ikarus/benchmarks/rnrs-benchmarks/parsing.ss

; Hacked to change error to fatal-error.
; (One of the benchmarked systems has a problem with calls to error.)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
; Parsing benchmark.
;
; Reads nboyer.sch into a string before timing begins.
;
; The timed portion of the benchmark parses the string
; representation of nboyer.sch 1000 times.
;
; The output of that parse is checked by comparing it
; the the value returned by the read procedure.
;
; Usage:
;     (parsing-benchmark n input)
;
; n defaults to 1000, and input defaults to "nboyer.sch".
;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  
(library (rnrs-benchmarks parsing)
  (export main)
  (import (rnrs) (rnrs-benchmarks))

  (define (parsing-benchmark . rest)
    (let* ((n (if (null? rest) 1000 (car rest)))
           (input (if (or (null? rest) (null? (cdr rest)))
                      "nboyer.sch"
                      (cadr rest)))
           (input-string (read-file-as-string input))
           (answer (call-with-input-file
                    input
                    (lambda (in)
                      (do ((x (read in) (read in))
                           (answer '() x))
                          ((eof-object? x)
                           answer)))))
           (benchmark-name
            (string-append "parsing:" input ":" (number->string n))))
      (run-benchmark benchmark-name
                     n
                     (lambda (x) (equal? x answer))
                     (lambda (input-string)
                       (lambda () (parse-string input-string)))
                     input-string)))
  
  (define (read-from-string-port-benchmark . rest)
    (let* ((n (if (null? rest) 1000 (car rest)))
           (input (if (or (null? rest) (null? (cdr rest)))
                      "nboyer.sch"
                      (cadr rest)))
           (input-string (read-file-as-string input))
           (answer (call-with-input-file
                    input
                    (lambda (in)
                      (do ((x (read in) (read in))
                           (answer '() x))
                          ((eof-object? x)
                           answer)))))
           (benchmark-name
            (string-append "reading:" input ":" (number->string n))))
      (run-benchmark benchmark-name
                     n
                     (lambda ()
                       (let ((in (open-input-string input-string)))
                         (do ((x (read in) (read in))
                              (y #f x))
                             ((eof-object? x) y))))
                     (lambda (x) (equal? x answer)))))
  
  (define (read-file-as-string name)
    (call-with-input-file
     name
     (lambda (in)
       (do ((x (read-char in) (read-char in))
            (chars '() (cons x chars)))
           ((eof-object? x)
            (list->string (reverse chars)))))))
  
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  ;
  ; The parser used for benchmarking.
  ;
  ; Given a string containing Scheme code, parses the entire
  ; string and returns the last <datum> read from the string.
  ;
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  
  (define (parse-string input-string)
  
    ; Constants and local variables.
  
    (let* (; Constants.
  
           ; Any character that doesn't appear within nboyer.sch
           ; (or the input file, if different) can be used to
           ; represent end-of-file.
  
           (eof #\~)
  
           ; length of longest token allowed
           ; (this allows static allocation in C)
  
           (max_token_size 1024)
  
           ; Encodings of error messages.
  
           (errLongToken 1)                 ; extremely long token
           (errincompletetoken 2)      ; any lexical error, really
           (errLexGenBug 3)                         ; can't happen
  
           ; State for one-token buffering in lexical analyzer.
  
           (kindOfNextToken 'z1)      ; valid iff nextTokenIsReady
           (nextTokenIsReady #f)
  
           (tokenValue "")  ; string associated with current token
  
           (totalErrors 0)                         ; errors so far
           (lineNumber 1)       ; rudimentary source code location
           (lineNumberOfLastError 0)                       ; ditto
  
           ; A string buffer for the characters of the current token.
  
           (string_accumulator (make-string max_token_size))
  
           ; Number of characters in string_accumulator.
  
           (string_accumulator_length 0)
  
           ; A single character of buffering.
           ; nextCharacter is valid iff nextCharacterIsReady
  
           (nextCharacter #\space)
           (nextCharacterIsReady #f)
  
           ; Index of next character to be read from input-string.
  
