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389 lines
16 KiB
EmacsLisp
389 lines
16 KiB
EmacsLisp
;;; electric.el --- window maker and Command loop for `electric' modes
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;; Copyright (C) 1985-1986, 1995, 2001-2011 Free Software Foundation, Inc.
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;; Author: K. Shane Hartman
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;; Maintainer: FSF
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;; Keywords: extensions
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
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;;; Commentary:
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;; "Electric" has been used in Emacs to refer to different things.
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;; Among them:
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;;
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;; - electric modes and buffers: modes that typically pop-up in a modal kind of
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;; way a transient buffer that automatically disappears as soon as the user
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;; is done with it.
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;;
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;; - electric keys: self inserting keys which additionally perform some side
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;; operation which happens to be often convenient at that time. Examples of
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;; such side operations are: reindenting code, inserting a newline,
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;; ... auto-fill-mode and abbrev-mode can be considered as built-in forms of
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;; electric key behavior.
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;;; Code:
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(eval-when-compile (require 'cl))
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;; This loop is the guts for non-standard modes which retain control
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;; until some event occurs. It is a `do-forever', the only way out is
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;; to throw. It assumes that you have set up the keymap, window, and
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;; everything else: all it does is read commands and execute them -
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;; providing error messages should one occur (if there is no loop
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;; function - which see). The required argument is a tag which should
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;; expect a value of nil if the user decides to punt. The second
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;; argument is the prompt to be used: if nil, use "->", if 'noprompt,
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;; don't use a prompt, if a string, use that string as prompt, and if
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;; a function of no variable, it will be evaluated in every iteration
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;; of the loop and its return value, which can be nil, 'noprompt or a
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;; string, will be used as prompt. Given third argument non-nil, it
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;; INHIBITS quitting unless the user types C-g at toplevel. This is
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;; so user can do things like C-u C-g and not get thrown out. Fourth
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;; argument, if non-nil, should be a function of two arguments which
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;; is called after every command is executed. The fifth argument, if
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;; provided, is the state variable for the function. If the
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;; loop-function gets an error, the loop will abort WITHOUT throwing
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;; (moral: use unwind-protect around call to this function for any
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;; critical stuff). The second argument for the loop function is the
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;; conditions for any error that occurred or nil if none.
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(defun Electric-command-loop (return-tag
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&optional prompt inhibit-quitting
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loop-function loop-state)
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(let (cmd
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(err nil)
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(inhibit-quit inhibit-quitting)
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(prompt-string prompt))
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(while t
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(if (functionp prompt)
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(setq prompt-string (funcall prompt)))
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(if (not (stringp prompt-string))
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(setq prompt-string (unless (eq prompt-string 'noprompt) "->")))
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(setq cmd (read-key-sequence prompt-string))
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(setq last-command-event (aref cmd (1- (length cmd)))
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this-command (key-binding cmd t)
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cmd this-command)
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;; This makes universal-argument-other-key work.
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(setq universal-argument-num-events 0)
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(if (or (prog1 quit-flag (setq quit-flag nil))
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(eq last-input-event ?\C-g))
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(progn (setq unread-command-events nil
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prefix-arg nil)
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;; If it wasn't cancelling a prefix character, then quit.
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(if (or (= (length (this-command-keys)) 1)
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(not inhibit-quit)) ; safety
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(progn (ding)
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(message "Quit")
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(throw return-tag nil))
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(setq cmd nil))))
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(setq current-prefix-arg prefix-arg)
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(if cmd
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(condition-case conditions
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(progn (command-execute cmd)
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(setq last-command this-command)
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(if (or (prog1 quit-flag (setq quit-flag nil))
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(eq last-input-event ?\C-g))
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(progn (setq unread-command-events nil)
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(if (not inhibit-quit)
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(progn (ding)
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(message "Quit")
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(throw return-tag nil))
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(ding)))))
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(buffer-read-only (if loop-function
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(setq err conditions)
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(ding)
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(message "Buffer is read-only")
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(sit-for 2)))
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(beginning-of-buffer (if loop-function
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(setq err conditions)
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(ding)
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(message "Beginning of Buffer")
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(sit-for 2)))
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(end-of-buffer (if loop-function
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(setq err conditions)
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(ding)
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(message "End of Buffer")
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(sit-for 2)))
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(error (if loop-function
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(setq err conditions)
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(ding)
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(message "Error: %s"
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(if (eq (car conditions) 'error)
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(car (cdr conditions))
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(prin1-to-string conditions)))
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(sit-for 2))))
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(ding))
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(if loop-function (funcall loop-function loop-state err))))
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(ding)
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(throw return-tag nil))
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;; This function is like pop-to-buffer, sort of.
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;; The algorithm is
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;; If there is a window displaying buffer
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;; Select it
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;; Else if there is only one window
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;; Split it, selecting the window on the bottom with height being
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;; the lesser of max-height (if non-nil) and the number of lines in
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;; the buffer to be displayed subject to window-min-height constraint.
