;;; elec-pair.el --- Automatic parenthesis pairing -*- lexical-binding:t -*- ;; Copyright (C) 2013-2024 Free Software Foundation, Inc. ;; Author: João Távora ;; This file is part of GNU Emacs. ;; GNU Emacs is free software: you can redistribute it and/or modify ;; it under the terms of the GNU General Public License as published by ;; the Free Software Foundation, either version 3 of the License, or ;; (at your option) any later version. ;; GNU Emacs is distributed in the hope that it will be useful, ;; but WITHOUT ANY WARRANTY; without even the implied warranty of ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;; GNU General Public License for more details. ;; You should have received a copy of the GNU General Public License ;; along with GNU Emacs. If not, see . ;;; Commentary: ;;; Code: (require 'electric) (eval-when-compile (require 'cl-lib)) ;;; Electric pairing. (defcustom electric-pair-pairs `((?\" . ?\") (,(nth 0 electric-quote-chars) . ,(nth 1 electric-quote-chars)) (,(nth 2 electric-quote-chars) . ,(nth 3 electric-quote-chars))) "Alist of pairs that should be used regardless of major mode. Pairs of delimiters in this list are a fallback in case they have no syntax relevant to `electric-pair-mode' in the mode's syntax table. See also the variable `electric-pair-text-pairs'." :version "24.1" :group 'electricity :type '(repeat (cons character character))) (defcustom electric-pair-text-pairs `((?\" . ?\") (,(nth 0 electric-quote-chars) . ,(nth 1 electric-quote-chars)) (,(nth 2 electric-quote-chars) . ,(nth 3 electric-quote-chars))) "Alist of pairs that should always be used in comments and strings. Pairs of delimiters in this list are a fallback in case they have no syntax relevant to `electric-pair-mode' in the syntax table defined in `electric-pair-text-syntax-table'." :version "24.4" :group 'electricity :type '(repeat (cons character character))) (defcustom electric-pair-skip-self #'electric-pair-default-skip-self "If non-nil, skip char instead of inserting a second closing paren. When inserting a closing paren character right before the same character, just skip that character instead, so that hitting ( followed by ) results in \"()\" rather than \"())\". This can be convenient for people who find it easier to hit ) than \\[forward-char]. Can also be a function of one argument (the closer char just inserted), in which case that function's return value is considered instead." :version "24.1" :group 'electricity :type '(choice (const :tag "Never skip" nil) (const :tag "Help balance" electric-pair-default-skip-self) (const :tag "Always skip" t) function)) (defcustom electric-pair-inhibit-predicate #'electric-pair-default-inhibit "Predicate to prevent insertion of a matching pair. The function is called with a single char (the opening char just inserted). If it returns non-nil, then `electric-pair-mode' will not insert a matching closer." :version "24.4" :group 'electricity :type '(choice (const :tag "Conservative" electric-pair-conservative-inhibit) (const :tag "Help balance" electric-pair-default-inhibit) (const :tag "Always pair" ignore) function)) (defcustom electric-pair-preserve-balance t "Non-nil if default pairing and skipping should help balance parentheses. The default values of `electric-pair-inhibit-predicate' and `electric-pair-skip-self' check this variable before delegating to other predicates responsible for making decisions on whether to pair/skip some characters based on the actual state of the buffer's parentheses and quotes." :version "24.4" :group 'electricity :type 'boolean) (defcustom electric-pair-delete-adjacent-pairs t "If non-nil, backspacing an open paren also deletes adjacent closer. Can also be a function of no arguments, in which case that function's return value is considered instead." :version "24.4" :group 'electricity :type '(choice (const :tag "Yes" t) (const :tag "No" nil) function)) (defcustom electric-pair-open-newline-between-pairs t "If non-nil, a newline between adjacent parentheses opens an extra one. Can also be a function of no arguments, in