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55 lines
2.1 KiB
EmacsLisp
55 lines
2.1 KiB
EmacsLisp
2 years ago
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(defvar backup-before-save-directory (file-name-concat user-emacs-directory "backups"))
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(unless (file-exists-p backup-before-save-directory)
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(mkdir backup-before-save-directory))
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(defun backup-before-save-format-path (path number)
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(format "%s.~%s~" path number))
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(defun backup-before-save-extension (path)
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(let* ((i (string-search "." (reverse path)))
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(extension (substring path (- (length path) i))))
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extension))
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(defun backup-before-save-no-extension (path)
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(let* ((i (string-search "." (reverse path)))
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(no-extension (substring path 0 (- (length path) (+ i 1)))))
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no-extension))
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(defun backup-before-save-number (path)
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(let* ((extension (backup-before-save-extension path))
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(extracted (substring extension 1 (- (length extension) 1)))
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(as-number (unless (zerop (length extracted))
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(string-to-number extracted))))
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as-number))
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(defun backup-before-save-shift-path (path)
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(let* ((without-extension (backup-before-save-no-extension path))
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(number (backup-before-save-number path))
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(next-number (+ number 1))
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(shifted-path (backup-before-save-format-path
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without-extension
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next-number)))
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shifted-path))
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(defun backup-before-save-shift-backup (path)
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(let ((next-path (backup-before-save-shift-path path)))
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(when (file-exists-p next-path)
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(backup-before-save-shift-backup next-path))
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(rename-file path next-path)))
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(defun backup-before-save-function ()
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(unless backup-inhibited
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(let* ((full-path (buffer-file-name))
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(base-path (file-name-nondirectory full-path))
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(backup-full-path (file-name-concat backup-before-save-directory base-path))
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(backup-full-path-numbered (backup-before-save-format-path backup-full-path 0)))
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(when (file-exists-p full-path)
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(when (file-exists-p backup-full-path-numbered)
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(backup-before-save-shift-backup backup-full-path-numbered))
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(copy-file full-path backup-full-path-numbered)))))
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(add-hook 'before-save-hook 'backup-before-save-function)
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(provide 'backup-before-save)
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