Fix a cacheing bug, which led to inordinately slow c-beginning-of-defun.
[emacs.git] / lisp / minibuf-eldef.el
blob76ae11e3c60736ced638037e38db00cb561dbeb7
1 ;;; minibuf-eldef.el --- Only show defaults in prompts when applicable -*- lexical-binding: t -*-
2 ;;
3 ;; Copyright (C) 2000-2016 Free Software Foundation, Inc.
4 ;;
5 ;; Author: Miles Bader <miles@gnu.org>
6 ;; Keywords: convenience
8 ;; This file is part of GNU Emacs.
10 ;; GNU Emacs is free software: you can redistribute it and/or modify
11 ;; it under the terms of the GNU General Public License as published by
12 ;; the Free Software Foundation, either version 3 of the License, or
13 ;; (at your option) any later version.
15 ;; GNU Emacs is distributed in the hope that it will be useful,
16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 ;; GNU General Public License for more details.
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
23 ;;; Commentary:
25 ;; Defines the mode `minibuffer-electric-default-mode'.
27 ;; When active, minibuffer prompts that show a default value only show
28 ;; the default when it's applicable -- that is, when hitting RET would
29 ;; yield the default value. If the user modifies the input such that
30 ;; hitting RET would enter a non-default value, the prompt is modified
31 ;; to remove the default indication (which is restored if the input is
32 ;; ever restore to the match the initial input).
34 ;;; Code:
36 (defvar minibuffer-eldef-shorten-default)
38 (defun minibuffer-default--in-prompt-regexps ()
39 `(("\\( (default\\(?: is\\)? \\(.*\\))\\):? \\'"
40 1 ,(if minibuffer-eldef-shorten-default " [\\2]"))
41 ("([^(]+?\\(, default\\(?: is\\)? \\(.*\\)\\)):? \\'" 1)
42 ("\\( \\[.*\\]\\):? *\\'" 1)))
44 (defcustom minibuffer-eldef-shorten-default nil
45 "If non-nil, shorten \"(default ...)\" to \"[...]\" in minibuffer prompts."
46 :set (lambda (symbol value)
47 (set-default symbol value)
48 (setq-default minibuffer-default-in-prompt-regexps
49 (minibuffer-default--in-prompt-regexps)))
50 :type 'boolean
51 :group 'minibuffer
52 :version "24.3")
54 (defvar minibuffer-default-in-prompt-regexps
55 (minibuffer-default--in-prompt-regexps)
56 "A list of regexps matching the parts of minibuffer prompts showing defaults.
57 When `minibuffer-electric-default-mode' is active, these regexps are
58 used to identify the portions of prompts to elide.
60 Each entry is of the form (REGEXP MATCH-NUM &optional REWRITE),
61 where REGEXP should match the default part of the prompt,
62 MATCH-NUM is the subgroup that matched the actual default indicator,
63 and REWRITE, if present, is a string to pass to `replace-match' that
64 should be displayed in its place.")
67 ;;; Internal variables
69 ;; A list of minibuffers to which we've added a post-command-hook.
70 (defvar minibuf-eldef-frobbed-minibufs nil)
72 ;;; The following are all local variables in the minibuffer
74 ;; Input pre-inserted into the minibuffer before the user can edit it.
75 (defvar minibuf-eldef-initial-input)
76 (make-variable-buffer-local 'minibuf-eldef-initial-input)
77 ;; and the length of the buffer with it inserted.
78 (defvar minibuf-eldef-initial-buffer-length)
79 (make-variable-buffer-local 'minibuf-eldef-initial-buffer-length)
81 ;; True if the current minibuffer prompt contains the default spec.
82 (defvar minibuf-eldef-showing-default-in-prompt)
83 (make-variable-buffer-local 'minibuf-eldef-showing-default-in-prompt)
85 ;; An overlay covering the default portion of the prompt
86 (defvar minibuf-eldef-overlay)
87 (make-variable-buffer-local 'minibuf-eldef-overlay)
90 ;;; Hook functions
92 ;; This function goes on minibuffer-setup-hook
93 (defun minibuf-eldef-setup-minibuffer ()
94 "Set up a minibuffer for `minibuffer-electric-default-mode'.
95 The prompt and initial input should already have been inserted."
96 (let ((regexps minibuffer-default-in-prompt-regexps)
97 (match nil)
98 (inhibit-point-motion-hooks t))
99 (save-excursion
100 (save-restriction
101 ;; Narrow to only the prompt.
