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120 lines
3.0 KiB
Scheme
120 lines
3.0 KiB
Scheme
(module lex-sre mzscheme
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(require (lib "lex.ss" "parser-tools"))
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(provide (rename sre-* *)
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(rename sre-+ +)
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?
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(rename sre-= =)
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(rename sre->= >=)
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**
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(rename sre-or or)
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:
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seq
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&
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~
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(rename sre-- -)
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(rename sre-/ /)
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/-only-chars)
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(define-lex-trans sre-*
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(syntax-rules ()
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((_ re ...)
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(repetition 0 +inf.0 (union re ...)))))
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(define-lex-trans sre-+
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(syntax-rules ()
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((_ re ...)
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(repetition 1 +inf.0 (union re ...)))))
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(define-lex-trans ?
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(syntax-rules ()
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((_ re ...)
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(repetition 0 1 (union re ...)))))
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(define-lex-trans sre-=
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(syntax-rules ()
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((_ n re ...)
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(repetition n n (union re ...)))))
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(define-lex-trans sre->=
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(syntax-rules ()
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((_ n re ...)
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(repetition n +inf.0 (union re ...)))))
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(define-lex-trans **
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(syntax-rules ()
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((_ low #f re ...)
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(** low +inf.0 re ...))
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((_ low high re ...)
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(repetition low high (union re ...)))))
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(define-lex-trans sre-or
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(syntax-rules ()
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((_ re ...)
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(union re ...))))
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(define-lex-trans :
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(syntax-rules ()
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((_ re ...)
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(concatenation re ...))))
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(define-lex-trans seq
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(syntax-rules ()
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((_ re ...)
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(concatenation re ...))))
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(define-lex-trans &
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(syntax-rules ()
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((_ re ...)
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(intersection re ...))))
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(define-lex-trans ~
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(syntax-rules ()
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((_ re ...)
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(char-complement (union re ...)))))
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;; char-set difference
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(define-lex-trans (sre-- stx)
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(syntax-case stx ()
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((_)
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(raise-syntax-error #f
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"must have at least one argument"
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stx))
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((_ big-re re ...)
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(syntax (intersect big-re (~ (union re) ...))))))
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(define-lex-trans (sre-/ stx)
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(syntax-case stx ()
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((_ range ...)
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(let ((chars
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(apply append (map (lambda (r)
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(let ((x (syntax-e r)))
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(cond
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((char? x) (list x))
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((string? x) (string->list x))
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(else
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(raise-syntax-error
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#f
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"not a char or string"
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stx
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r)))))
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(syntax->list (syntax (range ...)))))))
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(unless (even? (length chars))
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(raise-syntax-error
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#f
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"not given an even number of characters"
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stx))
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#`(/-only-chars #,@chars)))))
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(define-lex-trans /-only-chars
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(syntax-rules ()
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((_ c1 c2)
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(char-range c1 c2))
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((_ c1 c2 c ...)
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(union (char-range c1 c2)
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(/-only-chars c ...)))))
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)
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