block-travel.el

;;; block-travel.el --- Move to previous/next blank line  -*- lexical-binding: t; -*-

;; Copyright (C) 2022-2025 Shen, Jen-Chieh

;; Author: Shen, Jen-Chieh <jcs090218@gmail.com>
;; Maintainer: Shen, Jen-Chieh <jcs090218@gmail.com>
;; URL: https://github.com/emacs-vs/block-travel
;; Version: 0.1.0
;; Package-Requires: ((emacs "26.1"))
;; Keywords: convenience

;; This file is not part of GNU Emacs.

;; 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 <https://www.gnu.org/licenses/>.

;;; Commentary:
;;
;; Move to previous/next blank line
;;

;;; Code:

(defgroup block-travel nil
  "Move to previous/next blank line."
  :prefix "block-travel-"
  :group 'tool
  :link '(url-link :tag "Repository" "https://github.com/emacs-vs/block-travel"))

(defcustom block-travel-regex "^[[:space:]]*\n"
  "Regex to navigate to blank lines."
  :type 'string
  :group 'block-travel)

;;
;; (@* "Util" )
;;

(defun block-travel--current-line-empty-p ()
  "Current line empty, but accept spaces/tabs in there.  (not absolute)."
  (save-excursion (beginning-of-line) (looking-at "[[:space:]]*$")))

;;
;; (@* "Core" )
;;

;;;###autoload
(defun block-travel-up (&optional _)
  "Move to the previous line containing nothing but whitespaces or tabs."
  (interactive "^P")
  (let ((sr-pt (save-excursion (re-search-backward block-travel-regex nil t))))
    (goto-char (or sr-pt (point-min)))))

;;;###autoload
(defun block-travel-down (&optional _)
  "Move to the next line containing nothing but whitespaces or tabs."
  (interactive "^P")
  (when (block-travel--current-line-empty-p) (forward-line 1))
  (let ((sr-pt (save-excursion (re-search-forward block-travel-regex nil t))))
    (goto-char (or sr-pt (point-max)))
    (when sr-pt (forward-line -1))))

(provide 'block-travel)
;;; block-travel.el ends here