102 (goto-char (point-min))
103 (narrow-to-region (point) (minibuffer-prompt-end))
104 ;; See if the prompt contains a default input indicator.
105 (while regexps
106 (setq match (pop regexps))
107 (cond
108 ((not (re-search-forward (if (stringp match) match (car match))
109 nil t))
110 ;; No match yet, try the next rule.
111 (setq match nil))
112 ((and (consp (cdr-safe match)) (nth 2 match))
113 ;; Matched a replacement rule.
114 (let* ((inhibit-read-only t)
115 (buffer-undo-list t)
116 (submatch (nth 1 match))
117 (replacement (nth 2 match))
118 (props (text-properties-at (match-beginning submatch))))
119 (replace-match replacement nil nil nil submatch)
120 (set-text-properties (match-beginning submatch)
121 (match-end submatch)
122 props)
123 ;; Replacement done, now keep trying with subsequent rules.
124 (setq match nil)
125 (goto-char (point-min))))
126 ;; Matched a non-replacement (i.e. electric hide) rule, no need to
127 ;; keep trying.
128 (t (setq regexps nil))))))
129 (if (not match)
130 ;; No match for electric hiding, so just make sure our
131 ;; post-command-hook isn't left around.
132 (remove-hook 'post-command-hook #'minibuf-eldef-update-minibuffer t)
133 ;; Yup; set things up so we can frob the prompt as the state of
134 ;; the input string changes.
135 (setq match (if (consp match) (cdr match) 0))
136 (setq match (if (consp match) (car match) match))
137 (setq minibuf-eldef-overlay
138 (make-overlay (match-beginning match) (match-end match)))
139 (setq minibuf-eldef-showing-default-in-prompt t)
140 (setq minibuf-eldef-initial-input
141 (minibuffer-contents-no-properties))
142 (setq minibuf-eldef-initial-buffer-length (point-max))
143 (add-to-list 'minibuf-eldef-frobbed-minibufs (current-buffer))
144 (add-hook 'post-command-hook #'minibuf-eldef-update-minibuffer nil t))))
146 ;; post-command-hook to swap prompts when necessary
147 (defun minibuf-eldef-update-minibuffer ()
148 "Update a minibuffer's prompt to include a default only when applicable.
149 This is intended to be used as a minibuffer post-command-hook for
150 `minibuffer-electric-default-mode'; the minibuffer should have already
151 been set up by `minibuf-eldef-setup-minibuffer'."
152 (unless (eq minibuf-eldef-showing-default-in-prompt
153 (and (= (point-max) minibuf-eldef-initial-buffer-length)
154 (string-equal (minibuffer-contents-no-properties)
155 minibuf-eldef-initial-input)))
156 ;; Swap state.
157 (setq minibuf-eldef-showing-default-in-prompt
158 (not minibuf-eldef-showing-default-in-prompt))
159 (overlay-put minibuf-eldef-overlay 'invisible
160 (not minibuf-eldef-showing-default-in-prompt))))
163 ;;;###autoload
164 (define-minor-mode minibuffer-electric-default-mode
165 "Toggle Minibuffer Electric Default mode.
166 With a prefix argument ARG, enable Minibuffer Electric Default
167 mode if ARG is positive, and disable it otherwise. If called
168 from Lisp, enable the mode if ARG is omitted or nil.
170 Minibuffer Electric Default mode is a global minor mode. When
171 enabled, minibuffer prompts that show a default value only show
172 the default when it's applicable -- that is, when hitting RET
173 would yield the default value. If the user modifies the input
174 such that hitting RET would enter a non-default value, the prompt
175 is modified to remove the default indication."
176 :global t
177 :group 'minibuffer
178 (if minibuffer-electric-default-mode
179 ;; Enable the mode
180 (add-hook 'minibuffer-setup-hook 'minibuf-eldef-setup-minibuffer)
181 ;; Disable the mode
182 (remove-hook 'minibuffer-setup-hook 'minibuf-eldef-setup-minibuffer)
183 ;; Remove our entry from any post-command-hook variable's it's still in
184 (dolist (minibuf minibuf-eldef-frobbed-minibufs)
185 (with-current-buffer minibuf
186 (remove-hook 'post-command-hook #'minibuf-eldef-update-minibuffer t)))
187 (setq minibuf-eldef-frobbed-minibufs nil)))
190 (provide 'minibuf-eldef)
192 ;;; minibuf-eldef.el ends here