;;; electric.el --- window maker and Command loop for `electric' modes
;; Copyright (C) 1985-1986, 1995, 2001-2018 Free Software Foundation,
;; Inc.
;; Author: K. Shane Hartman
;; Maintainer: emacs-devel@gnu.org
;; Keywords: extensions
;; 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 <https://www.gnu.org/licenses/>.
;;; Commentary:
;; "Electric" has been used in Emacs to refer to different things.
;; Among them:
;;
;; - electric modes and buffers: modes that typically pop-up in a modal kind of
;; way a transient buffer that automatically disappears as soon as the user
;; is done with it.
;;
;; - electric keys: self inserting keys which additionally perform some side
;; operation which happens to be often convenient at that time. Examples of
;; such side operations are: reindenting code, inserting a newline,
;; ... auto-fill-mode and abbrev-mode can be considered as built-in forms of
;; electric key behavior.
;;; Code:
;; This loop is the guts for non-standard modes which retain control
;; until some event occurs. It is a `do-forever', the only way out is
;; to throw. It assumes that you have set up the keymap, window, and
;; everything else: all it does is read commands and execute them -
;; providing error messages should one occur (if there is no loop
;; function - which see). The required argument is a tag which should
;; expect a value of nil if the user decides to punt. The second
;; argument is the prompt to be used: if nil, use "->", if 'noprompt,
;; don't use a prompt, if a string, use that string as prompt, and if
;; a function of no variable, it will be evaluated in every iteration
;; of the loop and its return value, which can be nil, 'noprompt or a
;; string, will be used as prompt. Given third argument non-nil, it
;; INHIBITS quitting unless the user types C-g at toplevel. This is
;; so user can do things like C-u C-g and not get thrown out. Fourth
;; argument, if non-nil, should be a function of two arguments which
;; is called after every command is executed. The fifth argument, if
;; provided, is the state variable for the function. If the
;; loop-function gets an error, the loop will abort WITHOUT throwing
;; (moral: use unwind-protect around call to this function for any
;; critical stuff). The second argument for the loop function is the
;; conditions for any error that occurred or nil if none.
(defun Electric-command-loop (return-tag
&optional prompt inhibit-quitting
loop-function loop-state)
(let (cmd
(err nil)
(inhibit-quit inhibit-quitting)
(prompt-string prompt))
(while t
(if (functionp prompt)
(setq prompt-string (funcall prompt)))
(if (not (stringp prompt-string))
(setq prompt-string (unless (eq prompt-string 'noprompt) "->")))
(setq cmd (read-key-sequence prompt-string))
(setq last-command-event (aref cmd (1- (length cmd)))
this-command (key-binding cmd t)
cmd this-command)
(if (or (prog1 quit-flag (setq quit-flag nil))
(eq last-input-event ?\C-g))
(progn (setq unread-command-events nil
prefix-arg nil)
;; If it wasn't canceling a prefix character, then quit.
(if (or (= (length (this-command-keys)) 1)
(not inhibit-quit)) ; safety
(progn (ding)
(message "Quit")
(throw return-tag nil))
(setq cmd nil))))
(setq current-prefix-arg prefix-arg)
(if cmd
(condition-case conditions
(progn (command-execute cmd)
(setq last-command this-command)
(if (or (prog1 quit-flag (setq quit-flag nil))
(eq last-input-event ?\C-g))
(progn (setq unread-command-events nil)
(if (not inhibit-quit)
(progn (ding)
(message "Quit")
(throw return-tag nil))
(ding)))))
(buffer-read-only (if loop-function
(setq err conditions)
(ding)
(message "Buffer is read-only")
(sit-for 2)))
(beginning-of-buffer (if loop-function
(setq err conditions)
(ding)
(message "Beginning of Buffer")
(sit-for 2)))
(end-of-buffer (if loop-function
(setq err conditions)
(ding)
(message "End of Buffer")
(sit-for 2)))
(error (if loop-function
(setq err conditions)
(ding)
(message "Error: %s"
(if (eq (car conditions) 'error)
(car (cdr conditions))
(prin1-to-string conditions)))
(sit-for 2))))
(ding))
(if loop-function (funcall loop-function loop-state err))))
(ding)
(throw return-tag nil))
;; This function is like pop-to-buffer, sort of.
