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emacs/lisp/rfn-eshadow.el
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;;; rfn-eshadow.el --- Highlight `shadowed' part of read-file-name input text
;;
;; Copyright (C) 2000-2020 Free Software Foundation, Inc.
;;
;; Author: Miles Bader <miles@gnu.org>
;; Keywords: convenience minibuffer
;; Package: emacs
;; 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 3 of the License, 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. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;;
;; Defines the mode `file-name-shadow-mode'.
;;
;; The `read-file-name' function passes its result through
;; `substitute-in-file-name', so any part of the string preceding
;; multiple slashes (or a drive indicator on MS-DOS/MS-Windows) is
;; ignored.
;;
;; If `file-name-shadow-mode' is active, any part of the
;; minibuffer text that would be ignored because of this is given the
;; properties in `file-name-shadow-properties', which may
;; be used to make the ignored text invisible, dim, etc.
;;
;;; Code:
;;; Customization
(defconst file-name-shadow-properties-custom-type
'(list
(checklist :inline t
(const :tag "Invisible"
:doc "Make shadowed part of filename invisible"
:format "%t%n%h"
:inline t
(invisible t intangible t))
(list :inline t
:format "%v"
:tag "Face"
:doc "Display shadowed part of filename using a different face"
(const :format "" face)
(face :value file-name-shadow))
(list :inline t
:format "%t: %v%h"
:tag "Brackets"
;; Note the 4 leading spaces in the doc string;
;; this is hack to get around the fact that the
;; newline after the second string widget comes
;; from the string widget, and doesn't indent
;; correctly. We could use a :size attribute to
;; make the second string widget not have a
;; terminating newline, but this makes it impossible
;; to enter trailing whitespace, and it's desirable
;; that it be possible.
:doc " Surround shadowed part of filename with brackets"
(const :format "" before-string)
(string :format "%v" :size 4 :value "{")
(const :format "" after-string)
;; see above about why the 2nd string doesn't use :size
(string :format " and: %v" :value "} "))
(list :inline t
:format "%t: %v%n%h"
:tag "String"
:doc "Display a string instead of the shadowed part of filename"
(const :format "" display)
(string :format "%v" :size 15 :value "<...ignored...>"))
(const :tag "Avoid"
:doc "Try to keep cursor out of shadowed part of filename"
:format "%t%n%h"
:inline t
(field shadow)))
(repeat :inline t
:tag "Other Properties"
(list :inline t
:format "%v"
(symbol :tag "Property")
(sexp :tag "Value")))))
(defcustom file-name-shadow-properties
;; FIXME: should we purecopy this?
'(face file-name-shadow field shadow)
"Properties given to the `shadowed' part of a filename in the minibuffer.
Only used when `file-name-shadow-mode' is active.
If Emacs is not running under a window system,
`file-name-shadow-tty-properties' is used instead."
:type file-name-shadow-properties-custom-type
:group 'minibuffer
:version "22.1")
(defcustom file-name-shadow-tty-properties
(purecopy '(before-string "{" after-string "} " field shadow))
"Properties given to the `shadowed' part of a filename in the minibuffer.
Only used when `file-name-shadow-mode' is active and Emacs
is not running under a window-system; if Emacs is running under a window
system, `file-name-shadow-properties' is used instead."
:type file-name-shadow-properties-custom-type
:group 'minibuffer
:version "22.1")
(defface file-name-shadow
'((t :inherit shadow))
"Face used by `file-name-shadow-mode' for the shadow."
:group 'minibuffer
:version "22.1")
(defvar rfn-eshadow-setup-minibuffer-hook nil
"Minibuffer setup functions from other packages.")
(defvar rfn-eshadow-update-overlay-hook nil
"Customer overlay functions from other packages")
;;; Internal variables
;; A list of minibuffers to which we've added a post-command-hook.
(defvar rfn-eshadow-frobbed-minibufs nil)
;; An overlay covering the shadowed part of the filename (local to the
;; minibuffer).
(defvar-local rfn-eshadow-overlay nil)
;;; Hook functions
;; This function goes on minibuffer-setup-hook
(defun rfn-eshadow-setup-minibuffer ()
"Set up a minibuffer for `file-name-shadow-mode'.
The prompt and initial input should already have been inserted."
