4.4BSD/usr/src/contrib/emacs-18.57/lisp/electric.el
;; electric -- Window maker and Command loop for `electric' modes.
;; Copyright (C) 1985, 1986 Free Software Foundation, Inc.
;; Principal author K. Shane Hartman
;; 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 1, 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; see the file COPYING. If not, write to
;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
(provide 'electric) ; zaaaaaaap
;; perhaps this should be in subr.el...
(defun shrink-window-if-larger-than-buffer (window)
(save-excursion
(set-buffer (window-buffer window))
(let ((w (selected-window)) ;save-window-excursion can't win
(buffer-file-name buffer-file-name)
(p (point))
(n 0)
(window-min-height 0)
(buffer-read-only nil)
(modified (buffer-modified-p)))
(unwind-protect
(progn
(select-window window)
(goto-char (point-min))
(while (pos-visible-in-window-p (point-max))
;; defeat file locking... don't try this at home, kids!
(setq buffer-file-name nil)
(insert ?\n) (setq n (1+ n)))
(if (> n 0) (shrink-window (1- n))))
(delete-region (point-min) (point))
(set-buffer-modified-p modified)
(goto-char p)
(select-window w)))))
;; 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 a prompt string (defaults to "->"). 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-quit
loop-function loop-state)
(if (not prompt) (setq prompt "->"))
(let (cmd (err nil))
(while t
(setq cmd (read-key-sequence (if (stringp prompt)
prompt (funcall prompt))))
(setq last-command-char (aref cmd (1- (length cmd)))
this-command (key-binding cmd)
cmd this-command)
(if (or (prog1 quit-flag (setq quit-flag nil))
(= last-input-char ?\C-g))
(progn (setq unread-command-char -1
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)
(if (or (prog1 quit-flag (setq quit-flag nil))
(= last-input-char ?\C-g))
(progn (setq unread-command-char -1)
(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 screen.
;;
;; 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)
(target-height)
(lines))
(if (not buf)
(error "Buffer %s does not exist" buffer)
(save-excursion
(set-buffer buf)
(setq lines (count-lines (point-min) (point-max)))
(setq target-height
(min (max (if max-height (min max-height (1+ lines)) (1+ lines))
window-min-height)
(save-window-excursion
(delete-other-windows)
(1- (window-height (selected-window)))))))
(cond ((and (eq (window-buffer win) buf))
(select-window win))
(one-window
(goto-char (window-start win))
(pop-to-buffer buffer)
(setq win (selected-window))
(enlarge-window (- target-height (window-height win))))
(t
(switch-to-buffer buf)))
(if (and (not max-height)
(> target-height (window-height (selected-window))))
(progn (goto-char (window-start win))
(enlarge-window (- target-height (window-height win)))))
(goto-char (point-min))
win)))