#lang racket
(require parser-tools/lex)
(require parser-tools/lex-sre)



(define-empty-tokens unary-tokens (L_PAREN R_PAREN  NUM_CONVERTER SEPERATOR EOF))
(define-tokens value-tokens ( CHAR ID NUM NEWLINE))


(define-lex-abbrev digits (+ (char-set "0123456789")))
(define-lex-abbrev raw-id (: (or "_" (/ "a" "z") (/ "A" "Z")) (* (or "_" "-" "!" "?" (/ "0" "9") (/ "a" "z") (/ "A" "Z")))))
(define-lex-abbrev any-other-char (~ (char-set "0123456789@\\{}%|")))

(define uahgi2-lexer
 (lexer-src-pos
   ["\n" (token-NEWLINE lexeme)] ; newline
   [whitespace (token-CHAR lexeme)] ; whitespace
   [(: "\\"(char-set "@\\{}%|")) (token-CHAR (substring lexeme
                      1 (string-length lexeme)))]
  [(: "@" raw-id) (token-ID (string->symbol(substring lexeme
                      1 (string-length lexeme))))] ; @id 
  ["{" (token-L_PAREN)] ; {
  ["}" (token-R_PAREN)] ; }
  ["|" (token-SEPERATOR)] ; |  seperator
  ["`" (token-NUM_CONVERTER)] ; ` convert to number
   [digits (token-NUM (string->number lexeme))] ;123
   [(: (? (char-set "-")) digits "." digits) ; 123.456
    (token-NUM (string->number lexeme))]
   [ (: "%" (complement (: any-string "%" any-string)) "%") ; %COMMENT%
    (return-without-pos (uahgi2-lexer input-port))]
    [(eof) (token-EOF)]
  [any-other-char (token-CHAR lexeme)] ; any char into char
)) 




(define (looping-lex str)
    (define in (open-input-string str))
    (port-count-lines! in)
    (let loop ([v (uahgi2-lexer in)])
      (cond [(void? (position-token-token v)) (loop (uahgi2-lexer in))]
            [(eq? 'EOF (position-token-token v)) '()]
            [else (cons v (loop (uahgi2-lexer in)))])))


(provide uahgi2-lexer unary-tokens value-tokens looping-lex)