overlay is used.  In the non-sticky cases, this overlay is
-;; active only on the selected window.  A hook is added to
-;; `post-command-hook' to activate the overlay and move it to the line
-;; about point.
-
-;; You could make variable `global-hl-line-mode' buffer-local and set
-;; it to nil to avoid highlighting specific buffers, when the global
-;; mode is used.
-
-;; By default the whole line is highlighted.  The range of highlighting
-;; can be changed by defining an appropriate function as the
-;; buffer-local value of `hl-line-range-function'.
-
 ;;; Code:
 
-(defvar-local hl-line-overlay nil
-  "Overlay used by Hl-Line mode to highlight the current line.")
+(make-obsolete-variable 'hl-line-overlay nil "29.1")
+(make-obsolete-variable 'global-hl-line-overlay nil "29.1")
+(make-obsolete-variable 'global-hl-line-overlays nil "29.1")
+(make-obsolete-variable 'global-hl-line-sticky-flag nil "29.1")
+(make-obsolete-variable 'hl-line-overlay-buffer nil "29.1")
+(make-obsolete-variable 'hl-line-range-function nil "29.1")
 
-(defvar-local global-hl-line-overlay nil
-  "Overlay used by Global-Hl-Line mode to highlight the current line.")
+(defvar-local hl-line--overlay nil
+  "Keep state else scan entire buffer in `post-command-hook'.")
 
-(defvar global-hl-line-overlays nil
-  "Overlays used by Global-Hl-Line mode in various buffers.
-Global-Hl-Line keeps displaying one overlay in each buffer
-when `global-hl-line-sticky-flag' is non-nil.")
+;; 1. define-minor-mode creates buffer-local hl-line--overlay
+;; 2. overlay wiped by kill-all-local-variables
+;; 3. post-command-hook dupes overlay
+;; Solution: prevent step 2.
+(put 'hl-line--overlay 'permanent-local t)
 
 (defgroup hl-line nil
   "Highlight the current line."
   :version "21.1"
   :group 'convenience)
 
-(defface hl-line
-  '((t :inherit highlight :extend t))
-  "Default face for highlighting the current line in Hl-Line mode."
+(defface hl-line-face '((t :inherit highlight :extend t))
+  "Default face for highlighting the current line in hl-line-mode."
   :version "22.1"
   :group 'hl-line)
 
-(defcustom hl-line-face 'hl-line
-  "Face with which to highlight the current line in Hl-Line mode."
-  :type 'face
-  :group 'hl-line
-  :set (lambda (symbol value)
-        (set symbol value)
-        (dolist (buffer (buffer-list))
-          (with-current-buffer buffer
-            (when (overlayp hl-line-overlay)
-              (overlay-put hl-line-overlay 'face hl-line-face))))
-        (when (overlayp global-hl-line-overlay)
-          (overlay-put global-hl-line-overlay 'face hl-line-face))))
-
 (defcustom hl-line-sticky-flag t
-  "Non-nil means the HL-Line mode highlight appears in all windows.
-Otherwise Hl-Line mode will highlight only in the selected
-window.  Setting this variable takes effect the next time you use
-the command `hl-line-mode' to turn Hl-Line mode on.
-
-This variable has no effect in Global Highlight Line mode.
-For that, use `global-hl-line-sticky-flag'."
+  "Non-nil to preserve highlighting overlay when focus leaves window."
   :type 'boolean
   :version "22.1"
+  :group 'hl-line
+  :set (lambda (symbol value)
+         (set-default symbol value)
+         (unless value
+           (let ((selected (window-buffer (selected-window))))
+             (dolist (buffer (buffer-list))
+               (unless (eq buffer selected)
+                 (with-current-buffer buffer
+                   (hl-line-unhighlight))))))))
+
+(defcustom hl-line-overlay-priority -50
+  "Priority used on the overlay used by hl-line."
+  :type 'integer
+  :version "22.1"
   :group 'hl-line)
 
-(defcustom global-hl-line-sticky-flag nil
-  "Non-nil means the Global HL-Line mode highlight appears in all windows.
-Otherwise Global Hl-Line mode will highlight only in the selected
-window.  Setting this variable takes effect the next time you use
-the command `global-hl-line-mode' to turn Global Hl-Line mode on."
-  :type 'boolean
-  :version "24.1"
+(defcustom hl-line-highlight-hook nil
+  "After hook for `hl-line-highlight'.
+Currently used in calendar/todo-mode."
+  :type 'hook
   :group 'hl-line)
 
