43 lines
1.4 KiB
Scheme
43 lines
1.4 KiB
Scheme
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;;; Procedures that appear in code produced by (RX ...).
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;;; In sexp syntax, a ,<exp> or ,@<exp> form may evaluate to a string, char,
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;;; char-set, or regexp value. Coerce one of these to a regexp value.
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(define (coerce-dynamic-regexp x)
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(cond
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((string? x) (make-re-string x))
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((char? x) (make-re-string (string x)))
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((char-set? x) (make-re-char-set x))
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((regexp? x) x)
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(else (error "Cannot coerce value to regular expression." x))))
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;;; In a char-set context (e.g., as an operand of the SRE - operator),
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;;; a ,<exp> or form must be coercable to a char-set.
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(define (coerce-dynamic-charset x)
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(cond
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((string? x)
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(if (= 1 (string-length x)) (string->char-set x)
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(error "Multi-char string not allowed as ,<exp> or ,@<exp> SRE in char-class context."
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x)))
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((char? x) (char-set x))
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((char-set? x) x)
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((re-char-set? x) (re-char-set:cset x))
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(else (error "Cannot coerce value to character set" x))))
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(define (spec->char-set in? loose ranges)
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(let ((doit (lambda (loose ranges)
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(fold (lambda (r cset)
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(let ((from (char->ascii (car r)))
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(to (char->ascii (cdr r))))
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(do ((i from (+ i 1))
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(cs cset (char-set-adjoin! cs (ascii->char i))))
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((> i to) cs))))
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(string->char-set loose)
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ranges))))
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(if in?
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(doit loose ranges)
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(char-set-complement! (doit loose ranges)))))
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