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82 lines
2.7 KiB
Scheme
82 lines
2.7 KiB
Scheme
; "withfile.scm", with-input-from-file and with-output-to-file for Scheme
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; Copyright (c) 1992, 1993 Aubrey Jaffer
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;;
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;Permission to copy this software, to redistribute it, and to use it
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;for any purpose is granted, subject to the following restrictions and
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;understandings.
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;
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;1. Any copy made of this software must include this copyright notice
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;in full.
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;
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;2. I have made no warrantee or representation that the operation of
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;this software will be error-free, and I am under no obligation to
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;provide any services, by way of maintenance, update, or otherwise.
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;
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;3. In conjunction with products arising from the use of this
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;material, there shall be no use of my name in any advertising,
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;promotional, or sales literature without prior written consent in
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;each case.
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(require 'dynamic-wind)
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(define withfile:current-input (current-input-port))
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(define withfile:current-output (current-output-port))
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(define (current-input-port) withfile:current-input)
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(define (current-output-port) withfile:current-output)
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(define (with-input-from-file file thunk)
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(define oport withfile:current-input)
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(define port (open-input-file file))
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(dynamic-wind (lambda () (set! oport withfile:current-input)
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(set! withfile:current-input port))
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(lambda() (let ((ans (thunk))) (close-input-port port) ans))
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(lambda() (set! withfile:current-input oport))))
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(define (with-output-from-file file thunk)
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(define oport withfile:current-output)
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(define port (open-output-file file))
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(dynamic-wind (lambda() (set! oport withfile:current-output)
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(set! withfile:current-output port))
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(lambda() (let ((ans (thunk))) (close-output-port port) ans))
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(lambda() (set! withfile:current-output oport))))
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(define peek-char
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(let ((peek-char peek-char))
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(lambda opt
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(peek-char (if (null? opt) withfile:current-input (car opt))))))
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(define read-char
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(let ((read-char read-char))
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(lambda opt
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(read-char (if (null? opt) withfile:current-input (car opt))))))
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(define read
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(let ((read read))
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(lambda opt
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(read (if (null? opt) withfile:current-input (car opt))))))
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(define write-char
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(let ((write-char write-char))
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(lambda (obj . opt)
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(write-char obj (if (null? opt) withfile:current-output (car opt))))))
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(define write
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(let ((write write))
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(lambda (obj . opt)
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(write obj (if (null? opt) withfile:current-output (car opt))))))
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(define display
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(let ((display display))
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(lambda (obj . opt)
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(display obj (if (null? opt) withfile:current-output (car opt))))))
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(define newline
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(let ((newline newline))
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(lambda opt
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(newline (if (null? opt) withfile:current-output (car opt))))))
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(define force-output
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(let ((force-output force-output))
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(lambda opt
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(force-output (if (null? opt) withfile:current-output (car opt))))))
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