31 lines
1.2 KiB
Scheme
31 lines
1.2 KiB
Scheme
#lang scheme/base
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;; This module provides the string that should replace xxxxxxx's in
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;; file names. The version number is combined to a single integer,
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;; and converted to a string in base 36. The version is X.Y.Z.W, with
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;; the general restrictions that Y<100 and Z<1000. This code further
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;; assumes X<200, W<1000 and will throw an error if not -- if that
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;; happens it's time to change the naming scheme or add more x's.
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(provide filename-version-part)
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(require version/utils)
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(define (num->str n digits)
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(let ([radix (string-length digits)])
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(let loop ([n n] [r '()])
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(if (<= n 0)
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(list->string r)
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(loop (quotient n radix)
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(cons (string-ref digits (modulo n radix)) r))))))
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(define filename-version-part
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(let loop ([n 0]
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[l (version->list (version))]
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[radix '(200 100 1000 1000)])
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(cond [(null? l)
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(let ([s (num->str n "0123456789abcdefghijklmnopqrstuvwxyz")])
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(string-append (make-string (- 7 (string-length s)) #\_) s))]
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[(not (< -1 (car l) (car radix)))
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(error 'version "internal error, see dynext/filename-version.ss")]
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[else (loop (+ (car l) (* (car radix) n)) (cdr l) (cdr radix))])))
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