which case that function's return value is considered instead." :version "24.4" :group 'electricity :type '(choice (const :tag "Yes" t) (const :tag "No" nil) function)) (defcustom electric-pair-skip-whitespace t "If non-nil skip whitespace when skipping over closing parens. The specific kind of whitespace skipped is given by the variable `electric-pair-skip-whitespace-chars'. The symbol `chomp' specifies that the skipped-over whitespace should be deleted. Can also be a function of no arguments, in which case that function's return value is considered instead." :version "24.4" :group 'electricity :type '(choice (const :tag "Yes, jump over whitespace" t) (const :tag "Yes, and delete whitespace" chomp) (const :tag "No, no whitespace skipping" nil) function)) (defcustom electric-pair-skip-whitespace-chars (list ?\t ?\s ?\n) "Whitespace characters considered by `electric-pair-skip-whitespace'." :version "24.4" :group 'electricity :type '(choice (set (const :tag "Space" ?\s) (const :tag "Tab" ?\t) (const :tag "Newline" ?\n)) (repeat (character :value " ")))) (defvar-local electric-pair-skip-whitespace-function #'electric-pair--skip-whitespace "Function to use to skip whitespace forward. Before attempting a skip, if `electric-pair-skip-whitespace' is non-nil, this function is called. It move point to a new buffer position, presumably skipping only whitespace in between.") (defun electric-pair-analyze-conversion (string) "Notice that STRING has been deleted by an input method. If the last character of STRING is an electric pair character, and the character after point is too, then delete that other character." (let* ((prev (aref string (1- (length string)))) (next (char-after)) (syntax-info (electric-pair-syntax-info prev)) (syntax (car syntax-info)) (pair (cadr syntax-info))) (when (and next pair (memq syntax '(?\( ?\" ?\$)) (eq pair next)) (delete-char 1)))) (defun electric-pair--skip-whitespace () "Skip whitespace forward, not crossing comment or string boundaries." (let ((saved (point)) (string-or-comment (nth 8 (syntax-ppss)))) (skip-chars-forward (apply #'string electric-pair-skip-whitespace-chars)) (unless (eq string-or-comment (nth 8 (syntax-ppss))) (goto-char saved)))) (defvar electric-pair-text-syntax-table prog-mode-syntax-table "Syntax table used when pairing inside comments and strings. `electric-pair-mode' considers this syntax table only when point in inside quotes or comments. If lookup fails here, `electric-pair-text-pairs' will be considered.") (defun electric-pair-conservative-inhibit (char) (or ;; I find it more often preferable not to pair when the ;; same char is next. (eq char (char-after)) ;; Don't pair up when we insert the second of "" or of ((. (and (eq char (char-before)) (eq char (char-before (1- (point))))) ;; I also find it often preferable not to pair next to a word. (eq (char-syntax (following-char)) ?w))) (defmacro electric-pair--with-syntax (string-or-comment &rest body) "Run BODY with appropriate syntax table active. STRING-OR-COMMENT is the start position of the string/comment in which we are, if applicable. Uses the text-mode syntax table if within a string or a comment." (declare (debug t) (indent 1)) `(electric-pair--with-syntax-1 ,string-or-comment (lambda () ,@body))) (defun electric-pair--with-syntax-1 (string-or-comment body-fun) (if (not string-or-comment) (funcall body-fun) ;; Here we assume that the `syntax-ppss' cache has already been filled ;; past `string-or-comment' with data corresponding to the "normal" syntax ;; (this should be the case because STRING-OR-COMMENT was returned ;; in the `nth 8' of `syntax-ppss'). ;; Maybe we should narrow-to-region so that `syntax-ppss' uses the narrow ;; cache? (syntax-ppss-flush-cache string-or-comment) (let ((syntax-propertize-function nil)) (unwind-protect (with-syntax-table electric-pair-text-syntax-table (funcall body-fun)) (syntax-ppss-flush-cache string-or-comment))))) (defun electric-pair-syntax-info (command-event) "Calculate a list (SYNTAX PAIR UNCONDITIONAL STRING-OR-COMMENT-START). SYNTAX is COMMAND-EVENT's