;; The algorithm is
;; If there is a window displaying buffer
;; Select it
;; Else if there is only one window
;; Split it, selecting the window on the bottom with height being
;; the lesser of max-height (if non-nil) and the number of lines in
;; the buffer to be displayed subject to window-min-height constraint.
;; Else
;; Switch to buffer in the current window.
;;
;; Then if max-height is nil, and not all of the lines in the buffer
;; are displayed, grab the whole frame.
;;
;; Returns selected window on buffer positioned at point-min.
(defun Electric-pop-up-window (buffer &optional max-height)
(let* ((win (or (get-buffer-window buffer) (selected-window)))
(buf (get-buffer buffer))
(one-window (one-window-p t))
(pop-up-windows t)
(pop-up-frames nil))
(if (not buf)
(error "Buffer %s does not exist" buffer)
(cond ((and (eq (window-buffer win) buf))
(select-window win))
(one-window
(pop-to-buffer buffer)
(setq win (selected-window)))
(t
(switch-to-buffer buf)))
;; Don't shrink the window, but expand it if necessary.
(goto-char (point-min))
(unless (= (point-max) (window-end win t))
;; This call is executed even if the window existed before, was
;; reused, ... contradicting a claim in the comment before this
;; function.
(fit-window-to-buffer win max-height nil nil nil t))
win)))
;;; Electric keys.
(defgroup electricity ()
"Electric behavior for self inserting keys."
:group 'editing)
(defun electric--after-char-pos ()
"Return the position after the char we just inserted.
Returns nil when we can't find this char."
(let ((pos (point)))
(when (or (eq (char-before) last-command-event) ;; Sanity check.
(save-excursion
(or (progn (skip-chars-backward " \t")
(setq pos (point))
(eq (char-before) last-command-event))
(progn (skip-chars-backward " \n\t")
(setq pos (point))
(eq (char-before) last-command-event)))))
pos)))
(defun electric--sort-post-self-insertion-hook ()
"Ensure order of electric functions in `post-self-insertion-hook'.
Hooks in this variable interact in non-trivial ways, so a
relative order must be maintained within it."
(setq-default post-self-insert-hook
(sort (default-value 'post-self-insert-hook)
#'(lambda (fn1 fn2)
(< (or (get fn1 'priority) 0)
(or (get fn2 'priority) 0))))))
;;; Electric indentation.
;; Autoloading variables is generally undesirable, but major modes
;; should usually set this variable by adding elements to the default
;; value, which only works well if the variable is preloaded.
;;;###autoload
(defvar electric-indent-chars '(?\n)
"Characters that should cause automatic reindentation.")
(defvar electric-indent-functions nil
"Special hook run to decide whether to auto-indent.
Each function is called with one argument (the inserted char), with
point right after that char, and it should return t to cause indentation,
`no-indent' to prevent indentation or nil to let other functions decide.")
(defvar-local electric-indent-inhibit nil
"If non-nil, reindentation is not appropriate for this buffer.
This should be set by major modes such as `python-mode' since
Python does not lend itself to fully automatic indentation.")
(defvar electric-indent-functions-without-reindent
'(indent-relative indent-to-left-margin indent-relative-maybe
py-indent-line coffee-indent-line org-indent-line yaml-indent-line
haskell-indentation-indent-line haskell-indent-cycle haskell-simple-indent
yaml-indent-line)
"List of indent functions that can't reindent.
If `indent-line-function' is one of those, then `electric-indent-mode' will
not try to reindent lines. It is normally better to make the major
mode set `electric-indent-inhibit', but this can be used as a workaround.")
(defun electric-indent-post-self-insert-function ()
"Function that `electric-indent-mode' adds to `post-self-insert-hook'.
This indents if the hook `electric-indent-functions' returns non-nil,
or if a member of `electric-indent-chars' was typed; but not in a string
or comment."
;; FIXME: This reindents the current line, but what we really want instead is
;; to reindent the whole affected text. That's the current line for simple
;; cases, but not all cases. We do take care of the newline case in an
;; ad-hoc fashion, but there are still missing cases such as the case of
;; electric-pair-mode wrapping a region with a pair of parens.
;; There might be a way to get it working by analyzing buffer-undo-list, but
;; it looks challenging.
(let (pos)
(when (and
electric-indent-mode
;; Don't reindent while inserting spaces at beginning of line.
