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[honu] use regular expressions to lex comments

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This commit is contained in:
Jon Rafkind 2011-07-29 10:02:11 -06:00
parent cd62f1983f
commit 7532515110
1 changed files with 26 additions and 3 deletions
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29
collects/honu/core/read.rkt
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@ -25,14 +25,28 @@
(define-lex-abbrev identifier (:: identifier-first-character
(:* identifier-character)))
(define-lex-abbrev number (:+ digit))
(define-lex-abbrev string (:: #\" (:* (:~ #\")) #\"))
(define-lex-abbrev string-character (:or (:: #\\ any-char)
(:~ #\")))
(define-lex-abbrev string (:: #\" (:* string-character) #\"))
(define-lex-abbrev block-comment (:: "/*"
(complement (:: any-string "*/" any-string))
"*/"))
(define-lex-abbrev line-comment (:: (:or "#" "//")
(:* (:~ "\n"))
;; we might hit eof before a \n
(:? "\n")))
(define honu-lexer
(lexer-src-pos
[(eof) (token-eof)]
[line-comment (token-whitespace)]
#;
[(:or "#" "//") (token-end-of-line-comment)]
["\n" (token-whitespace)]
[number (token-number (string->number lexeme))]
[block-comment (token-whitespace)]
#;
["/*" (token-block-comment)]
["." (token-identifier '|.|)]
["," (token-identifier '|,|)]
@ -44,8 +58,11 @@
[";" (token-identifier '|;|)]
;; strip the quotes from the resulting string
;; TODO: find a more optimal way
[string (token-string (substring (substring lexeme 1)
0 (- (string-length lexeme) 2)))]
[string (begin
#;
(printf "Parsed string '~a'\n" lexeme)
(token-string (substring (substring lexeme 1)
0 (- (string-length lexeme) 2))))]
["(" (token-left-parens)] [")" (token-right-parens)]
["[" (token-left-bracket)] ["]" (token-right-bracket)]
["{" (token-left-brace)] ["}" (token-right-brace)]
@ -288,6 +305,12 @@
(check-equal? (strip (lex-string "8 /* aosidfjasdf329023 */ 5"))
(list (token-number 8)
(token-number 5)))
(check-equal? (strip (lex-string "\"hello\""))
(list (token-string "hello")))
;; FIXME: how can we write a string with an escaped character in it?
#;
(check-equal? (strip (lex-string "\"hel\\\\\"lo\""))
(list (token-string "hel\"lo")))
(check-equal? (honu-read (open-input-string "f(5)"))
'(f (#%parens 5)))
(check-exn exn:fail? (lambda ()