elisp-mode.el: Show symbol documentation via 'help-echo'

diff --git a/lisp/help-at-pt.el b/lisp/help-at-pt.el
index 3c0c60bfa4d13c47edd43f860c8ed99de16ec67d..47732c7e8fdde2030d26353f829c622e6b8d5dfb 100644 (file)
--- a/lisp/help-at-pt.el
+++ b/lisp/help-at-pt.el
@@ -85,33 +85,29 @@ If this produces no string either, return nil."
 (declare-function widget-at "wid-edit" (&optional pos))
 
 ;;;###autoload
-(defun display-local-help (&optional inhibit-warning describe-button)
-  "Display in the echo area `kbd-help' or `help-echo' text at point.
+(defun display-local-help (&optional inhibit-warning _)
+  "Display `help-echo' text at point.
 This command displays the help message which is the string produced
-by the `kbd-help' property at point.  If `kbd-help' at point does not
-produce a string, but the `help-echo' property does, then that string
-is displayed instead.
-
-The string is passed through `substitute-command-keys' before it
-is displayed.
+by the `help-echo' property at point.
 
 If INHIBIT-WARNING is non-nil, do not display a warning message when
 there is no help property at point.
 
-If DESCRIBE-BUTTON in non-nil (interactively, the prefix arg), and
-there's a button/widget at point, pop up a buffer describing that
-button/widget instead."
-  (interactive (list nil current-prefix-arg))
-  (let ((help (help-at-pt-kbd-string)))
-    (cond
-     ((and describe-button (button-at (point)))
-      (button-describe))
-     ((and describe-button (widget-at (point)))
-      (widget-describe))
-     (help
-      (message "%s" (substitute-command-keys help)))
-     ((not inhibit-warning)
-      (message "No local help at point")))))
+(fn &optional INHIBIT-WARNING)"
+  (interactive)
+  (let* ((posn (posn-at-point))
+         (tooltip-frame-parameters
+          (cons `(left . ,(+ (car (posn-x-y posn))
+                             (window-pixel-left (posn-window posn))
+                             (string-pixel-width (string (char-after))) 10))
+                (cons `(top . ,(+ (cdr (posn-x-y (posn-at-point)))
+                                  (window-pixel-top (posn-window posn))
+                                  (line-pixel-height) 10))
+                      tooltip-frame-parameters))))
+    ;; TODO: Use a child frame like in `eldoc-box' instead of a tooltip.
+    (if-let ((help (help-at-pt-string)))
+        (tooltip-show (substitute-quotes help))
+      (unless inhibit-warning (message "No local help at point")))))
 
 (defvar help-at-pt-timer nil
   "Non-nil means that a timer is set that checks for local help.

diff --git a/lisp/help.el b/lisp/help.el
index 6af8458339b9b40e4953421a8fde7fd833819f42..e8481f49a6bfcd8ffaa7e204ab909f780b7c9274 100644 (file)
--- a/lisp/help.el
+++ b/lisp/help.el
@@ -59,7 +59,6 @@ buffer.")
 (defvar-keymap help-map
   :doc "Keymap for characters following the Help key."
   "."    #'display-local-help
-
   "C-a"  #'about-emacs
   "C-c"  #'describe-copying
   "C-d"  #'view-emacs-debugging

diff --git a/lisp/progmodes/elisp-mode.el b/lisp/progmodes/elisp-mode.el
index 2adbc85e22efae02774483b13ca2b08c9b0b069a..cb40cd80ec43846d3924df8996250f9b1ae65199 100644 (file)
--- a/lisp/progmodes/elisp-mode.el
+++ b/lisp/progmodes/elisp-mode.el
@@ -327,6 +327,10 @@ happens in interactive invocations."
 (defvar-keymap elisp--dynlex-modeline-map
   "<mode-line> <mouse-1>" #'elisp-enable-lexical-binding)
 
