Die Welt ist meine Vorstellung

elisp function to toggle symbol highlight at the point

22 August 2015

There is the built-in function in emacs to highlight/unhighlight phrases: 

(highlight-phrase REGEXP &optional FACE)
(unhighlight-regexp REGEXP)

They are bounded to key M-s h p and M-s h u respectively. But they are not so convenient that they need the user to input the phrase interactively.

So I write a small function to toggle highlight of the symbol at the point: 

(setq kimim-color-list '(hi-yellow hi-green hi-blue hi-pink))
(setq kimim-color-index 0)
(setq kimim-color-list-length (length kimim-color-list))

(defun kimim/toggle-highlight-tap ()
  "Toggle highlight pattern at the point"
  (interactive)
  (if (and (listp (get-text-property (point) 'face))
           (memq (car (get-text-property (point) 'face)) kimim-color-list))
      (unhighlight-regexp (thing-at-point 'symbol))
    (progn
      (highlight-regexp (thing-at-point 'symbol) (nth kimim-color-index kimim-color-list))
      (setq kimim-color-index (+ kimim-color-index 1))
      (if (>= kimim-color-index kimim-color-list-length)
          (setq kimim-color-index 0))
      )))

(global-set-key [f7] 'kimim/toggle-highlight-tap)

Firstly, a list of highlight color is defined for cycling different color for different symbols. Then the function kimim/toggle-highlight-tap is used to toggle the symbol to highlight or to unhighlight if it is highlighted. And finally, I bind this function to key F7 for quick access.