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51 lines
2.0 KiB
Scheme
51 lines
2.0 KiB
Scheme
#cs
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(module token mzscheme
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(require-for-syntax "token-syntax.ss")
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;; Defining tokens
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(provide define-tokens define-empty-tokens make-token token-name token-value token?)
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(define-struct token (name value) (make-inspector))
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(define-syntaxes (define-tokens define-empty-tokens)
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(let ((define-tokens-helper
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(lambda (stx empty?)
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(syntax-case stx ()
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((_ name (terms ...))
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(andmap identifier? (syntax->list (syntax (terms ...))))
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(datum->syntax-object
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#'here
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`(begin
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(define-syntax ,(syntax name)
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,(if empty?
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`(make-e-terminals-def (quote-syntax ,(syntax (terms ...))))
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`(make-terminals-def (quote-syntax ,(syntax (terms ...))))))
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,@(map
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(lambda (n)
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(if (eq? (syntax-object->datum n) 'error)
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(raise-syntax-error
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#f
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"Cannot define a token named error."
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stx))
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`(define (,(datum->syntax-object
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n
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(string->symbol
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(format "token-~a" (syntax-object->datum n)))
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n)
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,@(if empty? '() '(x)))
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(make-token ',n ,(if empty? #f 'x))))
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(syntax->list (syntax (terms ...)))))
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stx))
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((_ ...)
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(raise-syntax-error
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#f
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"must have the form (define-tokens name (symbol ...)) or (define-empty-tokens name (symbol ...))"
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stx))))))
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(values
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(lambda (stx) (define-tokens-helper stx #f))
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(lambda (stx) (define-tokens-helper stx #t)))))
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)
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