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emacs/lisp/electric.el

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;;; electric.el --- window maker and Command loop for `electric' modes
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;; Copyright (C) 1985, 1986, 1995, 2004 Free Software Foundation, Inc.
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;; Author: K. Shane Hartman
;; Maintainer: FSF
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;; Keywords: extensions
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;; 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
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;; the Free Software Foundation; either version 2, or (at your option)
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;; 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
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;; along with GNU Emacs; see the file COPYING. If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
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;;; Commentary:
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; zaaaaaaap
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;;; Code:
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;; 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
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;; 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
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;; 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-quit
loop-function loop-state)
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(let (cmd
(err nil)
(prompt-string prompt))
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(while t
(if (not (or (stringp prompt) (eq prompt nil) (eq prompt 'noprompt)))
(setq prompt-string (funcall prompt)))
(if (not (stringp prompt-string))
(if (eq prompt-string 'noprompt)
(setq prompt-string nil)
(setq prompt-string "->")))
(setq cmd (read-key-sequence prompt-string))
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(setq last-command-char (aref cmd (1- (length cmd)))
this-command (key-binding cmd t)
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cmd this-command)
;; This makes universal-argument-other-key work.
(setq universal-argument-num-events 0)
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(if (or (prog1 quit-flag (setq quit-flag nil))
(eq last-input-char ?\C-g))
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(progn (setq unread-command-events nil
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prefix-arg nil)
;; If it wasn't cancelling 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)
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(setq last-command this-command)
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(if (or (prog1 quit-flag (setq quit-flag nil))
(eq last-input-char ?\C-g))
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(progn (setq unread-command-events nil)
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(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))
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;; This function is like pop-to-buffer, sort of.
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;; 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
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;; are displayed, grab the whole frame.
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;;
;; 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))
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(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)))
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(t
(switch-to-buffer buf)))
(fit-window-to-buffer win max-height)
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(goto-char (point-min))
win)))
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(provide 'electric)
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;;; arch-tag: dae045eb-dc2d-4fb7-9f27-9cc2ce277be8
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;;; electric.el ends here