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.emacs.d/config/files/config-files-backup-on-save...

51 lines
1.8 KiB
EmacsLisp

(defvar config-files-backup-directory (file-name-concat user-emacs-directory "backups"))
(unless (file-exists-p config-files-backup-directory)
(mkdir config-files-backup-directory))
(defun config-files-format-backup-path (path number)
(format "%s.~%s~" path number))
(defun config-files-backup-extension (path)
(let* ((i (string-search "." (reverse path)))
(extension (substring path (- (length path) i))))
extension))
(defun config-files-backup-no-extension (path)
(let* ((i (string-search "." (reverse path)))
(no-extension (substring path 0 (- (length path) (+ i 1)))))
no-extension))
(defun config-files-backup-number (path)
(let* ((extension (config-files-backup-extension path))
(extracted (substring extension 1 (- (length extension) 1)))
(as-number (unless (zerop (length extracted))
(string-to-number extracted))))
as-number))
(defun config-files-shift-path (path)
(let* ((without-extension (config-files-backup-no-extension path))
(number (config-files-backup-number path))
(next-number (+ number 1))
(shifted-path (config-files-format-backup-path
without-extension
next-number)))
shifted-path))
(defun config-files-shift-backup (path)
(let ((next-path (config-files-shift-path path)))
(when (file-exists-p next-path)
(config-files-shift-backup next-path))
(rename-file path next-path)))
(defun config-files-backup-before-save ()
(unless backup-inhibited
(let* ((path (buffer-file-name))
(backup-path (config-files-format-backup-path path 0)))
(when (file-exists-p path)
(when (file-exists-p backup-path)
(config-files-shift-backup backup-path))
(copy-file path backup-path)))))
(add-hook 'before-save-hook 'config-files-backup-before-save)