--- /dev/null
+;;; plomvi.el --- poor man's vim emulation
+
+;; Copyright (C) 2019
+
+;; Author: Christian Heller <plom+plomvi@plomlompom.com>
+
+;; 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 <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; A very imperfect simulation of a small subset of Vim behavior, far
+;; from the sophistication of packages like evil; an intentionally
+;; thin wrapper around native Emacs behavior instead. To the author,
+;; it mostly serves to both avoid muscle memory context switches
+;; between Emacs and most basic Vim usages, and at the same time avoid
+;; the conceptual distances evil puts between the user and native
+;; Emacs logic. It does not care though to keep default Emacs
+;; keybindings intact, overwriting some common ones with those from
+;; the Vim universe.
+
+;;; Instructions:
+
+;; 1. load this script into your init file: (load ...)
+
+;; 2. to start plomvi by default, put this into your init file:
+;; (plomvi-global-mode 1)
+
+;; 3. define some otherwise unused keybinding to simulate what would
+;; be a jump back from Insert mode to Normal mode in Vim (but is de
+;; facto just a plomvi mode activation), such as this:
+;; (global-set-key (kbd "<f1>") 'plomvi-activate)
+
+
+
+(defun plomvi-nothing()
+ "Do nothing. Used to shadow self-insert bindings in `plomvi-editable-mode-map'."
+ (interactive))
+
+(defun plomvi-half-scroll()
+ "Scroll down half a screen width."
+ (interactive)
+ (scroll-up (/ (window-height) 2)))
+
+(defun plomvi-goto-line (count)
+ "Jump to line: on nil count, last one, else count."
+ (interactive "P")
+ (if (null count)
+ (goto-char (point-max))
+ (goto-char (point-min))
+ (forward-line (1- count))))
+
+(defun plomvi-prefix-zero-or-line-start (prev-prefix)
+ "If no prefix so far, jump to start of line, else start new prefix with 0."
+ (interactive "P")
+ (if (null prev-prefix)
+ (beginning-of-line)
+ (setq prefix-arg 0)))
+
+(defun plomvi-prompt (prompt-input)
+ "Provide super-basic : prompt that only accepts:
+q
+q!
+w
+w FILENAME
+wq
+vsplit
+split
+
+If search and replace syntax is detected, it recommends using `query-replace'
+instead.
+"
+ (interactive "M:")
+ (cond
+ ((string= prompt-input "q!")
+ (kill-emacs))
+ ((string= prompt-input "q")
+ (save-buffers-kill-emacs))
+ ((string= prompt-input "w")
+ (save-buffer))
+ ((string-match "^w [^ ]+" prompt-input)
+ (let ((file-name (substring prompt-input 2))) (write-file file-name)))
+ ((string-match "^%?s/" prompt-input)
+ (message "NOT IMPLEMENTED, consider using query-replace(-regexp)"))
+ ((string= prompt-input "wq")
+ ((lambda () (save-some-buffers t) (kill-emacs))))
+ ((string= prompt-input "vsplit")
+ (split-window-horizontally))
+ ((string= prompt-input "split")
+ (split-window-vertically))
+ (t (message "NOT IMPLEMENTED"))))
+
+(defun plomvi-newline-above ()
+ "Open and jump into new line above current line, deactivate `plomvi-mode'."
+ (interactive)
+ (beginning-of-line)
+ (insert "\n")
+ (previous-line)
+ (plomvi-deactivate))
+
+(defun plomvi-newline-below ()
+ "Open and jump into new line below current line, deactivate `plomvi-mode'."
+ (interactive)
+ (end-of-line)
+ (insert "\n")
+ (plomvi-deactivate))
+
+(defun plomvi-paste-backward ()
+ "Paste last kill leftwards in current line, or (if kill ends in \n) above it.
+
+Note that this ignores killed rectangles.
+"
+ (interactive)
+ (if (eq nil (string-match "\n$" (current-kill 0)))
+ (yank)
+ (beginning-of-line)
+ (yank)
+ (previous-line)))
+
+(defun plomvi-paste-forward ()
+ "Paste last kill rightwards in current line, or (if kill ends in \n) under it.
+
+Note that this ignores killed rectangles."
+ (interactive)
+ (if (eq nil (string-match "\n$" (current-kill 0)))
+ (progn
+ (right-char)
+ (yank))
+ (end-of-line)
+ (right-char)
+ (yank)
+ (previous-line)))
+
+(defun plomvi-region-kill()
+ "Kill marked region."
+ (interactive)
+ (kill-region (region-beginning) (region-end)))
+
+(defun plomvi-x()
+ "If rectangle or region marked, kill those; else, kill char after point."
