ikarus/scheme/ikarus.reader.ss

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;;; Ikarus Scheme -- A compiler for R6RS Scheme.
;;; Copyright (C) 2006,2007 Abdulaziz Ghuloum
;;;
;;; This program is free software: you can redistribute it and/or modify
;;; it under the terms of the GNU General Public License version 3 as
;;; published by the Free Software Foundation.
;;;
;;; This program is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;; General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with this program. If not, see <http://www.gnu.org/licenses/>.
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(library (ikarus reader)
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(export read read-initial read-token comment-handler get-datum)
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(import
(ikarus system $chars)
(ikarus system $fx)
(ikarus system $pairs)
(ikarus system $bytevectors)
(only (ikarus unicode-data) unicode-printable-char?)
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(except (ikarus) read read-token comment-handler get-datum))
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(define delimiter?
(lambda (c)
(or (char-whitespace? c)
(memq c '(#\( #\) #\[ #\] #\" #\# #\;)))))
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(define digit?
(lambda (c)
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(and ($char<= #\0 c) ($char<= c #\9))))
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(define char->num
(lambda (c)
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(fx- ($char->fixnum c) ($char->fixnum #\0))))
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(define initial?
(lambda (c)
(cond
[($char<= c ($fixnum->char 127))
(or (letter? c) (special-initial? c))]
[else (unicode-printable-char? c)])))
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(define letter?
(lambda (c)
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(or (and ($char<= #\a c) ($char<= c #\z))
(and ($char<= #\A c) ($char<= c #\Z)))))
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(define af?
(lambda (c)
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(or (and ($char<= #\a c) ($char<= c #\f))
(and ($char<= #\A c) ($char<= c #\F)))))
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(define af->num
(lambda (c)
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(if (and ($char<= #\a c) ($char<= c #\f))
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(fx+ 10 (fx- ($char->fixnum c) ($char->fixnum #\a)))
(fx+ 10 (fx- ($char->fixnum c) ($char->fixnum #\A))))))
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(define special-initial?
(lambda (c)
(memq c '(#\! #\$ #\% #\& #\* #\/ #\: #\< #\= #\> #\? #\^ #\_ #\~))))
(define subsequent?
(lambda (c)
(or (initial? c) (digit? c) (special-subsequent? c))))
(define special-subsequent?
(lambda (c)
(memq c '(#\+ #\- #\. #\@))))
(define tokenize-identifier
(lambda (ls p)
(let ([c (read-char p)])
(cond
[(eof-object? c) ls]
[(subsequent? c)
(tokenize-identifier (cons c ls) p)]
[(delimiter? c)
(unread-char c p)
ls]
[(char=? c #\\) (tokenize-backslash ls p)]
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[else
(unread-char c p)
(error 'tokenize "invalid identifier syntax"
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(list->string (reverse (cons c ls))))]))))
(define tokenize-string
(lambda (ls p)
(let ([c (read-char p)])
(cond
[(eof-object? c)
(error 'tokenize "end-of-file while inside a string")]
[($char= #\" c) ls]
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[($char= #\\ c)
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(let ([c (read-char p)])
(cond
[($char= #\a c) (tokenize-string (cons #\x7 ls) p)]
[($char= #\b c) (tokenize-string (cons #\x8 ls) p)]
[($char= #\t c) (tokenize-string (cons #\x9 ls) p)]
[($char= #\n c) (tokenize-string (cons #\xA ls) p)]
[($char= #\v c) (tokenize-string (cons #\xB ls) p)]
[($char= #\f c) (tokenize-string (cons #\xC ls) p)]
[($char= #\r c) (tokenize-string (cons #\xD ls) p)]
[($char= #\" c) (tokenize-string (cons #\x22 ls) p)]
[($char= #\\ c) (tokenize-string (cons #\x5C ls) p)]
[($char= #\x c) ;;; unicode escape \xXXX;
(let ([c (read-char p)])
(cond
[(eof-object? c)
(error 'tokenize "invalid eof inside string")]
[(hex c) =>
(lambda (n)
(let f ([n n])
(let ([c (read-char p)])
(cond
[(eof-object? n)
(error 'tokenize "invalid eof inside string")]
[(hex c) =>
(lambda (v) (f (+ (* n 16) v)))]
[($char= c #\;)
(tokenize-string
(cons (integer->char n) ls) p)]
[else
(error 'tokenize
"invalid char in escape sequence"
c)]))))]
[else
(error 'tokenize
"invalid char in escape sequence" c)]))]
;;; FIXME: handle whitespace
[else (error 'tokenize "invalid string escape" c)]))]
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[else
(tokenize-string (cons c ls) p)]))))
(define skip-comment
(lambda (p)
(let ([c (read-char p)])
(unless (eof-object? c)
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(let ([i ($char->fixnum c)])
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(unless (or (fx= i 10) (fx= i 13))
(skip-comment p)))))))
(define tokenize-dot
(lambda (p)
(let ([c (peek-char p)])
(cond
[(eof-object? c) 'dot]
[(delimiter? c) 'dot]
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[($char= c #\.) ; this is second dot
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(read-char p)
(let ([c (read-char p)])
(cond
[(eof-object? c)
(error 'tokenize "invalid syntax .. near end of file")]
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[($char= c #\.) ; this is the third
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(let ([c (peek-char p)])
(cond
[(eof-object? c) '(datum . ...)]