syntax character. PAIR is COMMAND-EVENT's pair. UNCONDITIONAL indicates the variables `electric-pair-pairs' or `electric-pair-text-pairs' were used to lookup syntax. STRING-OR-COMMENT-START indicates that point is inside a comment or string." (let* ((pre-string-or-comment (or (bobp) (nth 8 (save-excursion (syntax-ppss (1- (point))))))) (post-string-or-comment (nth 8 (syntax-ppss (point)))) (string-or-comment (and post-string-or-comment pre-string-or-comment)) (table-syntax-and-pair (electric-pair--with-syntax string-or-comment (list (char-syntax command-event) (or (matching-paren command-event) command-event)))) (fallback (if string-or-comment (append electric-pair-text-pairs electric-pair-pairs) electric-pair-pairs)) (direct (assq command-event fallback)) (reverse (rassq command-event fallback))) (cond ((memq (car table-syntax-and-pair) '(?\" ?\( ?\) ?\$)) (append table-syntax-and-pair (list nil string-or-comment))) (direct (if (eq (car direct) (cdr direct)) (list ?\" command-event t string-or-comment) (list ?\( (cdr direct) t string-or-comment))) (reverse (list ?\) (car reverse) t string-or-comment))))) (defun electric-pair--insert (char times) (let ((last-command-event char) (blink-matching-paren nil) (electric-pair-mode nil) ;; When adding the "closer" delimiter, a job his function is ;; frequently used for, we don't want to munch any extra ;; newlines above us. That would be the default behavior of ;; `electric-layout-mode', which potentially kicked in before ;; us to add these newlines, and is probably about to kick in ;; again after we add the closer. (electric-layout-allow-duplicate-newlines t)) (self-insert-command times))) (defun electric-pair--syntax-ppss (&optional pos where) "Like `syntax-ppss', but sometimes fallback to `parse-partial-sexp'. WHERE is a list defaulting to \\='(string comment) and indicates when to fallback to `parse-partial-sexp'." (let* ((pos (or pos (point))) (where (or where '(string comment))) (quick-ppss (syntax-ppss pos)) (in-string (and (nth 3 quick-ppss) (memq 'string where))) (in-comment (and (nth 4 quick-ppss) (memq 'comment where))) (s-or-c-start (cond (in-string (1+ (nth 8 quick-ppss))) (in-comment (goto-char (nth 8 quick-ppss)) (forward-comment (- (point-max))) (skip-syntax-forward " >!") (point))))) (if s-or-c-start (electric-pair--with-syntax s-or-c-start (parse-partial-sexp s-or-c-start pos)) ;; HACK! cc-mode apparently has some `syntax-ppss' bugs (if (memq major-mode '(c-mode c++ mode)) (parse-partial-sexp (point-min) pos) quick-ppss)))) ;; Balancing means controlling pairing and skipping of parentheses ;; so that, if possible, the buffer ends up at least as balanced as ;; before, if not more. The algorithm is slightly complex because ;; some situations like "()))" need pairing to occur at the end but ;; not at the beginning. Balancing should also happen independently ;; for different types of parentheses, so that having your {}'s ;; unbalanced doesn't keep `electric-pair-mode' from balancing your ;; ()'s and your []'s. (defun electric-pair--balance-info (direction string-or-comment) "Examine lists forward or backward according to DIRECTION's sign. STRING-OR-COMMENT is the position of the start of the comment/string in which we are, if applicable. Return a cons of two descriptions (MATCHED-P . PAIR) for the innermost and outermost lists that enclose point. The outermost list enclosing point is either the first top-level or first mismatched list found by listing up. If the outermost list is matched, don't rely on its PAIR. If point is not enclosed by any lists, return ((t) . (t))." (let* (innermost outermost (at-top-level-or-equivalent-fn ;; called when `scan-sexps' ran perfectly, when it found ;; a parenthesis pointing in the direction of travel. ;; Also when travel started inside a comment and exited it. (lambda () (setq outermost (list t)) (unless innermost (setq innermost (list t))))) (ended-prematurely-fn ;; called when `scan-sexps' crashed against a parenthesis ;; pointing opposite the direction of travel. After ;; traversing that character, the