* lisp/progmodes/hideshow.el: Simplify mouse binding; Use lexical-binding

(hs-set-up-overlay, hs-adjust-block-beginning): Use non-nil default for
function variables, so `add-function` can be used on them.
(hs-toggle-hiding): Make it work for mouse bindings as well.
(hs-minor-mode-map): Use it for the mouse binding.
(hs-grok-mode-type): Use bound-and-true-p.
(hs-life-goes-on): Use `declare` for the debug spec.
(hs-mouse-toggle-hiding): Make it an obsolete alias.

1 files changed, 24 insertions, 35 deletions

diff --git a/lisp/progmodes/hideshow.el b/lisp/progmodes/hideshow.el
index dcce2a6e2a9..1d62bb58750 100644
--- a/lisp/progmodes/hideshow.el
+++ b/lisp/progmodes/hideshow.el
@@ -1,4 +1,4 @@
-;;; hideshow.el --- minor mode cmds to selectively display code/comment blocks
+;;; hideshow.el --- minor mode cmds to selectively display code/comment blocks  -*- lexical-binding:t -*-
 
 ;; Copyright (C) 1994-2019 Free Software Foundation, Inc.
 
@@ -37,7 +37,7 @@
 ;;   hs-show-all                        C-c @ C-M-s
 ;;   hs-hide-level                      C-c @ C-l
 ;;   hs-toggle-hiding                   C-c @ C-c
-;;   hs-mouse-toggle-hiding             [(shift mouse-2)]
+;;   hs-toggle-hiding                   [(shift mouse-2)]
 ;;   hs-hide-initial-comment-block
 ;;
 ;; Blocks are defined per mode.  In c-mode, c++-mode and java-mode, they
@@ -55,8 +55,7 @@
 ;; Then, add the following to your init file:
 ;;
 ;; (load-library "hideshow")
-;; (add-hook 'X-mode-hook               ; other modes similarly
-;;           (lambda () (hs-minor-mode 1)))
+;; (add-hook 'X-mode-hook #'hs-minor-mode)           ; other modes similarly
 ;;
 ;; where X = {emacs-lisp,c,c++,perl,...}.  You can also manually toggle
 ;; hideshow minor mode by typing `M-x hs-minor-mode'.  After hideshow is
@@ -181,8 +180,8 @@
 ;; (5) Hideshow interacts badly with Ediff and `vc-diff'.  At the moment, the
 ;;     suggested workaround is to turn off hideshow entirely, for example:
 ;;
-;;     (add-hook 'ediff-prepare-buffer-hook 'turn-off-hideshow)
-;;     (add-hook 'vc-before-checkin-hook 'turn-off-hideshow)
+;;     (add-hook 'ediff-prepare-buffer-hook #'turn-off-hideshow)
+;;     (add-hook 'vc-before-checkin-hook #'turn-off-hideshow)
 ;;
 ;;     In the case of `vc-diff', here is a less invasive workaround:
 ;;
@@ -317,7 +316,7 @@ a block), `hs-hide-all', `hs-hide-block' and `hs-hide-level'.")
 These commands include the toggling commands (when the result is to show
 a block), `hs-show-all' and `hs-show-block'.")
 
-(defvar hs-set-up-overlay nil
+(defvar hs-set-up-overlay #'ignore
   "Function called with one arg, OV, a newly initialized overlay.
 Hideshow puts a unique overlay on each range of text to be hidden
 in the buffer.  Here is a simple example of how to use this variable:
@@ -329,7 +328,7 @@ in the buffer.  Here is a simple example of how to use this variable:
                            (count-lines (overlay-start ov)
                                         (overlay-end ov))))))
 
-  (setq hs-set-up-overlay \\='display-code-line-counts)
+  (setq hs-set-up-overlay #\\='display-code-line-counts)
 
 This example shows how to get information from the overlay as well
 as how to set its `display' property.  See `hs-make-overlay' and
@@ -355,7 +354,7 @@ Use the command `hs-minor-mode' to toggle or set this variable.")
     (define-key map "\C-c@\C-t"       'hs-hide-all)
     (define-key map "\C-c@\C-d"       'hs-hide-block)
     (define-key map "\C-c@\C-e"       'hs-toggle-hiding)
-    (define-key map [(shift mouse-2)] 'hs-mouse-toggle-hiding)
+    (define-key map [(shift mouse-2)] 'hs-toggle-hiding)
     map)
   "Keymap for hideshow minor mode.")
 
@@ -410,7 +409,7 @@ element (using `match-beginning') before calling `hs-forward-sexp-func'.")
 (defvar-local hs-block-end-regexp nil
   "Regexp for end of block.")
 
-(defvar-local hs-forward-sexp-func 'forward-sexp
+(defvar-local hs-forward-sexp-func #'forward-sexp
   "Function used to do a `forward-sexp'.
 Should change for Algol-ish modes.  For single-character block
 delimiters -- ie, the syntax table regexp for the character is
@@ -418,7 +417,7 @@ either `(' or `)' -- `hs-forward-sexp-func' would just be
 `forward-sexp'.  For other modes such as simula, a more specialized
 function is necessary.")
 