[(delimiter? c) '(datum . ...)]
[else
(error 'tokenize "invalid syntax"
(string-append "..." (string c)))]))]
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[else
(unread-char c p)
(error 'tokenize "invalid syntax"
(string-append ".." (string c)))]))]
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[else
(cons 'datum
(tokenize-decimal-no-digits p '(#\.) #f))]))))
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(define tokenize-char*
(lambda (i str p d)
(cond
[(fx= i (string-length str))
(let ([c (peek-char p)])
(cond
[(eof-object? c) d]
[(delimiter? c) d]
[else (error 'tokenize "invalid character after sequence"
(string-append (string c) str))]))]
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[else
(let ([c (read-char p)])
(cond
[(eof-object? c)
(error 'tokenize "invalid eof in the middle of expected sequence" str)]
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[($char= c (string-ref str i))
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(tokenize-char* (fxadd1 i) str p d)]
[else
(error 'tokenize
"invalid char while scanning string"
c str)]))])))
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(define tokenize-char-seq
(lambda (p str d)
(let ([c (peek-char p)])
(cond
[(eof-object? c) (cons 'datum (string-ref str 0))]
[(delimiter? c) (cons 'datum (string-ref str 0))]
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[($char= (string-ref str 1) c)
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(read-char p)
(tokenize-char* 2 str p d)]
[else (error 'tokenize "invalid syntax"
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(string-ref str 0) c)]))))
(define tokenize-char
(lambda (p)
(let ([c (read-char p)])
(cond
[(eof-object? c)
(error 'tokenize "invalid #\\ near end of file")]
[(eqv? #\n c)
(let ([c (peek-char p)])
(cond
[(eof-object? c)
(read-char p)
'(datum . #\n)]
[(eqv? #\u c)
(read-char p)
(tokenize-char-seq p "ul" '(datum . #\x0))]
[(eqv? #\e c)
(read-char p)
(tokenize-char-seq p "ewline" '(datum . #\xA))]
[(delimiter? c)
'(datum . #\n)]
[else
(error 'tokenize "invalid syntax"
(string #\# #\\ #\n c))]))]
[(eqv? #\a c)
(tokenize-char-seq p "alarm" '(datum . #\x7))]
[(eqv? #\b c)
(tokenize-char-seq p "backspace" '(datum . #\x8))]
[(eqv? #\t c)
(tokenize-char-seq p "tab" '(datum . #\x9))]
[(eqv? #\l c)
(tokenize-char-seq p "linefeed" '(datum . #\xA))]
[(eqv? #\v c)
(tokenize-char-seq p "vtab" '(datum . #\xB))]
[(eqv? #\p c)
(tokenize-char-seq p "page" '(datum . #\xC))]
[(eqv? #\r c)
(tokenize-char-seq p "return" '(datum . #\xD))]
[(eqv? #\e c)
(tokenize-char-seq p "esc" '(datum . #\x1B))]
[(eqv? #\s c)
(tokenize-char-seq p "space" '(datum . #\x20))]
[(eqv? #\d c)
(tokenize-char-seq p "delete" '(datum . #\x7F))]
[(eqv? #\x c)
(let ([n (peek-char p)])
(cond
[(or (eof-object? n) (delimiter? n))
'(datum . #\x)]
[(hex n) =>
(lambda (v)
(read-char p)
(let f ([v v])
(let ([c (read-char p)])
(cond
[(eof-object? c)
(cons 'datum (integer->char v))]
[(delimiter? c)
(unread-char c p)
(cons 'datum (integer->char v))]
[(hex c) =>
(lambda (v0)
(f (+ (* v 16) v0)))]
[else
(error 'tokenize "invalid character sequence")]))))]
[else
(error 'tokenize "invalid character sequence"
(string-append "#\\" (string n)))]))]
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[else
(let ([n (peek-char p)])
(cond
[(eof-object? n) (cons 'datum c)]
[(delimiter? n) (cons 'datum c)]
[else
(error 'tokenize "invalid syntax"
(string-append "#\\" (string c n)))]))]))))
(define (hex x)
(cond
[(and ($char<= #\0 x) ($char<= x #\9))
($fx- ($char->fixnum x) ($char->fixnum #\0))]
[(and ($char<= #\a x) ($char<= x #\z))
($fx- ($char->fixnum x)
($fx- ($char->fixnum #\a) 10))]
[(and ($char<= #\A x) ($char<= x #\Z))
($fx- ($char->fixnum x)
($fx- ($char->fixnum #\A) 10))]
[else #f]))
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(define multiline-error
(lambda ()
(error 'tokenize
"end of file encountered while inside a #|-style comment")))
(define apprev
(lambda (str i ac)
(cond
[(fx= i (string-length str)) ac]
[else
(apprev str (fx+ i 1) (cons (string-ref str i) ac))])))
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(define multiline-comment
(lambda (p)
(define f
(lambda (p ac)
(let ([c (read-char p)])
(cond
[(eof-object? c) (multiline-error)]
[($char= #\| c)
(let ([c (read-char p)])
(cond
[(eof-object? c) (multiline-error)]
[($char= #\# c) ac]
[else (f p (cons c ac))]))]
[($char= #\# c)
(let ([c (read-char p)])
(cond
[(eof-object? c) (multiline-error)]
[($char= #\| c)
(let ([v (multiline-comment p)])
(if (string? v)
(f p (apprev v 0 ac))
(f p ac)))]
[else
(f p (cons c (cons #\# ac)))]))]
[else (f p (cons c ac))]))))
(let ([ac (f p '())])
((comment-handler)
(list->string (reverse ac))))))
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(define tokenize-hash
