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beautiful-racket/beautiful-racket-lib/br/datum.rkt

46 lines
1.8 KiB
Racket

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#lang racket/base
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(provide format-datum format-datums)
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(define (blank? str)
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(for/and ([c (in-string str)])
(char-blank? c)))
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;; read "foo bar" the same way as "(foo bar)"
;; otherwise "bar" is dropped, which is too astonishing
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(define (string->datum str)
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(unless (blank? str)
(let ([result (read (open-input-string (format "(~a)" str)))])
(if (= (length result) 1)
(car result)
result))))
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(define (datum? x) (or (list? x) (symbol? x)))
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(define (format-datum datum-template . args)
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(unless (datum? datum-template)
(raise-argument-error 'format-datums "datum?" datum-template))
(string->datum (apply format (format "~a" datum-template)
(map (λ (arg) (if (syntax? arg)
(syntax->datum arg)
arg)) args))))
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(define (format-datums datum-template . argss)
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(unless (datum? datum-template)
(raise-argument-error 'format-datums "datum?" datum-template))
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(apply map (λ args (apply format-datum datum-template args)) argss))
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(module+ test
(require rackunit syntax/datum)
(check-equal? (string->datum "foo") 'foo)
(check-equal? (string->datum "(foo bar)") '(foo bar))
(check-equal? (string->datum "foo bar") '(foo bar))
(check-equal? (string->datum "42") 42)
(check-equal? (format-datum '(~a-bar-~a) "foo" "zam") '(foo-bar-zam))
(check-equal? (format-datum '(~a-bar-~a) #'foo #'zam) '(foo-bar-zam))
(check-equal? (format-datum (datum (~a-bar-~a)) "foo" "zam") '(foo-bar-zam))
(check-equal? (format-datum '~a "foo") 'foo)
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(check-equal? (format-datum '~a "foo") 'foo)
(check-equal? (format-datum '~a "") (void))
(check-equal? (format-datum '~a " ") (void))
(check-equal? (format-datums '(put ~a) '("foo" "zam")) '((put foo) (put zam))))