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7f171dbfa0
* module/ice-9/lineio.scm: Use (ice-9 rdelim) instead of (ice-9 readline) to remove readline dependency.
115 lines
3.8 KiB
Scheme
115 lines
3.8 KiB
Scheme
;;; installed-scm-file
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;;;; Copyright (C) 1996, 1998, 2001, 2003, 2006 Free Software Foundation, Inc.
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;;;;
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;;;; This library is free software; you can redistribute it and/or
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;;;; modify it under the terms of the GNU Lesser General Public
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;;;; License as published by the Free Software Foundation; either
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;;;; version 3 of the License, or (at your option) any later version.
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;;;;
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;;;; This library is distributed in the hope that it will be useful,
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;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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;;;; Lesser General Public License for more details.
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;;;;
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;;;; You should have received a copy of the GNU Lesser General Public
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;;;; License along with this library; if not, write to the Free Software
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;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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;;;;
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(define-module (ice-9 lineio)
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:use-module (ice-9 rdelim)
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:export (unread-string read-string lineio-port?
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make-line-buffering-input-port))
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;;; {Line Buffering Input Ports}
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;;;
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;;; [This is a work-around to get past certain deficiencies in the capabilities
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;;; of ports. Eventually, ports should be fixed and this module nuked.]
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;;;
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;;; A line buffering input port supports:
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;;;
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;;; read-string which returns the next line of input
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;;; unread-string which pushes a line back onto the stream
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;;;
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;;; The implementation of unread-string is kind of limited; it doesn't
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;;; interact properly with unread-char, or any of the other port
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;;; reading functions. Only read-string will get you back the things that
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;;; unread-string accepts.
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;;;
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;;; Normally a "line" is all characters up to and including a newline.
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;;; If lines are put back using unread-string, they can be broken arbitrarily
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;;; -- that is, read-string returns strings passed to unread-string (or
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;;; shared substrings of them).
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;;;
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;; read-string port
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;; unread-string port str
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;; Read (or buffer) a line from PORT.
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;;
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;; Not all ports support these functions -- only those with
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;; 'unread-string and 'read-string properties, bound to hooks
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;; implementing these functions.
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;;
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(define (unread-string str line-buffering-input-port)
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((object-property line-buffering-input-port 'unread-string) str))
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;;
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(define (read-string line-buffering-input-port)
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((object-property line-buffering-input-port 'read-string)))
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(define (lineio-port? port)
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(not (not (object-property port 'read-string))))
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;; make-line-buffering-input-port port
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;; Return a wrapper for PORT. The wrapper handles read-string/unread-string.
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;;
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;; The port returned by this function reads newline terminated lines from PORT.
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;; It buffers these characters internally, and parsels them out via calls
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;; to read-char, read-string, and unread-string.
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;;
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(define (make-line-buffering-input-port underlying-port)
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(let* (;; buffers - a list of strings put back by unread-string or cached
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;; using read-line.
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;;
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(buffers '())
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;; getc - return the next character from a buffer or from the underlying
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;; port.
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;;
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(getc (lambda ()
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(if (not buffers)
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(read-char underlying-port)
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(let ((c (string-ref (car buffers) 0)))
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(if (= 1 (string-length (car buffers)))
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(set! buffers (cdr buffers))
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(set-car! buffers (substring (car buffers) 1)))
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c))))
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(propogate-close (lambda () (close-port underlying-port)))
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(self (make-soft-port (vector #f #f #f getc propogate-close) "r"))
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(unread-string (lambda (str)
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(and (< 0 (string-length str))
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(set! buffers (cons str buffers)))))
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(read-string (lambda ()
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(cond
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((not (null? buffers))
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(let ((answer (car buffers)))
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(set! buffers (cdr buffers))
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answer))
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(else
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(read-line underlying-port 'concat)))))) ;handle-newline->concat
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(set-object-property! self 'unread-string unread-string)
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(set-object-property! self 'read-string read-string)
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self))
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