(lambda (p)
(tokenize-hash/c (read-char p) p)))
(define (skip-whitespace p caller)
(let ([c (read-char p)])
(cond
[(eof-object? c)
(error 'tokenize "invalid eof inside" caller)]
[(char-whitespace? c)
(skip-whitespace p caller)]
[else c])))
(define tokenize-hash/c
(lambda (c p)
(cond
[(eof-object? c) (error 'tokenize "invalid # near end of file")]
[(memq c '(#\t #\T))
(let ([c (peek-char p)])
(cond
[(eof-object? c) '(datum . #t)]
[(delimiter? c) '(datum . #t)]
[else (error 'tokenize
(format "invalid syntax near #~a" c))]))]
[(memq c '(#\f #\F))
(let ([c (peek-char p)])
(cond
[(eof-object? c) '(datum . #f)]
[(delimiter? c) '(datum . #f)]
[else (error 'tokenize
(format "invalid syntax near #~a" c))]))]
[($char= #\\ c) (tokenize-char p)]
[($char= #\( c) 'vparen]
[($char= #\' c) '(macro . syntax)]
[($char= #\` c) '(macro . quasisyntax)]
[($char= #\, c)
(let ([c (peek-char p)])
(cond
[(eqv? c #\@) (read-char p)
'(macro . unsyntax-splicing)]
[else '(macro . unsyntax)]))]
[($char= #\; c) 'hash-semi]
[($char= #\% c) '(macro . |#primitive|)]
[($char= #\| c) (multiline-comment p) (tokenize p)]
[($char= #\! c)
(let ([e (read-char p)])
(when (eof-object? e)
(error 'tokenize "invalid eof near #!"))
(case e
[(#\e)
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(when (eq? (port-mode p) 'r6rs-mode)
(error 'tokenize "invalid syntax: #!e"))
(read-char* p '(#\e) "of" "eof sequence" #f #f)
(cons 'datum (eof-object))]
[(#\r)
(read-char* p '(#\r) "6rs" "#!r6rs comment" #f #f)
(set-port-mode! p 'r6rs-mode)
(tokenize p)]
[(#\i)
(read-char* p '(#\i) "karus" "#!ikarus comment" #f #f)
(set-port-mode! p 'ikarus-mode)
(tokenize p)]
[else
(error 'tokenize
(format "invalid syntax near #!~a" e))]))]
[(digit? c)
(when (eq? (port-mode p) 'r6rs-mode)
(error 'tokenize "graph syntax is invalid in #!r6rs mode"
(format "#~a" c)))
(tokenize-hashnum p (char->num c))]
[($char= #\: c)
(when (eq? (port-mode p) 'r6rs-mode)
(error 'tokenize "gensym syntax is invalid in #!r6rs mode"
(format "#~a" c)))
(let* ([c (skip-whitespace p "gensym")]
[id0
(cond
[(initial? c)
(list->string
(reverse (tokenize-identifier (cons c '()) p)))]
[($char= #\| c)
(list->string
(reverse (tokenize-bar p '())))]
[else
(error 'tokenize
"invalid char inside gensym" c)])])
(cons 'datum (gensym id0)))]
[($char= #\{ c)
(when (eq? (port-mode p) 'r6rs-mode)
(error 'tokenize "gensym syntax is invalid in #!r6rs mode"
(format "#~a" c)))
(let* ([c (skip-whitespace p "gensym")]
[id0
(cond
[(initial? c)
(list->string
(reverse (tokenize-identifier (cons c '()) p)))]
[($char= #\| c)
(list->string
(reverse (tokenize-bar p '())))]
[else
(error 'tokenize
"invalid char inside gensym" c)])]
[c (skip-whitespace p "gensym")])
(cond
[($char= #\} c)
;(cons 'datum (gensym id0))]
(cons 'datum
(foreign-call "ikrt_strings_to_gensym" #f id0))]
[else
(let ([id1
(cond
[(initial? c)
(list->string
(reverse
(tokenize-identifier
(cons c '()) p)))]
[($char= #\| c)
(list->string
(reverse (tokenize-bar p '())))]
[else
(error 'tokenize
"invalid char inside gensym" c)])])
(let ([c (skip-whitespace p "gensym")])
(cond
[($char= #\} c)
(cons 'datum
(foreign-call "ikrt_strings_to_gensym"
id0 id1))]
[else
(error 'tokenize
"invalid char inside gensym" c)])))]))]
[($char= #\v c)
(let ([c (read-char p)])
(cond
[($char= #\u c)
(let ([c (read-char p)])
(cond
[($char= c #\8)
(let ([c (read-char p)])
(cond
[($char= c #\() 'vu8]
[(eof-object? c)
(error 'tokenize "invalid eof object after #vu8")]
[else (error 'tokenize
(format "invalid sequence #vu8~a" c))]))]
[(eof-object? c)
(error 'tokenize "invalid eof object after #vu")]
[else (error 'tokenize
(format "invalid sequence #vu~a" c))]))]
[(eof-object? c)
(error 'tokenize "invalid eof object after #v")]
[else (error 'tokenize
(format "invalid sequence #v~a" c))]))]
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[(memq c '(#\e #\E))
(cons 'datum (tokenize-exactness-mark p (list c #\#) 'e))]
[(memq c '(#\i #\I))
(cons 'datum (tokenize-exactness-mark p (list c #\#) 'i))]
[(memq c '(#\b #\B))
(cons 'datum (tokenize-radix-mark p (list c #\#) 2))]
[(memq c '(#\x #\X))
(cons 'datum (tokenize-radix-mark p (list c #\#) 16))]
[(memq c '(#\o #\O))
(cons 'datum (tokenize-radix-mark p (list c #\#) 8))]
[(memq c '(#\d #\D))
(cons 'datum (tokenize-radix-mark p (list c #\#) 10))]
[($char= #\@ c)
(when (eq? (port-mode p) 'r6rs-mode)
(error 'tokenize "fasl syntax is invalid in #!r6rs mode"
(format "#~a" c)))
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(error 'read "FIXME: fasl read disabled")
'(cons 'datum ($fasl-read p))]
[else
(unread-char c p)
(error 'tokenize
(format "invalid syntax #~a" c))])))
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(define (tokenize-exactness-mark p ls exact?)
