{"id":10020821,"date":"2025-06-07T16:46:40","date_gmt":"2025-06-07T08:46:40","guid":{"rendered":"https:\/\/itmax.cn\/?p=10020821"},"modified":"2025-06-07T16:46:40","modified_gmt":"2025-06-07T08:46:40","slug":"%e5%9c%a8-emacs-%e7%bc%93%e5%86%b2%e5%8c%ba%e9%87%8c%e8%a1%8c%e8%b5%b0%e7%9a%84%e5%a7%bf%e5%8a%bf","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10020821","title":{"rendered":"\u5728 Emacs \u7f13\u51b2\u533a\u91cc\u884c\u8d70\u7684\u59ff\u52bf"},"content":{"rendered":"

=> \u4e0a\u4e00\u7bc7<\/strong>\uff1a\u7f13\u51b2\u533a\u2014\u2014Emacs \u65e0\u5f62\u4e4b\u8c61<\/a><\/p><\/blockquote>\n

\u524d\u8a00<\/h2>\n

\u73b0\u5728\uff0cEmacs \u7684\u7f13\u51b2\u533a\uff0c\u4f60\u5e94\u8be5\u5df2\u7ecf\u80fd\u591f\u62db\u4e4b\u5373\u6765\uff0c\u6325\u4e4b\u5373\u53bb\u4e86\uff0c\u5e94\u8be5\u4e5f\u80fd\u5728\u4f17\u591a\u7f13\u51b2\u533a\u4e4b\u95f4\u968f\u610f\u7a7f\u8d8a\uff0c\u4e5f\u5e94\u8be5\u968f\u65f6\u80fd\u8ba9\u67d0\u4e2a\u7f13\u51b2\u533a\u5448\u73b0\u5728\u67d0\u4e2a\u7a97\u53e3\u91cc\u7ea4\u6beb\u6bd5\u9732\u3002\u4e0d\u8fc7\uff0c\u82e5\u8981\u5145\u5206\u8fd0\u7528\u7f13\u51b2\u533a\u8574\u542b\u7684\u529b\u91cf\uff0c\u4f60\u8fd8\u9700\u8981\u5b66\u4f1a\u4e00\u4e9b\u7b80\u5355\u7684 Elisp \u8868\u8fbe\u5f0f\uff0c\u901a\u8fc7\u5b83\u4eec\u53ef\u4ee5\u89e6\u6478\u7f13\u51b2\u533a\u5185\u7684\u4e00\u5207\u3002<\/p>\n

\u9012\u5f52<\/h2>\n

\u4f60\u5df2\u7ecf\u77e5\u9053\u4e86\uff0c\u901a\u8fc7 point-min<\/code> \u548c point-max<\/code> \u51fd\u6570\u53ef\u4ee5\u83b7\u5f97\u5f53\u524d\u7f13\u51b2\u533a\u7684\u9996\u90e8\u548c\u5c3e\u90e8\u4f4d\u7f6e\uff0c\u4e5f\u5df2\u7ecf\u77e5\u9053\u4e86\u53ef\u4ee5\u901a\u8fc7 forward-char<\/code> \u548c backward-char<\/code> \u51fd\u6570\u53ef\u4ee5\u5728\u7f13\u51b2\u533a\u5185\u79fb\u52a8\u5149\u6807\uff0c\u4f46\u662f\u4f60\u77e5\u9053\u5982\u4f55\u4ece\u5f53\u524d\u7f13\u51b2\u533a\u7684\u8d77\u59cb\u4f4d\u7f6e\u5f00\u59cb\uff0c\u4f9d\u5e8f\u89e6\u6478\u6bcf\u4e2a\u5b57\u7b26\uff0c\u76f4\u81f3\u7f13\u51b2\u533a\u5c3e\u90e8\u5417\uff1f<\/p>\n

\u5047\u8bbe\u5f53\u524d\u7f13\u51b2\u533a\u4e00\u5171\u6709 5 \u4e2a\u5b57\u7b26\uff0c\u4f8b\u5982\u300cHello\u300d\uff0c\u6211\u53ef\u4ee5\u5199\u51fa\u50cf\u4e0b\u9762\u8fd9\u6837\u7684\u611a\u8822\u7684\u51fd\u6570\uff0c\u5b83\u521a\u597d\u80fd\u904d\u5386 5 \u4e2a\u5b57\u7b26\u3002<\/p>\n

(defun stupid-walker ()\n  (message "%c" (char-after 1))\n  (message "%c" (char-after 2))\n  (message "%c" (char-after 3))\n  (message "%c" (char-after 4))\n  (message "%c" (char-after 5)))<\/code><\/pre>\n
Emacs \u51fd\u6570 char-after<\/code> \u53ef\u4ee5\u83b7\u5f97\u4f4d\u4e8e\u5149\u6807\u4e4b\u540e\u7684\u7b2c\u4e00\u4e2a\u5b57\u7b26\u3002\u8981\u83b7\u5f97\u5149\u6807\u4e4b\u524d\u7684\u7b2c\u4e00\u4e2a\u5b57\u7b26\uff0c\u53ef\u4ee5\u7528 char-before<\/code>\u3002message<\/code> \u8868\u8fbe\u5f0f\u4e2d\u7684 %c<\/code> \u7528\u4e8e\u683c\u5f0f\u5316\u8f93\u51fa\u5b57\u7b26\u3002\u5728\u4e0a\u8ff0\u5047\u60f3\u7684\u573a\u666f\u91cc\uff0c\u82e5\u5bf9\u8868\u8fbe\u5f0f (stupid-walker)<\/code> \u6c42\u503c\uff0c*Messages*<\/code> \u7f13\u51b2\u533a\u5219\u6709\u4ee5\u4e0b\u8f93\u51fa\uff1a<\/p>\n
H\ne\nl [2 times]\no<\/code><\/pre>\n
\u6211\u4eec\u53ef\u4ee5\u8ba9 stupid-walker<\/code> \u53d8\u5f97\u806a\u660e\u4e00\u4e9b\uff0c\u4f8b\u5982<\/p>\n
(defun clever-walker (i)\n  (message "%c" (char-after i)))<\/code><\/pre>\n
\u82e5\u8981\u4f9d\u5e8f\u904d\u5386\u4e0a\u8ff0\u5047\u60f3\u7684\u7f13\u51b2\u533a\u4e2d\u6bcf\u4e2a\u5b57\u7b26\uff0c\u53ea\u9700<\/p>\n
(clever-walker 1)\n(clever-walker 2)\n(clever-walker 3)\n(clever-walker 4)\n(clever-walker 5)<\/code><\/pre>\n
\u76f4\u5230\u6709\u4e00\u5929\uff0c\u8fd9\u4e2a\u806a\u660e\u7684\u884c\u8005\u5ffd\u7136\u5f00\u609f\u4e86\uff0c\u5723\u4eba\u4e4b\u9053\uff0c\u543e\u6027\u81ea\u8db3\uff0c\u4e0d\u5047\u5916\u6c42\uff01<\/strong>\u6211\u4f55\u5fc5\u4e00\u76f4\u7b49\u5f85\u5916\u754c\u4fee\u6539 i<\/code> \u7684\u503c\u518d\u4f20\u7ed9\u6211\u5462\uff0c\u6211\u5b8c\u5168\u53ef\u4ee5\u81ea\u5df1\u4fee\u6539\uff0c\u800c\u4e14\u6211\u751a\u81f3\u53ef\u4ee5\u81ea\u5df1\u5bf9\u81ea\u5df1\u6c42\u503c\uff1a<\/p>\n
