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27 lines
1.2 KiB
Racket
27 lines
1.2 KiB
Racket
11 years ago
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#lang racket/base
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(require racket/contract)
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;; convert a bytecount into a string
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(define/contract (bytecount->string bytecount)
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(integer? . -> . string?)
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(define (format-with-threshold threshold suffix)
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;; upconvert by factor of 100 to get two digits after decimal
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(format "~a ~a" (exact->inexact (/ (round ((* bytecount 100) . / . threshold)) 100)) suffix))
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(define threshold-kilobyte 1000)
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(define threshold-megabyte (threshold-kilobyte . * . threshold-kilobyte))
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(define threshold-gigabyte (threshold-megabyte . * . threshold-kilobyte))
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(define threshold-terabyte (threshold-gigabyte . * . threshold-kilobyte))
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(cond
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[(bytecount . >= . threshold-terabyte) (format-with-threshold threshold-terabyte "TB")]
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[(bytecount . >= . threshold-gigabyte) (format-with-threshold threshold-gigabyte "GB")]
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[(bytecount . >= . threshold-megabyte) (format-with-threshold threshold-megabyte "MB")]
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[(bytecount . >= . threshold-kilobyte) (format-with-threshold threshold-kilobyte "KB")]
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[else (format "~a bytes" bytecount)]))
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;; for use inside quasiquote
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;; instead of ,(when ...) use ,@(when/splice ...)
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;; to avoid voids
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(define-syntax-rule (when/splice test body) (if test (list body) '()))
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