(let ([c (read-char p)])
(cond
[(eof-object? c) (num-error "eof object" ls)]
[(radix-digit c 10) =>
(lambda (d)
(tokenize-integer p (cons c ls) exact? 10 d))]
[(char=? c #\.)
(tokenize-decimal-no-digits p (cons c ls) exact?)]
[(char=? c #\-)
(- (tokenize-integer-no-digits p (cons c ls) exact? 10))]
[(char=? c #\+)
(tokenize-integer-no-digits p (cons c ls) exact? 10)]
[(char=? c #\#)
(let ([c1 (read-char p)])
(cond
[(eof-object? c1)
(num-error "eof object" (cons c ls))]
[(memv c1 '(#\b #\B))
(tokenize-radix/exactness-marks p (cons* c1 c ls) exact? 2)]
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[(memv c1 '(#\x #\X))
(tokenize-radix/exactness-marks p (cons* c1 c ls) exact? 16)]
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[(memv c1 '(#\o #\O))
(tokenize-radix/exactness-marks p (cons* c1 c ls) exact? 8)]
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[(memv c1 '(#\d #\D))
(tokenize-radix/exactness-marks p (cons* c1 c ls) exact? 10)]
[else (num-error "invalid sequence" (cons* c1 c ls))]))]
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[else (num-error "invalid sequence" (cons c ls))])))
(define (tokenize-radix-mark p ls radix)
(let ([c (read-char p)])
(cond
[(eof-object? c) (num-error "eof object" ls)]
[(radix-digit c radix) =>
(lambda (d)
(tokenize-integer p (cons c ls) #f radix d))]
[(char=? c #\.)
(unless (= radix 10)
(num-error "invalid decimal" (cons c ls)))
(tokenize-decimal-no-digits p (cons c ls) #f)]
[(char=? c #\-)
(- (tokenize-integer-no-digits p (cons c ls) #f radix))]
[(char=? c #\+)
(tokenize-integer-no-digits p (cons c ls) #f radix)]
[(char=? c #\#)
(let ([c1 (read-char p)])
(cond
[(eof-object? c1)
(num-error "eof object" (cons c ls))]
[(memv c1 '(#\e #\E))
(tokenize-radix/exactness-marks p (cons c1 (cons c ls))
'e radix)]
[(memv c1 '(#\i #\I))
(tokenize-radix/exactness-marks p (cons c1 (cons c ls))
'i radix)]
[else (num-error "invalid sequence" (cons* c1 c ls))]))]
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[else (num-error "invalid sequence" (cons c ls))])))
(define (tokenize-radix/exactness-marks p ls exact? radix)
(let ([c (read-char p)])
(cond
[(eof-object? c) (num-error "eof object" ls)]
[(radix-digit c radix) =>
(lambda (d)
(tokenize-integer p (cons c ls) exact? radix d))]
[(char=? c #\.)
(unless (= radix 10)
(num-error "invalid decimal" (cons c ls)))
(tokenize-decimal-no-digits p (cons c ls) exact?)]
