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;;; Chickadee Game Toolkit
;;; Copyright (C) 2014 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2016 David Thompson <dthompson2@worcester.edu>
;;;
;;; Licensed under the Apache License, Version 2.0 (the "License");
;;; you may not use this file except in compliance with the License.
;;; You may obtain a copy of the License at
;;;
;;; http://www.apache.org/licenses/LICENSE-2.0
;;;
;;; Unless required by applicable law or agreed to in writing, software
;;; distributed under the License is distributed on an "AS IS" BASIS,
;;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
;;; See the License for the specific language governing permissions and
;;; limitations under the License.
(define-module (chickadee utils)
#:use-module (ice-9 match)
#:export (file-extension
absolute-file-name
tmpdir
memoize
for-range))
(define (file-extension file-name)
(match (string-split file-name #\.)
((_ ... ext) ext)))
(define (absolute-file-name file-name)
(if (absolute-file-name? file-name)
file-name
(string-append (getcwd) "/" file-name)))
(define (tmpdir)
(or (getenv "TMPDIR") "/tmp"))
;; Written by Ludovic Courtès. Taken from GNU Guix.
(define (memoize proc)
"Return a memoizing version of PROC."
(let ((cache (make-hash-table)))
(lambda args
(let ((results (hash-ref cache args)))
(if results
(apply values results)
(let ((results (call-with-values (lambda () (apply proc args))
list)))
(hash-set! cache args results)
(apply values results)))))))
(define-syntax for-range
(syntax-rules ()
((_ ((var end start inc)) body ...)
(let* ((s start) ; evaluate start/end only once
(e end)
(reverse? (< e s))
(start* (if reverse? e s))
(end* (if reverse? s e))
(inc* (abs inc)))
(let loop ((var start*))
(when (< var end*)
body ...
(loop (+ var inc*))))))
((_ ((var end start)) body ...)
(for-range ((var end start 1)) body ...))
((_ ((var end)) body ...)
(for-range ((var end 0 1)) body ...))
((_ ((var args ...) rest ...) body ...)
(for-range ((var args ...))
(for-range (rest ...)
body ...)))))
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