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Emacs: Defining Keys to Navigate Brackets

Xah Lee, 2011-05-06

Here are some convenient keys to move cursor by brackets. Very useful in coding C, Java, Python, HTML, or other languages.

Commands to Navigate Brackets

(defun forward-open-bracket ()
  "Move cursor to the next occurrence of one of ( { [ <."
  (interactive)
  (forward-char 1)
  (search-forward-regexp "(\\|{\\|\\[\\|<\\|〔\\|【\\|〖\\|〈\\|「\\|“\\|‘\\|‹\\|«")
  (backward-char 1)
  )

(defun backward-open-bracket ()
  "Move cursor to the previous occurrence of one of ( { [ <."
  (interactive)
  (search-backward-regexp "(\\|{\\|\\[\\|<\\|〔\\|【\\|〖\\|〈\\|「\\|“\\|‘\\|‹\\|«")
  )

(defun forward-close-bracket ()
  "Move cursor to the next occurrence of one of ) } ] >."
  (interactive)
  (search-forward-regexp ")\\|\\]\\|}\\|>\\|〕\\|】\\|〗\\|〉\\|」\\| ”\\| ’\\| ›\\| »")
 )

(defun backward-close-bracket ()
  "Move cursor to the next occurrence of one of ) } ] >."
  (interactive)
  (backward-char 1)
  (search-backward-regexp ")\\|\\]\\|}\\|>\\|〕\\|】\\|〗\\|〉\\|」\\| ”\\| ’\\| ›\\| »")
  (forward-char 1)
  )

These commands lets you move cursor around any brackets, () {} [] but also < > and few other common unicode matching pairs “” ‘’ ‹› «» 【】 〖〗 〈〉 〔〕 「」. (See: Matching Brackets in Unicode.)

You can assign them keys. See: Emacs: How to Define Keyboard Shortcuts.

What Keys to Use?

Good keys are the arrow keys, with a combination of Alt, Shift, or Win and Menu keys by mapping emacs's Hyper and Super to them. For me, i use the Win key with Super. Here's my code:

(cond
 ((string-equal system-type "windows-nt") ; Windows

  ;; setting the PC keyboard's various keys to
  ;; Super or Hyper, for emacs running on Windows.
  (setq w32-pass-lwindow-to-system nil 
        w32-pass-rwindow-to-system nil 
        w32-pass-apps-to-system nil 
        w32-lwindow-modifier 'super ;; Left Windows key 
        w32-rwindow-modifier 'hyper ;; Right Windows key 
        w32-apps-modifier 'hyper) ;; Menu key
  )
 ((string-equal system-type "darwin") ; Mac
  (setq mac-option-modifier 'super) ) )

(global-set-key (kbd "<s-left>") 'backward-open-bracket)
(global-set-key (kbd "<s-right>") 'forward-open-bracket)
(global-set-key (kbd "<s-up>") 'backward-close-bracket)
(global-set-key (kbd "<s-down>") 'forward-close-bracket)

For detail about setting up hyper or super key, see: Emacs: How to define Super ＆ Hyper Keys.

Emacs's Keys To Navigate Nested Code

The above commands is a very good complement to emacs built-in keys to navigate trees made of nested matching brackets as in lisp and html code.

Built-in Keys to Navigate Lisp Code

The keys to navigate lisp code are:

• 【Ctrl+Alt+←】 “backward-sexp”
• 【Ctrl+Alt+→】 “forward-sexp”
• 【Ctrl+Alt+↑】 “backward-up-list”
• 【Ctrl+Alt+↓】 “down-list”

Highlighting Matching Brackets

Emacs will also highlight matching brackets. When your cursor is on a matching pair, emacs will highlight the matching brackets, or, the code between them, depending on your settings. For how to turn it on or set your preferences, see: How to Edit Lisp Code with Emacs.

Select Code Between Matching Brackets

Also, you can define a command so that when cursor is on a opening bracket, you can press a key to have the whole code enclosed by the matching bracket selected. See the command “extend-selection” at Suggestions on Emacs's mark-word Command.

Built-in Keys for Navigating Matching HTML Tags

For html, when in “html-mode”, it has “sgml-skip-tag-backward” 【Ctrl+c Ctrl+b】 and “sgml-skip-tag-forward” 【Ctrl+c Ctrl+f】.

For more productivity tips with html, see: Emacs and HTML Tips.