           (input-index 0)
  
           (input-length (string-length input-string))
          )
  
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
      ;
      ; LexGen generated the code for the state machine.
      ;
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
    
      (define (scanner0)
        (let loop ((c (scanchar)))
          (if (char-whitespace? c)
              (begin
                (consumechar)
                (set! string_accumulator_length 0)
                (loop (scanchar)))))
        (let ((c (scanchar)))
          (if (char=? c eof) (accept 'eof) (state0 c))))
    
      (define (state0 c)
        (case c
          ((#\`) (consumechar) (accept 'backquote))
          ((#\') (consumechar) (accept 'quote))
          ((#\)) (consumechar) (accept 'rparen))
          ((#\() (consumechar) (accept 'lparen))
          ((#\;) (consumechar) (state29 (scanchar)))
          ((#\+ #\-) (consumechar) (state28 (scanchar)))
          ((#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9)
           (consumechar)
           (state27 (scanchar)))
          ((#\.) (consumechar) (state16 (scanchar)))
          ((#\a
            #\b
            #\c
            #\d
            #\e
            #\f
            #\g
            #\h
            #\i
            #\j
            #\k
            #\l
            #\m
            #\n
            #\o
            #\p
            #\q
            #\r
            #\s
            #\t
            #\u
            #\v
            #\w
            #\x
            #\y
            #\z
            #\A
            #\B
            #\C
            #\D
            #\E
            #\F
            #\G
            #\H
            #\I
            #\J
            #\K
            #\L
            #\M
            #\N
            #\O
            #\P
            #\Q
            #\R
            #\S
            #\T
            #\U
            #\V
            #\W
            #\X
            #\Y
            #\Z
            #\!
            #\$
            #\%
            #\&
            #\*
            #\/
            #\:
            #\<
            #\=
            #\>
            #\?
            #\^
            #\_
            #\~)
           (consumechar)
           (state14 (scanchar)))
          ((#\#) (consumechar) (state13 (scanchar)))
          ((#\") (consumechar) (state2 (scanchar)))
          ((#\,) (consumechar) (state1 (scanchar)))
          (else
           (if (char-whitespace? c)
               (begin (consumechar) (state30 (scanchar)))
               (scannererror errincompletetoken)))))
      (define (state1 c)
        (case c
          ((#\@) (consumechar) (accept 'splicing))
          (else (accept 'comma))))
      (define (state2 c)
        (case c
          ((#\") (consumechar) (accept 'string))
          (else
           (if (isnotdoublequote? c)
               (begin (consumechar) (state2 (scanchar)))
               (scannererror errincompletetoken)))))
      (define (state3 c)
        (case c
          ((#\n) (consumechar) (state8 (scanchar)))
          (else (scannererror errincompletetoken))))
      (define (state4 c)
        (case c
          ((#\i) (consumechar) (state3 (scanchar)))
          (else (scannererror errincompletetoken))))
      (define (state5 c)
        (case c
          ((#\l) (consumechar) (state4 (scanchar)))
          (else (scannererror errincompletetoken))))
      (define (state6 c)
        (case c
          ((#\w) (consumechar) (state5 (scanchar)))
          (else (scannererror errincompletetoken))))
      (define (state7 c)
        (case c
          ((#\e) (consumechar) (state6 (scanchar)))
          (else (scannererror errincompletetoken))))
      (define (state8 c)
        (case c
          ((#\e) (consumechar) (accept 'character))
          (else (scannererror errincompletetoken))))
      (define (state9 c)
        (case c
          ((#\c) (consumechar) (state8 (scanchar)))
          (else (scannererror errincompletetoken))))
      (define (state10 c)
        (case c
          ((#\a) (consumechar) (state9 (scanchar)))
          (else (scannererror errincompletetoken))))
      (define (state11 c)
        (case c
          ((#\p) (consumechar) (state10 (scanchar)))
          (else (scannererror errincompletetoken))))
      (define (state12 c)
        (case c
          ((#\s) (consumechar) (state11 (scanchar)))
          ((#\n) (consumechar) (state7 (scanchar)))
          (else
           (if (char? c)
               (begin (consumechar) (accept 'character))
               (scannererror errincompletetoken)))))
      (define (state13 c)
        (case c
          ((#\() (consumechar) (accept 'vecstart))
          ((#\t #\f) (consumechar) (accept 'boolean))
          ((#\\) (consumechar) (state12 (scanchar)))
          (else (scannererror errincompletetoken))))
      (define (state14 c)
        (case c
          ((#\a
            #\b
            #\c
            #\d
            #\e
            #\f
            #\g
            #\h
            #\i
            #\j
            #\k
            #\l
            #\m
            #\n
            #\o
            #\p
            #\q
            #\r
            #\s
            #\t
            #\u
            #\v
            #\w
            #\x
            #\y
            #\z
            #\A
            #\B
            #\C
            #\D
            #\E
            #\F
            #\G
            #\H
            #\I
            #\J
            #\K
            #\L
            #\M
            #\N
            #\O
            #\P
            #\Q
            #\R
            #\S
            #\T
            #\U
