Map of Emacs Users

[Emacs Tips] 注释

M-x comment-dwim (Do What I Mean) 是最聪明的一种注释方式。如果已经选定了区域，那么就是注释或者反注释；如果没有选定区域，那么就是在这行末尾添加注释。

默认的键绑定是 M-;

注释还可以选择不同的模式，不同注释符号，在不同的编程语言模式下都不同。

控制注释符号的是变量 comment-start 和 comment-end，用 C-h v 查看，用例如 (setq comment-start "//") 修改。

变量 comment-style 控制注释的样式。可以用例如 (setq comment-style 'box) 修改。
以下是各种注释风格的示例。

int main()
{
/*     this is a comment line. */
/*     comment style 'plain */

    /* this is a comment line. */
    /* comment style 'indent */

    /* this is a comment line. */
    /* comment style 'aligned  */

    /* this is a comment line.
     * comment style 'multi-line */

    /* 
     * this is a comment line. 
     * comment style 'extra-line
     */

    /***************************/
    /* this is a comment line. */
    /* comment style 'box      */
    /***************************/

    /****************************
     * this is a comment line.  *
     * comment style 'box-multi *
     ****************************/
}

再提供一个直接注释一行的函数。有时候比 comment-dwim 更有效。有选中区域的话就是注释或反注释这个区域；反之注释或者反注释光标所在的行。

(defun huangq-comment-dwim (&optional n)
  "Comment do-what-i-mean"
  (interactive "p")
  (apply 'comment-or-uncomment-region
         (if (and mark-active transient-mark-mode)
             (list (region-beginning) (region-end))
           (if (> n 0)
               (list (line-beginning-position) (line-end-position n))
             (list (line-beginning-position n) (line-end-position))))))

[Emacs Tips] 插入相邻一行的字符

类似于 VIM 插入状态下的 C-y 和 C-e，也就是插入光标所在上一行或者下一行的字符。
例如： VIM 插入状态下的 C-y 和 C-e，也就是插入光标所在上一行或者下一行的字符。

写程序的时候还是挺有用的

;;;###autoload
(defun my-insert-char-next-line (arg)
  "insert char below the cursor"
  (interactive "p")
  (let ((col (current-column))
        char)
    (setq char
          (save-excursion
            (forward-line arg)
            (move-to-column col)
            (if (= (current-column) col)
                (char-after))))
    (if char
        (insert-char char 1)
      (message (concat "Can't get charactor in "
                       (if  (< arg 0)
                           "previous"
                         "next")
                       (progn (setq arg (abs arg))
                              (if (= arg 1) ""
                                (concat " " (number-to-string arg))))
                       " line.")))))

;;;###autoload
(defun my-insert-char-prev-line (arg)
  "insert char above the cursor"
  (interactive "p")
  (my-insert-char-next-line (- arg)))

用的键绑定是 C-x ( 和 C-x )

(global-set-key (kbd "C-)") 'my-insert-char-next-line)
(global-set-key (kbd "C-(") 'my-insert-char-prev-line)

[Emacs Tips] isearch 查找 (2)

注：有些函数非原创，因为年代长久，很难找到出处，就不一一注明了。

一些加快查找速度的函数。

1. 查找选定区域的内容。Emacs 有无数用来选定 (mark) 的函数，所以选定容易，但是没有直接查找选定内容的函数。下面这个函数提供此功能，按 F3 就是 isearch 当前选定的词，继续按 C-s 就可以查找了。

(defvar my-isearch-string nil)
(setq my-isearch-string "")

(defun my-isearch-region-forward ()
  "isearch region if mark is acktive"
  (interactive)
  (if mark-active
      (let ((beg (region-beginning))
            (end (region-end)))
        (setq my-isearch-string (filter-buffer-substring beg end nil))
        (deactivate-mark)
        (if (> (length my-isearch-string) 0)
            (progn
              (goto-char beg)
              (isearch-update-ring my-isearch-string)
              (add-hook 'isearch-mode-end-hook 'my-isearch-end-hook)
              (isearch-mode t)          ;hack isearch-forward
              (isearch-repeat 'forward)
              (message "%s" isearch-string)))) ;print debug msg
    (if (> (length my-isearch-string) 0)
        (progn
          (isearch-repeat 'forward))
      (message "no region selected")
      )))

(global-set-key (kbd "<f3>") 'my-isearch-region-forward)

(defun my-isearch-end-hook ()
  (remove-hook 'isearch-mode-end-hook 'my-isearch-end-hook)
  (setq my-isearch-string ""))

2. 查找当前词，类似于 VIM 的 *，这里用的键绑定是 C-* .

(defvar my-isearch-word "")

(defun my-isearch-word ()
  (interactive)
  (when (not mark-active)
    (let (word-beg word-end)
      (unless (looking-at "\\<")
        (if (eq (char-syntax (char-after)) ?w)
            (backward-word)
          (and (forward-word) (backward-word)))
        )
      (setq word-beg (point))
      (forward-word)
      (setq word-end (point))
      (setq my-isearch-word (filter-buffer-substring word-beg word-end nil t))
      (backward-word)
      )
    (when (> (length my-isearch-word) 0)
      (setq my-isearch-word (concat "\\<" my-isearch-word "\\>"))
      (isearch-update-ring my-isearch-word t)
      (add-hook 'isearch-mode-end-hook 'my-isearch-word-end-hook)
      (isearch-mode t t)
      (isearch-repeat 'forward)
      (message "%s" isearch-string))))

(global-set-key (kbd "C-*") 'my-isearch-word)