(defun clever-walker (i)\n  (message "%c" (char-after i))\n  (clever-walker (+ i 1)))<\/code><\/pre>\n
\u4e4b\u540e\uff0cclever-walker<\/code> \u53d1\u73b0\uff0c\u5b83\u53ea\u9700\u8981\u4ece\u5916\u754c\u83b7\u5f97 1\uff0c\u7136\u540e\u5c31\u80fd\u4e00\u76f4\u8d70\u5230\u5730\u8001\u5929\u8352\u4e86\uff0c\u5929\u5f97\u4e00\u4ee5\u6e05\uff0c\u5730\u5f97\u4e00\u4ee5\u5b81\uff0c\u4faf\u738b\u5f97\u4e00\u4e3a\u5929\u4e0b\u6b63\u3002<\/p>\n
(clever-walker 1)<\/code><\/pre>\n
\u5f53 clever-walker<\/code> \u53d1\u73b0\u81ea\u5df1\u7684\u786e\u53ef\u4ee5\u4ece 1 \u5f00\u59cb\uff0c\u4e00\u76f4\u8d70\u4e0b\u53bb\uff0c\u5e76\u89e6\u78b0\u5230\u4e86\u5f53\u524d\u7f13\u51b2\u533a\u91cc\u7684\u6bcf\u4e2a\u5b57\u7b26\uff0c\u7136\u540e\u4ed6\u53ea\u9700\u660e\u767d\u5728\u4f55\u5904\u505c\u6b62\u524d\u8fdb\uff0c\u4fbf\u5b8c\u6210\u4e86\u4efb\u52a1\u3002<\/p>\n
(defun clever-walker (i)\n  (when (< i (point-max))\n    (message "%c" (char-after i))\n    (clever-walker (+ i 1))))\n\n(clever-walker 1)<\/code><\/pre>\n
\u4e0a\u8ff0\u4ee3\u7801\u4e2d\u7684 (< i (point-max))<\/code>\uff0c\u60f3\u5fc5\u4f60\u80fd\u624d\u51fa\u5b83\u7684\u542b\u4e49\uff0c\u5373\u6bd4\u8f83 i<\/code> \u662f\u5426\u5c0f\u4e8e (point-max)<\/code>\u3002clever-walker<\/code> \u662f\u6211\u4eec\u7528 Elisp \u5199\u7684\u7b2c\u4e00\u4e2a\u9012\u5f52\u51fd\u6570\u3002<\/p>\n
\u4e00\u4e2a\u51fd\u6570\uff0c\u82e5\u5b83\u5bf9\u81ea\u8eab\u6c42\u503c\uff0c\u4fbf\u662f\u9012\u5f52\u7684\u3002\u4e5f\u8bb8 Elisp \u7684\u4f5c\u8005\u62c5\u5fc3\u6211\u4eec\u6ca1\u6709\u738b\u9633\u660e\u9f99\u573a\u609f\u9053\u7684\u5929\u8d4b\uff0c\u6545\u800c\u521b\u9020\u4e86 while<\/code> \u8868\u8fbe\u5f0f\uff0c\u4f7f\u5f97\u4e0d\u5f00\u609f\u7684\u4eba\u4e5f\u80fd\u505a\u5230\u5f00\u609f\u8005\u80fd\u505a\u5230\u7684\u4e8b\u60c5\uff0c\u4f8b\u5982<\/p>\n
(defun clever-walker (i)\n    (while (< i (point-max))\n      (message "%c" (char-after i))\n      (setq i (+ i 1))))\n\n(clever-walker 1)<\/code><\/pre>\n
\u4e0a\u8ff0\u4ee3\u7801\u4e2d\uff0cEmacs \u53ef\u5bf9 while<\/code> \u4e4b\u540e\u7b2c\u4e00\u4e2a\u6761\u4ef6\u8868\u8fbe\u5f0f (< i (point-max))<\/code> \u6c42\u503c\uff0c\u82e5\u7ed3\u679c\u4e3a\u771f\uff0c\u5373 t<\/code>\uff0c\u5219\u5bf9\u540e\u7eed\u8868\u8fbe\u5f0f\u4f9d\u5e8f\u6c42\u503c\uff0c\u7136\u540e\u5468\u800c\u590d\u59cb\uff0c\u76f4\u81f3\u7b2c\u4e00\u4e2a\u6761\u4ef6\u8868\u8fbe\u5f0f\u7684\u6c42\u503c\u7ed3\u679c\u4e3a\u5047\uff0c\u5373 nil<\/code>\u3002\u4e5f\u8bb8\u4f60\u4f9d\u7136\u8bb0\u5f97\uff0cElisp \u91cc\u7684\u4efb\u4f55\u8868\u8fbe\u5f0f\uff0c\u5fc5\u987b\u8981\u6709\u6c42\u503c\u7ed3\u679c\u3002while<\/code> \u8868\u8fbe\u5f0f\u7684\u6c42\u503c\u7ed3\u679c\u603b\u662f nil<\/code>\uff0c\u4ea6\u5373\u5b83\u4e0d\u9700\u8981\u7ed3\u679c\u3002<\/p>\n
\u518d\u8c08 let<\/h2>\n
\u5018\u82e5\u91c7\u7528\u79fb\u52a8\u5149\u6807\u7684\u65b9\u5f0f\u904d\u5386\u7f13\u51b2\u533a\uff0c\u4e0a\u8ff0 clever-walker<\/code> \u7684\u53c2\u6570 i<\/code> \u4fbf\u53ef\u7701\u53bb\u3002\u4f8b\u5982<\/p>\n
(defun clever-walker ()\n    (goto-char (point-min)) ;; \u5c06\u5149\u6807\u79fb\u5230\u5f53\u524d\u7f13\u51b2\u533a\u9996\u90e8\n    (while (< (point) (point-max))\n      (message "%c" (char-after (point)))\n      (forward-char)))\n\n(clever-walker)<\/code><\/pre>\n
\u4e0a\u8ff0\u4ee3\u7801\u4e2d\u7684 point<\/code> \u51fd\u6570\u53ef\u4ee5\u83b7\u53d6\u5149\u6807\u5f53\u524d\u4f4d\u7f6e\u3002\u539f\u5148\u7531\u53c2\u6570 i<\/code> \u5b8c\u6210\u7684\u5de5\u4f5c\uff0c\u73b0\u5728\u7531 point<\/code> \u51fd\u6570\u5b8c\u6210\uff0c\u7a0b\u5e8f\u7684\u6027\u80fd\u4f1a\u6709\u6240\u964d\u4f4e\uff0c\u4e0d\u8fc7\u4e5f\u4e0d\u5fc5\u4e3a\u6b64\u800c\u7126\u8651\uff0c\u4e24\u79cd\u65b9\u5f0f\u7686\u53ef\u7528\u3002\u82e5\u5728\u610f\u6027\u80fd\uff0c\u5e94\u8be5\u5c06 clever-walker<\/code> \u5b9a\u4e49\u4e3a<\/p>\n
