/usr/share/gauche-0.9/0.9.4/lib/gauche/vport.scm is in gauche 0.9.4-6.
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;;; gauche.vport - virtual port
;;;
;;; Copyright (c) 2004-2014 Shiro Kawai <shiro@acm.org>
;;;
;;; Redistribution and use in source and binary forms, with or without
;;; modification, are permitted provided that the following conditions
;;; are met:
;;;
;;; 1. Redistributions of source code must retain the above copyright
;;; notice, this list of conditions and the following disclaimer.
;;;
;;; 2. Redistributions in binary form must reproduce the above copyright
;;; notice, this list of conditions and the following disclaimer in the
;;; documentation and/or other materials provided with the distribution.
;;;
;;; 3. Neither the name of the authors nor the names of its contributors
;;; may be used to endorse or promote products derived from this
;;; software without specific prior written permission.
;;;
;;; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
;;; "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
;;; LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
;;; A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
;;; OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
;;; SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
;;; TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
;;; PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
;;; LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
;;; NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
;;; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
;;;
(define-module gauche.vport
(use gauche.uvector)
(export <virtual-input-port>
<virtual-output-port>
<buffered-input-port>
<buffered-output-port>
open-input-uvector
open-output-uvector
open-input-limited-length-port
))
(select-module gauche.vport)
(dynamic-load "gauche--vport")
;;=======================================================
;; A port backed up by an uniform vector
;;
(define (open-input-uvector uvector)
(let* ([src (if (u8vector? uvector)
uvector
(uvector-alias <u8vector> uvector))]
[index 0]
[len (u8vector-length src)])
(define (filler buf)
(if (>= index len)
#f
(let1 req (u8vector-length buf)
(if (>= req (- len index))
(rlet1 count (- len index)
(u8vector-copy! buf 0 src index)
(inc! index count))
(begin
(u8vector-copy! buf 0 src index (+ index req))
(inc! index req)
req)))))
(define (seeker offset whence)
(cond [(= whence SEEK_SET)
(set! index (clamp offset 0 len))]
[(= whence SEEK_CUR)
(set! index (clamp (+ index offset) 0 len))]
[(= whence SEEK_END)
(set! index (clamp (+ len offset) 0 len))])
index)
(make <buffered-input-port> :fill filler :seek seeker)))
(define (open-output-uvector uvector)
(let* ([dst (if (u8vector? uvector)
uvector
(uvector-alias <u8vector> uvector))]
[index 0]
[len (u8vector-length dst)])
(define (flusher buf force?)
(let1 req (u8vector-length buf)
(cond [(>= index len) req] ;; simply discard the data
[(> req (- len index))
(let1 count (- len index)
(u8vector-copy! dst index buf 0 count)
(inc! index count)
req)]
[else
(u8vector-copy! dst index buf 0 req)
(inc! index req)
req])))
(define (seeker offset whence)
(cond [(= whence SEEK_SET)
(set! index (clamp offset 0 len))]
[(= whence SEEK_CUR)
(set! index (clamp (+ index offset) 0 len))]
[(= whence SEEK_END)
(set! index (clamp (+ len offset) 0 len))])
index)
(make <buffered-output-port> :flush flusher :seek seeker)))
;;=======================================================
;; A port with limited-length input/output
;;
(define (open-input-limited-length-port source limit
:key (limit-reached #f)
(eof-reached #f) (closed #f))
(let ([nrest limit]
[eof #f])
(define (filler buf)
(if (or (<= nrest 0) eof)
(if limit-reached (limit-reached buf) 0)
(let* ([len (u8vector-length buf)]
[nread (read-block! buf source 0 (min nrest len))])
(cond [(eof-object? nread)
(set! eof #t)
(if eof-reached (eof-reached buf) 0)]
[else
(dec! nrest nread)
nread]))))
(define (closer)
(when closed (closed)))
(make <buffered-input-port> :fill filler :close closer)))
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