[(char=? c #\-)
(- (tokenize-integer-no-digits p (cons c ls) exact? radix))]
[(char=? c #\+)
(tokenize-integer-no-digits p (cons c ls) exact? radix)]
[else (num-error "invalid sequence" (cons c ls))])))
(define (tokenize-integer p ls exact? radix ac)
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(define (tokenize-denom-start p ls exact? radix num)
(let ([c (read-char p)])
(cond
[(eof-object? c) (num-error "eof object" ls)]
[(radix-digit c radix) =>
(lambda (d)
(tokenize-denom p (cons c ls) exact? radix num d))]
[(char=? c #\-)
(tokenize-denom-no-digits p (cons c ls) exact? radix (- num))]
[(char=? c #\+)
(tokenize-denom-no-digits p (cons c ls) exact? radix num)]
[else (num-error "invalid sequence" (cons c ls))])))
(define (tokenize-denom-no-digits p ls exact? radix num)
(let ([c (read-char p)])
(cond
[(eof-object? c) (num-error "eof object" ls)]
[(radix-digit c radix) =>
(lambda (d)
(tokenize-denom p (cons c ls) exact? radix num d))]
[else (num-error "invalid sequence" (cons c ls))])))
(define (tokenize-denom p ls exact? radix num ac)
(let ([c (read-char p)])
(cond
[(eof-object? c)
(if (= ac 0)
(num-error "zero denominator" ls)
(convert/exact exact? (/ num ac)))]
[(radix-digit c radix) =>
(lambda (d)
(tokenize-denom p (cons c ls) exact? radix num
(+ (* radix ac) d)))]
[(delimiter? c)
(unread-char c p)
(if (= ac 0)
(num-error "zero denominator" ls)
(convert/exact exact? (/ num ac)))]
[else (num-error "invalid sequence" (cons c ls))])))
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(let ([c (read-char p)])
(cond
[(eof-object? c) (convert/exact exact? ac)]
[(radix-digit c radix) =>
(lambda (d)
(tokenize-integer p (cons c ls) exact? radix
(+ (* ac radix) d)))]
[(char=? c #\.)
(unless (= radix 10)
(num-error "invalid decimal" (cons c ls)))
(tokenize-decimal p (cons c ls) exact? ac 0)]
[(char=? c #\/)
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(tokenize-denom-start p (cons #\/ ls) exact? radix ac)]
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[(memv c '(#\e #\E)) ; exponent
(unless (= radix 10)
(num-error "invalid decimal" (cons c ls)))
(let ([ex (tokenize-exponent-start p (cons c ls))])
(convert/exact (or exact? 'i)
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(* ac (expt radix ex))))]
[(delimiter? c)
(unread-char c p)
(convert/exact exact? ac)]
[else (num-error "invalid sequence" (cons c ls))])))
(define (tokenize-exponent-start p ls)
(define (tokenize-exponent-no-digits p ls)
(let ([c (read-char p)])
(cond
[(eof-object? c) (num-error "eof object" ls)]
[(radix-digit c 10) =>
(lambda (d)
(tokenize-exponent p (cons c ls) d))]
[else (num-error "invalid sequence" (cons c ls))])))
(define (tokenize-exponent p ls ac)
(let ([c (read-char p)])
(cond
[(eof-object? c) ac]
[(radix-digit c 10) =>
(lambda (d)
(tokenize-exponent p (cons c ls)
(+ (* ac 10) d)))]
[(delimiter? c)
(unread-char c p)
ac]
[else (num-error "invalid sequence" (cons c ls))])))
(let ([c (read-char p)])
(cond
[(eof-object? c) (num-error "eof object" ls)]
[(radix-digit c 10) =>
(lambda (d)
(tokenize-exponent p (cons c ls) d))]
[(char=? c #\-)
(- (tokenize-exponent-no-digits p (cons c ls)))]
[(char=? c #\+)
(tokenize-exponent-no-digits p (cons c ls))]
[else (num-error "invalid sequence" (cons c ls))])))
(define (tokenize-decimal p ls exact? ac exp)
(let ([c (read-char p)])
(cond
[(eof-object? c)
(let ([ac (* ac (expt 10 exp))])
(convert/exact (or exact? 'i) ac))]
[(radix-digit c 10) =>
(lambda (d)
(tokenize-decimal p (cons c ls) exact?
(+ (* ac 10) d) (- exp 1)))]
[(memv c '(#\e #\E))
(let ([ex (tokenize-exponent-start p (cons c ls))])
(let ([ac (* ac (expt 10 (+ exp ex)))])
(convert/exact (or exact? 'i) ac)))]
[(delimiter? c)
(unread-char c p)
(let ([ac (* ac (expt 10 exp))])
(convert/exact (or exact? 'i) ac))]
[else (num-error "invalid sequence" (cons c ls))])))
(define (tokenize-decimal-no-digits p ls exact?)
(let ([c (read-char p)])
(cond
[(eof-object? c) (num-error "eof object" ls)]
[(radix-digit c 10) =>
(lambda (d)
(tokenize-decimal p (cons c ls) exact? d -1))]
[else (num-error "invalid sequence" (cons c ls))])))
(define (convert/exact exact? n)
(if (eq? exact? 'i)
(exact->inexact n)
n))
(define (radix-digit c radix)
(case radix
[(10)
(cond
[(char<=? #\0 c #\9)
(fx- (char->integer c) (char->integer #\0))]
[else #f])]
[(16)
(cond
[(char<=? #\0 c #\9)
(fx- (char->integer c) (char->integer #\0))]
[(char<=? #\a c #\f)
(fx- (char->integer c) (fx- (char->integer #\a) 10))]
[(char<=? #\A c #\F)
(fx- (char->integer c) (fx- (char->integer #\A) 10))]
[else #f])]
[(8)
(cond
[(char<=? #\0 c #\7)
(fx- (char->integer c) (char->integer #\0))]
[else #f])]
[(2)
(case c
[(#\0) 0]
[(#\1) 1]
[else #f])]
[else (error 'radix-digit "invalid radix" radix)]))
(define (read-char* p ls str who ci? delimited?)
(let f ([i 0] [ls ls])
(cond
[(fx= i (string-length str))
(when delimited?