-(defvar hl-line-range-function nil
-  "If non-nil, function to call to return highlight range.
-The function of no args should return a cons cell; its car value
-is the beginning position of highlight and its cdr value is the
-end position of highlight in the buffer.
-It should return nil if there's no region to be highlighted.
-
-This variable is expected to be made buffer-local by modes.")
-
-(defvar hl-line-overlay-buffer nil
-  "Most recently visited buffer in which Hl-Line mode is enabled.")
-
-(defvar hl-line-overlay-priority -50
-  "Priority used on the overlay used by hl-line.")
-
 ;;;###autoload
 (define-minor-mode hl-line-mode
-  "Toggle highlighting of the current line (Hl-Line mode).
-
-Hl-Line mode is a buffer-local minor mode.  If
-`hl-line-sticky-flag' is non-nil, Hl-Line mode highlights the
-line about the buffer's point in all windows.  Caveat: the
-buffer's point might be different from the point of a
-non-selected window.  Hl-Line mode uses the function
-`hl-line-highlight' on `post-command-hook' in this case.
-
-When `hl-line-sticky-flag' is nil, Hl-Line mode highlights the
-line about point in the selected window only."
+  "Toggle highlighting of the current line."
   :group 'hl-line
   (if hl-line-mode
       (progn
-        ;; In case `kill-all-local-variables' is called.
-        (add-hook 'change-major-mode-hook #'hl-line-unhighlight nil t)
         (hl-line-highlight)
-        (setq hl-line-overlay-buffer (current-buffer))
+        (add-hook 'change-major-mode-hook #'hl-line-unhighlight nil t)
        (add-hook 'post-command-hook #'hl-line-highlight nil t))
     (remove-hook 'post-command-hook #'hl-line-highlight t)
-    (hl-line-unhighlight)
-    (remove-hook 'change-major-mode-hook #'hl-line-unhighlight t)))
-
-(defun hl-line-make-overlay ()
-  (let ((ol (make-overlay (point) (point))))
-    (overlay-put ol 'priority hl-line-overlay-priority) ;(bug#16192)
-    (overlay-put ol 'face hl-line-face)
-    ol))
-
-(defun hl-line-highlight ()
-  "Activate the Hl-Line overlay on the current line."
-  (if hl-line-mode     ; Might be changed outside the mode function.
-      (progn
-        (unless (overlayp hl-line-overlay)
-          (setq hl-line-overlay (hl-line-make-overlay))) ; To be moved.
-        (overlay-put hl-line-overlay
-                     'window (unless hl-line-sticky-flag (selected-window)))
-       (hl-line-move hl-line-overlay)
-        (hl-line-maybe-unhighlight))
-    (hl-line-unhighlight)))
+    (remove-hook 'change-major-mode-hook #'hl-line-unhighlight t)
+    (let (hl-line-sticky-flag)
+      (hl-line-unhighlight))))
 
 (defun hl-line-unhighlight ()
-  "Deactivate the Hl-Line overlay on the current line."
-  (when (overlayp hl-line-overlay)
-    (delete-overlay hl-line-overlay)
-    (setq hl-line-overlay nil)))
+  (unless hl-line-sticky-flag
+    (when hl-line--overlay
+      (delete-overlay hl-line--overlay)
+      (setq hl-line--overlay nil))))
 
-(defun hl-line-maybe-unhighlight ()
-  "Maybe deactivate the Hl-Line overlay on the current line.
-Specifically, when `hl-line-sticky-flag' is nil deactivate all
-such overlays in all buffers except the current one."
-  (let ((hlob hl-line-overlay-buffer)
-        (curbuf (current-buffer)))
-    (when (and (buffer-live-p hlob)
-               (not hl-line-sticky-flag)
-               (not (eq curbuf hlob))
-               (not (minibufferp)))
-      (with-current-buffer hlob
-        (hl-line-unhighlight)))
-    (when (and (overlayp hl-line-overlay)
-               (eq (overlay-buffer hl-line-overlay) curbuf))
-      (setq hl-line-overlay-buffer curbuf))))
+(defun hl-line-highlight ()
+  (unless (minibufferp)
+    (unless hl-line--overlay
+      (setq hl-line--overlay
+            (let ((ol (make-overlay (point) (point))))
+              (prog1 ol
+                (overlay-put ol 'priority hl-line-overlay-priority)
+                (overlay-put ol 'face 'hl-line-face)))))
+    (move-overlay hl-line--overlay
+                  (line-beginning-position)
+                  (line-beginning-position 2))
+    (run-hooks 'hl-line-highlight-hook)))
+
+(defun hl-line-turn-on ()
+  (unless (minibufferp)
+    (let (inhibit-quit)
+      (hl-line-mode 1))))
 