(defun clever-walker ()\n  (goto-char (point-min))\n  (let (i n)\n    (setq i (point))\n    (setq n (point-max))\n    (while (< i n)\n      (message "%c" (char-after i))\n      (forward-char)\n      (setq i (point)))))<\/code><\/pre>\n
\u4e0d\u77e5\u4f60\u662f\u5426\u6ce8\u610f\u5230\u4e86\uff0c\u5728 let<\/code> \u8868\u8fbe\u5f0f\u5b9a\u4e49\u5c40\u90e8\u53d8\u91cf\u65f6\uff0c\u53ef\u4ee5\u4e0d\u5bf9\u5176\u8d4b\u4e88\u521d\u503c\uff0c\u76f4\u63a5\u50cf\u51fd\u6570\u53c2\u6570\u90a3\u6837\uff0c\u6784\u9020\u51fa\u5c40\u90e8\u53d8\u91cf\u5217\u8868\uff0c\u7136\u540e\u5728\u540e\u7eed\u7684\u8fc7\u7a0b\u4e2d\u7528 setq<\/code> \u8d4b\u503c\u3002\u672a\u8d4b\u521d\u503c\u7684\u5c40\u90e8\u53d8\u91cf\uff0c\u5176\u503c\u9ed8\u8ba4\u662f nil<\/code>\uff0c\u4ea6\u5373<\/p>\n
(let (a b c)\n  ... ... ...)<\/code><\/pre>\n
\u7b49\u6548\u4e8e<\/p>\n
(let ((a nil)\n      (b nil)\n      (c nil))\n  ... ... ...)<\/code><\/pre>\n
\u4ea6\u7b49\u6548\u4e8e<\/p>\n
(let (a b c)\n  (setq a nil\n        b nil\n        c nil)\n  ... ... ...)<\/code><\/pre>\n
\u9010\u884c\u904d\u5386<\/h2>\n
Emacs \u51fd\u6570 forward-line<\/code> \u53ef\u5c06\u5149\u6807\u79fb\u52a8\u5230\u4e0b\u4e00\u884c\u7684\u5f00\u5934\u3002\u57fa\u4e8e\u8be5\u51fd\u6570\uff0c\u6211\u4eec\u80fd\u66f4\u5927\u8de8\u5ea6\u904d\u5386\u5f53\u524d\u7f13\u51b2\u533a\u3002\u4f8b\u5982<\/p>\n
(defun clever-walker ()\n  (goto-char (point-min))\n  (while (< (point) (point-max))\n    (message "%s" (buffer-substring (pos-bol) (pos-eol)))\n    (forward-line)))\n\n(clever-walker)<\/code><\/pre>\n
buffer-substring<\/code> \u53ef\u4ee5\u4ece\u5f53\u524d\u7f13\u51b2\u533a\u63d0\u53d6\u6307\u5b9a\u533a\u95f4\u7684\u5185\u5bb9\u3002pos-bol<\/code> \u548c pos-eol<\/code> \u5206\u522b\u7528\u4e8e\u83b7\u53d6\u5149\u6807\u6240\u5728\u7684\u4e00\u884c\u6587\u672c\u7684\u9996\u90e8\u548c\u5c3e\u90e8\u4f4d\u7f6e\uff0c\u8fd9\u4e24\u4e2a\u4f4d\u7f6e\u4fbf\u53ef\u6784\u6210 buffer-substring<\/code> \u6240\u9700\u7684\u533a\u95f4\u3002<\/p>\n
pos-bol<\/code> \u548c pos-eol<\/code> \u8fd9\u4e24\u4e2a\u51fd\u6570\u662f\u5728 Emacs 29 \u7248\u672c\u5f15\u5165\u7684\uff0c\u4e4b\u524d\u5b83\u4eec\u7684\u540d\u5b57\u8f83\u957f\uff0c\u5206\u522b\u662f line-beginning-position<\/code> \u548c line-end-position<\/code>\u3002<\/p>\n
Emacs \u6ca1\u6709\u63d0\u4f9b backward-line<\/code> \u51fd\u6570\uff0c\u4f46\u662f\u53ef\u4ee5\u7528 (forward-line -1)<\/code> \u5c06\u5149\u6807\u79fb\u52a8\u5230\u4e0a\u4e00\u884c\u7684\u9996\u90e8\u3002<\/p>\n
\u7531\u4e8e Emacs \u529f\u80fd\u4e30\u5bcc\u4e14\u5f3a\u5927\uff0c\u7f13\u51b2\u533a\u5185\u7684\u6587\u5b57\u6709\u65f6\u4f1a\u5e26\u6709\u4e00\u4e9b\u5c5e\u6027\uff0c\u4f8b\u5982\u5b57\u4f53\u548c\u989c\u8272\u7b49\u4fe1\u606f\u3002buffer-substring<\/code> \u63d0\u53d6\u7684\u5185\u5bb9\uff0c\u4e5f\u4f1a\u5e26\u6709\u8fd9\u4e9b\u5c5e\u6027\u3002\u5018\u82e5\u53ea\u662f\u60f3\u63d0\u53d6\u7eaf\u7cb9\u7684\u6587\u5b57\uff0c\u5e94\u8be5\u7528\u540d\u5b57\u66f4\u957f\u7684 buffer-substring-no-properties<\/code> \u51fd\u6570\uff0c\u5176\u7528\u6cd5\u4e0e buffer-substring<\/code> \u540c\u3002<\/p>\n
\u6536\u96c6<\/h2>\n
\u6709\u65f6\uff0c\u53ef\u80fd\u9700\u8981\u4ece\u7f13\u51b2\u533a\u91cc\u6c72\u53d6\u4e00\u90e8\u5206\u5185\u5bb9\u3002\u8fd9\u4e00\u9700\u6c42\uff0c\u53ef\u4ee5\u5728\u5bf9\u7f13\u51b2\u533a\u9010\u5b57\u6216\u9010\u884c\u904d\u5386\u7684\u8fc7\u7a0b\u4e2d\uff0c\u4ee5\u5b57\u7b26\u4e32\u7d2f\u52a0\u7684\u65b9\u5f0f\u5b9e\u73b0\u3002Emacs \u7684 concat<\/code> \u51fd\u6570\uff0c\u53ef\u5c06\u4e24\u4e2a\u5b57\u7b26\u4e32\u8fde\u63a5\u8d77\u6765\uff0c\u57fa\u4e8e\u8be5\u51fd\u6570\u53ef\u5b9e\u73b0\u5b57\u7b26\u4e32\u7d2f\u52a0\u3002\u4f8b\u5982<\/p>\n
;; \u6c42\u503c\u7ed3\u679c\u5e94\u8be5\u4e3a hello world!\n(let ((acc ""))\n  (setq acc (concat acc "hello"))\n  (setq acc (concat acc " world!"))\n  (message "%s" acc))<\/code><\/pre>\n
