Racket 词法分析器 - return 缺点列表

Question

我是 Racket 的新手，但对此非常兴奋。我一直在为 WWW-Authenticate headers 编写一个简单的词法分析器。我对词法分析感觉很好，但现在我想更改我的输出。

#lang racket

(require parser-tools/lex)
(require (prefix-in : parser-tools/lex-sre))

(define in (open-input-string "MsRtcOAuth href=\"https://foo.com/WebTicket/oauthtoken\",grant_type=\"urn:microsoft.rtc:windows,urn:microsoft.rtc:anonmeeting,password\", Bearer trusted_issuers=\"\", client_id=\"00000004-0000-0ff1-ce00-000000000000\""))


(define key-lexer
  (lexer

   ;anything not an "="
   [(:* (char-complement #\=)) 
    ;=>
    (cons `(KEY, lexeme)
      (equals-lexer input-port))]

   ;eof
  [(eof) '()]))

(define equals-lexer
  (lexer
   [#\= 
    ;=>
     (value-lexer input-port)]

   ;eof
    [(eof) '()]))

(define value-lexer
  (lexer
   ;values are anything between two " "
   [(concatenation #\" (:* (char-complement #\")) #\")
    ;=>
    (cons `(VAL, lexeme)
          (comma-lexer input-port))]

   ;eof
   [(eof) '()]))

(define comma-lexer
  (lexer
   [(concatenation (:* whitespace) #\, (:* whitespace))
    ;=>
    (key-lexer input-port)]

   ;eof
   [(eof) '()]))

(key-lexer in)

现在，输出如下所示：

'((KEY "MsRtcOAuth href")
(VAL "\"https://foo.com/WebTicket/oauthtoken\"")
(KEY "grant_type")
(VAL "\"urn:microsoft.rtc:windows,urn:microsoft.rtc:anonmeeting,password\"")
(KEY "Bearer trusted_issuers")
(VAL "\"\"")
(KEY "client_id")
(VAL "\"00000004-0000-0ff1-ce00-000000000000\""))

我更喜欢的是成对列表，类似于：

(("MsRtcOAuth href" . "\"https://foo.com/WebTicket/oauthtoken\"")
("grant_type" . "\"urn:microsoft.rtc:windows,urn:microsoft.rtc:anonmeeting,password\"") etc...

非常感谢任何帮助或指点。谢谢！

Answer 1

这里有一种方法可以将您已有的变成您想要的：

(define (prettify key-val-pairs)
  (match key-val-pairs
    [(list (list 'KEY key) (list 'VAL val) more ...)
     (cons (list key val)
           (prettify more))]
    [_ key-val-pairs]))


(prettify
'((KEY "MsRtcOAuth href")
  (VAL "\"https://foo.com/WebTicket/oauthtoken\"")
  (KEY "grant_type")
  (VAL "\"urn:microsoft.rtc:windows,urn:microsoft.rtc:anonmeeting,password\"")
  (KEY "Bearer trusted_issuers")
  (VAL "\"\"")
  (KEY "client_id")
  (VAL "\"00000004-0000-0ff1-ce00-000000000000\"")))

输出：

'(("MsRtcOAuth href" "\"https://foo.com/WebTicket/oauthtoken\"")
  ("grant_type" "\"urn:microsoft.rtc:windows,urn:microsoft.rtc:anonmeeting,password\"")
  ("Bearer trusted_issuers" "\"\"")
  ("client_id" "\"00000004-0000-0ff1-ce00-000000000000\""))

Racket 词法分析器 - return 缺点列表

Racket lexer - return list of cons

parsing

racket