--- /dev/null
+;;; minibuf-eldef.el --- Only show defaults in prompts when applicable
+;;
+;; Copyright (C) 2000 Free Software Foundation, Inc.
+;;
+;; Author: Miles Bader <miles@gnu.org>
+;; Keywords: convenience
+
+;; 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 2, 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, Inc., 59 Temple Place - Suite 330,
+;; Boston, MA 02111-1307, USA.
+
+;;; Commentary:
+;;
+;; Defines the mode `minibuffer-electric-default-mode'.
+;;
+;; When active, minibuffer prompts that show a default value only show
+;; the default when it's applicable -- that is, when hitting RET would
+;; yield the default value. If the user modifies the input such that
+;; hitting RET would enter a non-default value, the prompt is modified
+;; to remove the default indication (which is restored if the input is
+;; ever restore to the match the initial input).
+
+;;; Code:
+
+(defvar minibuffer-default-in-prompt-regexps
+ '(("\\( (default\\>.*)\\):? \\'" . 1))
+ "*A list of regexps matching the parts of minibuffer prompts showing defaults.
+When `minibuffer-electric-default-mode' is active, these regexps are
+used to identify the portions of prompts to elide.
+
+Each entry is either a string, which should be a regexp matching the
+default portion of the prompt, or a cons cell, who's car is a regexp
+matching the default part of the prompt, and who's cdr indicates the
+regexp subexpression that matched.")
+
+\f
+;;; Internal variables
+
+;; A list of minibuffers to which we've added a post-command-hook.
+(defvar minibuf-eldef-frobbed-minibufs nil)
+
+;;; The following are all local variables in the minibuffer
+
+;; Input pre-inserted into the minibuffer before the user can edit it.
+(defvar minibuf-eldef-initial-input)
+(make-variable-buffer-local 'minibuf-eldef-initial-input)
+;; and the length of the buffer with it inserted.
+(defvar minibuf-eldef-initial-buffer-length)
+(make-variable-buffer-local 'minibuf-eldef-initial-buffer-length)
+
+;; True if the current minibuffer prompt contains the default spec.
+(defvar minibuf-eldef-showing-default-in-prompt)
+(make-variable-buffer-local 'minibuf-eldef-showing-default-in-prompt)
+
+;; An overlay covering the default portion of the prompt
+(defvar minibuf-eldef-overlay)
+(make-variable-buffer-local 'minibuf-eldef-overlay)
+
+\f
+;;; Hook functions
+
+;; This function goes on minibuffer-setup-hook
+(defun minibuf-eldef-setup-minibuffer ()
+ "Set up a minibuffer for `minibuffer-electric-default-mode'.
+The prompt and initial input should already have been inserted."
+ (let ((prompt (field-string-no-properties (point-min)))
+ (regexps minibuffer-default-in-prompt-regexps)
+ (match nil)
+ (inhibit-point-motion-hooks t))
+ (save-excursion
+ (save-restriction
+ ;; Narrow to only the prompt
+ (goto-char (point-min))
+ (narrow-to-region (point) (field-end))
+ ;; See the prompt contains a default input indicator
+ (while regexps
+ (setq match (pop regexps))
+ (if (re-search-forward (if (stringp match) match (car match)) nil t)
+ (setq regexps nil)
+ (setq match nil)))))
+ (if (not match)
+ ;; Nope, so just make sure our post-command-hook isn't left around.
+ (remove-hook 'post-command-hook #'minibuf-eldef-update-minibuffer t)
+ ;; Yup; set things up so we can frob the prompt as the state of
+ ;; the input string changes.
+ (setq match (if (consp match) (cdr match) 0))
+ (setq minibuf-eldef-overlay
+ (make-overlay (match-beginning match) (match-end match)))
+ (setq minibuf-eldef-showing-default-in-prompt t)
+ (setq minibuf-eldef-initial-input
+ (field-string-no-properties (point-max)))
+ (setq minibuf-eldef-initial-buffer-length (point-max))
+ (add-to-list 'minibuf-eldef-frobbed-minibufs (current-buffer))
+ (add-hook 'post-command-hook #'minibuf-eldef-update-minibuffer nil t))))
+
+;; post-command-hook to swap prompts when necessary
+(defun minibuf-eldef-update-minibuffer ()
+ "Update a minibuffer's prompt to include a default only when applicable.
+This is intended to be used as a minibuffer post-command-hook for
+`minibuffer-electric-default-mode'; the minibuffer should have already
+been set up by `minibuf-eldef-setup-minibuffer'."
+ (unless (eq minibuf-eldef-showing-default-in-prompt
+ (and (= (point-max) minibuf-eldef-initial-buffer-length)
+ (string-equal (field-string-no-properties (point-max))
+ minibuf-eldef-initial-input)))
+ ;; swap state
+ (setq minibuf-eldef-showing-default-in-prompt
+ (not minibuf-eldef-showing-default-in-prompt))
+ (cond (minibuf-eldef-showing-default-in-prompt
+ (overlay-put minibuf-eldef-overlay 'invisible nil)
+ (overlay-put minibuf-eldef-overlay 'intangible nil))
+ (t
+ (overlay-put minibuf-eldef-overlay 'invisible t)
+ (overlay-put minibuf-eldef-overlay 'intangible t)))))
+
+\f
+;;; Note this definition must be at the end of the file, because
+;;; `define-minor-mode' actually calls the mode-function if the
+;;; associated variable is non-nil, which requires that all needed
+;;; functions be already defined. [This is arguably a bug in d-m-m]
+;;;###autoload
+(define-minor-mode minibuffer-electric-default-mode
+ "Toggle Minibuffer Electric Default mode
+When active, minibuffer prompts that show a default value only show the
+default when it's applicable -- that is, when hitting RET would yield
+the default value. If the user modifies the input such that hitting RET
+would enter a non-default value, the prompt is modified to remove the
+default indication.
+
+With prefix argument ARG, turn on if positive, otherwise off.
+Returns non-nil if the new state is enabled."
+ :global t
+ :group 'minibuffer
+ (if minibuffer-electric-default-mode
+ ;; Enable the mode
+ (add-hook 'minibuffer-setup-hook 'minibuf-eldef-setup-minibuffer)
+ ;; Disable the mode
+ (remove-hook 'minibuffer-setup-hook 'minibuf-eldef-setup-minibuffer)
+ ;; Remove our entry from any post-command-hook variable's it's still in
+ (dolist (minibuf minibuf-eldef-frobbed-minibufs)
+ (with-current-buffer minibuf
+ (remove-hook 'post-command-hook #'minibuf-eldef-update-minibuffer t)))
+ (setq minibuf-eldef-frobbed-minibufs nil)))
+
+
+(provide 'minibuf-eldef)
+
+;;; minibuf-eldef.el ends here