\u57fa\u4e8e\u4e0a\u8ff0\u4ee3\u7801\uff0c\u4fbf\u53ef\u5728\u904d\u5386\u5f53\u524d\u7f13\u51b2\u533a\u7684\u8fc7\u7a0b\u4e2d\u6536\u96c6\u6587\u5b57\uff0c\u4f8b\u5982<\/p>\n
(defun walker ()\n  (goto-char (point-min))\n  (let ((acc ""))\n    (while (< (point) (point-max))\n      (setq acc (concat acc (string (char-after (point)))))\n      (forward-char))\n    acc))<\/code><\/pre>\n
string<\/code> \u51fd\u6570\u53ef\u5c06\u4e00\u4e2a\u6216\u4e00\u7cfb\u5217\u7684\u5b57\u7b26\u4e32\u8054\u8d77\u6765\u53d8\u4e3a\u5b57\u7b26\u4e32\u3002\u6ce8\u610f\uff0c\u4e0a\u8ff0\u4ee3\u7801\u6700\u7ec8\u4ee5 acc<\/code> \u4f5c\u4e3a let<\/code> \u8868\u8fbe\u5f0f\u7684\u6c42\u503c\u7ed3\u679c\u3002\u7531\u4e8e let<\/code> \u8868\u8fbe\u5f0f\u662f\u51fd\u6570 walker<\/code> \u5b9a\u4e49\u4e2d\u7684\u6700\u540e\u4e00\u4e2a\u8868\u8fbe\u5f0f\uff0c\u6545\u800c\u5176\u6c42\u503c\u7ed3\u679c\u4e5f\u662f walker<\/code> \u7684\u6c42\u503c\u7ed3\u679c\uff0c\u5373\u5f53\u524d\u7f13\u51b2\u533a\u5185\u7684\u6240\u6709\u5b57\u7b26\u3002\u5018\u82e5\u7f13\u51b2\u533a\u5185\u6240\u6709\u5b57\u7b26\u7686\u65e0\u5c5e\u6027\uff0c\u6211\u4eec\u6240\u5199\u7684 walker<\/code> \u51fd\u6570\uff0c\u7b49\u6548\u4e8e Emacs \u63d0\u4f9b\u7684 buffer-string<\/code> \u51fd\u6570\uff0c\u770b\u4f3c\u6211\u4eec\u5728\u767d\u8d39\u5de5\u592b\uff0c\u5b9e\u5219\u4e0d\u7136\uff0c\u56e0\u4e3a\u6211\u4eec\u53ef\u4ee5\u6839\u636e\u5177\u4f53\u60c5\u51b5\uff0c\u968f\u65f6\u7ec8\u6b62\u6587\u5b57\u6536\u96c6\u8fc7\u7a0b\uff0c\u4f8b\u5982\uff0c\u9047\u300c\u6c34\u300d\u5219\u6b62\u2026\u2026<\/p>\n
\u57fa\u4e8e while<\/code> \u8868\u8fbe\u5f0f\u5199\u51fa\u80fd\u9047\u300c\u6c34\u300d\u5219\u505c\u6b62\u7684 walker<\/code>\uff0c\u76ee\u524d\u5c1a\u65e0\u6cd5\u505a\u5230\uff0c\u539f\u56e0\u662f\u6211\u4eec\u4e0d\u77e5\u5982\u4f55\u63d0\u524d\u8df3\u51fa while<\/code> \u8868\u8fbe\u5f0f\u6240\u8868\u8fbe\u7684\u5468\u800c\u590d\u59cb\u7684\u903b\u8f91\u3002\u7528\u9012\u5f52\u51fd\u6570\uff0c\u4e5f\u65e0\u6cd5\u5b9e\u73b0\uff0c\u56e0\u4e3a\u9700\u8981\u5904\u7406\u7684\u903b\u8f91\u8d85\u51fa\u4e86 when<\/code> \u7684\u8868\u8fbe\u80fd\u529b\uff0c\u5b83\u53ea\u80fd\u8868\u8fbe\u5bf9\u6761\u4ef6\u4e3a\u771f\u6216\u4e3a\u5047\u7684\u4f5c\u51fa\u5355\u4e00\u54cd\u5e94\uff0c\u800c\u65e0\u6cd5\u5206\u522b\u4f5c\u51fa\u54cd\u5e94\u3002\u6b64\u523b\uff0c\u6211\u4eec\u89e6\u53ca\u4e86\u6240\u638c\u63e1\u7684\u77e5\u8bc6\u7684\u8fb9\u754c\u3002<\/p>\n
\u9002\u53ef\u800c\u6b62<\/h2>\n
Elisp \u53ef\u901a\u8fc7 catch<\/code> \u548c throw<\/code> \u8868\u8fbe\u5f0f\u5b9e\u73b0\u4e00\u6bb5\u7a0b\u5e8f\u7684\u9000\u51fa\u3002cache<\/code> \u8868\u8fbe\u5f0f\u7528\u4e8e\u5728\u4e00\u6bb5\u7a0b\u5e8f\u8fd0\u884c\u524d\u8bbe\u5b9a\u9000\u51fa\u6807\u8bb0\u3002\u4f8b\u5982<\/p>\n
(catch 'here\n  (message "step 1")\n  (message "step 2")\n  (message "step 3"))<\/code><\/pre>\n
\u5bf9\u4e0a\u8ff0\u8868\u8fbe\u5f0f\u6c42\u503c\uff0c\u4e09\u4e2a message<\/code> \u8868\u8fbe\u5f0f\u4f1a\u88ab\u9646\u7eed\u6c42\u503c\uff0c\u6700\u540e\u7684 message<\/code> \u8868\u8fbe\u5f0f\u7684\u6c42\u503c\u7ed3\u679c\u2014\u2014\u5b57\u7b26\u4e32 "step 3"<\/code> \u4f1a\u88ab Emacs \u4f5c\u4e3a catch<\/code> \u8868\u8fbe\u5f0f\u7684\u6c42\u503c\u7ed3\u679c\u3002\u73b0\u5728\u60f3\u5fc5\u4f60\u5df2\u7ecf\u5bf9 Emacs \u5bf9 Elisp \u7a0b\u5e8f\u7684\u8fd9\u79cd\u6c42\u503c\u903b\u8f91\u9887\u4e3a\u719f\u6089\u4e86\uff0c\u5373 Emacs \u5bf9\u4e00\u7ec4\u8868\u8fbe\u5f0f\u4f9d\u5e8f\u6c42\u503c\u65f6\uff0c\u6700\u540e\u4e00\u4e2a\u8868\u8fbe\u5f0f\u7684\u6c42\u503c\u7ed3\u679c\u4fbf\u662f\u8fd9\u7ec4\u8868\u8fbe\u5f0f\u7684\u6c42\u503c\u7ed3\u679c\u3002\u53e6\u5916\uff0c\u5373\u4f7f\u6211\u4e4b\u524d\u6ca1\u6709\u8bf4\u8fc7\uff0c\u4f55\u8c13 message<\/code> \u7684\u6c42\u503c\u7ed3\u679c\uff0c\u60f3\u5fc5\u4f60\u4e5f\u80fd\u731c\u5230\uff0cmessage<\/code> \u4f1a\u5c06\u81ea\u5df1\u8f93\u51fa\u7684\u5b57\u7b26\u4e32\u4f5c\u4e3a\u6c42\u503c\u7ed3\u679c\u3002<\/p>\n