            #\V
            #\W
            #\X
            #\Y
            #\Z
            #\!
            #\$
            #\%
            #\&
            #\*
            #\/
            #\:
            #\<
            #\=
            #\>
            #\?
            #\^
            #\_
            #\~
            #\0
            #\1
            #\2
            #\3
            #\4
            #\5
            #\6
            #\7
            #\8
            #\9
            #\+
            #\-
            #\.
            #\@)
           (consumechar)
           (state14 (scanchar)))
          (else (accept 'id))))
      (define (state15 c)
        (case c
          ((#\.) (consumechar) (accept 'id))
          (else (scannererror errincompletetoken))))
      (define (state16 c)
        (case c
          ((#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9)
           (consumechar)
           (state18 (scanchar)))
          ((#\.) (consumechar) (state15 (scanchar)))
          (else (accept 'period))))
      (define (state17 c)
        (case c
          ((#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9)
           (consumechar)
           (state18 (scanchar)))
          (else (scannererror errincompletetoken))))
      (define (state18 c)
        (case c
          ((#\e #\s #\f #\d #\l)
           (consumechar)
           (state22 (scanchar)))
          ((#\#) (consumechar) (state19 (scanchar)))
          ((#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9)
           (consumechar)
           (state18 (scanchar)))
          (else (accept 'number))))
      (define (state19 c)
        (case c
          ((#\e #\s #\f #\d #\l)
           (consumechar)
           (state22 (scanchar)))
          ((#\#) (consumechar) (state19 (scanchar)))
          (else (accept 'number))))
      (define (state20 c)
        (case c
          ((#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9)
           (consumechar)
           (state20 (scanchar)))
          (else (accept 'number))))
      (define (state21 c)
        (case c
          ((#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9)
           (consumechar)
           (state20 (scanchar)))
          (else (scannererror errincompletetoken))))
      (define (state22 c)
        (case c
          ((#\+ #\-) (consumechar) (state21 (scanchar)))
          ((#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9)
           (consumechar)
           (state20 (scanchar)))
          (else (scannererror errincompletetoken))))
      (define (state23 c)
        (case c
          ((#\#) (consumechar) (state23 (scanchar)))
          (else (accept 'number))))
      (define (state24 c)
        (case c
          ((#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9)
           (consumechar)
           (state24 (scanchar)))
          ((#\#) (consumechar) (state23 (scanchar)))
          (else (accept 'number))))
      (define (state25 c)
        (case c
          ((#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9)
           (consumechar)
           (state24 (scanchar)))
          (else (scannererror errincompletetoken))))
      (define (state26 c)
        (case c
          ((#\#) (consumechar) (state26 (scanchar)))
          ((#\/) (consumechar) (state25 (scanchar)))
          ((#\e #\s #\f #\d #\l)
           (consumechar)
           (state22 (scanchar)))
          ((#\.) (consumechar) (state19 (scanchar)))
          (else (accept 'number))))
      (define (state27 c)
        (case c
          ((#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9)
           (consumechar)
           (state27 (scanchar)))
          ((#\#) (consumechar) (state26 (scanchar)))
          ((#\/) (consumechar) (state25 (scanchar)))
          ((#\e #\s #\f #\d #\l)
           (consumechar)
           (state22 (scanchar)))
          ((#\.) (consumechar) (state18 (scanchar)))
          (else (accept 'number))))
      (define (state28 c)
        (case c
          ((#\0 #\1 #\2 #\3 #\4 #\5 #\6 #\7 #\8 #\9)
           (consumechar)
           (state27 (scanchar)))
          ((#\.) (consumechar) (state17 (scanchar)))
          (else (accept 'id))))
      (define (state29 c)
        (case c
          ((#\newline)
           (consumechar)
           (begin
             (set! string_accumulator_length 0)
             (state0 (scanchar))))
          (else
           (if (isnotnewline? c)
               (begin (consumechar) (state29 (scanchar)))
               (scannererror errincompletetoken)))))
      (define (state30 c)
        (case c
          (else
           (if (char-whitespace? c)
               (begin (consumechar) (state30 (scanchar)))
               (begin
                 (set! string_accumulator_length 0)
                 (state0 (scanchar)))))))
      (define (state31 c)
        (case c
          (else
           (begin
             (set! string_accumulator_length 0)
             (state0 (scanchar))))))
      (define (state32 c) (case c (else (accept 'id))))
      (define (state33 c)
        (case c (else (accept 'boolean))))
      (define (state34 c)
        (case c (else (accept 'character))))
      (define (state35 c)
        (case c (else (accept 'vecstart))))
      (define (state36 c)
        (case c (else (accept 'string))))
      (define (state37 c)
        (case c (else (accept 'lparen))))
      (define (state38 c)
        (case c (else (accept 'rparen))))
      (define (state39 c)
        (case c (else (accept 'quote))))
      (define (state40 c)
        (case c (else (accept 'backquote))))
      (define (state41 c)
        (case c (else (accept 'splicing))))
  