(when minibuffer-completing-file-name
(setq rfn-eshadow-overlay
(make-overlay (minibuffer-prompt-end) (minibuffer-prompt-end)))
;; Give rfn-eshadow-overlay the user's props.
(let ((props
(if window-system
file-name-shadow-properties
file-name-shadow-tty-properties)))
(while props
(overlay-put rfn-eshadow-overlay (pop props) (pop props))))
;; Turn on overlay evaporation so that we don't have to worry about
;; odd effects when the overlay sits empty at the beginning of the
;; minibuffer.
(overlay-put rfn-eshadow-overlay 'evaporate t)
;; Add our post-command hook, and make sure can remove it later.
(add-to-list 'rfn-eshadow-frobbed-minibufs (current-buffer))
(add-hook 'post-command-hook #'rfn-eshadow-update-overlay nil t)
;; Run custom hook
(run-hooks 'rfn-eshadow-setup-minibuffer-hook)))
(defsubst rfn-eshadow-sifn-equal (goal pos)
(equal goal (condition-case nil
(substitute-in-file-name
(buffer-substring-no-properties pos (point-max)))
;; `substitute-in-file-name' can fail on partial input.
(error nil))))
;; post-command-hook to update overlay
(defun rfn-eshadow-update-overlay ()
"Update `rfn-eshadow-overlay' to cover shadowed part of minibuffer input.
This is intended to be used as a minibuffer `post-command-hook' for
`file-name-shadow-mode'; the minibuffer should have already
been set up by `rfn-eshadow-setup-minibuffer'."
(condition-case nil
(let* ((non-essential t)
(goal (substitute-in-file-name (minibuffer-contents)))
(mid (overlay-end rfn-eshadow-overlay))
(start (minibuffer-prompt-end))
(end (point-max)))
(unless
;; Catch the common case where the shadow does not need to move.
(and mid
(or (eq mid end)
(not (rfn-eshadow-sifn-equal goal (1+ mid))))
(or (eq mid start)
(rfn-eshadow-sifn-equal goal mid)))
;; Binary search for the greatest position still equivalent to
;; the whole.
(while (or (< (1+ start) end)
(if (and (< (1+ end) (point-max))
(rfn-eshadow-sifn-equal goal (1+ end)))
;; (SIFN end) != goal, but (SIFN (1+end)) == goal,
;; We've reached a discontinuity: this can happen
;; e.g. if `end' point to "/:...".
(setq start (1+ end) end (point-max))))
(setq mid (/ (+ start end) 2))
(if (rfn-eshadow-sifn-equal goal mid)
(setq start mid)
(setq end mid)))
(move-overlay rfn-eshadow-overlay (minibuffer-prompt-end) start))
;; Run custom hook
(run-hooks 'rfn-eshadow-update-overlay-hook))
;; `substitute-in-file-name' can fail on partial input.
(error nil)))
(define-minor-mode file-name-shadow-mode
"Toggle file-name shadowing in minibuffers (File-Name Shadow mode).
File-Name Shadow mode is a global minor mode. When enabled, any
part of a filename being read in the minibuffer that would be
ignored (because the result is passed through
`substitute-in-file-name') is given the properties in
`file-name-shadow-properties', which can be used to make that
portion dim, invisible, or otherwise less visually noticeable."
:global t
;; We'd like to use custom-initialize-set here so the setup is done
;; before dumping, but at the point where the defcustom is evaluated,
;; the corresponding function isn't defined yet, so
;; custom-initialize-set signals an error.
:initialize 'custom-initialize-delay
:init-value t
:group 'minibuffer
:version "22.1"
(if file-name-shadow-mode
;; Enable the mode
(add-hook 'minibuffer-setup-hook 'rfn-eshadow-setup-minibuffer)
;; Disable the mode
(remove-hook 'minibuffer-setup-hook 'rfn-eshadow-setup-minibuffer)
;; Remove our entry from any post-command-hook variable's it's still in
(dolist (minibuf rfn-eshadow-frobbed-minibufs)
(with-current-buffer minibuf
(remove-hook 'post-command-hook #'rfn-eshadow-update-overlay t)))
(setq rfn-eshadow-frobbed-minibufs nil)))
(provide 'rfn-eshadow)
;;; rfn-eshadow.el ends here