文字列をbyte単位でぶった切る

Gaucheで。こんな感じでいいのかなー。

• https://gist.github.com/valvallow/5783251

	#!/usr/local/bin/gosh
	(use gauche.parseopt)
	(use gauche.uvector)
	(use srfi-13)
	(define (usage cmd)
	(print "usage: " cmd " [option ...] string length")
	(print " options:")
	(print " h|help print this help")
	(print " r|rest print rest string")
	(exit))
	(define (string-take-byte str n)
	(call-with-input-string str
	(^p (let rec ((i n)(acc '()))
	(if (zero? i)
	(u8vector->string (list->u8vector (reverse acc)))
	(rec (- i 1)(cons (read-byte p) acc)))))))
	(define (string-split-byte str n)
	(let1 taken (string-incomplete->complete (string-take-byte str n) :omit)
	(values taken (string-drop str (string-length taken)))))
	(define (main args)
	(let-args (cdr args)
	((help "h|help" => (cut usage (car args)))
	(rest "r|rest")
	(else (opt . _)
	(print "Unknown option : " opt)
	(usage (car args)))
	. rest-args)
	(if (or (null? rest-args)
	(null? (cdr rest-args)))
	(usage (car args))
	(let* ((str (car rest-args))
	(bytes (clamp (x->integer (cadr rest-args))
	0
	(u8vector-length (string->u8vector str)))))
	(receive (taken tail)
	(string-split-byte str bytes)
	(display (if rest tail taken)))))))

view raw string-byte-split.scm hosted with ❤ by GitHub