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
      ;
      ; End of state machine generated by LexGen.
      ;
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
      ;
      ; ParseGen generated the code for the strong LL(1) parser.
      ;
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
    
      (define (parse-datum)
        (case (next-token)
          ((splicing comma backquote quote lparen vecstart)
           (let ((ast1 (parse-compound-datum)))
             (identity ast1)))
          ((boolean number character string id)
           (let ((ast1 (parse-simple-datum)))
             (identity ast1)))
          (else
           (parse-error
             '<datum>
             '(backquote
                boolean
                character
                comma
                id
                lparen
                number
                quote
                splicing
                string
                vecstart)))))
      
      (define (parse-simple-datum)
        (case (next-token)
          ((id)
           (let ((ast1 (parse-symbol))) (identity ast1)))
          ((string) (begin (consume-token!) (makeString)))
          ((character) (begin (consume-token!) (makeChar)))
          ((number) (begin (consume-token!) (makeNum)))
          ((boolean) (begin (consume-token!) (makeBool)))
          (else
           (parse-error
             '<simple-datum>
             '(boolean character id number string)))))
      
      (define (parse-symbol)
        (case (next-token)
          ((id) (begin (consume-token!) (makeSym)))
          (else (parse-error '<symbol> '(id)))))
      
      (define (parse-compound-datum)
        (case (next-token)
          ((vecstart)
           (let ((ast1 (parse-vector))) (identity ast1)))
          ((lparen quote backquote comma splicing)
           (let ((ast1 (parse-list))) (identity ast1)))
          (else
           (parse-error
             '<compound-datum>
             '(backquote comma lparen quote splicing vecstart)))))
      
      (define (parse-list)
        (case (next-token)
          ((splicing comma backquote quote)
           (let ((ast1 (parse-abbreviation)))
             (identity ast1)))
          ((lparen)
           (begin
             (consume-token!)
             (let ((ast1 (parse-list2))) (identity ast1))))
          (else
           (parse-error
             '<list>
             '(backquote comma lparen quote splicing)))))
      
      (define (parse-list2)
        (case (next-token)
          ((id string
               character
               number
               boolean
               vecstart
               lparen
               quote
               backquote
               comma
               splicing)
           (let ((ast1 (parse-datum)))
             (let ((ast2 (parse-list3))) (cons ast1 ast2))))
          ((rparen) (begin (consume-token!) (emptyList)))
          (else
           (parse-error
             '<list2>
             '(backquote
                boolean
                character
                comma
                id
                lparen
                number
                quote
                rparen
                splicing
                string
                vecstart)))))
      
