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brag/parser-tools/lex-plt-v200.rkt

24 lines
558 B
Racket

#lang racket/base
(require (for-syntax racket/base)
yaragg/parser-tools/lex
(prefix-in : yaragg/parser-tools/lex-sre))
(provide epsilon ~
(rename-out [:* *]
[:+ +]
[:? ?]
[:or :]
[:& &]
[:: @]
[:~ ^]
[:/ -]))
(define-lex-trans (epsilon stx)
(syntax-case stx ()
[(_) #'""]))
(define-lex-trans (~ stx)
(syntax-case stx ()
[(_ RE) #'(complement RE)]))