299 lines
10 KiB
Scheme
299 lines
10 KiB
Scheme
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; Copyright (c) 1993, 1994 Richard Kelsey and Jonathan Rees. See file COPYING.
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; Additional port types
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(define close-port (structure-ref primitives close-port))
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(define write-string (structure-ref ports write-string))
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; Keeping track of a port's current row and column.
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(define-record-type port-location
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()
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((row 0)
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(column 0)))
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(define make-port-location port-location-maker)
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(define (update-row-and-column location char)
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(cond ((eof-object? char) (values))
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((char=? char #\newline)
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(set-port-location-row! location (+ 1 (port-location-row location)))
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(set-port-location-column! location 0))
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(else
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(set-port-location-column! location
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(+ 1 (port-location-column location))))))
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(define (update-row-and-column-from-string location string)
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(let loop ((i 0)
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(row (port-location-row location))
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(column (port-location-column location)))
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(cond ((>= i (string-length string))
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(set-port-location-row! location row)
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(set-port-location-column! location column))
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((char=? #\newline (string-ref string i))
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(loop (+ i 1) (+ row 1) 0))
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(else
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(loop (+ i 1) row (+ column 1))))))
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; Input ports that keep track of the current row and column.
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(define-record-type input-port-data
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(sub-port)
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((location (make-port-location))))
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(define input-port-methods
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(make-input-port-methods
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(lambda (data)
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(close-port (input-port-data-sub-port data)))
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(lambda (data)
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(let ((char (read-char (input-port-data-sub-port data))))
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(update-row-and-column (input-port-data-location data) char)
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char))
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(lambda (data)
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(peek-char (input-port-data-sub-port data)))
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(lambda (data)
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(char-ready? (input-port-data-sub-port data)))
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(lambda (data)
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(port-location-column (input-port-data-location data)))
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(lambda (data)
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(port-location-row (input-port-data-location data)))))
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(define (make-tracking-input-port sub-port)
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(make-extensible-input-port (input-port-data-maker sub-port)
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input-port-methods))
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; Output ports that keep track of the current row and column.
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(define-record-type output-port-data
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(sub-port)
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((location (make-port-location))))
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(define output-port-methods
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(make-output-port-methods
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(lambda (data)
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(close-port (output-port-data-sub-port data)))
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(lambda (data char)
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(write-char char (output-port-data-sub-port data))
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(update-row-and-column (output-port-data-location data) char))
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(lambda (data string)
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(write-string string (output-port-data-sub-port data))
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(update-row-and-column-from-string (output-port-data-location data)
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string))
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(lambda (data)
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(force-output (output-port-data-sub-port data)))
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(lambda (data)
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(let ((location (output-port-data-location data)))
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(cond ((not (= 0 (port-location-column location)))
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(write-char #\newline (output-port-data-sub-port data))
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(set-port-location-column! location 0)
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(set-port-location-row! location
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(+ 1 (port-location-row location)))))))
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(lambda (data)
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(port-location-column (output-port-data-location data)))
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(lambda (data)
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(port-location-row (output-port-data-location data)))))
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(define (make-tracking-output-port sub-port)
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(make-extensible-output-port (output-port-data-maker sub-port)
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output-port-methods))
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;------------------------------------------------------------------------------
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; String input ports
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(define-record-type string-input-port-data
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(string)
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((location (make-port-location))
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(index 0)))
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(define (make-string-input-port string)
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(make-extensible-input-port (string-input-port-data-maker string)
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string-input-port-methods))
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(define string-input-port-methods
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(make-input-port-methods
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(lambda (data)
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(set-string-input-port-data-index!
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(string-length (string-input-port-data-string data))))
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(lambda (data)
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(let ((string (string-input-port-data-string data))
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(index (string-input-port-data-index data)))
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(cond ((>= index (string-length string))
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eof-object)
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(else
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(let ((char (string-ref string index)))
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(set-string-input-port-data-index! data (+ index 1))
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(update-row-and-column (string-input-port-data-location data)
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char)
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char)))))
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(lambda (data)
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(let ((string (string-input-port-data-string data))
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(index (string-input-port-data-index data)))
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(if (>= index (string-length string))
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eof-object
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(string-ref string index))))
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(lambda (data)
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(let ((string (string-input-port-data-string data))
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(index (string-input-port-data-index data)))
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(< index (string-length string))))
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(lambda (data)
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(port-location-column (string-input-port-data-location data)))
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(lambda (data)
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(port-location-row (string-input-port-data-location data)))))
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;------------------------------------------------------------------------------
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; String output ports
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(define-record-type string-output-port-data
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()
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((location (make-port-location))
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(strings '())
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(index string-port-string-length)
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(open? #t)))
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(define (make-string-output-port)
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(make-extensible-output-port (string-output-port-data-maker)
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string-output-port-methods))
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; The length of the strings used in STRING-OUTPUT-PORTs.
