127 lines
4.7 KiB
EmacsLisp
127 lines
4.7 KiB
EmacsLisp
;;; hybrid-linum-mode.el --- Hybrid line numbers in Emacs -*- lexical-binding: t -*-
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;; Author: Jakub Nowak
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;; Maintainer: Jakub Nowak
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;; Version: 1.0
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;; Package-Requires: none
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;; Homepage: git.cyan.sh/birdt_/hybrid-linum-mode
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;; This file is not part of GNU Emacs
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;; This program is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; This program is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with this program. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;; This is not likely particularly fast, but it should not be particularly slow either.
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;;; Code:
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(defface relative-line-number-face
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'((t :inherit shadow))
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"Face used for showing surrounding (relative) line numbers."
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:group 'basic-faces
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:group 'hybrid-linum-mode)
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(defface current-line-number-face
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'((t :inherit font-lock-keyword-face))
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"Face used for showing the current (absolute) line number."
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:group 'basic-faces
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:group 'hybrid-linum-mode)
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(defcustom current-line-number-display-function
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(lambda () (number-to-string (line-number-at-pos last-post-command-position)))
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"Function that returns the string to display at the current line."
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:type 'function
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:group 'hybrid-linum-mode)
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(defun relative-line-number (&optional pos)
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"Return relative line number for POS (defaults to point).
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The current line returns 0."
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(let* ((pos-line (line-number-at-pos (or pos (point))))
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(current-line (line-number-at-pos (point))))
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(abs (- pos-line current-line))))
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(defun build-hybrid-line-number ()
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"Generate line number string for current line."
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(let* ((line (number-to-string (relative-line-number last-post-command-position))))
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(propertize
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(if (equal "0" line)
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(funcall current-line-number-display-function)
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(concat " "
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(when (= 1 (length line)) " ") ;; Pad with an extra space if the number is a single digit.
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line " "))
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'face (if (equal "0" line)
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'current-line-number-face
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'relative-line-number-face))))
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(defun display-hybrid-line-numbers (start limit)
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"Display line numbers in the margin between START and LIMIT."
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(goto-char start)
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(while (< (point) limit)
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(let ((line-str (build-hybrid-line-number))
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(ov (make-overlay (line-beginning-position) (line-beginning-position))))
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(overlay-put ov 'hybrid-linum-margin t)
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(overlay-put ov 'before-string
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(propertize " "
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'display `((margin left-margin) ,line-str))))
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(forward-line 1)))
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(defvar last-post-command-position 0
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"Holds the cursor position from the last run of post-command-hooks.")
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(make-variable-buffer-local 'last-post-command-position)
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(defvar hybrid-linum-mode-enabled )
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(defvar previous-margin-width 0
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"Holds the previous margin width before hybrid-linum-mode was activated.")
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(make-variable-buffer-local 'previous-margin-width)
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(defvar previous-line-number-mode 0
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"Holds the previous value of display-line-numbers-mode before hybrid-linum-mode was activated.")
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(make-variable-buffer-local 'previous-line-number-mode)
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(defun update-linenum-on-cursor-move ()
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"Update hybrid line number if the cursor position changed."
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(unless (equal (point) last-post-command-position)
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(setq last-post-command-position (point))
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(save-excursion
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(remove-overlays (point-min) (point-max) 'hybrid-linum-margin t)
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(display-hybrid-line-numbers (window-start) (window-end)))))
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(define-minor-mode hybrid-linum-mode
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"Show left-aligned line numbers in the left margin."
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:init-value nil
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(if hybrid-linum-mode
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(progn
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(setq previous-line-number-mode display-line-numbers)
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(setq previous-margin-width left-margin-width)
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(setq display-line-numbers nil)
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(setq left-margin-width 5)
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(setq last-post-command-position (point))
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(set-window-buffer nil (current-buffer))
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(remove-overlays (point-min) (point-max) 'hybrid-linum-margin t)
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(save-excursion
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(display-hybrid-line-numbers (window-start) (window-end)))
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(add-hook 'post-command-hook #'update-linenum-on-cursor-move 0 t))
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(remove-overlays (point-min) (point-max) 'hybrid-linum-margin t)
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(remove-hook 'post-command-hook #'update-linenum-on-cursor-move)
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(setq left-margin-width previous-margin-width)
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(setq display-line-numbers previous-line-number-mode)
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(set-window-buffer nil (current-buffer))))
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(provide 'hybrid-linum-mode)
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;;; hybrid-linum-mode.el ends here
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