\u5018\u82e5\u53ea\u662f\u7528\u4e8e\u5bf9\u4e00\u7ec4\u8868\u8fbe\u5f0f\u6c42\u503c\uff0c\u90a3\u4e48 catch<\/code> \u5e76\u4e0d\u6bd4 let<\/code> \u66f4\u9ad8\u660e\uff0c\u5173\u952e\u5728\u4e8e catch<\/code> \u5728\u8fd9\u7ec4\u8868\u8fbe\u5f0f\u4e4b\u524d\u8bbe\u5b9a\u7684\u6807\u8bb0\uff0c\u540e\u7eed\u7684\u8868\u8fbe\u5f0f\u53ef\u6839\u636e\u60c5\u51b5\u968f\u65f6\u8df3\u8f6c\u81f3\u8be5\u6807\u8bb0\u6240\u5728\u4f4d\u7f6e\uff0c\u5e76\u5728\u6b64\u63d0\u4f9b\u4e00\u4e2a\u6c42\u503c\u7ed3\u679c\u4f5c\u4e3a catch<\/code> \u8868\u8fbe\u5f0f\u7684\u6c42\u503c\u7ed3\u679c\uff0c\u4ea6\u5373\u5728\u6b64\u7ec8\u7ed3 catch<\/code> \u8868\u8fbe\u5f0f\uff0c\u8be5\u8fc7\u7a0b\u53ef\u901a\u8fc7 throw<\/code> \u8868\u8fbe\u5f0f\u5b9e\u73b0\u3002\u4f8b\u5982<\/p>\n
(catch 'here\n  (message "step 1")\n  (throw 'here (message "step 2"))\n  (message "step 3"))<\/code><\/pre>\n
\u4e0a\u8ff0\u7684 catch<\/code> \u8868\u8fbe\u5f0f\uff0c\u7b2c 3 \u6761 message<\/code> \u8868\u8fbe\u5f0f\u6c38\u65e0\u673a\u4f1a\u88ab\u6c42\u503c\uff0c\u56e0\u4e3a\u5728\u5176\u4e4b\u524d\uff0cthrow<\/code> \u8868\u8fbe\u5f0f\u4ee5\u7b2c\u4e8c\u6761 message<\/code> \u8868\u8fbe\u5f0f\u7ec8\u7ed3\u4e86 catch<\/code> \u8868\u8fbe\u5f0f\uff0c\u4ea6\u5373\u7b2c\u4e8c\u6761 message<\/code> \u8868\u8fbe\u5f0f\u7684\u6c42\u503c\u7ed3\u679c\u4fbf\u662f catch<\/code> \u8868\u8fbe\u5f0f\u7684\u6c42\u503c\u7ed3\u679c\uff0c\u6545\u800c\u5bf9\u4e0a\u8ff0\u8868\u8fbe\u5f0f\u6c42\u503c\uff0c\u7ed3\u679c\u5e94\u8be5\u662f "step 2"<\/code>\u3002<\/p>\n
\u57fa\u4e8e catch\/throw<\/code>\uff0c\u4fbf\u53ef\u5728\u904d\u5386\u5f53\u524d\u7f13\u51b2\u533a\u7684\u8fc7\u7a0b\u4e2d\u5b9e\u73b0\u9047\u300c\u6c34\u300d\u5219\u6b62\u3002\u4f8b\u5982<\/p>\n
(defun walker ()\n  (goto-char (point-min))\n  (let ((acc "") x)\n    (catch 'break\n      (while (< (point) (point-max))\n    (setq x (char-after (point)))\n    (when (char-equal x ?\u6c34)\n      (throw 'break acc))\n    (setq acc (concat acc (string x)))\n    (forward-char))\n    acc)))<\/code><\/pre>\n
\u4e0a\u8ff0\u4ee3\u7801\u4e2d\uff0c(throw 'break acc)<\/code> \u4f1a\u4ee5 acc<\/code> \u4f5c\u4e3a\u6c42\u503c\u7ed3\u679c\u7ec8\u7ed3 cache<\/code>\u3002\u7531\u4e8e cache<\/code> \u8868\u8fbe\u5f0f\u662f\u5176\u5916\u56f4\u7684 let<\/code> \u8868\u8fbe\u5f0f\u4e2d\u6700\u540e\u4e00\u4e2a\u8868\u8fbe\u5f0f\uff0c\u5176\u6c42\u503c\u7ed3\u679c acc<\/code> \u81ea\u7136\u4e5f\u662f let<\/code> \u8868\u8fbe\u5f0f\u7684\u6c42\u503c\u7ed3\u679c\u3002\u53c8\u7531\u4e8e let<\/code> \u8868\u8fbe\u5f0f\u662f\u51fd\u6570 walker<\/code> \u4e2d\u7684\u6700\u540e\u4e00\u4e2a\u8868\u8fbe\u5f0f\uff0c\u5176\u6c42\u503c\u7ed3\u679c\u81ea\u7136\u4e5f\u662f walker<\/code> \u7684\u6c42\u503c\u7ed3\u679c\uff0c\u6545\u800c walker<\/code> \u5728\u9047\u5230\u300c\u6c34\u300d\u5b57\u65f6\uff0c\u6c42\u503c\u7ed3\u679c\u4fbf\u662f\u5f53\u65f6\u7684 acc<\/code>\u3002\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u5018\u82e5\u5728\u904d\u5386\u7f13\u51b2\u533a\u7684\u8fc7\u7a0b\u4e2d\u4e00\u503c\u672a\u9047\u5230\u300c\u6c34\u300d\uff0ccatch<\/code> \u8868\u8fbe\u5f0f\u6700\u540e\u7684\u6c42\u503c\u7ed3\u679c\u4e5f\u662f acc<\/code>\uff0c\u6b64\u65f6\u7684 acc<\/code> \u4fdd\u5b58\u7684\u662f\u5f53\u524d\u7f13\u51b2\u533a\u7684\u5168\u90e8\u5185\u5bb9\u3002<\/p>\n
\u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u4e0a\u8ff0\u4ee3\u7801\u4e2d\u4f7f\u7528\u4e86\u6b64\u524d\u672a\u66fe\u7528\u8fc7\u7684\u51fd\u6570 char-equal<\/code>\uff0c\u5b83\u53ef\u7528\u4e8e\u6bd4\u8f83\u4e24\u4e2a\u5b57\u7b26\u662f\u5426\u76f8\u540c\u3002?\u6c34<\/code> \u8868\u793a\u300c\u6c34\u300d\u5b57\u7684\u5b57\u9762\u91cf\u3002\u5728\u5176\u4ed6\u7f16\u7a0b\u8bed\u8a00\u4e2d\uff0c\u8868\u8fbe\u5b57\u7b26\u7684\u5b57\u9762\u91cf\uff0c\u901a\u5e38\u7528\u5355\u5f15\u53f7\uff0c\u4f8b\u5982 'a'<\/code> \u8868\u793a\u5b57\u7b26 a<\/code> \u7684\u5b57\u9762\u91cf\uff0c\u4f46\u662f\u8fd9\u4e9b\u7f16\u7a0b\u8bed\u8a00\u5374\u65e0\u6cd5\u5bf9\u6c49\u5b57\u5982\u6b64\u8868\u793a\uff0c\u539f\u56e0\u662f\u5355\u5f15\u53f7\u8868\u8fbe\u7684\u5b57\u9762\u91cf\uff0c\u957f\u5ea6\u901a\u5e38\u53ea\u6709 1 \u4e2a\u5b57\u8282\uff0c\u800c\u6c49\u5b57\u90fd\u662f\u591a\u4e2a\u5b57\u8282\u7684\u3002\u76f8\u6bd4\u4e4b\u4e0b\uff0cElisp \u7684\u95ee\u53f7\u8868\u793a\u6cd5\u53ef\u7528\u4e8e\u8868\u8fbe\u6c49\u5b57\u5b57\u7b26\uff0c\u9887\u4e3a\u5148\u8fdb\u7684\uff0c\u4f60\u4e5f\u53ef\u4ee5\u7528\u8fd9\u79cd\u5f62\u5f0f\u8868\u8fbe\u5355\u5b57\u8282\u5b57\u7b26\uff0c\u4f8b\u5982\u6240\u6709\u5b57\u6bcd\u3001\u6570\u5b57\u3001\u4e0b\u5212\u7ebf\u7b49\u5b57\u7b26\u3002<\/p>\n