idea is to travel one sexp ;; in the opposite direction looking for a matching ;; delimiter. (lambda () (let* ((pos (point)) (matched (save-excursion (cond ((< direction 0) (condition-case nil (eq (char-after pos) (electric-pair--with-syntax string-or-comment (matching-paren (char-before (scan-sexps (point) 1))))) (scan-error nil))) (t ;; In this case, no need to use ;; `scan-sexps', we can use some ;; `electric-pair--syntax-ppss' in this ;; case (which uses the quicker ;; `syntax-ppss' in some cases) (let* ((ppss (electric-pair--syntax-ppss (1- (point)))) (start (car (last (nth 9 ppss)))) (opener (char-after start))) (and start (eq (char-before pos) (or (electric-pair--with-syntax string-or-comment (matching-paren opener)) opener)))))))) (actual-pair (if (> direction 0) (char-before (point)) (char-after (point))))) (unless innermost (setq innermost (cons matched actual-pair))) (unless matched (setq outermost (cons matched actual-pair))))))) (save-excursion (while (not outermost) (condition-case err (electric-pair--with-syntax string-or-comment (scan-sexps (point) (if (> direction 0) (point-max) (- (point-max)))) (funcall at-top-level-or-equivalent-fn)) (scan-error (cond ((or ;; some error happened and it is not of the "ended ;; prematurely" kind... (not (string-match "ends prematurely" (nth 1 err))) ;; ... or we were in a comment and just came out of ;; it. (and string-or-comment (not (nth 8 (syntax-ppss))))) (funcall at-top-level-or-equivalent-fn)) (t ;; exit the sexp (goto-char (nth 3 err)) (funcall ended-prematurely-fn))))))) (cons innermost outermost))) (defvar electric-pair-string-bound-function 'point-max "Next buffer position where strings are syntactically unexpected. Value is a function called with no arguments and returning a buffer position. Major modes should set this variable buffer-locally if they experience slowness with `electric-pair-mode' when pairing quotes.") (defun electric-pair--unbalanced-strings-p (char) "Return non-nil if there are unbalanced strings started by CHAR." (let* ((selector-ppss (syntax-ppss)) (relevant-ppss (save-excursion (if (nth 4 selector-ppss) ; comment (electric-pair--syntax-ppss (progn (goto-char (nth 8 selector-ppss)) (forward-comment (point-max)) (skip-syntax-backward " >!") (point))) (syntax-ppss (funcall electric-pair-string-bound-function))))) (string-delim (nth 3 relevant-ppss))) (or (eq t string-delim) (eq char string-delim)))) (defun electric-pair--inside-string-p (char) "Return non-nil if point is inside a string started by CHAR. A comments text is parsed with `electric-pair-text-syntax-table'. Also consider strings within comments, but not strings within strings." ;; FIXME: could also consider strings within strings by examining ;; delimiters. (let ((ppss (electric-pair--syntax-ppss (point) '(comment)))) (memq (nth 3 ppss) (list t char)))) (defmacro electric-pair--save-literal-point-excursion (&rest body) ;; FIXME: need this instead of `save-excursion' when functions in ;; BODY, such as `electric-pair-inhibit-if-helps-balance' and ;; `electric-pair-skip-if-helps-balance' modify and restore the ;; buffer in a way that modifies the marker used by save-excursion. (let ((point (make-symbol "point"))) `(let ((,point (point))) (unwind-protect (progn ,@body) (goto-char ,point))))) (defun electric-pair-inhibit-if-helps-balance (char) "Return non-nil if auto-pairing of CHAR would hurt parentheses' balance. Works by first removing the character from the buffer, then doing some list calculations, finally restoring the situation as if nothing happened." (pcase (electric-pair-syntax-info char) (`(,syntax ,pair ,_ ,s-or-c) (catch 'done ;; FIXME: modify+undo is *very* tricky business. We used to ;; use `delete-char' followed by `insert', but this changed the ;; position some markers. The real fix would be to compute the ;; result without having to modify the buffer at all. (atomic-change-group ;; Don't use `delete-char'; that may modify the head of the ;; undo list. (delete-region (- (point) (prefix-numeric-value current-prefix-arg)) (point)) (throw 'done (cond ((eq ?