-(defvar-local hs-adjust-block-beginning nil
+(defvar-local hs-adjust-block-beginning #'identity
   "Function used to tweak the block beginning.
 The block is hidden from the position returned by this function,
 as opposed to hiding it from the position returned when searching
@@ -575,10 +574,8 @@ and then further adjusted to be at the end of the line."
         ;; `p' is the point at the end of the block beginning, which
         ;; may need to be adjusted
         (save-excursion
-          (if hs-adjust-block-beginning
-              (goto-char (funcall hs-adjust-block-beginning
-                                  header-end))
-            (goto-char header-end))
+          (goto-char (funcall (or hs-adjust-block-beginning #'identity)
+                              header-end))
           (setq p (line-end-position)))
         ;; `q' is the point at the end of the block
         (hs-forward-sexp mdata 1)
@@ -657,9 +654,8 @@ If `hs-special-modes-alist' has information associated with the
 current buffer's major mode, use that.
 Otherwise, guess start, end and `comment-start' regexps; `forward-sexp'
 function; and adjust-block-beginning function."
-  (if (and (boundp 'comment-start)
-           (boundp 'comment-end)
-           comment-start comment-end)
+  (if (and (bound-and-true-p comment-start)
+           (bound-and-true-p comment-end))
       (let* ((lookup (assoc major-mode hs-special-modes-alist))
              (start-elem (or (nth 1 lookup) "\\s(")))
         (if (listp start-elem)
@@ -677,8 +673,8 @@ function; and adjust-block-beginning function."
                                           (substring c-start-regexp
                                                      0 (1- (match-end 0)))
                                         c-start-regexp)))
-              hs-forward-sexp-func (or (nth 4 lookup) 'forward-sexp)
-              hs-adjust-block-beginning (nth 5 lookup)))
+              hs-forward-sexp-func (or (nth 4 lookup) #'forward-sexp)
+              hs-adjust-block-beginning (or (nth 5 lookup) #'identity)))
     (setq hs-minor-mode nil)
     (error "%s Mode doesn't support Hideshow Minor Mode"
            (format-mode-line mode-name))))
@@ -729,13 +725,12 @@ Return point, or nil if original point was not in a block."
   "Evaluate BODY forms if variable `hs-minor-mode' is non-nil.
 In the dynamic context of this macro, `inhibit-point-motion-hooks'
 and `case-fold-search' are both t."
+  (declare (debug t))
   `(when hs-minor-mode
      (let ((inhibit-point-motion-hooks t)
            (case-fold-search t))
        ,@body)))
 
-(put 'hs-life-goes-on 'edebug-form-spec '(&rest form))
-
 (defun hs-overlay-at (position)
   "Return hideshow overlay at POSITION, or nil if none to be found."
   (let ((overlays (overlays-at position))
@@ -895,24 +890,18 @@ The hook `hs-hide-hook' is run; see `run-hooks'."
      (message "Hiding blocks ... done"))
    (run-hooks 'hs-hide-hook)))
 
-(defun hs-toggle-hiding ()
+(defun hs-toggle-hiding (&optional e)
   "Toggle hiding/showing of a block.
-See `hs-hide-block' and `hs-show-block'."
+See `hs-hide-block' and `hs-show-block'.
+Argument E should be the event that triggered this action."
   (interactive)
   (hs-life-goes-on
+   (posn-set-point (event-end e))
    (if (hs-already-hidden-p)
        (hs-show-block)
      (hs-hide-block))))
 
-(defun hs-mouse-toggle-hiding (e)
-  "Toggle hiding/showing of a block.
-This command should be bound to a mouse key.
-Argument E is a mouse event used by `mouse-set-point'.
-See `hs-hide-block' and `hs-show-block'."
-  (interactive "@e")
-  (hs-life-goes-on
-   (mouse-set-point e)
-   (hs-toggle-hiding)))
+(define-obsolete-function-alias 'hs-mouse-toggle-hiding #'hs-toggle-hiding "27.1")
 
 (defun hs-hide-initial-comment-block ()
   "Hide the first block of comments in a file.
@@ -939,7 +928,7 @@ The value (hs . t) is added to `buffer-invisibility-spec'.
 
 The main commands are: `hs-hide-all', `hs-show-all', `hs-hide-block',
 `hs-show-block', `hs-hide-level' and `hs-toggle-hiding'.  There is also
-`hs-hide-initial-comment-block' and `hs-mouse-toggle-hiding'.
+`hs-hide-initial-comment-block'.
 
 Turning hideshow minor mode off reverts the menu bar and the
 variables to default values and disables the hideshow commands.
@@ -957,7 +946,7 @@ Key bindings:
         (hs-grok-mode-type)
         ;; Turn off this mode if we change major modes.
         (add-hook 'change-major-mode-hook
-                  'turn-off-hideshow
+                  #'turn-off-hideshow
                   nil t)
         (easy-menu-add hs-minor-mode-menu)
         (set (make-local-variable 'line-move-ignore-invisible) t)