br-parser-tools/collects/parser-tools/examples/read.ss

;; This implements the equivalent of mzscheme's read-syntax for R5RS scheme.
;; It has not been thoroughly tested.  Also it will read an entire file into a 
;; list of syntax objects, instead of returning one syntax object at a time

 ;; Everything in this module will be read with case sensitivity.
#cs
(module read mzscheme

  (require (lib "lex.ss" "parser-tools")
           (lib "yacc.ss" "parser-tools")
           (lib "readerr.ss" "syntax"))
  
  (define-tokens data (DATUM))
  (define-empty-tokens delim (OP CP HASHOP QUOTE QUASIQUOTE UNQUOTE UNQUOTE-SPLICING DOT EOF))

  (define scheme-lexer
    (lexer-src-pos
     
     ;; Skip comments, without accumulating extra position information
     [(: whitespace comment) (return-without-pos (scheme-lexer input-port))]

     ["#t" (token-DATUM #t)]
     ["#f" (token-DATUM #f)]
     [(@ "#\\" any) (token-DATUM (caddr (string->list lexeme)))]
     ["#\\space" (token-DATUM #\space)]
     ["#\\newline" (token-DATUM #\newline)]
     [(: (@ initial (* subsequent)) "+" "-" "...") (token-DATUM (string->symbol lexeme))]
     [#\" (token-DATUM (list->string (get-string-token input-port)))]
     [#\( 'OP]
     [#\) 'CP]
     [#\[ 'OP]
     [#\] 'CP]
     ["#(" 'HASHOP]
     [num2 (token-DATUM (string->number lexeme 2))]
     [num8 (token-DATUM (string->number lexeme 8))]
     [num10 (token-DATUM (string->number lexeme 10))]
     [num16 (token-DATUM (string->number lexeme 16))]
     ["'" 'QUOTE]
     ["`" 'QUASIQUOTE]
     ["," 'UNQUOTE]
     [",@" 'UNQUOTE-SPLICING]
     ["." 'DOT]
     [(eof) 'EOF]))
   
  (define get-string-token
    (lexer
     [(^ #\" #\\) (cons (car (string->list lexeme))
			(get-string-token input-port))]
     [(@ #\\ #\\) (cons #\\ (get-string-token input-port))]
     [(@ #\\ #\") (cons #\" (get-string-token input-port))]
     [#\" null]))
  
  
  (define-lex-abbrevs
   [any (- #\000 #\377)]
   [letter (: (- "a" "z") (- #\A #\Z))]
   [digit (- #\0 #\9)]
   [whitespace (: #\newline #\return #\tab #\space #\vtab)]
   [initial (: letter "!" "$" "%" "&" "*" "/" ":" "<" "=" ">" "?" "^" "_" "~" "@")]
   [subsequent (: initial digit "+" "-" #\. "@")]
   [comment (@ #\; (* (^ #\newline)) #\newline)]
   
;   [numR (@ prefixR complexR)]
;   [complexR (: realR
;                (@ realR "@" realR)
;                (@ realR "+" urealR "i")
;                (@ realR "-" urealR "i")
;                (@ realR "+i")
;                (@ realR "-i")
;                (@ "+" urealR "i")
;                (@ "-" urealR "i")
;                (@ "+i")
;                (@ "-i"))]
;   [realR (@ sign urealR)]
;   [urealR (: uintegerR (@ uintegerR "/" uintegerR) decimalR)]
;   [uintegerR (@ (+ digitR) (* #\#))]
;   [prefixR (: (@ radixR exactness)
;               (@ exactness radixR))]
   
   [num2 (@ prefix2 complex2)]
   [complex2 (: real2
                (@ real2 "@" real2)
                (@ real2 "+" ureal2 "i")
                (@ real2 "-" ureal2 "i")
                (@ real2 "+i")
                (@ real2 "-i")
                (@ "+" ureal2 "i")
                (@ "-" ureal2 "i")
                (@ "+i")
                (@ "-i"))]
   [real2 (@ sign ureal2)]
   [ureal2 (: uinteger2 (@ uinteger2 "/" uinteger2))]
   [uinteger2 (@ (+ digit2) (* #\#))]
   [prefix2 (: (@ radix2 exactness)
               (@ exactness radix2))]
   [radix2 "#b"]
   [digit2 (: "0" "1")]
   [num8 (@ prefix8 complex8)]
   [complex8 (: real8
                (@ real8 "@" real8)
                (@ real8 "+" ureal8 "i")
                (@ real8 "-" ureal8 "i")
                (@ real8 "+i")
                (@ real8 "-i")
                (@ "+" ureal8 "i")
                (@ "-" ureal8 "i")
                (@ "+i")
                (@ "-i"))]
   [real8 (@ sign ureal8)]
   [ureal8 (: uinteger8 (@ uinteger8 "/" uinteger8))]
   [uinteger8 (@ (+ digit8) (* #\#))]
   [prefix8 (: (@ radix8 exactness)
               (@ exactness radix8))]
   [radix8 "#o"]
   [digit8 (- "0" "7")]
   