\( syntax) (let* ((pair-data (electric-pair--balance-info 1 s-or-c)) (outermost (cdr pair-data))) (cond ((car outermost) nil) (t (eq (cdr outermost) pair))))) ((eq syntax ?\") (electric-pair--unbalanced-strings-p char))))))))) (defun electric-pair-skip-if-helps-balance (char) "Return non-nil if skipping CHAR would benefit parentheses' balance. Works by first removing the character from the buffer, then doing some list calculations, finally restoring the situation as if nothing happened." (let ((num (prefix-numeric-value current-prefix-arg))) (pcase (electric-pair-syntax-info char) (`(,syntax ,pair ,_ ,s-or-c) (unwind-protect (progn (delete-char (- num)) (cond ((eq syntax ?\)) (let* ((pair-data (electric-pair--balance-info (- num) s-or-c)) (innermost (car pair-data)) (outermost (cdr pair-data))) (and (cond ((car outermost) (car innermost)) ((car innermost) (not (eq (cdr outermost) pair))))))) ((eq syntax ?\") (electric-pair--inside-string-p char)))) (insert (make-string num char))))))) (defun electric-pair-default-skip-self (char) (if electric-pair-preserve-balance (electric-pair-skip-if-helps-balance char) t)) (defun electric-pair-default-inhibit (char) (if electric-pair-preserve-balance (electric-pair-inhibit-if-helps-balance char) (electric-pair-conservative-inhibit char))) (defun electric-pair-post-self-insert-function () "Member of `post-self-insert-hook'. Do main work for `electric-pair-mode'. If the newly inserted character C has delimiter syntax, this function may decide to insert additional paired delimiters, or skip the insertion of the new character altogether by jumping over an existing identical character, or do nothing. The decision is taken by order of preference: * According to `use-region-p'. If this returns non-nil this function will unconditionally \"wrap\" the region in the corresponding delimiter for C; * According to C alone, by looking C up in the tables `electric-pair-pairs' or `electric-pair-text-pairs' (which see); * According to C's syntax and the syntactic state of the buffer (both as defined by the major mode's syntax table). This is done by looking up the variables `electric-pair-inhibit-predicate', `electric-pair-skip-self' and `electric-pair-skip-whitespace' (which see)." (let* ((pos (and electric-pair-mode (electric--after-char-pos))) (num (when pos (prefix-numeric-value current-prefix-arg))) (beg (when num (- pos num))) (skip-whitespace-info)) (pcase (electric-pair-syntax-info last-command-event) (`(,syntax ,pair ,unconditional ,_) (cond ((null pos) nil) ((zerop num) nil) ;; Wrap a pair around the active region. ;; ((and (memq syntax '(?\( ?\) ?\" ?\$)) (use-region-p)) ;; FIXME: To do this right, we'd need a post-self-insert-function ;; so we could add-function around it and insert the closer after ;; all the rest of the hook has run. (if (or (eq syntax ?\") (and (eq syntax ?\)) (>= (point) (mark))) (and (not (eq syntax ?\))) (>= (mark) (point)))) (save-excursion (goto-char (mark)) (electric-pair--insert pair num)) (delete-region beg pos) (electric-pair--insert pair num) (goto-char (mark)) (electric-pair--insert last-command-event num))) ;; Backslash-escaped: no pairing, no skipping. ((save-excursion (goto-char beg) (not (zerop (% (skip-syntax-backward "\\") 2)))) (let ((current-prefix-arg (1- num))) (electric-pair-post-self-insert-function))) ;; Skip self. ((and (memq syntax '(?\) ?\" ?\$)) (and (or unconditional (if (functionp electric-pair-skip-self) (electric-pair--save-literal-point-excursion (goto-char pos) (funcall electric-pair-skip-self last-command-event)) electric-pair-skip-self)) (save-excursion (when (and (not (and unconditional (eq syntax ?\"))) (setq skip-whitespace-info (if (and (not (eq electric-pair-skip-whitespace 'chomp)) (functionp electric-pair-skip-whitespace)) (funcall electric-pair-skip-whitespace) electric-pair-skip-whitespace))) (funcall electric-pair-skip-whitespace-function)) (eq (char-after) last-command-event)))) ;; This is too late: rather than insert&delete we'd want to only ;; skip (or insert in overwrite mode). The difference is in what ;; goes in the undo-log and in the intermediate state which might ;; be visible to other post-self-insert-hook. We'll just have to ;; live with it for now. (when skip-whitespace-info (funcall electric-pair-skip-whitespace-function)) (delete-region beg (if (eq skip-whitespace-info 'chomp) (point) pos)) (forward-char num)) ;; Insert matching pair. ((and (memq syntax '(?