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45 lines
1.8 KiB
Racket
45 lines
1.8 KiB
Racket
#lang racket/base
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(require (for-syntax racket/base br/syntax) br/define)
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(provide (except-out (all-defined-out) string->datum))
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(define (blank? str)
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(or (zero? (string-length str))
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(andmap char-blank? (string->list str))))
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;; read "foo bar" the same way as "(foo bar)"
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;; otherwise "bar" is dropped, which is too astonishing
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(define (string->datum str)
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(if (blank? str)
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(void)
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(let ([result (read (open-input-string (format "(~a)" str)))])
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(if (= (length result) 1)
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(car result)
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result))))
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(define (datum? x)
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(or (list? x) (symbol? x)))
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(define (format-datum datum-template . args)
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(string->datum (apply format (format "~a" datum-template) (map (λ(arg) (if (syntax? arg)
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(syntax->datum arg)
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arg)) args))))
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;; todo: rephrase errors from `format` or `map` in terms of `format-datums`
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(define (format-datums datum-template . argss)
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(apply map (λ args (apply format-datum datum-template args)) argss))
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(module+ test
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(require rackunit syntax/datum)
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(check-equal? (string->datum "foo") 'foo)
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(check-equal? (string->datum "(foo bar)") '(foo bar))
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(check-equal? (string->datum "foo bar") '(foo bar))
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(check-equal? (string->datum "42") 42)
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(check-equal? (format-datum '(~a-bar-~a) "foo" "zam") '(foo-bar-zam))
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(check-equal? (format-datum '(~a-bar-~a) #'foo #'zam) '(foo-bar-zam))
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(check-equal? (format-datum (datum (~a-bar-~a)) "foo" "zam") '(foo-bar-zam))
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(check-equal? (format-datum '~a "foo") 'foo)
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(check-equal? (format-datum '~a "foo") 'foo)
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(check-equal? (format-datum '~a "") (void))
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(check-equal? (format-datum '~a " ") (void))
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(check-equal? (format-datums '(put ~a) '("foo" "zam")) '((put foo) (put zam))))
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