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;;; "strcase.scm" String casing functions.
; Written 1992 by Dirk Lutzebaeck (lutzeb@cs.tu-berlin.de)
;
; This code is in the public domain.
; Modified by Aubrey Jaffer Nov 1992.
; Authors of the original version were Ken Dickey and Aubrey Jaffer.
;string-upcase, string-downcase, string-capitalize
; are obvious string conversion procedures and are non destructive.
;string-upcase!, string-downcase!, string-capitalize!
; are destructive versions.
(define (string-upcase! str)
(do ((i (- (string-length str) 1) (- i 1)))
((< i 0) str)
(string-set! str i (char-upcase (string-ref str i)))))
(define (string-upcase str)
(string-upcase! (string-copy str)))
(define (string-downcase! str)
(do ((i (- (string-length str) 1) (- i 1)))
((< i 0) str)
(string-set! str i (char-downcase (string-ref str i)))))
(define (string-downcase str)
(string-downcase! (string-copy str)))
(define (string-capitalize! str) ; "hello" -> "Hello"
(let ((non-first-alpha #f) ; "hELLO" -> "Hello"
(str-len (string-length str))) ; "*hello" -> "*Hello"
(do ((i 0 (+ i 1))) ; "hello you" -> "Hello You"
((= i str-len) str)
(let ((c (string-ref str i)))
(if (char-alphabetic? c)
(if non-first-alpha
(string-set! str i (char-downcase c))
(begin
(set! non-first-alpha #t)
(string-set! str i (char-upcase c))))
(set! non-first-alpha #f))))))
(define (string-capitalize str)
(string-capitalize! (string-copy str)))
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