\( ?\" ?\$)) (not overwrite-mode) (or unconditional (not (electric-pair--save-literal-point-excursion (goto-char pos) (funcall electric-pair-inhibit-predicate last-command-event))))) (save-excursion (electric-pair--insert pair num)))))))) (defun electric-pair-open-newline-between-pairs-psif () "Honor `electric-pair-open-newline-between-pairs'. Member of `post-self-insert-hook' if `electric-pair-mode' is on." (when (and (if (functionp electric-pair-open-newline-between-pairs) (funcall electric-pair-open-newline-between-pairs) electric-pair-open-newline-between-pairs) (eq last-command-event ?\n) (< (1+ (point-min)) (point) (point-max)) (eq (save-excursion (skip-chars-backward "\t\s") (char-before (- (point) (prefix-numeric-value current-prefix-arg)))) (matching-paren (char-after)))) (save-excursion (newline 1 t)))) (defun electric-pair-will-use-region () (and (use-region-p) (memq (car (electric-pair-syntax-info last-command-event)) '(?\( ?\) ?\" ?\$)))) (defun electric-pair-delete-pair (arg &optional killp) "When between adjacent paired delimiters, delete both of them. ARG and KILLP are passed directly to `backward-delete-char-untabify', which see." (interactive "*p\nP") (delete-char arg) (backward-delete-char-untabify arg killp)) (defvar electric-pair-mode-map (let ((map (make-sparse-keymap))) (define-key map "\177" `(menu-item "" electric-pair-delete-pair :filter ,(lambda (cmd) (let* ((prev (char-before)) (next (char-after)) (syntax-info (and prev (electric-pair-syntax-info prev))) (syntax (car syntax-info)) (pair (cadr syntax-info))) (and next pair (memq syntax '(?\( ?\" ?\$)) (eq pair next) (if (functionp electric-pair-delete-adjacent-pairs) (funcall electric-pair-delete-adjacent-pairs) electric-pair-delete-adjacent-pairs) cmd))))) map) "Keymap used by `electric-pair-mode'.") ;;;###autoload (define-minor-mode electric-pair-mode "Toggle automatic parens pairing (Electric Pair mode). Electric Pair mode is a global minor mode. When enabled, typing an open parenthesis automatically inserts the corresponding closing parenthesis, and vice versa. (Likewise for brackets, etc.). If the region is active, the parentheses (brackets, etc.) are inserted around the region instead. To toggle the mode in a single buffer, use `electric-pair-local-mode'." :global t :group 'electricity (if electric-pair-mode (progn (add-hook 'post-self-insert-hook #'electric-pair-post-self-insert-function ;; Prioritize this to kick in after ;; `electric-layout-post-self-insert-function': that ;; considerably simplifies interoperation when ;; `electric-pair-mode', `electric-layout-mode' and ;; `electric-indent-mode' are used together. ;; Use `vc-region-history' on these lines for more info. 50) (add-hook 'post-self-insert-hook #'electric-pair-open-newline-between-pairs-psif 50) (add-hook 'self-insert-uses-region-functions #'electric-pair-will-use-region)) (remove-hook 'post-self-insert-hook #'electric-pair-post-self-insert-function) (remove-hook 'post-self-insert-hook #'electric-pair-open-newline-between-pairs-psif) (remove-hook 'self-insert-uses-region-functions #'electric-pair-will-use-region))) ;;;###autoload (define-minor-mode electric-pair-local-mode "Toggle `electric-pair-mode' only in this buffer." :variable ( electric-pair-mode . (lambda (val) (setq-local electric-pair-mode val))) (cond ((eq electric-pair-mode (default-value 'electric-pair-mode)) (kill-local-variable 'electric-pair-mode)) ((not (default-value 'electric-pair-mode)) ;; Locally enabled, but globally disabled. (electric-pair-mode 1) ; Setup the hooks. (setq-default electric-pair-mode nil) ; But keep it globally disabled. ))) (provide 'elec-pair) ;;; elec-pair.el ends here