同じ単語(シンボル)をハイライト表示する

EmacsのOverlayを使ってみるテスト。カーソル位置にある単語(symbol-at-pointで取得できるもの)と同じ単語をハイライト表示させます。

show-paren-modeみたいにタイマーを使ったほうが良いかも。

(eval-when-compile (require 'cl))

(defvar *hl-same-symbol::text* "")
(defvar *hl-same-symbol::list* nil)
(defvar hl-same-symbol-face 'highlight)

(defun hl-same-symbol::highlight (text)
  (setf *hl-same-symbol::text* text)
  ;; (highlight-regexp (regexp-quote text) hl-same-symbol-face)
  (let ((len (length text)))
    (save-excursion
      (dolist (win (window-list))
	(with-current-buffer (window-buffer win)
	  (goto-char (window-start win))
	  (while (let ((pos (search-forward text nil t)))
		   (and pos (< (- pos len) (window-end win))))
	    (hl-same-symbol::highlight-internal text len)))))))

(defun hl-same-symbol::highlight-internal (text len)
  (let ((sym (symbol-at-point)))
    (when (and sym (equal (symbol-name sym) text))
      (let ((overlay (make-overlay (- (point) len) (point))))
	(overlay-put overlay 'face hl-same-symbol-face)
	(push overlay *hl-same-symbol::list*)
	overlay))))

(defun hl-same-symbol::unhighlight ()
  ;; (unhighlight-regexp (regexp-quote *hl-same-symbol::text*))
  (mapcar 'delete-overlay *hl-same-symbol::list*)
  (setf *hl-same-symbol::list* nil))

(defun hl-same-symbol::post-command-hook ()
  (let ((sym (symbol-at-point)))
    (cond
     ((and sym (equal (symbol-name sym) *hl-same-symbol::text*))
      'nothing-to-do)
     (sym
      (hl-same-symbol::unhighlight)
      (hl-same-symbol::highlight (symbol-name sym)))
     (t
      (hl-same-symbol::unhighlight)))
    t))

(defun hl-same-symbol ()
  (interactive)
  (if (find 'hl-samey-symbol::post-command-hook post-command-hook)
      (remove-hook 'post-command-hook 'hl-same-symbol::post-command-hook)
    (add-hook 'post-command-hook 'hl-same-symbol::post-command-hook)))