# ParenthesisMatching

One of Emacs’ strengths is the way it matches parentheses. Depending on what mode the buffer is in, different things are considered to be parentheses; for example, in EmacsLispMode, hitting “(” followed by “)” will briefly highlight the open parenthesis if it is visible on screen, and if it is not visible, it will print a message in the echo area showing you the context of the open that you just closed. (This is the default behavior; you or your site manager can change the default.)

Nearly all modes support “(,)” as parentheses, and most also support square brackets “[,]” and curly brackets “{,}”. However, you can make any pair of characters a parenthesis-pair, by using the following command:

    (modify-syntax-entry ?^ "($") (modify-syntax-entry ?$ ")^")

The first command modifies the current EmacsSyntaxTable to make “^” an open parenthesis, to be matched to “$”. The second command does the opposite. You can modify a specific EmacsSyntaxTable like this:  (modify-syntax-entry ?^ "($" perl-mode-syntax-table)

This adds ^ as an open parenthesis matching \$ in perl mode’s syntax table. You could add that statement to your .emacs file along with the corresponding closed parenthesis statement.

You can remove a pair of delimiters, just by redefining them as words constituents or punctuation characters. For example, if you want the command forward-sexp, bound by default to C-M-f, to ignore the meaning of [ and ] as parenthesis delimiters, put the following in your InitFile:

  (defvar my-wacky-syntax-table
(let ((table (make-syntax-table)))
(modify-syntax-entry ?[ "w" table)
(modify-syntax-entry ?] "w" table)
table))

(global-set-key "\C-\M-f" '(lambda ()
(interactive)
(with-syntax-table my-wacky-syntax-table (forward-sexp))))

You can make my-wacky-syntax-table available to all commands by using:

  (set-syntax-table my-wacky-syntax-table)

Note that opening delimiters can be matched in regular expressions with \s(. For closing delimiters, use \s)

See NavigatingParentheses for motion commands available for these expressions.

## Smartparens

Unfortunately, syntax-table matching has a limitation of only allowing pairs of one character. This is inconvenient in modes like LaTeX mode where many pairs are two or more characters, for example: \{ \}, , \big( \big), but also C mode where you can have a comment pair /* */ and many more.

Smartparens handle these cases and enable you to navigate and highlight arbitrarily complex (see note 1) user-defined pairs. It mirrors most of the built-in navigation/manipulation functions in emacs and adds more. For a complete up-to-date list refer to the readme section on github homepage.

Note 1: currently up to length of 10, but that is only for optimization purposes, the limit can be raised

CategoryParentheses