\u6211\u77e5\u9053\uff0c\u4e0a\u8ff0\u7684 walker<\/code> \u51fd\u6570\u7684\u903b\u8f91\u5df2\u9887\u4e3a\u590d\u6742\u4e86\uff0c\u7406\u89e3\u8d77\u6765\u5e76\u975e\u6613\u4e8b\u3002\u9605\u8bfb Elisp \u4ee3\u7801\u6216\u8005\u5176\u4ed6 Lisp \u8bed\u8a00\u7684\u4ee3\u7801\u65f6\uff0c\u5934\u8111\u9700\u8981\u4fdd\u6301\u6e05\u9192\uff0c\u8bb0\u4f4f\u7a0b\u5e8f\u7684\u6700\u540e\u4e00\u4e2a\u8868\u8fbe\u5f0f\u7684\u6c42\u503c\u7ed3\u679c\u4fbf\u662f\u7a0b\u5e8f\u7684\u6c42\u503c\u7ed3\u679c\uff0c\u800c\u6bcf\u4e00\u6761\u8868\u8fbe\u5f0f\u90fd\u53ef\u4ee5\u89c6\u4e3a\u4e00\u6bb5\u7a0b\u5e8f\u2026\u2026\u8fd8\u8bb0\u5f97 Lisp \u673a\u7684\u7075\u9b42\u5417\uff1f\u7684\u786e\u5b58\u5728\u5f88\u591a Lisp \u8bed\u8a00\uff0cElisp \u53ea\u662f\u5176\u4e2d\u4e4b\u4e00\u3002\u5728\u8ba1\u7b97\u673a\u79d1\u5b66\u9886\u57df\uff0c\u4e00\u79cd\u88ab\u5e7f\u4e3a\u63a8\u5d07\u7684 Lisp \u8bed\u8a00\u53eb\u4f5c Scheme\u3002<\/p>\n
\u5018\u82e5\u4f60\u61c2\u5f97\u4e00\u4e9b C \u8bed\u8a00\uff0c\u6211\u53ef\u4ee5\u7528\u4f2a C \u8bed\u8a00\u91cd\u65b0\u63cf\u8ff0 walker<\/code> \u7684\u903b\u8f91\uff0c\u5982\u4e0b\uff1a<\/p>\n
String walker(void) {\n        goto_char(point-min());\n        String acc = "";\n        while (point() < point_max()) {\n                Char x = char_after(point());\n                if (x \u4e3a '\u6c34') return acc;\n                acc = concat(acc, string(x));\n                forward_char();\n        }\n        return acc;\n}<\/code><\/pre>\n
\u4e0a\u8ff0\u4ee3\u7801\u53ea\u662f\u4f2a C \u4ee3\u7801\uff0c\u53ea\u80fd\u7528\u4e8e\u8868\u610f\uff0c\u5e76\u4e0d\u5408\u4e4e C \u8bed\u6cd5\uff0c\u4f46\u662f\u901a\u8fc7\u5b83\uff0c\u4e5f\u8bb8\u4f60\u80fd\u5f7b\u5e95\u660e\u767d Elisp \u7248\u672c\u7684 walker<\/code> \u51fd\u6570\u6240\u8868\u8fbe\u7684\u903b\u8f91\u3002<\/p>\n
\u6761\u4ef6\u8868\u8fbe\u5f0f<\/h2>\n
Elisp \u7684\u6761\u4ef6\u8868\u8fbe\u5f0f\u4e0d\u6b62\u6709 when<\/code>\uff0c\u5b83\u4e5f\u63d0\u4f9b\u4e86\u5f88\u591a\u5176\u4ed6\u7f16\u7a0b\u8bed\u8a00\u90fd\u6709\u7684 if<\/code> \u8868\u8fbe\u5f0f\uff0c\u53ea\u662f\u5f62\u5f0f\u4e0a\u6709\u4e9b\u602a\u5f02\uff0c\u4f8b\u5982<\/p>\n
(let ((x ?\u706b))\n  (if (char-equal x ?\u6c34)\n      (message "true")\n    (message "false")))<\/code><\/pre>\n
\u4e0a\u8ff0\u8868\u8fbe\u5f0f\u7684\u6c42\u503c\u7ed3\u679c\u662f "false"<\/code>\uff0c\u4e14\u5728 *Messages*<\/code> \u7f13\u51b2\u533a\u8f93\u51fa false<\/code>\u3002<\/p>\n
if<\/code> \u8868\u8fbe\u7684\u5f62\u5f0f\u53ef\u8868\u8ff0\u4e3a<\/p>\n
(if \u903b\u8f91\u8868\u8fbe\u5f0f\n    (\u7a0b\u5e8f\u5206\u652f 1)\n  (\u7a0b\u5e8f\u5206\u652f 2))<\/code><\/pre>\n
\u82e5\u7528\u4f2a C \u4ee3\u7801\u8868\u8fbe\u4e0e\u4e0a\u8ff0\u903b\u8f91\u7b49\u6548\u7684\u5f62\u5f0f\uff0c\u5373<\/p>\n
if (\u903b\u8f91\u8868\u8fbe\u5f0f\n  \u7a0b\u5e8f\u5206\u652f 1\n} else {\n  \u7a0b\u5e8f\u5206\u652f 2\n}<\/code><\/pre>\n
\u4ea6\u5373 Elisp \u7684 if<\/code> \u8868\u8fbe\u5f0f\u91cc\u662f\u6697\u542b else<\/code> \u5206\u652f\u7684\uff0c\u4f46\u662f if<\/code> \u8868\u8fbe\u5f0f\u4e2d\u7684\u4e24\u4e2a\u7a0b\u5e8f\u5206\u652f\u8868\u8fbe\u5f0f\uff0c\u90fd\u662f\u5355\u4e00\u8868\u8fbe\u5f0f\uff0c\u4ea6\u5373\u65e0\u6cd5\u5199\u4e3a\u4e00\u7ec4\u8868\u8fbe\u5f0f\uff0c\u4f8b\u5982<\/p>\n
(let ((x ?\u706b))\n  (if (char-equal x ?\u6c34)\n      (message "true")\n      (message "x \u662f\u6c34")\n    (message "false")\n    (message "\u6c34\u706b\u4e0d\u5bb9")))<\/code><\/pre>\n
