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109 lines
2.5 KiB
Racket
109 lines
2.5 KiB
Racket
#lang racket/base
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(require parser-tools/lex
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(prefix-in : parser-tools/lex-sre)
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"parser.rkt"
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"rule-structs.rkt")
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(provide lex/1 tokenize)
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;; A newline can be any one of the following.
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(define-lex-abbrev NL (:or "\r\n" "\r" "\n"))
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;; Slightly modified from the read.rkt example in parser-tools, treating
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;; +, :, and * as reserved, non-identifier characters.
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(define-lex-abbrevs
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[letter (:or (:/ "a" "z") (:/ #\A #\Z))]
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[digit (:/ #\0 #\9)]
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[id-char (:or letter digit (char-set "-.!$%&/=?^_~@"))]
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)
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(define-lex-abbrev id
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(:& (complement (:+ digit))
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(:+ id-char)))
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(define lex/1
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(lexer-src-pos
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[(:: "'"
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(:* (:or "\\'" (:~ "'" "\\")))
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"'")
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(token-LIT lexeme)]
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[(:: "\""
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(:* (:or "\\\"" (:~ "\"" "\\")))
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"\"")
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(token-LIT lexeme)]
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["("
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(token-LPAREN lexeme)]
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["["
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(token-LBRACKET lexeme)]
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["<"
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(token-LANGLE lexeme)]
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[")"
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(token-RPAREN lexeme)]
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["]"
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(token-RBRACKET lexeme)]
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[">"
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(token-RANGLE lexeme)]
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["|"
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(token-PIPE lexeme)]
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[(:or "+" "*")
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(token-REPEAT lexeme)]
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[whitespace
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;; Skip whitespace
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(return-without-pos (lex/1 input-port))]
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;; Skip comments up to end of line
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[(:: (:or "#" ";")
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(complement (:: (:* any-char) NL (:* any-char)))
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(:or NL ""))
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;; Skip comments up to end of line.
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(return-without-pos (lex/1 input-port))]
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[(eof)
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(token-EOF lexeme)]
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[(:: id (:* whitespace) ":")
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(token-RULE_HEAD lexeme)]
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[id
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(token-ID lexeme)]
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;; We call the error handler for everything else:
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[(:: any-char)
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(let-values ([(rest-of-text end-pos-2)
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(lex-nonwhitespace input-port)])
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((current-parser-error-handler)
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#f
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'error
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(string-append lexeme rest-of-text)
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(position->pos start-pos)
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(position->pos end-pos-2)))]))
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;; This is the helper for the error production.
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(define lex-nonwhitespace
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(lexer
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[(:+ (char-complement whitespace))
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(values lexeme end-pos)]
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[any-char
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(values lexeme end-pos)]
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[(eof)
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(values "" end-pos)]))
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;; position->pos: position -> pos
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;; Coerses position structures from parser-tools/lex to our own pos structures.
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(define (position->pos a-pos)
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(pos (position-offset a-pos)
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(position-line a-pos)
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(position-col a-pos)))
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;; tokenize: input-port -> (-> token)
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(define (tokenize ip
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#:source [source (object-name ip)])
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(lambda ()
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(parameterize ([file-path source])
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(lex/1 ip))))
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