 ;;;###autoload
-(define-minor-mode global-hl-line-mode
-  "Toggle line highlighting in all buffers (Global Hl-Line mode).
-
-If `global-hl-line-sticky-flag' is non-nil, Global Hl-Line mode
-highlights the line about the current buffer's point in all live
-windows.
-
-Global-Hl-Line mode uses the function `global-hl-line-highlight'
-on `post-command-hook'."
-  :global t
+(define-globalized-minor-mode global-hl-line-mode
+  hl-line-mode hl-line-turn-on
   :group 'hl-line
-  (if global-hl-line-mode
-      (progn
-        ;; In case `kill-all-local-variables' is called.
-        (add-hook 'change-major-mode-hook #'global-hl-line-unhighlight)
-        (global-hl-line-highlight-all)
-       (add-hook 'post-command-hook #'global-hl-line-highlight))
-    (global-hl-line-unhighlight-all)
-    (remove-hook 'post-command-hook #'global-hl-line-highlight)
-    (remove-hook 'change-major-mode-hook #'global-hl-line-unhighlight)))
-
-(defun global-hl-line-highlight ()
-  "Highlight the current line in the current window."
-  (when global-hl-line-mode    ; Might be changed outside the mode function.
-    (unless (window-minibuffer-p)
-      (unless (overlayp global-hl-line-overlay)
-        (setq global-hl-line-overlay (hl-line-make-overlay))) ; To be moved.
-      (unless (member global-hl-line-overlay global-hl-line-overlays)
-       (push global-hl-line-overlay global-hl-line-overlays))
-      (overlay-put global-hl-line-overlay 'window
-                  (unless global-hl-line-sticky-flag
-                    (selected-window)))
-      (hl-line-move global-hl-line-overlay)
-      (global-hl-line-maybe-unhighlight))))
-
-(defun global-hl-line-highlight-all ()
-  "Highlight the current line in all live windows."
-  (walk-windows (lambda (w)
-                  (with-current-buffer (window-buffer w)
-                    (global-hl-line-highlight)))
-                nil t))
-
-(defun global-hl-line-unhighlight ()
-  "Deactivate the Global-Hl-Line overlay on the current line."
-  (when (overlayp global-hl-line-overlay)
-    (delete-overlay global-hl-line-overlay)
-    (setq global-hl-line-overlay nil)))
-
-(defun global-hl-line-maybe-unhighlight ()
-  "Maybe deactivate the Global-Hl-Line overlay on the current line.
-Specifically, when `global-hl-line-sticky-flag' is nil deactivate
-all such overlays in all buffers except the current one."
-  (mapc (lambda (ov)
-         (let ((ovb (overlay-buffer ov)))
-            (when (and (not global-hl-line-sticky-flag)
-                       (bufferp ovb)
-                       (not (eq ovb (current-buffer)))
-                       (not (minibufferp)))
-             (with-current-buffer ovb
-                (global-hl-line-unhighlight)))))
-        global-hl-line-overlays))
-
-(defun global-hl-line-unhighlight-all ()
-  "Deactivate all Global-Hl-Line overlays."
-  (mapc (lambda (ov)
-         (let ((ovb (overlay-buffer ov)))
-           (when (bufferp ovb)
-               (with-current-buffer ovb
-                 (global-hl-line-unhighlight)))))
-       global-hl-line-overlays)
-  (setq global-hl-line-overlays nil))
-
-(defun hl-line-move (overlay)
-  "Move the Hl-Line overlay.
-If `hl-line-range-function' is non-nil, move the OVERLAY to the position
-where the function returns.  If `hl-line-range-function' is nil, fill
-the line including the point by OVERLAY."
-  (let (tmp b e)
-    (if hl-line-range-function
-       (setq tmp (funcall hl-line-range-function)
-             b   (car tmp)
-             e   (cdr tmp))
-      (setq tmp t
-           b (line-beginning-position)
-           e (line-beginning-position 2)))
-    (if tmp
-       (move-overlay overlay b e)
-      (move-overlay overlay 1 1))))
-
-(defun hl-line-unload-function ()
-  "Unload the Hl-Line library."
-  (global-hl-line-mode -1)
-  (save-current-buffer
-    (dolist (buffer (buffer-list))
-      (set-buffer buffer)
-      (when hl-line-mode (hl-line-mode -1))))
-  ;; continue standard unloading
-  nil)
+  :version "29.1")
 