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;; Else
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;; Switch to buffer in the current window.
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;;
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;; Then if max-height is nil, and not all of the lines in the buffer
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;; are displayed, grab the whole frame.
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;;
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;; Returns selected window on buffer positioned at point-min.
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(defun Electric-pop-up-window (buffer &optional max-height)
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(let* ((win (or (get-buffer-window buffer) (selected-window)))
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(buf (get-buffer buffer))
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(one-window (one-window-p t))
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(pop-up-windows t)
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(pop-up-frames nil))
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(if (not buf)
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(error "Buffer %s does not exist" buffer)
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(cond ((and (eq (window-buffer win) buf))
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(select-window win))
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(one-window
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(pop-to-buffer buffer)
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(setq win (selected-window)))
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(t
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(switch-to-buffer buf)))
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;; Don't shrink the window, but expand it if necessary.
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(goto-char (point-min))
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(unless (= (point-max) (window-end win t))
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(fit-window-to-buffer win max-height))
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win)))
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;;; Electric keys.
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(defgroup electricity ()
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"Electric behavior for self inserting keys."
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:group 'editing)
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(defun electric--after-char-pos ()
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"Return the position after the char we just inserted.
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Returns nil when we can't find this char."
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(let ((pos (point)))
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(when (or (eq (char-before) last-command-event) ;; Sanity check.
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(save-excursion
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(or (progn (skip-chars-backward " \t")
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(setq pos (point))
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(eq (char-before) last-command-event))
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(progn (skip-chars-backward " \n\t")
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(setq pos (point))
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(eq (char-before) last-command-event)))))
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pos)))
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;; Electric indentation.
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;; Autoloading variables is generally undesirable, but major modes
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;; should usually set this variable by adding elements to the default
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;; value, which only works well if the variable is preloaded.
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;;;###autoload
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(defvar electric-indent-chars '(?\n)
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"Characters that should cause automatic reindentation.")
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(defun electric-indent-post-self-insert-function ()
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;; FIXME: This reindents the current line, but what we really want instead is
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;; to reindent the whole affected text. That's the current line for simple
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;; cases, but not all cases. We do take care of the newline case in an
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;; ad-hoc fashion, but there are still missing cases such as the case of
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;; electric-pair-mode wrapping a region with a pair of parens.
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;; There might be a way to get it working by analyzing buffer-undo-list, but
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;; it looks challenging.
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(let (pos)
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(when (and (memq last-command-event electric-indent-chars)
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;; Don't reindent while inserting spaces at beginning of line.
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(or (not (memq last-command-event '(?\s ?\t)))
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(save-excursion (skip-chars-backward " \t") (not (bolp))))
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(setq pos (electric--after-char-pos))
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;; Not in a string or comment.
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(not (nth 8 (save-excursion (syntax-ppss pos)))))
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;; For newline, we want to reindent both lines and basically behave like
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;; reindent-then-newline-and-indent (whose code we hence copied).
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(when (< (1- pos) (line-beginning-position))
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(let ((before (copy-marker (1- pos) t)))
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(save-excursion
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(unless (memq indent-line-function
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'(indent-relative indent-to-left-margin
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indent-relative-maybe))
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;; Don't reindent the previous line if the indentation function
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;; is not a real one.
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(goto-char before)
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(indent-according-to-mode))
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;; We are at EOL before the call to indent-according-to-mode, and
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;; after it we usually are as well, but not always. We tried to
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;; address it with `save-excursion' but that uses a normal marker
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;; whereas we need `move after insertion', so we do the
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;; save/restore by hand.
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(goto-char before)
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;; Remove the trailing whitespace after indentation because
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;; indentation may (re)introduce the whitespace.
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(delete-horizontal-space t))))
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(unless (memq indent-line-function '(indent-to-left-margin))
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(indent-according-to-mode)))))
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;;;###autoload
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(define-minor-mode electric-indent-mode
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"Automatically reindent lines of code when inserting particular chars.
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`electric-indent-chars' specifies the set of chars that should cause reindentation."
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:global t
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:group 'electricity
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(if electric-indent-mode
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(add-hook 'post-self-insert-hook
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#'electric-indent-post-self-insert-function)
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(remove-hook 'post-self-insert-hook
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#'electric-indent-post-self-insert-function))
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;; FIXME: electric-indent-mode and electric-layout-mode interact
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;; in non-trivial ways. It turns out that electric-indent-mode works
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;; better if it is run *after* electric-layout-mode's hook.
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(when (memq #'electric-layout-post-self-insert-function
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(memq #'electric-indent-post-self-insert-function
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(default-value 'post-self-insert-hook)))
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(remove-hook 'post-self-insert-hook
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#'electric-layout-post-self-insert-function)
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(add-hook 'post-self-insert-hook
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#'electric-layout-post-self-insert-function)))
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;; Electric pairing.
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(defcustom electric-pair-pairs
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'((?\" . ?\"))
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"Alist of pairs that should be used regardless of major mode."