(let ([c (peek-char p)])
(when (and (not (eof-object? c)) (not (delimiter? c)))
(error 'tokenize
(format "invalid ~a: ~s" who
(list->string (reverse (cons c ls))))))))]
[else
(let ([c (read-char p)])
(cond
[else
(cond
[(eof-object? c)
(error 'tokenize
(format "invalid eof inside ~a" who))]
[(or (and (not ci?) (char=? c (string-ref str i)))
(and ci? (char=? (char-downcase c) (string-ref str i))))
(f (add1 i) (cons c ls))]
[else
(unread-char c p)
(error 'tokenize
(format "invalid ~a: ~s" who
(list->string (reverse (cons c ls)))))])]))])))
(define (tokenize-integer/nan/inf-no-digits p ls)
(let ([c (read-char p)])
(cond
[(eof-object? c) (num-error "invalid eof" ls)]
[(radix-digit c 10) =>
(lambda (d)
(tokenize-integer p (cons c ls) #f 10 d))]
[(char=? c #\.)
(tokenize-decimal-no-digits p (cons c ls) #f)]
[(memv c '(#\i #\I))
(read-char* p (cons #\i ls) "nf.0" "number sequence" #t #t)
+inf.0]
[(memv c '(#\n #\N))
(read-char* p (cons #\i ls) "an.0" "number sequence" #t #t)
+nan.0]
[else (num-error "invalid sequence" (cons c ls))])))
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(define (tokenize-integer-no-digits p ls exact? radix?)
(let ([c (read-char p)])
(cond
[(eof-object? c) (num-error "invalid eof" ls)]
[(radix-digit c (or radix? 10)) =>
(lambda (d)
(tokenize-integer p (cons c ls) exact? (or radix? 10) d))]
[(char=? c #\.)
(when (and radix? (not (= radix? 10)))
(num-error "invalid decimal" (cons c ls)))
(tokenize-decimal-no-digits p (cons c ls) exact?)]
[else (num-error "invalid sequence" (cons c ls))])))
(define (num-error str ls)
(error 'read "invalid numeric sequence"
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(list->string (reverse ls))))
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(define (tokenize-hashnum p n)
(let ([c (read-char p)])
(cond
[(eof-object? c)
(error 'tokenize "invalid eof inside #n mark/ref")]
[($char= #\= c) (cons 'mark n)]
[($char= #\# c) (cons 'ref n)]
[(digit? c)
(tokenize-hashnum p (fx+ (fx* n 10) (char->num c)))]
[else
(unread-char c p)
(error 'tokenize "invalid char while inside a #n mark/ref" c)])))
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(define tokenize-bar
(lambda (p ac)
(let ([c (read-char p)])
(cond
[(eof-object? c)
(error 'tokenize "unexpected eof while reading symbol")]
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[($char= #\\ c)
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(let ([c (read-char p)])
(cond
[(eof-object? c)
(error 'tokenize "unexpected eof while reading symbol")]
[else (tokenize-bar p (cons c ac))]))]
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[($char= #\| c) ac]
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[else (tokenize-bar p (cons c ac))]))))
(define (tokenize-backslash main-ac p)
(let ([c (read-char p)])
(cond
[(eof-object? c)
(error 'tokenize "invalid eof after symbol escape")]
[($char= #\x c)
(let ([c (read-char p)])
(cond
[(eof-object? c)
(error 'tokenize "invalid eof after \\x")]
[(hex c) =>
(lambda (v)
(let f ([v v] [ac `(,c #\x #\\)])
(let ([c (read-char p)])
(cond
[(eof-object? c)
(error 'tokenize
(format "invalid eof after ~a"
(list->string (reverse ac))))]
[($char= #\; c)
(tokenize-identifier (cons (integer->char v) main-ac) p)]
[(hex c) =>
(lambda (v0)
(f (+ (* v 16) v0) (cons c ac)))]
[else
(error 'tokenize "invalid sequence"
(list->string (cons c (reverse ac))))]))))]
[else
(unread-char c p)
(error 'tokenize
(format "invalid sequence \\x~a" c))]))]
[else
(unread-char c p)
(error 'tokenize
(format "invalid sequence \\~a" c))])))
(define tokenize/c
(lambda (c p)
(cond
[(eof-object? c) (eof-object)]
[(char-whitespace? c) (tokenize p)]
[($char= #\( c) 'lparen]
[($char= #\) c) 'rparen]
[($char= #\[ c) 'lbrack]
[($char= #\] c) 'rbrack]
[($char= #\' c) '(macro . quote)]
[($char= #\` c) '(macro . quasiquote)]
[($char= #\, c)
(let ([c (peek-char p)])
(cond
[(eof-object? c) '(macro . unquote)]
[($char= c #\@)
(read-char p)
'(macro . unquote-splicing)]
[else '(macro . unquote)]))]
[($char= #\# c) (tokenize-hash p)]
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[(radix-digit c 10) =>
(lambda (d)
(cons 'datum
(tokenize-integer p (list c) #f 10 d)))]
[(initial? c)
(let ([ls (reverse (tokenize-identifier (cons c '()) p))])
(cons 'datum (string->symbol (list->string ls))))]
[($char= #\" c)
(let ([ls (tokenize-string '() p)])
(cons 'datum (list->string (reverse ls))))]
[($char= #\; c)
(skip-comment p)
(tokenize p)]
[(memq c '(#\+))
(let ([c (peek-char p)])
(cond
[(eof-object? c) '(datum . +)]
[(delimiter? c) '(datum . +)]
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[else
(cons 'datum
(tokenize-integer/nan/inf-no-digits p '(#\+)))]))]
[(memq c '(#\-))
(let ([c (peek-char p)])
(cond
[(eof-object? c) '(datum . -)]
[(delimiter? c) '(datum . -)]
[($char= c #\>)
(read-char p)
(let ([ls (tokenize-identifier '() p)])
(let ([str (list->string (cons* #\- #\> (reverse ls)))])
(cons 'datum (string->symbol str))))]
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[else
(cons 'datum
(- (tokenize-integer/nan/inf-no-digits p '(#\-))))]))]
[($char= #\. c)
(tokenize-dot p)]
[($char= #\| c)
(when (eq? (port-mode p) 'r6rs-mode)
(error 'tokenize "|symbol| syntax is invalid in #!r6rs mode"))
(let ([ls (reverse (tokenize-bar p '()))])
(cons 'datum (string->symbol (list->string ls))))]
[($char= #\\ c)
(cons 'datum
(string->symbol
(list->string
(reverse (tokenize-backslash '() p)))))]
[else
(unread-char c p)
(error 'tokenize "invalid syntax" c)])))
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(define tokenize
(lambda (p)
(tokenize/c (read-char p) p)))
(define tokenize-initial
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(lambda (p)
