117 lines
3.7 KiB
Scheme
117 lines
3.7 KiB
Scheme
#| -*-Scheme-*-
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Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
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1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
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2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016,
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2017, 2018, 2019, 2020 Massachusetts Institute of Technology
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This file is part of MIT/GNU Scheme.
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MIT/GNU Scheme is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or (at
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your option) any later version.
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MIT/GNU Scheme is distributed in the hope that it will be useful, but
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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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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with MIT/GNU Scheme; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301,
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USA.
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|#
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;;;; Buffer Input Ports
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(define (with-input-from-mark mark thunk #!optional receiver)
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(let ((port (make-buffer-input-port mark (group-end mark))))
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(let ((value
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(parameterize ((current-input-port port))
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(thunk))))
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(if (default-object? receiver)
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value
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(receiver value (input-port/mark port))))))
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(define (with-input-from-region region thunk)
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(parameterize ((current-input-port
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(make-buffer-input-port (region-start region)
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(region-end region))))
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(thunk)))
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(define (call-with-input-mark mark procedure)
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(procedure (make-buffer-input-port mark (group-end mark))))
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(define (call-with-input-region region procedure)
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(procedure
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(make-buffer-input-port (region-start region) (region-end region))))
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(define (make-buffer-input-port start end)
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;; This uses indices, so it can only be used locally
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;; where there is no buffer-modification happening.
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(make-port buffer-input-port-type
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(make-bstate (mark-group start)
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(mark-index start)
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(mark-index end)
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(mark-index start))))
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(define (input-port/mark port)
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(let ((operation (textual-port-operation port 'BUFFER-MARK)))
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(if (not operation)
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(error:bad-range-argument port 'INPUT-PORT/MARK))
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(operation port)))
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(define-structure bstate
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(group #f read-only #t)
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(start #f read-only #t)
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(end #f read-only #t)
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(index #f))
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(define buffer-input-port-type
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(make-port-type
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`((BUFFER-MARK
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,(lambda (port)
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(let ((state (port/state port)))
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(make-mark (bstate-group state)
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(bstate-index state)))))
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(CHAR-READY?
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,(lambda (port)
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(let ((state (port/state port)))
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(fix:< (bstate-index state)
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(bstate-end state)))))
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(PEEK-CHAR
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,(lambda (port)
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(let ((state (port/state port)))
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(let ((index (bstate-index state)))
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(if (fix:< index (bstate-end state))
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(group-right-char (bstate-group state) index)
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(eof-object))))))
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(READ-CHAR
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,(lambda (port)
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(let ((state (port/state port)))
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(let ((index (bstate-index state)))
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(if (fix:< index (bstate-end state))
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(let ((char (group-right-char (bstate-group state) index)))
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(set-bstate-index! state (fix:+ index 1))
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char)
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(eof-object))))))
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(UNREAD-CHAR
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,(lambda (port char)
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(let ((state (port/state port)))
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(let ((index (bstate-index state)))
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(if (fix:<= index (bstate-start state))
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(error "No character to unread:" port))
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(if (not (char=? (group-left-char (bstate-group state) index)
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char))
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(error "Incorrect char being unread:" char))
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(set-bstate-index! state (fix:- index 1))))))
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(WRITE-SELF
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,(lambda (port output)
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(write-string " from buffer at " output)
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(write (input-port/mark port) output))))
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#f))
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