(or (not (memq last-command-event '(?\s ?\t)))
(save-excursion (skip-chars-backward " \t") (not (bolp))))
(setq pos (electric--after-char-pos))
(save-excursion
(goto-char pos)
(let ((act (or (run-hook-with-args-until-success
'electric-indent-functions
last-command-event)
(memq last-command-event electric-indent-chars))))
(not
(or (memq act '(nil no-indent))
;; In a string or comment.
(unless (eq act 'do-indent) (nth 8 (syntax-ppss))))))))
;; If we error during indent, silently give up since this is an
;; automatic action that the user didn't explicitly request.
;; But we don't want to suppress errors from elsewhere in *this*
;; function, hence the `condition-case' and `throw' (Bug#18764).
(catch 'indent-error
;; For newline, we want to reindent both lines and basically
;; behave like reindent-then-newline-and-indent (whose code we
;; hence copied).
(let ((at-newline (<= pos (line-beginning-position))))
(when at-newline
(let ((before (copy-marker (1- pos) t)))
(save-excursion
(unless (or (memq indent-line-function
electric-indent-functions-without-reindent)
electric-indent-inhibit)
;; Don't reindent the previous line if the
;; indentation function is not a real one.
(goto-char before)
(condition-case-unless-debug ()
(indent-according-to-mode)
(error (throw 'indent-error nil))))
;; We are at EOL before the call to
;; `indent-according-to-mode', and after it we usually
;; are as well, but not always. We tried to address
;; it with `save-excursion' but that uses a normal
;; marker whereas we need `move after insertion', so
;; we do the save/restore by hand.
(goto-char before)
(when (eolp)
;; Remove the trailing whitespace after indentation because
;; indentation may (re)introduce the whitespace.
(delete-horizontal-space t)))))
(unless (and electric-indent-inhibit
(not at-newline))
(condition-case-unless-debug ()
(indent-according-to-mode)
(error (throw 'indent-error nil)))))))))
(put 'electric-indent-post-self-insert-function 'priority 60)
(defun electric-indent-just-newline (arg)
"Insert just a newline, without any auto-indentation."
(interactive "*P")
(let ((electric-indent-mode nil))
(newline arg 'interactive)))
;;;###autoload
(define-key global-map "\C-j" 'electric-newline-and-maybe-indent)
;;;###autoload
(defun electric-newline-and-maybe-indent ()
"Insert a newline.
If `electric-indent-mode' is enabled, that's that, but if it
is *disabled* then additionally indent according to major mode.
Indentation is done using the value of `indent-line-function'.
In programming language modes, this is the same as TAB.
In some text modes, where TAB inserts a tab, this command indents to the
column specified by the function `current-left-margin'."
(interactive "*")
(if electric-indent-mode
(electric-indent-just-newline nil)
(newline-and-indent)))
;;;###autoload
(define-minor-mode electric-indent-mode
"Toggle on-the-fly reindentation (Electric Indent mode).
When enabled, this reindents whenever the hook `electric-indent-functions'
returns non-nil, or if you insert a character from `electric-indent-chars'.
This is a global minor mode. To toggle the mode in a single buffer,
use `electric-indent-local-mode'."
:global t :group 'electricity
:initialize 'custom-initialize-delay
:init-value t
(if (not electric-indent-mode)
(unless (catch 'found
(dolist (buf (buffer-list))
(with-current-buffer buf
(if electric-indent-mode (throw 'found t)))))
(remove-hook 'post-self-insert-hook
#'electric-indent-post-self-insert-function))
(add-hook 'post-self-insert-hook
#'electric-indent-post-self-insert-function)
(electric--sort-post-self-insertion-hook)))
;;;###autoload
(define-minor-mode electric-indent-local-mode
"Toggle `electric-indent-mode' only in this buffer."
:variable (buffer-local-value 'electric-indent-mode (current-buffer))
(cond
((eq electric-indent-mode (default-value 'electric-indent-mode))
(kill-local-variable 'electric-indent-mode))
((not (default-value 'electric-indent-mode))
;; Locally enabled, but globally disabled.
(electric-indent-mode 1) ; Setup the hooks.
(setq-default electric-indent-mode nil) ; But keep it globally disabled.
)))
;;; Electric newlines after/before/around some chars.
