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

49 lines
1.8 KiB
Scheme

#cs
(module token mzscheme
(require-for-syntax "token-syntax.ss")
;; Defining tokens
(provide define-tokens define-empty-tokens make-token token-name token-value token?)
(define-struct token (name value) (make-inspector))
(define-syntaxes (define-tokens define-empty-tokens)
(let ((define-tokens-helper
(lambda (stx empty?)
(syntax-case stx ()
((_ name (terms ...))
(andmap identifier? (syntax->list (syntax (terms ...))))
(datum->syntax-object
#'here
`(begin
(define-syntax ,(syntax name)
(make-terminals-def (quote-syntax ,(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 ...)) or (define-empty-tokens name (symbol ...))"
stx))))))
(values
(lambda (stx) (define-tokens-helper stx #f))
(lambda (stx) (define-tokens-helper stx #t)))))
)