(let ([c (read-char p)])
(cond
[(eof-object? c) c]
[($char= #\# c)
(let ([c (read-char p)])
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(cond
[(eof-object? c)
(error 'tokenize "invalid eof after #")]
[($char= #\! c)
(skip-comment p)
(tokenize p)]
[else
(tokenize-hash/c c p)]))]
[else (tokenize/c c p)]))))
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(define read-list-rest
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(lambda (p locs k end mis)
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(let ([t (tokenize p)])
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(cond
[(eof-object? t)
(error 'read "end of file encountered while reading list")]
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[(eq? t end) (values '() locs k)]
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[(eq? t mis)
(error 'read "paren mismatch")]
[(eq? t 'dot)
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(let-values ([(d locs k) (read-expr p locs k)])
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(let ([t (tokenize p)])
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(cond
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[(eq? t end) (values d locs k)]
[(eq? t mis)
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(error 'read "paren mismatch")]
[(eq? t 'dot)
(error 'read "cannot have two dots in a list")]
[else
(error 'read
(format "expecting ~a, got ~a" end t))])))]
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[(eq? t 'hash-semi)
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(let-values ([(ignored locs k) (read-expr p locs k)])
(read-list-rest p locs k end mis))]
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[else
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(let-values ([(a locs k) (parse-token p locs k t)])
(let-values ([(d locs k) (read-list-rest p locs k end mis)])
(let ([x (cons a d)])
(values x locs
(if (or (loc? a) (loc? d))
(extend-k-pair x k)
k)))))]))))
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(define read-list-init
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(lambda (p locs k end mis)
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(let ([t (tokenize p)])
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(cond
[(eof-object? t)
(error 'read "end of file encountered while reading list")]
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[(eq? t end) (values '() locs k)]
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[(eq? t mis)
(error 'read "paren mismatch")]
[(eq? t 'dot)
(error 'read "invalid dot while reading list")]
[(eq? t 'hash-semi)
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(let-values ([(ignored locs k) (read-expr p locs k)])
(read-list-init p locs k end mis))]
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[else
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(let-values ([(a locs k) (parse-token p locs k t)])
(let-values ([(d locs k) (read-list-rest p locs k end mis)])
(let ([x (cons a d)])
(values x locs
(if (or (loc? a) (loc? d))
(extend-k-pair x k)
k)))))]))))
(define extend-k-pair
(lambda (x k)
(lambda ()
(let ([a (car x)])
(when (loc? a)
(set-car! x (loc-value a))))
(let ([d (cdr x)])
(when (loc? d)
(set-cdr! x (loc-value d))))
(k))))
(define vector-put
(lambda (v k i ls)
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(cond
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[(null? ls) k]
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[else
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(let ([a (car ls)])
(vector-set! v i a)
(vector-put v
(if (loc? a)
(lambda ()
(vector-set! v i (loc-value (vector-ref v i)))
(k))
k)
(fxsub1 i) (cdr ls)))])))
(define bytevector-put
(lambda (v k i ls)
(cond
[(null? ls) k]
[else
(let ([a (car ls)])
(cond
[(fixnum? a)
(unless (and (fx<= 0 a) (fx<= a 255))
(error 'read
(format "invalid value ~s in a bytevector" a)))
($bytevector-set! v i a)
(bytevector-put v k ($fxsub1 i) ($cdr ls))]
[else (error 'read "invalid value inside a bytevector" a)]))])))
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(define read-vector
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(lambda (p locs k count ls)
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(let ([t (tokenize p)])
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(cond
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[(eof-object? t)
(error 'read "end of file encountered while reading a vector")]
[(eq? t 'rparen)
(let ([v (make-vector count)])
(let ([k (vector-put v k (fxsub1 count) ls)])
(values v locs k)))]
[(eq? t 'rbrack)
(error 'read "unexpected ] while reading a vector")]
[(eq? t 'dot)
(error 'read "unexpected . while reading a vector")]
[(eq? t 'hash-semi)
(let-values ([(ignored locs k) (read-expr p locs k)])
(read-vector p locs k count ls))]
[else
(let-values ([(a locs k) (parse-token p locs k t)])
(read-vector p locs k (fxadd1 count) (cons a ls)))]))))
(define read-bytevector
(lambda (p locs k count ls)
(let ([t (tokenize p)])
(cond
[(eof-object? t)
(error 'read "end of file encountered while reading a bytevector")]
[(eq? t 'rparen)
(let ([v ($make-bytevector count)])
(let ([k (bytevector-put v k (fxsub1 count) ls)])
(values v locs k)))]
[(eq? t 'rbrack)
(error 'read "unexpected ] while reading a bytevector")]
[(eq? t 'dot)
(error 'read "unexpected . while reading a bytevector")]
[(eq? t 'hash-semi)
(let-values ([(ignored locs k) (read-expr p locs k)])
(read-bytevector p locs k count ls))]
[else
(let-values ([(a locs k) (parse-token p locs k t)])
(read-bytevector p locs k (fxadd1 count) (cons a ls)))]))))
(define-struct loc (value set?))