\u867d\u7136\u4e0a\u8ff0\u8868\u8fbe\u5f0f\u4e5f\u80fd\u6c42\u503c\uff0c\u4f46\u662f\u5e76\u975e\u6211\u4eec\u6240\u671f\u671b\u7684\uff0c\u4ea6\u5373\u7a0b\u5e8f\u5206\u652f 1 \u5e76\u975e<\/p>\n
(message "true")\n(message "x \u662f\u6c34")<\/code><\/pre>\n
\u800c\u7a0b\u5e8f\u5206\u652f 2\uff0c\u4e5f\u5e76\u975e<\/p>\n
(message "false")\n(message "\u6c34\u706b\u4e0d\u5bb9")<\/code><\/pre>\n
\u6211\u4eec\u53ef\u4ee5\u518d\u7528\u4e00\u6b21\u4f2a C \u4ee3\u7801\u8868\u8fbe\u4e0a\u8ff0\u7684 if<\/code> \u8868\u8fbe\u5f0f\u7684\u903b\u8f91\uff0c\u5982\u4e0b<\/p>\n
Char x = '\u706b';\nif (x \u4e3a '\u6c34') {\n        message("true");\n} else {\n        message("x \u662f\u6c34");\n}\nmessage("false");\nmessage("\u6c34\u706b\u4e0d\u5bb9");<\/code><\/pre>\n
\u90a3\u4e48\uff0c\u6211\u4eec\u8be5\u5982\u4f55\u7528 Elisp \u7684 if<\/code> \u8868\u8fbe\u6211\u4eec\u60f3\u8981\u7684\u903b\u8f91\u7684\uff0c\u4ea6\u5373\u8868\u8fbe\u4e0e\u4ee5\u4e0b\u4f2a C \u4ee3\u7801\u76f8\u540c\u7684\u903b\u8f91\u3002<\/p>\n
Char x = '\u706b';\nif (x \u4e3a '\u6c34') {\n        message("true");\n        message("x \u662f\u6c34");\n} else {\n        message("false");\n        message("\u6c34\u706b\u4e0d\u5bb9");  \n}<\/code><\/pre>\n
\u7b54\u6848\u662f\u4f7f\u7528 progn<\/code> \u8868\u8fbe\u5f0f\uff0c\u8be5\u8868\u8fbe\u5f0f\u7684\u529f\u7528\u7c7b\u4f3c\u4e0a\u8ff0\u4f2a C \u4ee3\u7801\u7684\u82b1\u62ec\u53f7\uff0c\u53ef\u4ee5\u5c06\u4e00\u7ec4\u8868\u8fbe\u5f0f\u5305\u88f9\u8d77\u6765\uff0c\u6210\u4e3a\u4e00\u4e2a\u8868\u8fbe\u5f0f\u3002\u4f8b\u5982<\/p>\n
(let ((x ?\u706b))\n  (if (char-equal x ?\u6c34)\n      (progn\n        (message "true")\n        (message "x \u662f\u6c34"))\n    (progn\n      (message "false")\n      (message "\u6c34\u706b\u4e0d\u5bb9"))))<\/code><\/pre>\n
\u4e4b\u524d\u662f\u56e0 Elisp \u7684 if<\/code> \u8868\u8fbe\u5f0f\u6709\u4e00\u4e9b\u4ee4\u4eba\u8d39\u89e3\uff0c\u6240\u4ee5\u6211\u4e00\u76f4\u5728\u7528 when<\/code>\uff0c\u4f46 if<\/code> \u7ec8\u7a76\u662f\u65e0\u6cd5\u907f\u5f00\u7684\u3002\u4e0d\u8fc7\uff0c\u5b9e\u9645\u4e0a\u4e5f\u4e0d\u96be\uff0c\u53ea\u8981\u4f60\u638c\u63e1\u4e86 if<\/code> \u7684\u903b\u8f91\u4ee5\u53ca progn<\/code> \u7684\u4f5c\u7528\u3002<\/p>\n
\u4e0d\u8fc7\uff0cif<\/code> \u53ea\u80fd\u5bf9\u903b\u8f91\u8868\u8fbe\u5f0f\u6210\u7acb\u548c\u4e0d\u6210\u7acb\u4e24\u79cd\u60c5\u51b5\u4f5c\u51fa\u54cd\u5e94\u3002\u5728\u5f88\u591a\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u9700\u8981\u54cd\u5e94\u6761\u4ef6\u662f\u8d85\u8d8a\u903b\u8f91\u8868\u8fbe\u5f0f\u7684\u3002\u5176\u4ed6\u7f16\u7a0b\u8bed\u8a00\u63d0\u4f9b\u4e86 else if<\/code> \u6216 elif<\/code> \u4f5c\u4e3a\u9644\u52a0\u7684\u7a0b\u5e8f\u5206\u652f\u3002\u4f8b\u5982\uff0c\u5728 C \u8bed\u8a00\u91cc\u53ef\u4ee5\u5b9e\u73b0\u4ee5\u4e0b\u903b\u8f91\uff1a<\/p>\n
if (x \u4e3a '\u6c34') {\n        ... ... ...;\n} else if (x \u4e3a '\u706b') {\n        ... ... ...;\n} else if (x \u4e3a '\u6728') {\n        ... ... ...;\n} else {\n        ... ... ...;\n}<\/code><\/pre>\n
\u5bf9\u4e8e\u4e0a\u8ff0\u903b\u8f91\uff0cElisp \u7684 if<\/code> \u65e0\u80fd\u4e3a\u529b\uff0c\u4e0d\u8fc7\uff0cElisp \u6709 cond<\/code> \u8868\u8fbe\u5f0f\u53ef\u6a21\u62df\u4e0a\u8ff0\u903b\u8f91\uff0c\u4f8b\u5982<\/p>\n
(cond\n  ((char-equal x ?\u6c34) (... ... ...))\n  ((char-equal x ?\u706b) (... ... ...))\n  ((char-equal x ?\u6728) (... ... ...))\n  (t (... ... ...)))<\/code><\/pre>\n
\u8bf7\u6ce8\u610f\u4e0a\u8ff0\u4f2a Elisp \u4ee3\u7801\u4e2d\u7684\u6700\u540e\u4e00\u884c\uff0c\u6211\u4eec\u7528\u771f\u503c t<\/code> \u6a21\u62df\u4e0a\u8ff0 C \u4f2a\u4ee3\u7801\u91cc\u7684 else<\/code> \u5b9e\u73b0\u515c\u5e95\u5904\u7406\uff0c\u7528\u4e8e\u5904\u7406\u4e4b\u524d\u7684\u6761\u4ef6\u7686\u4e0d\u6210\u7acb\u7684\u60c5\u51b5\u3002<\/p>\n
