31 lines
905 B
EmacsLisp
31 lines
905 B
EmacsLisp
(defun split-into-ranges (numbers)
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(let* ((last-number (pop numbers))
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(range (list last-number))
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ranges)
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(dolist (n numbers)
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(if (= n (1+ last-number))
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(push n range)
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(push (nreverse range) ranges)
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(setq range (list n)))
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(setq last-number n))
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(nreverse (cons (nreverse range) ranges))))
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(defun format-range (range)
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(cond
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((not range)
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(error "invalid range"))
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((= (length range) 1)
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(number-to-string (car range)))
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((= (length range) 2)
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(format "%d,%d" (car range) (cadr range)))
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(t
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(format "%d-%d" (car range) (car (last range))))))
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(defun rangext (numbers)
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(mapconcat #'format-range (split-into-ranges numbers) ","))
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(rangext '(0 1 2 4 6 7 8 11 12 14
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15 16 17 18 19 20 21 22 23 24
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25 27 28 29 30 31 32 33 35 36
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37 38 39))
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;; => "0-2,4,6-8,11,12,14-25,27-33,35-39"
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