70 lines
1.7 KiB
Scheme
70 lines
1.7 KiB
Scheme
;;
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;; utils.scm
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;;
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;; Various utilities so that no external libraries are needed.
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;;
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;; ISC License
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;;
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;; Copyright 2023 Brmlab, z.s.
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;; Dominik Pantůček <dominik.pantucek@trustica.cz>
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;;
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;; Permission to use, copy, modify, and/or distribute this software
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;; for any purpose with or without fee is hereby granted, provided
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;; that the above copyright notice and this permission notice appear
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;; in all copies.
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;;
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;; THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
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;; WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
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;; WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
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;; AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
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;; CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
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;; OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
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;; NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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;; CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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;;
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(declare (unit utils))
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(module
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utils
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(
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filter
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string-repeat
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utils-tests!
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)
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(import scheme
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(chicken base)
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(chicken string)
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testing)
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;; Returns a list with elements matching pred? predicate.
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(define (filter pred? lst)
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(let loop ((lst lst)
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(res '()))
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(if (null? lst)
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(reverse res)
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(if (pred? (car lst))
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(loop (cdr lst)
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(cons (car lst) res))
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(loop (cdr lst)
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res)))))
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;; Repeats given string.
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(define (string-repeat str rep)
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(let loop ((rep rep)
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(res '()))
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(if (> rep 0)
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(loop (sub1 rep)
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(cons str res))
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(string-intersperse res ""))))
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;; Performs utils module self-tests.
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(define (utils-tests!)
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(run-tests
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utils
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(test-equal? filter (filter odd? '(1 2 3 4)) '(1 3))
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(test-equal? filter (filter odd? '(2 4)) '())
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))
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)
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