From: Eshel Yaron Date: Thu, 2 Nov 2023 15:58:31 +0000 (+0100) Subject: Add Completion Preview mode X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=refs%2Fheads%2Ffeature%2Fcompletion-preview;p=emacs.git Add Completion Preview mode This adds a new minor mode, 'completion-preview-mode', that displays in-buffer completion suggestions with an inline "preview" overlay. * lisp/completion-preview.el: New file. * doc/emacs/programs.texi (Symbol Completion): Document it. * etc/NEWS: Announce it. --- diff --git a/doc/emacs/programs.texi b/doc/emacs/programs.texi index 7746bc8bc23..69f3ae76fe3 100644 --- a/doc/emacs/programs.texi +++ b/doc/emacs/programs.texi @@ -1701,6 +1701,90 @@ completion to the buffer. @xref{Completion}. In Text mode and related modes, @kbd{M-@key{TAB}} completes words based on the spell-checker's dictionary. @xref{Spelling}. +@cindex completion preview +@cindex preview completion +@cindex suggestion preview +@cindex Completion Preview mode +@findex completion-preview-mode +@vindex completion-preview-mode + Completion Preview mode is a minor mode that shows you symbol +completion suggestions as type. When you enable Completion Preview +mode in a buffer (with @kbd{M-x completion-preview-mode}), Emacs +examines the text around point after certain commands you invoke and +automatically suggests a possible completion. Emacs displays this +suggestion with an inline preview right after point, so you see in +advance exactly how the text will look if you accept the completion +suggestion---that's why it's called a preview. + +For example, suppose that you have an Emacs Lisp buffer with the +following code: + +@lisp +(defun doit (foobarbaz) + fo@point{} +@end lisp + +If you type another @samp{o}, the preview appears after point, +suggesting that you complete the text to @samp{foobarbaz}: + +@lisp +(defun doit (foobarbaz) + foo@point{}barbaz +@end lisp + +Here, the text @samp{barbaz} after point is the completion preview. +You can accept the completion suggestion with @kbd{@key{TAB}} to +actually inserts @samp{barbaz} and move point after it: + +@lisp +(defun doit (foobarbaz) + foobarbaz@point{} +@end lisp + +If you want to ignore a completion suggestion, just go on editing or +moving around the buffer. Completion Preview mode continues to update +the suggestion as you type according to the text around point. + +@vindex completion-preview-active-mode-map +@findex completion-preview-prev-candidate +@findex completion-preview-next-candidate +The commands @code{completion-preview-next-candidate} and +@code{completion-preview-prev-candidate} allow you to cycle the +completion candidate that the preview suggests. These commands don't +have a default keybinding, but you can bind them, for example, to +@kbd{M-n} and @kbd{M-p} in @code{completion-preview-active-mode-map} +to have them handy whenever the preview is visible. + +@vindex completion-preview-exact-match-only +@vindex completion-preview-commands +@vindex completion-preview-minimum-symbol-length +If you set the user option @code{completion-preview-exact-match-only} +to non-@code{nil}, Completion Preview mode only suggests a completion +candidate when its the only possible completion for the (partial) +symbol at point. The user option @code{completion-preview-commands} +says which commands should trigger the completion preview; by default +those are only @code{self-insert-command} and +@code{delete-backward-char}, which correspond to when you type regular +characters in the buffer or delete them. The user option +@code{completion-preview-minimum-symbol-length} specifies a minimum +number of consecutive characters with word or symbol syntax that +should appear around point for Emacs to suggest a completion. By +default, this option is set to 3, so Emacs suggests a completion if +you type @samp{foo}, but typing just @samp{fo} doesn't trigger +completion preview. + +@vindex completion-preview-insert-on-completion +The user option @code{completion-preview-insert-on-completion} +controls what happens when you invoke @code{completion-at-point} while +the completion preview is visible. By default this option is +@code{nil}, which tells @code{completion-at-point} to ignore the +completion preview and show the list of completion candidates as +usual. If you set @code{completion-preview-insert-on-completion} to +non-@code{nil}, then @code{completion-at-point} inserts the preview +directly without looking for more candidates. To show the list of +candidates with this setting while the preview is visible, type +@kbd{C-g} to dismiss it before invoking @code{completion-at-point}. + @node MixedCase Words @section MixedCase Words @cindex camel case diff --git a/etc/NEWS b/etc/NEWS index 767e4c27b43..0841c8aa860 100644 --- a/etc/NEWS +++ b/etc/NEWS @@ -1028,6 +1028,12 @@ It highlights parens via ‘show-paren-mode’ and ‘blink-matching-paren’ in a user-friendly way, avoids reporting alleged paren mismatches and makes sexp navigation more intuitive. ++++ +*** New minor mode 'completion-preview-mode'. +This minor mode shows you symbol completion suggestions as you type, +using an inline preview. New user options in the 'completion-preview' +customization group control exactly when Emacs displays this preview. + --- ** The highly accessible Modus