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br-parser-tools/collects/parser-tools/private-lex/token-syntax.ss

41 lines
1.1 KiB
Scheme

#cs
(module token-syntax mzscheme
;; The things needed at compile time to handle definition of tokens
(provide make-terminals-def terminals-def-t terminals-def? define-tokens-helper)
(define-struct terminals-def (t))
(define (define-tokens-helper stx runtime empty?)
(syntax-case stx ()
((_ name (terms ...))
(andmap identifier? (syntax->list (syntax (terms ...))))
(datum->syntax-object
runtime
`(begin
(define-syntax ,(syntax name)
(make-terminals-def ',(syntax (terms ...))))
,@(map
(lambda (n)
(if (eq? (syntax-object->datum n) 'error)
(raise-syntax-error
#f
"Cannot define a token named error."
stx))
`(define (,(datum->syntax-object
n
(string->symbol
(format "token-~a" (syntax-object->datum n)))
n)
,@(if empty? '() '(x)))
(make-token ',n ,(if empty? #f 'x))))
(syntax->list (syntax (terms ...)))))
stx))
((_ ...)
(raise-syntax-error
#f
"must have the form (define-tokens name (symbol ...))"
stx))))
)