在emacs中从camelcase转换为_答案

【问题标题】：Converting from camelcase to _ in emacs在emacs中从camelcase转换为_
【发布时间】：2012-03-06 11:42:11
【问题描述】：

是否有一个 emacs 函数可以将驼峰大小写的单词转换为下划线？比如：

longVariableName

M-xto-underscore

long_variable_name

【问题讨论】：

您可能还对M-x glasses-mode 感兴趣，它神奇地在缓冲区中插入下划线而不修改底层文件。
@tripleee - 结果表明 this 现在是 Google 的热门歌曲。而且那个emacswiki页面有一堆垃圾，其中一个是函数，但该函数在一般情况下并不真正起作用。这里的答案更好。无论如何，在问答网站上责骂人们提问似乎真的没有必要。

标签： emacs elisp camelcasing

【解决方案1】：

使用 MELPA 或 https://github.com/akicho8/string-inflection 上提供的 string-inflection 包。

有用的键盘快捷键，复制自https://www.emacswiki.org/emacs/CamelCase：

;; Cycle between snake case, camel case, etc.
(require 'string-inflection)
(global-set-key (kbd "C-c i") 'string-inflection-cycle)
(global-set-key (kbd "C-c C") 'string-inflection-camelcase)        ;; Force to CamelCase
(global-set-key (kbd "C-c L") 'string-inflection-lower-camelcase)  ;; Force to lowerCamelCase
(global-set-key (kbd "C-c J") 'string-inflection-java-style-cycle) ;; Cycle through Java styles

【讨论】：

如果您希望以编程方式使用它，请使用string-inflection-underscore-function。
@RadonRosborough 现在string-inflection-underscore.

【解决方案2】：

我使用以下方法在驼峰和下划线之间切换：

(defun toggle-camelcase-underscores ()
  "Toggle between camelcase and underscore notation for the symbol at point."
  (interactive)
  (save-excursion
    (let* ((bounds (bounds-of-thing-at-point 'symbol))
           (start (car bounds))
           (end (cdr bounds))
           (currently-using-underscores-p (progn (goto-char start)
                                                 (re-search-forward "_" end t))))
      (if currently-using-underscores-p
          (progn
            (upcase-initials-region start end)
            (replace-string "_" "" nil start end)
            (downcase-region start (1+ start)))
        (replace-regexp "\\([A-Z]\\)" "_\\1" nil (1+ start) end)
        (downcase-region start (cdr (bounds-of-thing-at-point 'symbol)))))))

【讨论】：

【解决方案3】：

(progn (replace-regexp "\\([A-Z]\\)" "_\\1" nil (region-beginning) (region-end))
       (downcase-region (region-beginning) (region-end)))

【讨论】：

分配to-underscore（这样你就可以做到M-x to-underscore）：(defun to-underscore () (interactive) (progn (replace-regexp "\\([A-Z]\\)" "_\\1" nil (region-beginning) (region-end)) (downcase-region (region-beginning) (region-end))) )

【解决方案4】：

我在将 C# 代码转换为 PHP 时使用它。

(defun un-camelcase-word-at-point ()
  "un-camelcase the word at point, replacing uppercase chars with
the lowercase version preceded by an underscore.

The first char, if capitalized (eg, PascalCase) is just
downcased, no preceding underscore.
"
  (interactive)
  (save-excursion
    (let ((bounds (bounds-of-thing-at-point 'word)))
      (replace-regexp "\\([A-Z]\\)" "_\\1" nil
                      (1+ (car bounds)) (cdr bounds))
      (downcase-region (car bounds) (cdr bounds)))))

然后在我的 php-mode fn 中：

(local-set-key "\M-\C-C"  'un-camelcase-word-at-point)

【讨论】：

酷！让我们做我想要的。

【解决方案5】：

现在2018年还有另一种通用方式：magnars/s.el: The long lost Emacs string manipulation library. - github.com，关于 OP 问题的一些例子：

无论大小写蛇形（下划线分隔）：

(s-snake-case "some words") ;; => "some_words"
(s-snake-case "dashed-words") ;; => "dashed_words"
(s-snake-case "camelCasedWords") ;; => "camel_cased_words"

无论大小写驼峰式：

(s-lower-camel-case "some words") ;; => "someWords"
(s-lower-camel-case "dashed-words") ;; => "dashedWords"
(s-lower-camel-case "under_scored_words") ;; => "underScoredWords"

在其 repo 中查看更多示例。

【讨论】：

【解决方案6】：

如果您想使用s.el获取完整代码：

(defun to-snake-case (start end)
  "Change selected text to snake case format"
  (interactive "r")
  (if (use-region-p)
      (let ((camel-case-str (buffer-substring start end)))
        (delete-region start end)
        (insert (s-snake-case camel-case-str)))
    (message "No region selected")))

【讨论】：

【解决方案7】：

@ens 的回答很接近，但在 Emacs 26.1 上对我来说有点小问题。我修复了这个错误并添加了通过 C-u 前缀 arg 指定是否希望驼峰大小写的第一个字母为小写的功能：

(defun toggle-camelcase-underscores (first-lower-p)
  "Toggle between camelcase and underscore notation for the
symbol at point. If prefix arg, C-u, is supplied, then make first
letter of camelcase lowercase."
  (interactive "P")
  (save-excursion
    (let* ((bounds (bounds-of-thing-at-point 'symbol))
           (start (car bounds))
           (end (cdr bounds))
           (currently-using-underscores-p (progn (goto-char start)
                                                 (re-search-forward "_" end t))))
      (if currently-using-underscores-p
          (progn
            (replace-string "_" " " nil start end)
            (upcase-initials-region start end)
            (replace-string " " "" nil start end)
            (when first-lower-p
              (downcase-region start (1+ start))))
        (replace-regexp "\\([A-Z]\\)" "_\\1" nil (1+ start) end)
        (downcase-region start (cdr (bounds-of-thing-at-point 'symbol)))))))

【讨论】：