(defvar electric-layout-rules nil
"List of rules saying where to automatically insert newlines.
Each rule has the form (CHAR . WHERE) where CHAR is the char that
was just inserted and WHERE specifies where to insert newlines
and can be: nil, `before', `after', `around', `after-stay', or a
function of no arguments that returns one of those symbols.
The symbols specify where in relation to CHAR the newline
character(s) should be inserted. `after-stay' means insert a
newline after CHAR but stay in the same place.")
(defun electric-layout-post-self-insert-function ()
(let* ((rule (cdr (assq last-command-event electric-layout-rules)))
pos)
(when (and rule
(setq pos (electric--after-char-pos))
;; Not in a string or comment.
(not (nth 8 (save-excursion (syntax-ppss pos)))))
(let ((end (point-marker))
(sym (if (functionp rule) (funcall rule) rule)))
(set-marker-insertion-type end (not (eq sym 'after-stay)))
(goto-char pos)
(pcase sym
;; FIXME: we used `newline' down here which called
;; self-insert-command and ran post-self-insert-hook recursively.
;; It happened to make electric-indent-mode work automatically with
;; electric-layout-mode (at the cost of re-indenting lines
;; multiple times), but I'm not sure it's what we want.
;;
;; FIXME: check eolp before inserting \n?
('before (goto-char (1- pos)) (skip-chars-backward " \t")
(unless (bolp) (insert "\n")))
('after (insert "\n"))
('after-stay (save-excursion
(let ((electric-layout-rules nil))
(newline 1 t))))
('around (save-excursion
(goto-char (1- pos)) (skip-chars-backward " \t")
(unless (bolp) (insert "\n")))
(insert "\n"))) ; FIXME: check eolp before inserting \n?
(goto-char end)))))
(put 'electric-layout-post-self-insert-function 'priority 40)
;;;###autoload
(define-minor-mode electric-layout-mode
"Automatically insert newlines around some chars.
The variable `electric-layout-rules' says when and how to insert newlines."
:global t :group 'electricity
(cond (electric-layout-mode
(add-hook 'post-self-insert-hook
#'electric-layout-post-self-insert-function)
(electric--sort-post-self-insertion-hook))
(t
(remove-hook 'post-self-insert-hook
#'electric-layout-post-self-insert-function))))
;;; Electric quoting.
(defcustom electric-quote-comment t
"Non-nil means to use electric quoting in program comments."
:version "25.1"
:type 'boolean :safe 'booleanp :group 'electricity)
(defcustom electric-quote-string nil
"Non-nil means to use electric quoting in program strings."
:version "25.1"
:type 'boolean :safe 'booleanp :group 'electricity)
(defcustom electric-quote-chars '(?‘ ?’ ?“ ?”)
"Curved quote characters for `electric-quote-mode'.
This list's members correspond to left single quote, right single
quote, left double quote, and right double quote, respectively."
:version "26.1"
:type '(list character character character character)
:safe #'(lambda (x)
(pcase x
(`(,(pred characterp) ,(pred characterp)
,(pred characterp) ,(pred characterp))
t)))
:group 'electricity)
(defcustom electric-quote-paragraph t
"Non-nil means to use electric quoting in text paragraphs."
:version "25.1"
:type 'boolean :safe 'booleanp :group 'electricity)
(defcustom electric-quote-context-sensitive nil
"Non-nil means to replace \\=' with an electric quote depending on context.
If `electric-quote-context-sensitive' is non-nil, Emacs replaces
\\=' and \\='\\=' with an opening quote after a line break,
whitespace, opening parenthesis, or quote and leaves \\=` alone."
:version "26.1"
:type 'boolean :safe #'booleanp :group 'electricity)
(defcustom electric-quote-replace-double nil
"Non-nil means to replace \" with an electric double quote.
Emacs replaces \" with an opening double quote after a line
break, whitespace, opening parenthesis, or quote, and with a
closing double quote otherwise."
:version "26.1"
:type 'boolean :safe #'booleanp :group 'electricity)
(defvar electric-quote-inhibit-functions ()
"List of functions that should inhibit electric quoting.
When the variable `electric-quote-mode' is non-nil, Emacs will
call these functions in order after the user has typed an \\=` or
\\=' character. If one of them returns non-nil, electric quote
substitution is inhibited. The functions are called after the
\\=` or \\=' character has been inserted with point directly
after the inserted character. The functions in this hook should
not move point or change the current buffer.")
