You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
65 lines
3.1 KiB
Racket
65 lines
3.1 KiB
Racket
#lang br
|
|
(require brag/support)
|
|
(provide tokenize basic-lexer)
|
|
|
|
(define-lex-abbrevs
|
|
(integer (:+ numeric))
|
|
;; don't lex the leading "-": muddles "-X" and "Y-X"
|
|
(decimal (:or integer (:seq (:? integer) (:seq "." integer)))))
|
|
|
|
|
|
(define basic-lexer
|
|
(lexer-src-pos
|
|
[whitespace (token 'WHITE lexeme #:skip? #t
|
|
#:position (pos lexeme-start)
|
|
#:line (line lexeme-start)
|
|
#:column (col lexeme-start)
|
|
#:span (- (pos lexeme-end)
|
|
(pos lexeme-start)))]
|
|
[(:or (from/to "/*" "*/")
|
|
(:: decimal (:+ whitespace) (from/to (uc+lc "rem") "\n")))
|
|
(token 'COMMENT lexeme #:skip? #t
|
|
#:position (pos lexeme-start)
|
|
#:line (line lexeme-start)
|
|
#:column (col lexeme-start)
|
|
#:span (- (pos lexeme-end)
|
|
(pos lexeme-start)))]
|
|
[(:or (uc+lc "print" "for" "to" "step" "if"
|
|
"goto" "input" "let" "next"
|
|
"return" "clear" "list" "run"
|
|
"end" "then" "else" "gosub"
|
|
"and" "or" "stop" "let" "def" "dim" "on")
|
|
";" "=" "(" ")" "+" "-" "*" "/" "^"
|
|
"<=" ">=" "<>" "<" ">" "=" ":" ",") (token (string-downcase lexeme)
|
|
(string-downcase lexeme)
|
|
#:position (pos lexeme-start)
|
|
#:line (line lexeme-start)
|
|
#:column (col lexeme-start)
|
|
#:span (- (pos lexeme-end)
|
|
(pos lexeme-start)))]
|
|
[decimal (token 'NUMBER (string->number lexeme)
|
|
#:position (pos lexeme-start)
|
|
#:line (line lexeme-start)
|
|
#:column (col lexeme-start)
|
|
#:span (- (pos lexeme-end)
|
|
(pos lexeme-start)))]
|
|
[(:: alphabetic (:* (:or alphabetic numeric)) (:? "$")) (token 'ID (string->symbol lexeme)
|
|
#:position (pos lexeme-start)
|
|
#:line (line lexeme-start)
|
|
#:column (col lexeme-start)
|
|
#:span (- (pos lexeme-end)
|
|
(pos lexeme-start)))]
|
|
[(from/to "\"" "\"") (token 'STRING (trim-ends "\"" lexeme "\"")
|
|
#:position (+ (pos lexeme-start) 1)
|
|
#:line (line lexeme-start)
|
|
#:column (+ (col lexeme-start) 1)
|
|
#:span (- (pos lexeme-end)
|
|
(pos lexeme-start) 2))]))
|
|
|
|
(define (tokenize ip)
|
|
(port-count-lines! ip)
|
|
(define (next-token) (basic-lexer ip))
|
|
next-token)
|
|
|
|
(module+ main
|
|
(apply-tokenizer tokenize "\n10 rem foo\n15 print x\n20 rem\n")) |