\u73b0\u5728\uff0c\u53ef\u4ee5\u901a\u8fc7\u5b9a\u4e49\u7f16\u5199\u9047\u300c\u6c34\u300d\u5219\u6b62\u7684\u9012\u5f52\u7248\u672c\u7684 walker<\/code> \u51fd\u6570\u8ba9\u81ea\u5df1\u66f4\u52a0\u660e\u767d\uff0c\u4e3a\u4f55 if<\/code> \u4ee5\u53ca cond<\/code> \u8fd9\u6837\u7684\u6761\u4ef6\u8868\u8fbe\u5f0f\u4e0d\u53ef\u6216\u7f3a\u3002<\/p>\n
(defun walker (acc)\n  (if (< (point) (point-max))\n      (progn\n        (let ((x (char-after (point))))\n          (if (char-equal x ?\u6c34)\n              acc\n            (progn\n              (setq acc (concat acc (string x)))\n              (forward-char)\n              (walker acc)))))\n    acc))\n\n;;walker \u7684\u7528\u6cd5\n(progn\n  (goto-char (point-min))\n  (message "%s" (walker "")))<\/code><\/pre>\n
\u5982\u540c\u6ca1\u6709 catch\/throw<\/code> \u7684\u5e2e\u52a9\uff0c\u9047\u300c\u6c34\u300d\u5219\u6b62\u7684 while<\/code> \u8868\u8fbe\u5f0f\u5199\u4e0d\u51fa\u6765\uff0c\u82e5\u6ca1\u6709 if<\/code> \u7684\u5e2e\u52a9\uff0c\u9047\u300c\u6c34\u300d\u5219\u6b62\u7684\u9012\u5f52\u51fd\u6570\uff0c\u4e5f\u5199\u4e0d\u51fa\u6765\u3002\u4e5f\u8bb8\u4f60\u53c8\u4e00\u6b21\u770b\u4e0d\u61c2 Elisp \u4ee3\u7801\u4e86\uff0c\u4e0d\u8fc7\u4f60\u603b\u662f\u53ef\u4ee5\u5c1d\u8bd5\u5c06\u5176\u7ffb\u8bd1\u6210\u4f2a C \u4ee3\u7801\u53bb\u660e\u767d\u5b83\u3002\u4f8b\u5982<\/p>\n
void walker(String acc) {\n        if (point() < point_max()) {\n                Char x = char_after(point());\n                if (x \u4e3a '\u6c34') return acc;\n                else {\n                        acc = concat(acc, string(x));\n                        forward_char();\n                        walker(acc);\n                }\n        } else return acc;\n}<\/code><\/pre>\n
\u603b\u7ed3<\/h2>\n
\u4e5f\u8bb8\u4f60\u4f1a\u89c9\u5f97\u672c\u6587\u6709\u4e9b\u8d39\u8111\uff0c\u5b9e\u9645\u4e0a\u6211\u4e5f\u6709\u540c\u611f\uff0c\u6211\u56fd\u53e4\u4ee3\u54f2\u5b66\u5bb6\u738b\u9633\u660e\u5e94\u8be5\u4e5f\u6709\u540c\u611f\uff0c\u7279\u522b\u5f53\u4ed6\u53d1\u73b0\u5723\u4eba\u4e4b\u9053\u5373\u4e3a\u9012\u5f52\u7684\u90a3\u4e2a\u77ac\u95f4\u3002\u4e3b\u8981\u539f\u56e0\u662f\uff0c\u6211\u4eec\u4e0d\u7ecf\u610f\u95f4\u89e6\u53ca\u5230\u4e86\u8ba1\u7b97\u673a\u7f16\u7a0b\u7684\u4e00\u4e9b\u672c\u8d28\u95ee\u9898\uff0c\u5373\u4e00\u4e9b\u91cd\u8981\u7684\u7a0b\u5e8f\u903b\u8f91\u53ef\u4ee5\u57fa\u4e8e\u6709\u6761\u4ef6\u7ea6\u675f\u7684\u9012\u5f52\u4e88\u4ee5\u5b9e\u73b0\uff0c\u4e5f\u53ef\u57fa\u4e8e\u6709\u6761\u4ef6\u4e2d\u65ad\u7684 while<\/code> \u5faa\u73af\u4e88\u4ee5\u5b9e\u73b0\uff0c\u8fd9\u4e24\u79cd\u65b9\u5f0f\u662f\u7b49\u6548\u7684\uff0c\u524d\u8005\u5c5e\u4e8e\u51fd\u6570\u5f0f\u7f16\u7a0b\uff0c\u540e\u8005\u5c5e\u4e8e\u8fc7\u7a0b\u5f0f\u7f16\u7a0b\u3002\u81f3\u4e8e\u4e8c\u8005\u5b70\u4f18\u5b70\u52a3\uff0c\u81f3\u4eca\u4ecd\u4e89\u8bba\u672a\u4f11\uff0cElisp \u7684\u770b\u6cd5\u662f\uff0c\u4f60\u53ef\u4ee5\u6839\u636e\u81ea\u5df1\u7684\u504f\u597d\u9009\u62e9\uff0c\u4ea6\u53ef\u4e24\u8005\u6df7\u7528\u3002\u4f60\u770b\uff0cEmacs \u7528\u7740\u7528\u7740\uff0c\u4eba\u81ea\u7136\u5c31\u4f1a\u4e00\u4e9b\u7f16\u7a0b\u4e86\u3002<\/p>\n
https:\/\/segmentfault.com\/a\/1190000046618396<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
=> \u4e0a\u4e00\u7bc7\uff1a\u7f13\u51b2\u533a\u2014\u2014Emacs \u65e0\u5f62\u4e4b\u8c61 \u524d\u8a00 \u73b0\u5728\uff0cEmacs \u7684\u7f13\u51b2\u533a\uff0c\u4f60\u5e94\u8be5\u5df2\u7ecf\u80fd\u591f\u62db\u4e4b\u5373\u6765\uff0c […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[4],"tags":[],"class_list":["post-10020821","post","type-post","status-publish","format-standard","hentry","category-share"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10020821","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10020821"}],"version-history":[{"count":0,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10020821\/revisions"}],"wp:attachment":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10020821"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10020821"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10020821"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}