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:type '(repeat (cons character character)))
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(defcustom electric-pair-skip-self t
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"If non-nil, skip char instead of inserting a second closing paren.
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When inserting a closing paren character right before the same character,
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just skip that character instead, so that hitting ( followed by ) results
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in \"()\" rather than \"())\".
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This can be convenient for people who find it easier to hit ) than C-f."
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:type 'boolean)
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(defun electric-pair-post-self-insert-function ()
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(let* ((syntax (and (eq (char-before) last-command-event) ; Sanity check.
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(let ((x (assq last-command-event electric-pair-pairs)))
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(cond
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(x (if (eq (car x) (cdr x)) ?\" ?\())
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((rassq last-command-event electric-pair-pairs) ?\))
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(t (char-syntax last-command-event))))))
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;; FIXME: when inserting the closer, we should maybe use
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;; self-insert-command, although it may prove tricky running
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;; post-self-insert-hook recursively, and we wouldn't want to trigger
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;; blink-matching-open.
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(closer (if (eq syntax ?\()
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(cdr (or (assq last-command-event electric-pair-pairs)
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(aref (syntax-table) last-command-event)))
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last-command-event)))
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(cond
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;; Wrap a pair around the active region.
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((and (memq syntax '(?\( ?\" ?\$)) (use-region-p))
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(if (> (mark) (point))
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(goto-char (mark))
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;; We already inserted the open-paren but at the end of the region,
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;; so we have to remove it and start over.
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(delete-char -1)
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(save-excursion
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(goto-char (mark))
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(insert last-command-event)))
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(insert closer))
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;; Backslash-escaped: no pairing, no skipping.
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((save-excursion
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(goto-char (1- (point)))
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(not (zerop (% (skip-syntax-backward "\\") 2))))
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nil)
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;; Skip self.
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((and (memq syntax '(?\) ?\" ?\$))
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electric-pair-skip-self
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(eq (char-after) last-command-event))
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;; This is too late: rather than insert&delete we'd want to only skip (or
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;; insert in overwrite mode). The difference is in what goes in the
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;; undo-log and in the intermediate state which might be visible to other
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;; post-self-insert-hook. We'll just have to live with it for now.
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(delete-char 1))
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;; Insert matching pair.
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((not (or (not (memq syntax `(?\( ?\" ?\$)))
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overwrite-mode
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;; I find it more often preferable not to pair when the
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;; same char is next.
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(eq last-command-event (char-after))
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(eq last-command-event (char-before (1- (point))))
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;; I also find it often preferable not to pair next to a word.
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(eq (char-syntax (following-char)) ?w)))
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(save-excursion (insert closer))))))
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;;;###autoload
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(define-minor-mode electric-pair-mode
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"Automatically pair-up parens when inserting an open paren."
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:global t
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:group 'electricity
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(if electric-pair-mode
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(add-hook 'post-self-insert-hook
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#'electric-pair-post-self-insert-function)
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(remove-hook 'post-self-insert-hook
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#'electric-pair-post-self-insert-function)))
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;; Automatically add newlines after/before/around some chars.
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(defvar electric-layout-rules '()
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"List of rules saying where to automatically insert newlines.
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Each rule has the form (CHAR . WHERE) where CHAR is the char
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that was just inserted and WHERE specifies where to insert newlines
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and can be: nil, `before', `after', `around', or a function that returns
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one of those symbols.")
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(defun electric-layout-post-self-insert-function ()
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(let* ((rule (cdr (assq last-command-event electric-layout-rules)))
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pos)
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(when (and rule
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(setq pos (electric--after-char-pos))
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;; Not in a string or comment.
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(not (nth 8 (save-excursion (syntax-ppss pos)))))
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(let ((end (copy-marker (point) t)))
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(goto-char pos)
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(case (if (functionp rule) (funcall rule) rule)
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;; FIXME: we used `newline' down here which called
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;; self-insert-command and ran post-self-insert-hook recursively.
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;; It happened to make electric-indent-mode work automatically with
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;; electric-layout-mode (at the cost of re-indenting lines
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;; multiple times), but I'm not sure it's what we want.
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(before (goto-char (1- pos)) (skip-chars-backward " \t")
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(unless (bolp) (insert "\n")))
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(after (insert "\n")) ; FIXME: check eolp before inserting \n?
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(around (save-excursion
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(goto-char (1- pos)) (skip-chars-backward " \t")
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(unless (bolp) (insert "\n")))
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(insert "\n"))) ; FIXME: check eolp before inserting \n?
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(goto-char end)))))
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;;;###autoload
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(define-minor-mode electric-layout-mode
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"Automatically insert newlines around some chars."
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:global t
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:group 'electricity
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(if electric-layout-mode
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(add-hook 'post-self-insert-hook
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#'electric-layout-post-self-insert-function)
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(remove-hook 'post-self-insert-hook
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#'electric-layout-post-self-insert-function)))
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(provide 'electric)
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;;; electric.el ends here
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