(defun my-isearch-word-end-hook ()
  (remove-hook 'isearch-mode-end-hook 'my-isearch-word-end-hook)
  (setq my-isearch-word ""))

[Emacs Tips] isearch 查找 (1)

isearch (C-s) 是 Emacs 里最常用的查找方式，也是目前为止我在各种软件里，编辑器里用过最舒服的查找方式。

首先这是 incremental search，也就是递增方式的搜索，一边输入一边就开始查找了;
其次有 lazy highlight 功能，低亮显示 buffer 里所有找到的词。
这个功能是由 isearch-lazy-highlight 这个变量控制的，用 C-h v isearch-lazy-highlight 查看这个变量目前是不是真 t。



isearch-mode 也有很多键绑定，用 C-h f isearch-mode 查看。
具体就不详细写了。最常用的 C-w ，查找当前的词。(明天再给出一个更快更方便的查找方式)

建议可以试试相关的 Elisp 插件 color-moccor.el。
用了这个以后可以在 isearch 里敲 M-o，列出文件里的搜索结果; 或者 M-O (大写o) 列出所有 buffer 里的对应结果。

[Emacs Tips] 复制一行

从今天开始打算每天用中文介绍一个 Emacs 小技巧。都是很小的技巧而已。

首先是快速复制一行。基本思想是，光标在哪一行就复制哪一行，不用选定区域。如果区域已经选定了，那么就复制区域。类似于 VIM 的yy。

仍旧使用 M-w 的键绑定，和原先的习惯差不多。使用前提是启用了 transient-mark-mode，即高亮选定区域。实际使用中发现每行开头的空格一点用都没有，而且很碍事，所以今天改了一下，一般从第一个非空格的字符开始复制。

这里提供几个函数。
huangq-save-one-line 是复制一行；如果有参数，则从第一个不是空格的字符开始复制。
huangq-kill-ring-save 如果选定了区域，则复制区域；否则复制行。
huangq-save-line-dwim 如果选定了区域，复制区域；否则从第一个不是空格的字符开始复制。

最后是键绑定：

(global-set-key (kbd "M-w") 'huangq-save-line-dwim)

函数的实现：

;;;###autoload
(defun huangq-save-one-line (&optional arg)
  "save one line. If ARG, save one line from first non-white."
  (interactive "P")
  (save-excursion
    (if arg
        (progn
          (back-to-indentation)
          (kill-ring-save (point) (line-end-position)))
      (kill-ring-save (line-beginning-position) (line-end-position)))))

;;;###autoload
(defun huangq-kill-ring-save (&optional n)
  "If region is active, copy region. Otherwise, copy line."
  (interactive "p")
  (if (and mark-active transient-mark-mode)
      (kill-ring-save (region-beginning) (region-end))
    (if (> n 0)
        (kill-ring-save (line-beginning-position) (line-end-position n))
      (kill-ring-save (line-beginning-position n) (line-end-position)))))

;;;###autoload
(defun huangq-save-line-dwim (&optional arg)
  "If region is active, copy region.
If ARG is nil, copy line from first non-white.
If ARG is numeric, copy ARG lines.
If ARG is non-numeric, copy line from beginning of the current line."
  (interactive "P")
  (if (and mark-active transient-mark-mode)
      ;; mark-active, save region
      (kill-ring-save (region-beginning) (region-end))
    (if arg
        (if (numberp arg)
            ;; numeric arg, save ARG lines
            (huangq-kill-ring-save arg)
          ;; other ARG, save current line
          (huangq-save-one-line))
      ;; no ARG, save current line from first non-white
      (huangq-save-one-line t))))

flymake mode

How can I miss this wonderful feature until now?

Flymake is amazing. See the screenshot:


What you need is only a Makefile with an extra target "check-syntax":

check-syntax:
    gcc -o nul -Wall -Wextra -fsyntax-only $(CHK_SOURCES)

And of course type "M-x flymake-mode" when needed.

You can also customize the error and warning face in .emacs like:

(require 'flymake nil t)
(when (featurep 'flymake)
  (set-face-background 'flymake-errline "LightPink")
  (set-face-foreground 'flymake-errline "DarkRed")
  (set-face-bold-p 'flymake-errline t)
  (set-face-background 'flymake-warnline "LightBlue2")
  (set-face-foreground 'flymake-warnline "DarkBlue")
  (set-face-bold-p 'flymake-warnline t))

Search word at point in Emacs

查找光标上的单词

The default i-search command in Emacs is C-s, and then type the word you want to search. If your cursor is current on the beginning of the word, then you can type C-s C-w. This is case insensitive.

If you want to look for the exact word, then you can use the following code. Type C-* and search the word at the point. It works just like the Star * in VIM.

(defvar my-isearch-word "")

(defun my-isearch-word ()
  (interactive)
  (when (not mark-active)
    (let (word-beg word-end)
      (unless (looking-at "\\<")
        (if (eq (char-syntax (char-after)) ?w)
            (backward-word)
          (and (forward-word) (backward-word)))
        )
      (setq word-beg (point))
      (forward-word)
      (setq word-end (point))
      (setq my-isearch-word (filter-buffer-substring word-beg word-end nil t))
      (backward-word)
      )
    (when (> (length my-isearch-word) 0)
      (setq my-isearch-word (concat "\\<" my-isearch-word "\\>"))
      (isearch-update-ring my-isearch-word t)
      (add-hook 'isearch-mode-end-hook 'my-isearch-word-end-hook)
      (isearch-mode t t)
      (isearch-repeat 'forward)
      (message "%s" isearch-string))))

(global-set-key (kbd "C-*") 'my-isearch-word)