   [num10 (@ prefix10 complex10)]
   [complex10 (: real10
                (@ real10 "@" real10)
                (@ real10 "+" ureal10 "i")
                (@ real10 "-" ureal10 "i")
                (@ real10 "+i")
                (@ real10 "-i")
                (@ "+" ureal10 "i")
                (@ "-" ureal10 "i")
                (@ "+i")
                (@ "-i"))]
   [real10 (@ sign ureal10)]
   [ureal10 (: uinteger10 (@ uinteger10 "/" uinteger10) decimal10)]
   [uinteger10 (@ (+ digit10) (* #\#))]
   [prefix10 (: (@ radix10 exactness)
               (@ exactness radix10))]
   [radix10 (: (@) "#d")]
   [digit10 digit]
   [decimal10 (: (@ uinteger10 suffix)
                 (@ #\. (+ digit10) (* #\#) suffix)
                 (@ (+ digit10) #\. (* digit10) (* #\#) suffix)
                 (@ (+ digit10) (+ #\#) #\. (* #\#) suffix))]
   
   [num16 (@ prefix16 complex16)]
   [complex16 (: real16
                (@ real16 "@" real16)
                (@ real16 "+" ureal16 "i")
                (@ real16 "-" ureal16 "i")
                (@ real16 "+i")
                (@ real16 "-i")
                (@ "+" ureal16 "i")
                (@ "-" ureal16 "i")
                "+i"
                "-i")]
   [real16 (@ sign ureal16)]
   [ureal16 (: uinteger16 (@ uinteger16 "/" uinteger16))]
   [uinteger16 (@ (+ digit16) (* #\#))]
   [prefix16 (: (@ radix16 exactness)
               (@ exactness radix16))]
   [radix16 "#x"]
   [digit16 (: digit (- #\a #\f) (- #\A #\F))]
    
   
   [suffix (: (@) (@ exponent-marker sign (+ digit10)))]
   [exponent-marker (: "e" "s" "f" "d" "l")]
   [sign (: (@) "+" "-")]
   [exactness (: (@) "#i" "#e")])

  
  (define stx-for-original-property (read-syntax #f (open-input-string "original")))
  
  ;; A macro to build the syntax object
  (define-syntax (build-so stx)
    (syntax-case stx ()
      ((_ value start end)
       (with-syntax ((start-pos (datum->syntax-object 
                                 (syntax end)
                                 (string->symbol 
                                  (format "$~a-start-pos"
                                          (syntax-object->datum (syntax start))))))
                     (end-pos (datum->syntax-object 
                               (syntax end)
                               (string->symbol 
                                (format "$~a-end-pos"
                                        (syntax-object->datum (syntax end))))))
                     (source (datum->syntax-object
                              (syntax end)
                              'source-name)))
         (syntax
          (datum->syntax-object 
           #f
           value
           (list source 
                 (position-line start-pos)
                 (position-col start-pos)
                 (position-offset start-pos)
                 (- (position-offset end-pos)
                    (position-offset start-pos)))
           stx-for-original-property))))))
  
  (define (scheme-parser source-name)
    (parser
     (src-pos)

     (start s)
     (end EOF)
     (error (lambda (a name val start end)
              (raise-read-error 
               "read-error"
               source-name
               (position-line start)
               (position-col start)
               (position-offset start)
               (- (position-offset end)
                  (position-offset start)))))
     (tokens data delim)
     
     
     (grammar
      
      (s [(sexp-list) (reverse $1)])
      
      (sexp [(DATUM) (build-so $1 1 1)]
            [(OP sexp-list CP) (build-so (reverse $2) 1 3)]
            [(HASHOP sexp-list CP) (build-so (list->vector (reverse $2)) 1 3)]
            [(QUOTE sexp) (build-so (list 'quote $2) 1 2)]
            [(QUASIQUOTE sexp) (build-so (list 'quasiquote $2) 1 2)]
            [(UNQUOTE sexp) (build-so (list 'unquote $2) 1 2)]
            [(UNQUOTE-SPLICING sexp) (build-so (list 'unquote-splicing $2) 1 2)]
            [(OP sexp-list DOT sexp CP) (build-so (append (reverse $2) $4) 1 5)])
      
      (sexp-list [() null]
                 [(sexp-list sexp) (cons $2 $1)]))))
  
  (define (rs sn ip)
    (port-count-lines! ip)
    ((scheme-parser sn) (lambda () (scheme-lexer ip))))
  
  (define readsyntax
    (case-lambda ((sn) (rs sn (current-input-port)))
                 ((sn ip) (rs sn ip))))

  (provide (rename readsyntax read-syntax))
                        
  )