Restore old hl-line code

* lisp/hl-line.el: Restore old code to remove obsoletions.
(hl-line-overlay-priority): Make defcustom.

1 files changed, 214 insertions, 75 deletions

diff --git a/lisp/hl-line.el b/lisp/hl-line.el
index f1c2e1ebf23..20b3f4160fd 100644
--- a/lisp/hl-line.el
+++ b/lisp/hl-line.el
@@ -24,40 +24,58 @@
 
 ;;; Commentary:
 
-;;  Proper scuttling of unsticky overlays relies on `post-command-hook`
-;;  being called on a buffer switch and the stationarity of
-;;  `hl-line--buffer` across switches.  One could easily imagine
-;;  programatically defeating unsticky overlays by bypassing
-;; `post-command-hook`.
+;; 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.
 
-;;; Code:
+;; 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.
 
-(make-obsolete-variable 'hl-line-overlay 'hl-line--overlay "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 'hl-line--buffer "29.1")
-(make-obsolete-variable 'hl-line-range-function nil "29.1")
+;; 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'.
 
-(defvar-local hl-line--overlay nil
-  "The prevailing highlighting overlay per buffer.")
+;;; Code:
+
+(defvar-local hl-line-overlay nil
+  "Overlay used by Hl-Line mode to highlight the current line.")
 
-(defvar hl-line--buffer nil
-  "Used to track last buffer.")
+(defvar-local global-hl-line-overlay nil
+  "Overlay used by Global-Hl-Line mode to highlight the current line.")
 
-;; 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)
+(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.")
 
 (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
+  '((t :inherit highlight :extend t))
+  "Default face for highlighting the current line in Hl-Line mode."
   :version "22.1"
   :group 'hl-line)
 
@@ -69,77 +87,204 @@
          (set symbol value)
          (dolist (buffer (buffer-list))
            (with-current-buffer buffer
-             (when hl-line--overlay
-               (overlay-put hl-line--overlay 'face hl-line-face))))))
+             (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 to preserve highlighting overlay when focus leaves window."
+  "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'."
   :type 'boolean
   :version "22.1"
-  :group 'hl-line
-  :initialize #'custom-initialize-default
-  :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))))))))
+  :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"
+  :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.")
 
 (defcustom hl-line-overlay-priority -50
   "Priority used on the overlay used by hl-line."
   :type 'integer
-  :version "22.1"
-  :group 'hl-line)
-
-(defcustom hl-line-highlight-hook nil
-  "After hook for `hl-line-highlight'.
-Currently used in calendar/todo-mode."
-  :type 'hook
+  :version "28.1"
   :group 'hl-line)
 
 ;;;###autoload
 (define-minor-mode hl-line-mode
-  "Toggle highlighting of the current line."
+  "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."
   :group 'hl-line
   (if hl-line-mode
       (progn
-        (hl-line-highlight)
+        ;; 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 'post-command-hook #'hl-line-highlight nil t))
     (remove-hook 'post-command-hook #'hl-line-highlight t)
-    (remove-hook 'change-major-mode-hook #'hl-line-unhighlight 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)))
 
 (defun hl-line-unhighlight ()
-  (when hl-line--overlay
-    (delete-overlay hl-line--overlay)
-    (setq hl-line--overlay nil)))
+  "Deactivate the Hl-Line overlay on the current line."
+  (when (overlayp hl-line-overlay)
+    (delete-overlay hl-line-overlay)
+    (setq hl-line-overlay nil)))
 
-(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))
-    (when (and (not (eq hl-line--buffer (current-buffer)))
+(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)
-               (buffer-live-p hl-line--buffer))
-      (with-current-buffer hl-line--buffer
+               (not (eq curbuf hlob))
+               (not (minibufferp)))
+      (with-current-buffer hlob
         (hl-line-unhighlight)))
-    (setq hl-line--buffer (current-buffer))
-    (run-hooks 'hl-line-highlight-hook)))
+    (when (and (overlayp hl-line-overlay)
+               (eq (overlay-buffer hl-line-overlay) curbuf))
+      (setq hl-line-overlay-buffer curbuf))))
+
+;;;###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
+  :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 hl-line-turn-on ()
-  (unless (minibufferp)
-    (let (inhibit-quit)
-      (hl-line-mode 1))))
+(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."
@@ -151,12 +296,6 @@ Currently used in calendar/todo-mode."
   ;; continue standard unloading
   nil)
 
-;;;###autoload
-(define-globalized-minor-mode global-hl-line-mode
-  hl-line-mode hl-line-turn-on
-  :group 'hl-line
-  :version "29.1")
-
 (provide 'hl-line)
 
 ;;; hl-line.el ends here