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(define parse-token
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(lambda (p locs k t)
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(cond
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[(eof-object? t) (values (eof-object) locs k)]
[(eq? t 'lparen) (read-list-init p locs k 'rparen 'rbrack)]
[(eq? t 'lbrack) (read-list-init p locs k 'rbrack 'rparen)]
[(eq? t 'vparen) (read-vector p locs k 0 '())]
[(eq? t 'hash-semi)
(let-values ([(ignored locs k) (read-expr p locs k)])
(read-expr p locs k))]
[(eq? t 'vu8) (read-bytevector p locs k 0 '())]
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[(pair? t)
(cond
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[(eq? (car t) 'datum) (values (cdr t) locs k)]
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[(eq? (car t) 'macro)
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(let-values ([(expr locs k) (read-expr p locs k)])
(when (eof-object? expr)
(error 'read
(format "invalid eof after ~a read macro"
(cdr t))))
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(let ([x (list expr)])
(values (cons (cdr t) x) locs
(if (loc? expr)
(lambda ()
(set-car! x (loc-value expr))
(k))
k))))]
[(eq? (car t) 'mark)
(let ([n (cdr t)])
(let-values ([(expr locs k) (read-expr p locs k)])
(cond
[(assq n locs) =>
(lambda (x)
(let ([loc (cdr x)])
(when (loc-set? loc)
(error 'read "duplicate mark" n))
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(set-loc-value! loc expr)
(set-loc-set?! loc #t)
(values expr locs k)))]
[else
(let ([loc (make-loc expr #t)])
(let ([locs (cons (cons n loc) locs)])
(values expr locs k)))])))]
[(eq? (car t) 'ref)
(let ([n (cdr t)])
(cond
[(assq n locs) =>
(lambda (x)
(values (cdr x) locs k))]
[else
(let ([loc (make-loc #f #f)])
(let ([locs (cons (cons n loc) locs)])
(values loc locs k)))]))]
[else (error 'read "invalid token" t)])]
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[else
(error 'read
(format "unexpected ~s found" t))])))
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(define read-expr
(lambda (p locs k)
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(parse-token p locs k (tokenize p))))
(define read-expr-initial
(lambda (p locs k)
(parse-token p locs k (tokenize-initial p))))
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(define reduce-loc!
(lambda (x)
(let ([loc (cdr x)])
(unless (loc-set? loc)
(error 'read "referenced mark is not set" (car x)))
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(when (loc? (loc-value loc))
(let f ([h loc] [t loc])
(if (loc? h)
(let ([h1 (loc-value h)])
(if (loc? h1)
(begin
(when (eq? h1 t)
(error 'read "circular marks"))
(let ([v (f (loc-value h1) (loc-value t))])
(set-loc-value! h1 v)
(set-loc-value! h v)
v))
(begin
(set-loc-value! h h1)
h1)))
h))))))
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(define my-read
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(lambda (p)
(let-values ([(expr locs k) (read-expr p '() void)])
(cond
[(null? locs) expr]
[else
(for-each reduce-loc! locs)
(k)
(if (loc? expr)
(loc-value expr)
expr)]))))
(define read-initial
(lambda (p)
(let-values ([(expr locs k) (read-expr-initial p '() void)])
(cond
[(null? locs) expr]
[else
(for-each reduce-loc! locs)
(k)
(if (loc? expr)
(loc-value expr)
expr)]))))
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(define read-token
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(case-lambda
[() (tokenize (current-input-port))]
[(p)
(if (input-port? p)
(tokenize p)
(error 'read-token "not an input port" p))]))
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(define read
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(case-lambda
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[() (my-read (current-input-port))]
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[(p)
(if (input-port? p)
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(my-read p)
(error 'read "not an input port" p))]))
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(define (get-datum p)
(unless (input-port? p)
(error 'get-datum "not an input port"))
(my-read p))
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(define comment-handler
(make-parameter
(lambda (x) (void))
(lambda (x)
(unless (procedure? x)
(error 'comment-handler "not a procedure" x))
x)))
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)