elisp片段（2）--tag跳转

(defun goto-tag-of-current-word()
  "查找当前光标下的tag"
  (interactive)
  (let ((word (current-word)))
    (find-tag word)))
(defvar *preview-buffer-prefix* "*preview-buffer*"
  "设置指定名称的window为预览窗口")
(defvar *preview-buffer-name* "*preview-buffer*"
  "设置指定名称的window为预览窗口")
(defun get-preview-buffer-create()
  "获得preview-buffer"
  (get-buffer-create *preview-buffer-name*))
                             
(defun get-preview-window-create()
  "获得preview-window"
  (let ((preview-window (get-buffer-window *preview-buffer-name*)))
    (when (not preview-window);如果预览窗口不存在
      (message "新建预览窗口")
      (setf preview-window (split-window))
      (set-window-buffer preview-window (get-preview-buffer-create)))
    preview-window))
(defun goto-preview-window()
  "将光标移动到preview-window上"
  (interactive)
  (select-window (get-preview-window-create)))
 (defun find-current-tag-info(tag-name)
   "查找tag所在的文件名和位置"
  (let ((old-buffer (current-buffer))(old-pos (point))(tag-file-name)(tag-position))
      (save-selected-window
        (find-tag tag-name)
        (setf tag-file-name (buffer-file-name))
        (setf tag-position (point)))
    (switch-to-buffer old-buffer)
    (goto-char old-pos)))
(defun preview-buffer-p(buffer-or-name)
  "判断是否为preview-buffer"
  (let ((buffer-name))
    (if (bufferp buffer-or-name)
        (setf buffer-name (buffer-name buffer-or-name))
      (setf buffer-name buffer-or-name))
    (string-prefix-p *preview-buffer-prefix* buffer-name)))
       
(defun get-preview-buffer-name(buffer-or-name)
  "计算出preview-buffer的名称
如果buffer已经是preview-buffer则名称不变,否则在buffer名前加上preview-buffer-prefix"
  (let ((buffer-name))
    (if (bufferp buffer-or-name)
        (setf buffer-name (buffer-name buffer-or-name))
      (setf buffer-name buffer-or-name))
    (if (preview-buffer-p buffer-name)
        buffer-name
      (concat *preview-buffer-prefix* buffer-name))))
(defun preview-tag-of-current-word()
  "在预览窗口中查找当前光标下的tag"
  (interactive)
  (let ((old-buffer (current-buffer))(old-pos (point))(tag-buffer))
    (save-selected-window
      (find-tag (current-word))
      (setf tag-buffer (clone-indirect-buffer (get-preview-buffer-name (current-buffer)) nil)))
    (switch-to-buffer old-buffer)
    (goto-char old-pos)
    (goto-preview-window)
    (kill-this-buffer)
    (switch-to-buffer tag-buffer)
    (setf *preview-buffer-name* (buffer-name))
    ))