ikarus/src/ikarus.strings.ss

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(library (ikarus strings)
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(export string-length string-ref string-set! make-string string->list string=?)
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(import
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(except (ikarus) string-length string-ref string-set! make-string
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string->list string=?)
(only (scheme)
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$fx+ $fxsub1 $fxadd1 $char= $car $cdr
$fxzero? $fx= $fx<= $fx< $fx>=
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$string-length $string-ref
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$make-string $string-set!))
(define string-length
(lambda (x)
(unless (string? x)
(error 'string-length "~s is not a string" x))
($string-length x)))
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(define (string-ref s i)
(unless (string? s)
(error 'string-ref "~s is not a string" s))
(unless (fixnum? i)
(error 'string-ref "~s is not a valid index" i))
(unless (and ($fx< i ($string-length s))
($fx<= 0 i))
(error 'string-ref "index ~s is out of range for ~s" i s))
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($string-ref s i))
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(define string-set!
(lambda (s i c)
(unless (string? s)
(error 'string-set! "~s is not a string" s))
(unless (fixnum? i)
(error 'string-set! "~s is not a valid index" i))
(unless (and ($fx< i ($string-length s))
($fx>= i 0))
(error 'string-set! "index ~s is out of range for ~s" i s))
(unless (char? c)
(error 'string-set! "~s is not a character" c))
($string-set! s i c)))
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(define make-string
(let ()
(define fill!
(lambda (s i n c)
(cond
[($fx= i n) s]
[else
($string-set! s i c)
(fill! s ($fx+ i 1) n c)])))
(define make-string
(case-lambda
[(n)
(unless (and (fixnum? n) (fx>= n 0))
(error 'make-string "~s is not a valid length" n))
($make-string n)]
[(n c)
(unless (and (fixnum? n) (fx>= n 0))
(error 'make-string "~s is not a valid length" n))
(unless (char? c)
(error 'make-string "~s is not a character" c))
(fill! ($make-string n) 0 n c)]))
make-string))
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(module (string=?)
(define bstring=?
(lambda (s1 s2 i j)
(or ($fx= i j)
(and ($char= ($string-ref s1 i) ($string-ref s2 i))
(bstring=? s1 s2 ($fxadd1 i) j)))))
(define check-strings-and-return-false
(lambda (s*)
(cond
[(null? s*) #f]
[(string? ($car s*))
(check-strings-and-return-false ($cdr s*))]
[else (err ($car s*))])))
(define strings=?
(lambda (s s* n)
(or (null? s*)
(let ([a ($car s*)])
(unless (string? a)
(error 'string=? "~s is not a string" a))
(if ($fx= n ($string-length a))
(and (strings=? s ($cdr s*) n)
(bstring=? s a 0 n))
(check-strings-and-return-false ($cdr s*)))))))
(define (err x)
(error 'string=? "~s is not a string" x))
(define string=?
(case-lambda
[(s s1)
(if (string? s)
(if (string? s1)
(let ([n ($string-length s)])
(and ($fx= n ($string-length s1))
(bstring=? s s1 0 n)))
(err s1))
(err s))]
[(s . s*)
(if (string? s)
(strings=? s s* ($string-length s))
(err s))])))
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(define string->list
(lambda (x)
(unless (string? x)
(error 'string->list "~s is not a string" x))
(let f ([x x] [i ($string-length x)] [ac '()])
(cond
[($fxzero? i) ac]
[else
(let ([i ($fxsub1 i)])
(f x i (cons ($string-ref x i) ac)))]))))
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)