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[emacs.git] / lisp / minibuf-eldef.el
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1 ;;; minibuf-eldef.el --- Only show defaults in prompts when applicable
2 ;;
3 ;; Copyright (C) 2000, 2001, 2002, 2003, 2004,
4 ;; 2005, 2006, 2007 Free Software Foundation, Inc.
5 ;;
6 ;; Author: Miles Bader <miles@gnu.org>
7 ;; Keywords: convenience
9 ;; This file is part of GNU Emacs.
11 ;; GNU Emacs is free software; you can redistribute it and/or modify
12 ;; it under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation; either version 3, or (at your option)
14 ;; any later version.
16 ;; GNU Emacs is distributed in the hope that it will be useful,
17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 ;; GNU General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs; see the file COPYING. If not, write to the
23 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
24 ;; Boston, MA 02110-1301, USA.
26 ;;; Commentary:
28 ;; Defines the mode `minibuffer-electric-default-mode'.
30 ;; When active, minibuffer prompts that show a default value only show
31 ;; the default when it's applicable -- that is, when hitting RET would
32 ;; yield the default value. If the user modifies the input such that
33 ;; hitting RET would enter a non-default value, the prompt is modified
34 ;; to remove the default indication (which is restored if the input is
35 ;; ever restore to the match the initial input).
37 ;;; Code:
39 (defvar minibuffer-default-in-prompt-regexps
40 '(("\\( (default\\>.*)\\):? \\'" . 1) ("\\( \\[.*\\]\\):? *\\'" . 1))
41 "*A list of regexps matching the parts of minibuffer prompts showing defaults.
42 When `minibuffer-electric-default-mode' is active, these regexps are
43 used to identify the portions of prompts to elide.
45 Each entry is either a string, which should be a regexp matching the
46 default portion of the prompt, or a cons cell, who's car is a regexp
47 matching the default part of the prompt, and who's cdr indicates the
48 regexp subexpression that matched.")
51 ;;; Internal variables
53 ;; A list of minibuffers to which we've added a post-command-hook.
54 (defvar minibuf-eldef-frobbed-minibufs nil)
56 ;;; The following are all local variables in the minibuffer
58 ;; Input pre-inserted into the minibuffer before the user can edit it.
59 (defvar minibuf-eldef-initial-input)
60 (make-variable-buffer-local 'minibuf-eldef-initial-input)
61 ;; and the length of the buffer with it inserted.
62 (defvar minibuf-eldef-initial-buffer-length)
63 (make-variable-buffer-local 'minibuf-eldef-initial-buffer-length)
65 ;; True if the current minibuffer prompt contains the default spec.
66 (defvar minibuf-eldef-showing-default-in-prompt)
67 (make-variable-buffer-local 'minibuf-eldef-showing-default-in-prompt)
69 ;; An overlay covering the default portion of the prompt
70 (defvar minibuf-eldef-overlay)
71 (make-variable-buffer-local 'minibuf-eldef-overlay)
74 ;;; Hook functions
76 ;; This function goes on minibuffer-setup-hook
77 (defun minibuf-eldef-setup-minibuffer ()
78 "Set up a minibuffer for `minibuffer-electric-default-mode'.
79 The prompt and initial input should already have been inserted."
80 (let ((regexps minibuffer-default-in-prompt-regexps)
81 (match nil)
82 (inhibit-point-motion-hooks t))
83 (save-excursion
84 (save-restriction
85 ;; Narrow to only the prompt
86 (goto-char (point-min))
87 (narrow-to-region (point) (minibuffer-prompt-end))
88 ;; See the prompt contains a default input indicator
89 (while regexps
90 (setq match (pop regexps))
91 (if (re-search-forward (if (stringp match) match (car match)) nil t)
92 (setq regexps nil)
93 (setq match nil)))))
94 (if (not match)
95 ;; Nope, so just make sure our post-command-hook isn't left around.
96 (remove-hook 'post-command-hook #'minibuf-eldef-update-minibuffer t)
97 ;; Yup; set things up so we can frob the prompt as the state of
98 ;; the input string changes.
99 (setq match (if (consp match) (cdr match) 0))
100 (setq minibuf-eldef-overlay
101 (make-overlay (match-beginning match) (match-end match)))
102 (setq minibuf-eldef-showing-default-in-prompt t)
103 (setq minibuf-eldef-initial-input
104 (minibuffer-contents-no-properties))
105 (setq minibuf-eldef-initial-buffer-length (point-max))
106 (add-to-list 'minibuf-eldef-frobbed-minibufs (current-buffer))
107 (add-hook 'post-command-hook #'minibuf-eldef-update-minibuffer nil t))))
109 ;; post-command-hook to swap prompts when necessary
110 (defun minibuf-eldef-update-minibuffer ()
111 "Update a minibuffer's prompt to include a default only when applicable.
112 This is intended to be used as a minibuffer post-command-hook for
113 `minibuffer-electric-default-mode'; the minibuffer should have already
114 been set up by `minibuf-eldef-setup-minibuffer'."
115 (unless (eq minibuf-eldef-showing-default-in-prompt
116 (and (= (point-max) minibuf-eldef-initial-buffer-length)
117 (string-equal (minibuffer-contents-no-properties)
118 minibuf-eldef-initial-input)))
119 ;; swap state
120 (setq minibuf-eldef-showing-default-in-prompt
121 (not minibuf-eldef-showing-default-in-prompt))
122 (cond (minibuf-eldef-showing-default-in-prompt
123 (overlay-put minibuf-eldef-overlay 'invisible nil)
124 (overlay-put minibuf-eldef-overlay 'intangible nil))
126 (overlay-put minibuf-eldef-overlay 'invisible t)
127 (overlay-put minibuf-eldef-overlay 'intangible t)))))
130 ;;; Note this definition must be at the end of the file, because
131 ;;; `define-minor-mode' actually calls the mode-function if the
132 ;;; associated variable is non-nil, which requires that all needed
133 ;;; functions be already defined. [This is arguably a bug in d-m-m]
134 ;;;###autoload
135 (define-minor-mode minibuffer-electric-default-mode
136 "Toggle Minibuffer Electric Default mode.
137 When active, minibuffer prompts that show a default value only show the
138 default when it's applicable -- that is, when hitting RET would yield
139 the default value. If the user modifies the input such that hitting RET
140 would enter a non-default value, the prompt is modified to remove the
141 default indication.
143 With prefix argument ARG, turn on if positive, otherwise off.
144 Returns non-nil if the new state is enabled."
145 :global t
146 :group 'minibuffer
147 (if minibuffer-electric-default-mode
148 ;; Enable the mode
149 (add-hook 'minibuffer-setup-hook 'minibuf-eldef-setup-minibuffer)
150 ;; Disable the mode
151 (remove-hook 'minibuffer-setup-hook 'minibuf-eldef-setup-minibuffer)
152 ;; Remove our entry from any post-command-hook variable's it's still in
153 (dolist (minibuf minibuf-eldef-frobbed-minibufs)
154 (with-current-buffer minibuf
155 (remove-hook 'post-command-hook #'minibuf-eldef-update-minibuffer t)))
156 (setq minibuf-eldef-frobbed-minibufs nil)))
159 (provide 'minibuf-eldef)
161 ;; arch-tag: 7e421fae-c275-4729-b0da-7836af377d3d
162 ;;; minibuf-eldef.el ends here