      (define (parse-list3)
        (case (next-token)
          ((rparen
             period
             splicing
             comma
             backquote
             quote
             lparen
             vecstart
             boolean
             number
             character
             string
             id)
           (let ((ast1 (parse-data)))
             (let ((ast2 (parse-list4)))
               (pseudoAppend ast1 ast2))))
          (else
           (parse-error
             '<list3>
             '(backquote
                boolean
                character
                comma
                id
                lparen
                number
                period
                quote
                rparen
                splicing
                string
                vecstart)))))
      
      (define (parse-list4)
        (case (next-token)
          ((period)
           (begin
             (consume-token!)
             (let ((ast1 (parse-datum)))
               (if (eq? (next-token) 'rparen)
                   (begin (consume-token!) (identity ast1))
                   (parse-error '<list4> '(rparen))))))
          ((rparen) (begin (consume-token!) (emptyList)))
          (else (parse-error '<list4> '(period rparen)))))
      
      (define (parse-abbreviation)
        (case (next-token)
          ((quote backquote comma splicing)
           (let ((ast1 (parse-abbrev-prefix)))
             (let ((ast2 (parse-datum))) (list ast1 ast2))))
          (else
           (parse-error
             '<abbreviation>
             '(backquote comma quote splicing)))))
      
      (define (parse-abbrev-prefix)
        (case (next-token)
          ((splicing)
           (begin (consume-token!) (symSplicing)))
          ((comma) (begin (consume-token!) (symUnquote)))
          ((backquote)
           (begin (consume-token!) (symBackquote)))
          ((quote) (begin (consume-token!) (symQuote)))
          (else
           (parse-error
             '<abbrev-prefix>
             '(backquote comma quote splicing)))))
      
      (define (parse-vector)
        (case (next-token)
          ((vecstart)
           (begin
             (consume-token!)
             (let ((ast1 (parse-data)))
               (if (eq? (next-token) 'rparen)
                   (begin (consume-token!) (list2vector ast1))
                   (parse-error '<vector> '(rparen))))))
          (else (parse-error '<vector> '(vecstart)))))
      
      (define (parse-data)
        (case (next-token)
          ((id string
               character
               number
               boolean
               vecstart
               lparen
               quote
               backquote
               comma
               splicing)
           (let ((ast1 (parse-datum)))
             (let ((ast2 (parse-data))) (cons ast1 ast2))))
          ((rparen period) (emptyList))
          (else
           (parse-error
             '<data>
             '(backquote
                boolean
                character
                comma
                id
                lparen
                number
                period
                quote
                rparen
                splicing
                string
                vecstart)))))
    
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
      ;
      ; End of LL(1) parser generated by ParseGen.
      ;
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
      ;
      ; Help predicates used by the lexical analyzer's state machine.
      ;
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  
      (define (isnotdoublequote? c) (not (char=? c #\")))
      (define (isnotnewline? c) (not (char=? c #\newline)))
    
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
      ;
      ; Lexical analyzer.
      ;
      ; This code is adapted from the quirk23 lexical analyzer written
      ; by Will Clinger for a compiler course.
      ;
      ; The scanner and parser were generated automatically and then
      ; printed using an R5RS Scheme pretty-printer, so they do not
      ; preserve case.  In preparation for the case-sensitivity of
      ; R6RS Scheme, several identifiers and constants have been
      ; lower-cased in the hand-written code to match the generated
      ; code.
      ;
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
    
      ; next-token and consume-token! are called by the parser.
    
      ; Returns the current token.
    
      (define (next-token)
        (if nextTokenIsReady
            kindOfNextToken
            (begin (set! string_accumulator_length 0)
                   (scanner0))))
    
      ; Consumes the current token.
    
      (define (consume-token!)
        (set! nextTokenIsReady #f))
    
      ; Called by the lexical analyzer's state machine,
      ; hence the unfortunate lower case.
    