(defvar electric-pair-text-pairs)
(defun electric-quote-post-self-insert-function ()
"Function that `electric-quote-mode' adds to `post-self-insert-hook'.
This requotes when a quoting key is typed."
(when (and electric-quote-mode
(or (eq last-command-event ?\')
(and (not electric-quote-context-sensitive)
(eq last-command-event ?\`))
(and electric-quote-replace-double
(eq last-command-event ?\")))
(not (run-hook-with-args-until-success
'electric-quote-inhibit-functions))
(if (derived-mode-p 'text-mode)
electric-quote-paragraph
(and comment-start comment-use-syntax
(or electric-quote-comment electric-quote-string)
(let* ((syntax (syntax-ppss))
(beg (nth 8 syntax)))
(and beg
(or (and electric-quote-comment (nth 4 syntax))
(and electric-quote-string (nth 3 syntax)))
;; Do not requote a quote that starts or ends
;; a comment or string.
(eq beg (nth 8 (save-excursion
(syntax-ppss (1- (point)))))))))))
(pcase electric-quote-chars
(`(,q< ,q> ,q<< ,q>>)
(save-excursion
(let ((backtick ?\`))
(if (or (eq last-command-event ?\`)
(and (or electric-quote-context-sensitive
(and electric-quote-replace-double
(eq last-command-event ?\")))
(save-excursion
(backward-char)
(skip-syntax-backward "\\")
(or (bobp) (bolp)
(memq (char-before) (list q< q<<))
(memq (char-syntax (char-before))
'(?\s ?\())))
(setq backtick ?\')))
(cond ((search-backward (string q< backtick) (- (point) 2) t)
(replace-match (string q<<))
(when (and electric-pair-mode
(eq (cdr-safe
(assq q< electric-pair-text-pairs))
(char-after)))
(delete-char 1))
(setq last-command-event q<<))
((search-backward (string backtick) (1- (point)) t)
(replace-match (string q<))
(setq last-command-event q<))
((search-backward "\"" (1- (point)) t)
(replace-match (string q<<))
(setq last-command-event q<<)))
(cond ((search-backward (string q> ?') (- (point) 2) t)
(replace-match (string q>>))
(setq last-command-event q>>))
((search-backward "'" (1- (point)) t)
(replace-match (string q>))
(setq last-command-event q>))
((search-backward "\"" (1- (point)) t)
(replace-match (string q>>))
(setq last-command-event q>>))))))))))
(put 'electric-quote-post-self-insert-function 'priority 10)
;;;###autoload
(define-minor-mode electric-quote-mode
"Toggle on-the-fly requoting (Electric Quote mode).
When enabled, as you type this replaces \\=` with ‘, \\=' with ’,
\\=`\\=` with “, and \\='\\=' with ”. This occurs only in comments, strings,
and text paragraphs, and these are selectively controlled with
`electric-quote-comment', `electric-quote-string', and
`electric-quote-paragraph'.
Customize `electric-quote-chars' to use characters other than the
ones listed here.
This is a global minor mode. To toggle the mode in a single buffer,
use `electric-quote-local-mode'."
:global t :group 'electricity
:initialize 'custom-initialize-delay
:init-value nil
(if (not electric-quote-mode)
(unless (catch 'found
(dolist (buf (buffer-list))
(with-current-buffer buf
(if electric-quote-mode (throw 'found t)))))
(remove-hook 'post-self-insert-hook
#'electric-quote-post-self-insert-function))
(add-hook 'post-self-insert-hook
#'electric-quote-post-self-insert-function)
(electric--sort-post-self-insertion-hook)))
;;;###autoload
(define-minor-mode electric-quote-local-mode
"Toggle `electric-quote-mode' only in this buffer."
:variable (buffer-local-value 'electric-quote-mode (current-buffer))
(cond
((eq electric-quote-mode (default-value 'electric-quote-mode))
(kill-local-variable 'electric-quote-mode))
((not (default-value 'electric-quote-mode))
;; Locally enabled, but globally disabled.
(electric-quote-mode 1) ; Setup the hooks.
(setq-default electric-quote-mode nil) ; But keep it globally disabled.
)))
(provide 'electric)
;;; electric.el ends here