themes collection has eight items. The 'modus-operandi' and 'modus-vivendi' are the main themes that have diff --git a/lisp/completion-preview.el b/lisp/completion-preview.el new file mode 100644 index 00000000000..d21c0e042b7 --- /dev/null +++ b/lisp/completion-preview.el @@ -0,0 +1,266 @@ +;;; completion-preview.el --- Preview completion with inline overlay -*- lexical-binding: t; -*- + +;; Copyright (C) 2023 Free Software Foundation, Inc. + +;; Author: Eshel Yaron +;; Maintainer: Eshel Yaron +;; Keywords: abbrev convenience + +;; This program 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. + +;; This program 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 this program. If not, see . + +;;; Commentary: + +;; This library provides the Completion Preview mode. This minor mode +;; displays the top completion candidate for the symbol at point in an +;; overlay after point. If you want to enable Completion Preview mode +;; in all programming modes, add the following to your Emacs init: +;; +;; (add-hook 'prog-mode-hook #'completion-preview-mode) +;; +;; Also check out the customization group `completion-preview` for +;; some user options that you may want to tweak. + +;;; Code: + +(defgroup completion-preview nil + "In-buffer completion preview." + :group 'completion) + +(defcustom completion-preview-exact-match-only nil + "Whether to show completion preview only when there is an exact match. + +If this option is non-nil, Completion Preview mode only shows the +preview overlay when there is exactly one completion candidate +that matches the symbol at point, otherwise it shows the top +candidate also when there are multiple matching candidates." + :type 'boolean) + +(defcustom completion-preview-commands '(self-insert-command + delete-backward-char + backward-delete-char-untabify) + "List of commands that should trigger completion preview." + :type '(repeat (function :tag "Command" :value self-insert-command))) + +(defcustom completion-preview-minimum-symbol-length 3 + "Minimum length of the symbol at point for showing completion preview." + :type 'natnum) + +(defcustom completion-preview-hook + '(completion-preview-require-certain-commands + completion-preview-require-minimum-symbol-length) + "Hook for functions that determine whether to show preview completion. + +Completion Preview mode calls each of these functions in order +after each command, and only displays the completion preview when +all of the functions return non-nil." + :type 'hook) + +(defcustom completion-preview-insert-on-completion nil + "Whether \\[completion-at-point] inserts the previewed suggestion." + :type 'boolean) + +(defvar completion-preview-sort-function #'minibuffer--sort-by-length-alpha + "Sort function to use for choosing a completion candidate to preview.") + +(defface completion-preview + '((t :inherit shadow)) + "Face for completion preview overlay.") + +(defface completion-preview-exact + '((t :underline t :inherit completion-preview)) + "Face for exact completion preview overlay.") + +(defvar-keymap completion-preview-active-mode-map + :doc "Keymap for Completion Preview Active mode." + "C-i" #'completion-preview-insert + ;; "M-n" #'completion-preview-next-candidate + ;; "M-p" #'completion-preview-prev-candidate + ) + +(defvar-local completion-preview--overlay nil) + +(defvar completion-preview--internal-commands + '(completion-preview-next-candidate completion-preview-prev-candidate) + "List of commands that manipulate the completion preview.") + +(defun completion-preview--internal-command-p () + "Return non-nil if `this-command' manipulates the completion preview." + (memq this-command completion-preview--internal-commands)) + +(defun completion-preview-require-certain-commands () + "Check if `this-command' is one of `completion-preview-commands'." + (or (completion-preview--internal-command-p) + (memq this-command completion-preview-commands))) + +(defun completion-preview-require-minimum-symbol-length () + "Check if the length of symbol at point is at least above a certain threshold. +`completion-preview-minimum-symbol-length' determines that threshold." + (pcase (bounds-of-thing-at-point 'symbol) + (`(,beg . ,end) + (<= completion-preview-minimum-symbol-length (- end beg))))) + +(defun completion-preview-hide () + "Hide the completion preview." + (when completion-preview--overlay + (delete-overlay completion-preview--overlay) + (setq completion-preview--overlay nil))) + +(defun completion-preview--make-overlay (pos string) + "Make a new completion preview overlay at POS showing STRING." + (if completion-preview--overlay + (move-overlay completion-preview--overlay pos pos) + (setq completion-preview--overlay (make-overlay pos pos))) + (add-text-properties 0 1 '(cursor 1) string) + (overlay-put completion-preview--overlay 'after-string string) + completion-preview--overlay) + +(defun completion-preview--get (prop) + "Return property PROP of the completion preview overlay." + (overlay-get completion-preview--overlay prop)) + +(define-minor-mode completion-preview-active-mode + "Mode for when the completion preview is active." + :interactive nil + (if completion-preview-active-mode + (add-hook 'completion-at-point-functions #'completion-preview--insert -1 t) + (remove-hook 'completion-at-point-functions #'completion-preview--insert t) + (completion-preview-hide))) + +(defun completion-preview--exit-function (func) + "Return an exit function that hides the completion preview and calls FUNC." + (lambda (&rest args) + (completion-preview-active-mode -1) + (when func (apply func args)))) + +(defun completion-preview--update () + "Update completion preview." + (pcase (let ((completion-preview-insert-on-completion nil)) + (run-hook-with-args-until-success 'completion-at-point-functions)) + (`(,beg ,end ,table . ,plist) + (let* ((pred (plist-get plist :predicate)) + (exit-fn (completion-preview--exit-function + (plist-get plist :exit-function))) + (string (buffer-substring beg end)) + (md (completion-metadata string table pred)) + (sort-fn (or (completion-metadata-get md 'cycle-sort-function) + (completion-metadata-get md 'display-sort-function) + completion-preview-sort-function)) + (all (let ((completion-lazy-hilit t)) + (completion-all-completions string table pred + (- (point) beg) md))) + (last (last all)) + (base (or (cdr last) 0)) + (bbeg (+ beg base)) + (prefix (substring string base))) + (when last + (setcdr last nil) + (let* ((filtered (remove prefix (all-completions prefix all))) + (sorted (funcall sort-fn filtered)) + (multi (cadr sorted)) ; multiple candidates + (cand (car sorted))) + (when (and cand (not (and multi completion-preview-exact-match-only))) + (let* ((face (if multi 'completion-preview 'completion-preview-exact)) + (after (propertize (substring cand (length prefix)) 'face face)) + (ov (completion-preview--make-overlay end after))) + (overlay-put ov 'completion-preview-beg bbeg) + (overlay-put ov 'completion-preview-end end) + (overlay-put ov 'completion-preview-index 0) + (overlay-put ov 'completion-preview-cands sorted) + (overlay-put ov 'completion-preview-exit-fn exit-fn) + (completion-preview-active-mode))))))))) + +(defun completion-preview--show () + "Show completion preview." + (when completion-preview-active-mode + (let* ((beg (completion-preview--get 'completion-preview-beg)) + (cands (completion-preview--get 'completion-preview-cands)) + (index (completion-preview--get 'completion-preview-index)) + (cand (nth index cands)) + (len (length cand)) + (end (+ beg len)) + (cur (point)) + (face (get-text-property 0 'face (completion-preview--get 'after-string)))) + (if (and (< beg cur end) (string-prefix-p (buffer-substring beg cur) cand)) + (overlay-put (completion-preview--make-overlay + cur (propertize (substring cand (- cur beg)) + 'face face)) + 'completion-preview-end cur) + (completion-preview-active-mode -1)))) + (while-no-input (completion-preview--update))) + +(defun completion-preview--post-command () + "Create, update or delete completion preview post last command." + (if (run-hook-with-args-until-failure 'completion-preview-hook) + (or (completion-preview--internal-command-p) + (completion-preview--show)) + (completion-preview-active-mode -1))) + +(defun completion-preview--insert () + "Completion at point function for inserting the current preview." + (when (and completion-preview-active-mode + completion-preview-insert-on-completion) + (list (completion-preview--get 'completion-preview-beg) + (completion-preview--get 'completion-preview-end) + (list (nth (completion-preview--get 'completion-preview-index) + (completion-preview--get 'completion-preview-cands))) + :exit-function (completion-preview--get 'completion-preview-exit-fn)))) + +(defun completion-preview-insert () + "Insert the current completion preview." + (interactive) + (let ((completion-preview-insert-on-completion t)) + (completion-at-point))) + +(defun completion-preview-prev-candidate () + "Cycle the preview to the previous completion suggestion." + (interactive) + (completion-preview-next-candidate -1)) + +(defun completion-preview-next-candidate (direction) + "Cycle the preview to the next completion suggestion in DIRECTION. + +DIRECTION should be either 1 which means cycle forward, or -1 +which means cycle backward. Interactively, DIRECTION is the +prefix argument." + (interactive "p") + (when completion-preview-active-mode + (let* ((beg (completion-preview--get 'completion-preview-beg)) + (all (completion-preview--get 'completion-preview-cands)) + (cur (completion-preview--get 'completion-preview-index)) + (len (length all)) + (new (mod (+ cur direction) len)) + (str (nth new all)) + (pos (point))) + (while (or (<= (+ beg (length str)) pos) + (not (string-prefix-p (buffer-substring beg pos) str))) + (setq new (mod (+ new direction) len) str (nth new all))) + (let ((aft (propertize (substring str (- pos beg)) + 'face (if (< 1 len) + 'completion-preview + 'completion-preview-exact)))) + (add-text-properties 0 1 '(cursor 1) aft) + (overlay-put completion-preview--overlay 'completion-preview-index new) + (overlay-put completion-preview--overlay 'after-string aft))))) + +;;;###autoload +(define-minor-mode completion-preview-mode + "Show in-buffer completion preview as you type." + :lighter " CP" + (if completion-preview-mode + (add-hook 'post-command-hook #'completion-preview--post-command nil t) + (remove-hook 'post-command-hook #'completion-preview--post-command t) + (completion-preview-active-mode -1))) + +(provide 'completion-preview) +;;; completion-preview.el ends here