+ (interactive)
+ (cond
+ ((and (boundp 'rectangle-mark-mode) (eq t rectangle-mark-mode))
+ (kill-rectangle (region-beginning) (region-end)))
+ ((use-region-p)
+ (plomvi-region-kill))
+ (t
+ (delete-char 1))))
+
+(defun plomvi-rectangle-mark()
+ "Start marked rectangle, move right one char so a single column is visible."
+ (interactive)
+ (push-mark (point) nil t)
+ (rectangle-mark-mode)
+ (right-char))
+
+(defun plomvi-search-forward()
+ "Find next occurence of search string last targeted by isearch."
+ (interactive)
+ (search-forward isearch-string))
+
+(defun plomvi-search-backward()
+ "Find previous occurence of search string last targeted by isearch."
+ (interactive)
+ (search-backward isearch-string))
+
+
+(defun plomvi-copy-line()
+ "Copy current line into kill buffer."
+ (interactive)
+ (let ((keep_pos (point))) ; We sort of cheat: We kill the line, then we
+ (kill-whole-line) ; paste it back, and return point to its
+ (plomvi-paste-backward) ; original position.
+ (goto-char keep_pos))) ;
+
+(defun plomvi-copy-region()
+ "Copy marked region."
+ (interactive)
+ (copy-region-as-kill (region-beginning) (region-end)))
+
+(defun plomvi-replace-char (c)
+ "Replace char after point with c."
+ (interactive "cplomvi-replace-char")
+ (delete-char 1) (insert-char c) (left-char))
+
+;;; some attempt at a redo feature, not very successful, documented here for
+;;; research purposes
+;
+;(setq plomvi-in-redo nil) ; should be made buffer-local
+;(setq plomvi-undo-count 0) ; should be made buffer-local
+;(defun plomvi-undo()
+; (interactive)
+; (undo-only)
+; (setq plomvi-in-redo nil)
+; (setq plomvi-undo-count (+ plomvi-undo-count 1)))
+;(defun plomvi-redo()
+; (interactive)
+; (if (> plomvi-undo-count 0)
+; (progn
+; (if (null plomvi-in-redo)
+; (progn
+; (insert-char ?\s 1)
+; (undo)
+; (setq plomvi-in-redo t)))
+; (progn
+; (undo)
+; (setq plomvi-undo-count (- plomvi-undo-count 1))))))
+
+(defun plomvi-no-redo()
+ "Tell user what to do, since implementing vim redo was too much of a hassle."
+ (interactive)
+ (message "Vim-style redo not available. Try M-x for Emacs' undo-undo."))
+
+
+(defvar plomvi-basic-mode-map (make-sparse-keymap)
+ "Keymap for `plomvi-basic-mode', to be used on read-only buffers.
+
+In contrast to the keymap `plomvi-editable-mode' for editable buffers,
+this not only excludes keybindings for editing text, but also does not
+shadow keybindings that are bound to `self-insert-command'.
+
+Thus, it on the whole shadows much fewer keybindings of other keymaps
+that can therefore be used for other purposes.")
+(define-key plomvi-basic-mode-map (kbd ":") 'plomvi-prompt)
+(define-key plomvi-basic-mode-map (kbd "C-w") 'other-window)
+(define-key plomvi-basic-mode-map (kbd "k") 'previous-line)
+(define-key plomvi-basic-mode-map (kbd "j") 'next-line)
+(define-key plomvi-basic-mode-map (kbd "h") 'left-char)
+(define-key plomvi-basic-mode-map (kbd "l") 'right-char)
+(define-key plomvi-basic-mode-map (kbd "w") 'forward-word)
+(define-key plomvi-basic-mode-map (kbd "b") 'backward-word)
+(define-key plomvi-basic-mode-map (kbd "/") 'isearch-forward)
+(define-key plomvi-basic-mode-map (kbd "N") 'plomvi-search-backward)
+(define-key plomvi-basic-mode-map (kbd "n") 'plomvi-search-forward)
+(define-key plomvi-basic-mode-map (kbd "v") 'set-mark-command)
+(define-key plomvi-basic-mode-map (kbd "C-v") 'plomvi-rectangle-mark)
+(define-prefix-command 'plomvi-g-map)
+(define-key plomvi-basic-mode-map (kbd "g") 'plomvi-g-map)
+(define-key plomvi-g-map (kbd "g") 'beginning-of-buffer)
+(define-key plomvi-basic-mode-map (kbd "G") 'plomvi-goto-line)
+(define-key plomvi-basic-mode-map (kbd "$") 'end-of-line)
+(define-key plomvi-basic-mode-map (kbd "0") 'plomvi-prefix-zero-or-line-start)
+(define-key plomvi-basic-mode-map (kbd "1") 'digit-argument)
+(define-key plomvi-basic-mode-map (kbd "2") 'digit-argument)
+(define-key plomvi-basic-mode-map (kbd "3") 'digit-argument)
+(define-key plomvi-basic-mode-map (kbd "4") 'digit-argument)
+(define-key plomvi-basic-mode-map (kbd "5") 'digit-argument)
+(define-key plomvi-basic-mode-map (kbd "6") 'digit-argument)
+(define-key plomvi-basic-mode-map (kbd "7") 'digit-argument)
+(define-key plomvi-basic-mode-map (kbd "8") 'digit-argument)
+(define-key plomvi-basic-mode-map (kbd "9") 'digit-argument)
+(define-key plomvi-basic-mode-map (kbd "C-b") 'scroll-down)
+(define-key plomvi-basic-mode-map (kbd "C-f") 'scroll-up)
+(define-key plomvi-basic-mode-map (kbd "C-d") 'plomvi-half-scroll)
+(define-minor-mode plomvi-basic-mode
+ "plomvi mode for read-only buffers; uses `plomvi-basic-mode-map' to
+implement Vim-Normal-mode-style keybindings."