 (provide 'hl-line)
 
diff --git a/test/lisp/calendar/todo-mode-tests.el 
b/test/lisp/calendar/todo-mode-tests.el
index 0102b62c10..8715a32b88 100644
--- a/test/lisp/calendar/todo-mode-tests.el
+++ b/test/lisp/calendar/todo-mode-tests.el
@@ -130,8 +130,8 @@ In particular, all lines of a multiline item should be 
highlighted."
    (todo-toggle-item-highlighting)
    (let ((end (1- (todo-item-end)))
          (beg (todo-item-start)))
-     (should (eq (get-char-property beg 'face) 'hl-line))
-     (should (eq (get-char-property end 'face) 'hl-line))
+     (should (eq (get-char-property beg 'face) 'hl-line-face))
+     (should (eq (get-char-property end 'face) 'hl-line-face))
      (should (> (count-lines beg end) 1))
      (should (eq (next-single-char-property-change beg 'face) (1+ end))))
    (todo-toggle-item-highlighting)))   ; Turn off highlighting (for test 
rerun).
@@ -736,7 +736,7 @@ Subsequently moving to an item should show it highlighted."
    (todo-test--done-items-separator)
    (call-interactively #'todo-toggle-item-highlighting)
    (ert-simulate-command '(todo-previous-item))
-   (should (eq 'hl-line (get-char-property (point) 'face)))))
+   (should (eq 'hl-line-face (get-char-property (point) 'face)))))
 
 (ert-deftest todo-test-done-items-separator06-eol () ; bug#32343
   "Test enabling item highlighting at EOL of done items separator.
@@ -746,7 +746,7 @@ Subsequently moving to an item should show it highlighted."
    (todo-toggle-item-highlighting)
    (forward-line -1)
    (ert-simulate-command '(todo-previous-item))
-   (should (eq 'hl-line (get-char-property (point) 'face)))))
+   (should (eq 'hl-line-face (get-char-property (point) 'face)))))
 
 (ert-deftest todo-test-done-items-separator07 () ; bug#32343
   "Test item highlighting when crossing done items separator.
@@ -758,7 +758,7 @@ The highlighting should remain enabled."
    (todo-next-item)               ; Now on empty line above separator.
    (forward-line)                 ; Now on separator.
    (ert-simulate-command '(forward-line)) ; Now on first done item.
-   (should (eq 'hl-line (get-char-property (point) 'face)))))
+   (should (eq 'hl-line-face (get-char-property (point) 'face)))))
 
 (ert-deftest todo-test-current-file-in-edit-mode () ; bug#32437
   "Test the value of todo-current-todo-file in todo-edit-mode."
diff --git a/test/lisp/hl-line-tests.el b/test/lisp/hl-line-tests.el
new file mode 100644
index 0000000000..422d4ddae7
--- /dev/null
+++ b/test/lisp/hl-line-tests.el
@@ -0,0 +1,51 @@
+;;; hl-line-tests.el --- Test suite for hl-line. -*- lexical-binding: t -*-
+
+;; Copyright (C) 2022 Free Software Foundation, Inc.
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Code:
+(require 'ert)
+(require 'hl-line)
+
+(ert-deftest hl-line-sticky ()
+  (should hl-line-sticky-flag)
+  (with-temp-buffer
+    (let ((from-buffer (current-buffer)))
+      (hl-line-mode 1)
+      (save-excursion
+        (insert "foo"))
+      (hl-line-highlight)
+      (should (cl-some (apply-partially #'eq hl-line--overlay)
+                       (overlays-at (point))))
+      (switch-to-buffer (get-buffer-create "*scratch*"))
+      (hl-line-mode 1)
+      (save-excursion
+        (insert "bar"))
+      (hl-line-highlight)
+      (should (cl-some (apply-partially #'eq hl-line--overlay)
+                       (overlays-at (point))))
+      (should (buffer-local-value 'hl-line--overlay from-buffer))
+      (should-not (eq (buffer-local-value 'hl-line--overlay from-buffer)
+                      hl-line--overlay))
+      (customize-set-variable 'hl-line-sticky-flag nil)
+      (should hl-line--overlay)
+      (should (buffer-live-p from-buffer))
+      (should-not (buffer-local-value 'hl-line--overlay from-buffer)))))
+
+(provide 'hl-line-tests)
+
+;;; hl-line-tests.el ends here