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(define string-port-string-length 80)
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; Write a character to a string-output-port. If there is not room in the
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; current string, make a new one and put the character in that; otherwise put
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; the character in the current string and increment the index.
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(define (write-char-to-string char data)
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(let ((index (string-output-port-data-index data))
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(strings (string-output-port-data-strings data)))
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(cond ((>= index string-port-string-length)
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(let ((new (make-string string-port-string-length #\space)))
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(string-set! new 0 char)
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(set-string-output-port-data-strings! data (cons new strings))
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(set-string-output-port-data-index! data 1)))
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(else
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(string-set! (car strings) index char)
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(set-string-output-port-data-index! data (+ index 1))))))
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; UPDATE-ROW-AND-COLUMN-FROM-STRING could be integrated with this.
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(define (write-string-to-string from data)
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(let ((index (string-output-port-data-index data))
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(strings (string-output-port-data-strings data)))
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(let loop ((i 0) (index index) (strings strings))
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(cond ((>= i (string-length from))
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(set-string-output-port-data-index! data index)
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(set-string-output-port-data-strings! data strings))
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((>= index string-port-string-length)
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(let ((new (make-string string-port-string-length #\space)))
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(string-set! new 0 (string-ref from i))
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(loop (+ i 1) 1 (cons new strings))))
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(else
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(string-set! (car strings) index (string-ref from i))
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(loop (+ i 1) (+ index 1) strings))))))
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; Concatenates all of the strings of characters in WRITER into a single
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; string. Nothing is done if WRITER is not a string-output-port.
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(define (string-output-port-output port)
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(let* ((data (extensible-output-port-local-data port))
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(strings (string-output-port-data-strings data))
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(index (string-output-port-data-index data)))
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(if (null? strings)
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""
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(let* ((total (+ index (* (length (cdr strings))
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string-port-string-length)))
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(result (make-string total #\space)))
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(do ((i 0 (+ i string-port-string-length))
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(s (reverse (cdr strings)) (cdr s)))
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((null? s)
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(string-insert result (car strings) i index))
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(string-insert result (car s) i string-port-string-length))
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result))))
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; Copy the first COUNT characters from FROM to TO, putting them from START
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; onwards.
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(define (string-insert to from start count)
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(do ((i 0 (+ i 1)))
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((>= i count))
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(string-set! to (+ start i) (string-ref from i))))
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(define string-output-port-methods
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(make-output-port-methods
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(lambda (data)
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(set-string-output-port-data-open?! data #f))
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(lambda (data char)
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(cond ((string-output-port-data-open? data)
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(write-char-to-string char data)
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(update-row-and-column (string-output-port-data-location data)
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char))
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(else
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(error "writing to closed port" data)))) ; not a great argument
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(lambda (data string)
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(cond ((string-output-port-data-open? data)
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(write-string-to-string string data)
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(update-row-and-column-from-string
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(string-output-port-data-location data)
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string))
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(else
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(error "writing to closed port" data)))) ; not a great argument
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(lambda (data)
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#f) ; nothing to do on a force-output
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(lambda (data)
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(let ((location (string-output-port-data-location data)))
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(cond ((not (string-output-port-data-open? data))
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(error "writing to closed port" data)) ; not a great argument
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((not (= 0 (port-location-column location)))
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(write-char-to-string #\newline data)
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(set-port-location-column! location 0)
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(set-port-location-row! location
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(+ 1 (port-location-row location)))))))
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(lambda (data)
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(port-location-column (string-output-port-data-location data)))
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(lambda (data)
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(port-location-row (string-output-port-data-location data)))))
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(define (call-with-string-output-port proc)
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(let ((port (make-string-output-port)))
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(proc port)
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(string-output-port-output port)))
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;------------------------------------------------------------------------------
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; Output ports from a single character writer
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(define char-at-a-time-output-port-methods
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(make-output-port-methods
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(lambda (data) #f) ; nothing to do on a close
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(lambda (data char)
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(data char))
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(lambda (data string)
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(do ((i 0 (+ i 1)))
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((>= i (string-length string)))
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(data (string-ref string i))))
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(lambda (data)
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#f) ; nothing to do on a force-output
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(lambda (data)
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(data #\newline))
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(lambda (data)
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#f)
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(lambda (data)
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#f)))
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(define (make-char-at-a-time-output-port proc)
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(make-extensible-output-port proc
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char-at-a-time-output-port-methods))
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(define (write-one-line port count proc)
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(call-with-current-continuation
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(lambda (quit)
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(proc (make-char-at-a-time-output-port
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(lambda (char)
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(write-char char port)
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(set! count (- count 1))
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(if (<= count 0)
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(quit #f))))))))
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; Unix-specific kludge
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(define eof-object (call-with-input-file "/dev/null" read-char))
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