init

followcursor-mode.el

@@ -0,0 +1,128 @@
+(require 'hi-lock)
+
+(defgroup followcursor nil
+  "Follow Cursoe Mode."
+  :prefix "followcursor-"
+  :group 'emacs)
+
+(defcustom followcursor-highlight-there 'highlight-lines-matching-regexp
+  ;; also: highlight-regexp
+  "Function used to highlight matching things in there other buffer.")
+
+(defcustom followcursor-highlight-here 'highlight-regexp
+  "Function used to highlight matching things in there current buffer.")
+
+(defcustom followcursor-mark-thing 'followcursor-mark-symbol-lazy
+  "Custom mark function, must set region.
+Use the default or someting like:
+'(lambda() (thing-at-point 'word))")
+
+(make-variable-buffer-local
+ (defvar followcursor--last-point nil
+   "Buffer local variable storing last recorded cursor position."))
+
+(make-variable-buffer-local
+ (defvar followcursor-previous-thing nil
+   "Buffer local variable storing last thing at point, if any"))
+
+(defun followcursor--setup-ok ()
+  "Indicate if it is ok to run followcursor.
+Return t if there are currently 2 visible windows."
+  (interactive)
+  (if (eq (count-windows) 2)
+      t
+    nil))
+
+;; check previous 'thing and do nothing it's the same (eg when moving inside word)
+(defun followcursor--mark-and-highlight (mark-what hl-here hl-there)
+  "Marks thing at point using form ''WHAT and highlights using form ''WHICH."
+  (interactive)
+  (when (followcursor--setup-ok)
+    (let ((thing (funcall mark-what)))
+      (when thing
+        (unless (eq thing followcursor-previous-thing)
+          ;; highlight here
+          (hi-lock-mode 0)
+          (funcall hl-here thing)
+          (other-window 1)
+          ;; highlight there
+          (hi-lock-mode 0)
+          (funcall hl-there thing)
+          ;; go to here buffer
+          (other-window 1))))))
+
+(defun followcursor-mark-symbol-lazy ()
+  "Mark symbol at point, be tolerant about what constitutes a symbol."
+  (interactive)
+  (let ((thing nil)
+        (beg nil)
+        (end nil))
+    (when (not (looking-at "[ \t\n]"))
+      (save-excursion
+        (backward-word)
+        (while (looking-back "[-_\.]")
+          (backward-word))
+        (setq beg (point))
+        (forward-word)
+        (while (looking-at "[-_\.]")
+          (forward-word))
+        (setq end (point)))
+      (unless (eq beg end)
+        (buffer-substring-no-properties beg end)))))
+
+(defun followcursor-mode-enable ()
+  "Enable followcursor-mode."
+  (interactive)
+  (add-hook 'post-command-hook 'followcursor-mark-when-moved)
+  (hi-lock-mode 0)
+  (setq followcursor--last-point (point))
+  (followcursor-mark-when-moved))
+
+(defun followcursor-mode-disable ()
+  "Disable followcursor-mode."
+  (interactive)
+  (remove-hook 'post-command-hook 'followcursor-mark-when-moved)
+  (hi-lock-mode 0)
+  (other-window 1)
+  (hi-lock-mode 0)
+  (other-window 1))
+
+;;;###autoload
+(defun followcursor-mark-when-moved ()
+  "`post-hook-command' which runs when `point' moves.
+`followcursor-mode' must be enabled, only 2 windows must be visible.
+Mark current `followcursor-mark-thing' using `followcursor-highlight-here'
+and use `followcursor-highlight-there' for marking in the other window."
+  (interactive)
+  (unless (window-minibuffer-p)
+    (when followcursor-mode
+      (unless (eq this-command 'followcursor-mode)
+        (unless (eq followcursor--last-point (point))
+          (followcursor--mark-and-highlight
+           followcursor-mark-thing
+           followcursor-highlight-here
+           followcursor-highlight-there))))))
+
+(defun fcmh ()
+  (interactive)
+  (followcursor--mark-and-highlight
+           followcursor-mark-thing
+           followcursor-highlight-here
+           followcursor-highlight-there)
+  )
+
+;;;###autoload
+(define-minor-mode followcursor-mode
+  "Highlight lines in window A containing thing-at-point in window B."
+
+  :init-value nil
+  :lighter "FC"
+  :group "followcursor"
+  (if followcursor-mode
+      (followcursor-mode-enable)
+    (followcursor-mode-disable)))
+
+(provide 'followcursor-mode)
+
+;; followcursor-mode.el ends here
+