      (define (scannererror msg)
        (define msgtxt
          (cond ((= msg errLongToken)
                 "Amazingly long token")
                ((= msg errincompletetoken)
                 "in line ")
                ((= msg errLexGenBug)
                 "Bug in lexical analyzer (generated)")
                (else "Bug in lexical analyzer")))
        (fatal-error (string-append "Lexical Error: " msgtxt) lineNumber)
        (set! nextTokenIsReady #f)
        (set! nextCharacterIsReady #f)
        (next-token))
    
      ; Accepts a token of the given kind, returning that kind.
      ;
      ; For some kinds of tokens, a value for the token must also be
      ; recorded in tokenValue.
    
      (define (accept t)
        (if (memq t '(boolean character id number string))
            (set! tokenValue
                  (substring string_accumulator 0 string_accumulator_length)))
        (set! kindOfNextToken t)
        (set! nextTokenIsReady #t)
        t)
    
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
      ;
      ; Character i/o, so to speak.
      ; Uses the input-string as input.
      ;
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
    
      ; Returns the current character from the input.
    
      (define (scanchar)
        (if nextCharacterIsReady
            nextCharacter
            (begin (if (< input-index input-length)
                       (begin (set! nextCharacter
                                    (string-ref input-string input-index))
                              (set! input-index (+ input-index 1)))
                       (set! nextCharacter eof))
                   (set! nextCharacterIsReady #t)
                   ; For debugging, change #f to #t below.
                   (if #f
                       (write-char nextCharacter))
                   (scanchar))))
    
      ; Consumes the current character, and returns the next.
    
      (define (consumechar)
        (if (not nextCharacterIsReady)
            (scanchar))
        (if (< string_accumulator_length max_token_size)
            (begin (set! nextCharacterIsReady #f)
                   (if (char=? nextCharacter #\newline)
                       (set! lineNumber (+ lineNumber 1)))
                   (string-set! string_accumulator
                                string_accumulator_length
                                nextCharacter)
                   (set! string_accumulator_length
                         (+ string_accumulator_length 1)))
            (scannererror errLongToken)))
    
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
      ;
      ; Action procedures called by the parser.
      ;
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
    
      (define (emptyList) '())
    
      (define (identity x) x)
    
      (define (list2vector vals) (list->vector vals))
    
      (define (makeBool)
        (string=? tokenValue "#t"))
    
      (define (makeChar)
        (string-ref tokenValue 0))
    
      (define (makeNum)
        (string->number tokenValue))
    
      (define (makeString)
        ; Must strip off outer double quotes.
        ; Ought to process escape characters also, but we won't.
        (substring tokenValue 1 (- (string-length tokenValue) 1)))
    
      (define (makeSym)
        (string->symbol tokenValue))
    
      ; Like append, but allows the last argument to be a non-list.
    
      (define (pseudoAppend vals terminus)
        (if (null? vals)
            terminus
            (cons (car vals)
                  (pseudoAppend (cdr vals) terminus))))
    
      (define (symBackquote) 'quasiquote)
      (define (symQuote) 'quote)
      (define (symSplicing) 'unquote-splicing)
      (define (symUnquote) 'unquote)
    
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
      ;
      ; Error procedure called by the parser.
      ; As a hack, this error procedure recovers from end-of-file.
      ;
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
    
      (define (parse-error nonterminal expected-terminals)
        (if (eq? 'eof (next-token))
            'eof
            (begin
             (display "Syntax error in line ")
             (display lineNumber)
             (display " while parsing a ")
             (write nonterminal)
             (newline)
             (display "  Encountered a ")
             (display (next-token))
             (display " while expecting something in")
             (newline)
             (display "  ")
             (write expected-terminals)
             (newline)
             (fatal-error "Syntax error"))))
    
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
      ;
      ; Parses repeatedly, returning the last <datum> parsed.
      ;
      ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
    
      (do ((x (parse-datum) (parse-datum))
           (y 'eof x))
          ((eq? x 'eof)
           y))))
  
  (define (main . args)
    (parsing-benchmark parsing-iters "parsing-data.ss")))