+ nil " PV" plomvi-basic-mode-map)
+
+(defvar plomvi-editable-mode-map (make-sparse-keymap)
+ "Keymap for `plomvi-editable-mode'.
+
+Inherits from `plomvi-basic-mode-map', but adds keybindings for text editing
+and shadows keybindings bound to `self-insert-command' to avoid accidentally
+typing text outside of what would be Vim's Insert mode.")
+(set-keymap-parent plomvi-editable-mode-map plomvi-basic-mode-map)
+(define-key plomvi-editable-mode-map [remap self-insert-command] 'plomvi-nothing)
+(define-key plomvi-editable-mode-map (kbd "i") 'plomvi-deactivate)
+(define-key plomvi-editable-mode-map (kbd "x") 'plomvi-x)
+(define-key plomvi-editable-mode-map (kbd "o") 'plomvi-newline-below)
+(define-key plomvi-editable-mode-map (kbd "O") 'plomvi-newline-above)
+(define-key plomvi-editable-mode-map (kbd "r") 'plomvi-replace-char)
+(define-key plomvi-editable-mode-map (kbd "u") 'undo-only)
+(define-key plomvi-editable-mode-map (kbd "C-r") 'plomvi-no-redo)
+;(define-key plomvi-editable-mode-map (kbd "u") 'plomvi-undo)
+;(define-key plomvi-editable-mode-map (kbd "C-r") 'plomvi-redo)
+(define-key plomvi-editable-mode-map (kbd "I") 'string-insert-rectangle)
+(define-key plomvi-editable-mode-map (kbd "p") 'plomvi-paste-forward)
+(define-key plomvi-editable-mode-map (kbd "P") 'plomvi-paste-backward)
+(define-key plomvi-editable-mode-map (kbd "Y") 'plomvi-copy-line)
+(define-key plomvi-editable-mode-map (kbd "y") 'plomvi-copy-region)
+(define-key plomvi-editable-mode-map (kbd "D") 'plomvi-region-kill)
+(define-prefix-command 'plomvi-d-map)
+(define-key plomvi-editable-mode-map (kbd "d") 'plomvi-d-map)
+(define-key plomvi-d-map (kbd "w") 'kill-word)
+(define-key plomvi-d-map (kbd "$") 'kill-line)
+(define-key plomvi-d-map (kbd "d") 'kill-whole-line)
+(define-minor-mode plomvi-editable-mode
+ "plomvi mode for editable buffers; uses `plomvi-editable-mode-map' to
+shadow `self-insert-command' keybindings and implement Vim-Normal-mode-style
+keybindings."
+ nil " PVe" plomvi-editable-mode-map)
+
+(define-minor-mode plomvi-mode
+ "Imperfectly emulates a subset of Vim normal mode.
+
+Actually encapsulates either `plomvi-basic-mode' or `plomvi-editable-mode'.
+Use `plomvi-activate' and `plomvi-deactivate' to toggle those.")
+
+(defun plomvi-activate ()
+ "Outside mini-buffer, activate `plomvi-mode'.
+
+For read only-buffers, activate `plomvi-basic-mode'; else, `plomvi-editable-mode'."
+ (interactive)
+ (unless (minibufferp)
+ ;(universal-argument)
+ (plomvi-mode 1)
+ (if buffer-read-only
+ (plomvi-basic-mode 1)
+ (plomvi-editable-mode 1))))
+
+(defun plomvi-deactivate()
+ "Outside mini-buffer, deactivate `plomvi-mode'.
+
+For read only-buffers, deactivate `plomvi-basic-mode'; else, `plomvi-editable-mode'."
+ (interactive)
+ (plomvi-mode -1)
+ (if buffer-read-only
+ (plomvi-basic-mode -1)
+ (plomvi-editable-mode -1)))
+
+(define-globalized-minor-mode plomvi-global-mode plomvi-mode plomvi-activate)
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