+(defface elisp-symbol-at-mouse '((t :background "#f0fff0"))
+  "Face for highlighting the symbol at mouse in Emacs Lisp code."
+  :group 'lisp)
+
 (defface elisp-free-variable '((t :inherit underline))
   "Face for highlighting free variables in Emacs Lisp code."
   :group 'lisp)
@@ -414,14 +418,48 @@ happens in interactive invocations."
    (cl-case type
      (variable      (cond ((equal beg def) "Local variable definition")
                           (def             "Local variable")
-                          (t                "Special variable")))
+                          (t (if-let ((sym (intern (buffer-substring-no-properties beg end))))
+                                 (lambda (&rest _)
+                                   (if-let ((doc (documentation-property sym 'variable-documentation t)))
+                                       (format "Special variable `%S'.\n\n%s" sym doc)
+                                     "Special variable"))
+                               "Special variable"))))
      (block         (if (equal beg def) "Block definition" "Block"))
-     (face          "Face")
+     (face          (if-let ((sym (intern (buffer-substring-no-properties beg end))))
+                        (lambda (&rest _)
+                          (if-let ((doc (documentation-property sym 'face-documentation)))
+                              (format "Face `%S'.\n\n%s" sym doc)
+                            "Face"))
+                      "Face"))
      (function      (cond ((equal beg def) "Local function definition")
                           (def             "Local function call")
-                          (t                "Function call")))
-     (macro         "Macro call")
-     (special-form  "Special form")
+                          (t (if-let ((sym (intern (buffer-substring-no-properties beg end))))
+                                 (lambda (&rest _)
+                                   (with-temp-buffer
+                                     (let ((standard-output (current-buffer)))
+                                       (insert "`" (symbol-name sym) "' is ")
+                                       (describe-function-1 sym)
+                                       (help-make-xrefs))
+                                     (buffer-string)))
+                               "Function call"))))
+     (macro          (if-let ((sym (intern (buffer-substring-no-properties beg end))))
+                         (lambda (&rest _)
+                           (with-temp-buffer
+                             (let ((standard-output (current-buffer)))
+                               (insert "`" (symbol-name sym) "' is ")
+                               (describe-function-1 sym)
+                               (help-make-xrefs))
+                             (buffer-string)))
+                       "Macro call"))
+     (special-form  (if-let ((sym (intern (buffer-substring-no-properties beg end))))
+                        (lambda (&rest _)
+                          (with-temp-buffer
+                            (let ((standard-output (current-buffer)))
+                              (insert "`" (symbol-name sym) "' is ")
+                              (describe-function-1 sym)
+                              (help-make-xrefs))
+                            (buffer-string)))
+                      "Special form"))
      (throw-tag     "`throw'/`catch' tag")
      (warning-type  "Warning type")
      (feature       "Feature")
@@ -438,10 +476,16 @@ happens in interactive invocations."
      (defun         "Function definition")
      (defvar        "Special variable definition")
      (defface       "Face definition")
-     (major-mode    "Major mode"))))
+     (major-mode    (if-let ((sym (intern (buffer-substring-no-properties beg end))))
+                        (lambda (&rest _)
+                          (if-let ((doc (documentation sym)))
+                              (format "Major mode `%S'.\n\n%s" sym doc)
+                            "Major mode"))
+                      "Major mode")))))
 
 (defun elisp-fontify-symbol (type sym len id &optional def)
   (elisp--annotate-symbol-with-help-echo type sym (+ sym len) def)
+  (put-text-property sym (+ sym len) 'mouse-face 'elisp-symbol-at-mouse)
   (if (null id)
       (when-let ((face (cl-case type
                          (variable      'elisp-free-variable)
@@ -588,6 +632,9 @@ be used instead.
   (cl-pushnew 'help-echo
               (alist-get 'font-lock-extra-managed-props
                          (nthcdr 5 font-lock-defaults)))
+  (cl-pushnew 'mouse-face
+              (alist-get 'font-lock-extra-managed-props
+                         (nthcdr 5 font-lock-defaults)))
   (alist-set 'font-lock-fontify-region-function
              (nthcdr 5 font-lock-defaults)
              #'elisp-fontify-region)