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64 lines
2.9 KiB
Racket
64 lines
2.9 KiB
Racket
#lang racket/base
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(require "syntax-flatten.rkt" racket/list)
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(provide all-...-follow-wildcards generate-literals generate-bound-and-unbound-literals)
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(define (literal-identifier? pat-datum)
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(and (symbol? pat-datum)
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(not (memq pat-datum '(... _))) ; isn't a reserved identifier
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(let ([pat-str (symbol->string pat-datum)])
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(or (not (regexp-match #rx"[A-Z]" pat-str)) ; either doesn't contain at least one uppercase letter ...
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(not (equal? (string-upcase pat-str) pat-str)))))) ;... or doesn't contain all uppercase letters
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(define (wildcard-identifier? pat-datum)
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(and (symbol? pat-datum)
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(not (literal-identifier? pat-datum))
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(not (memq pat-datum '(... _)))))
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;; generate literals for any symbols that are not ... or _ and not IN_CAPS
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(define (generate-literals pats)
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(for*/list ([pat-arg (in-list (syntax-flatten pats))]
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[pat-datum (in-value (syntax->datum pat-arg))]
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#:when (literal-identifier? pat-datum))
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pat-arg))
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(define (generate-bound-and-unbound-literals pats #:treat-as-bound [bound-id #f])
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(define literals (generate-literals pats))
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(define-values (bound-literals unbound-literals)
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(partition (λ (i) (or (identifier-binding i)
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(and bound-id (bound-identifier=? i bound-id)))) literals))
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;; return as list of two lists so it's easy to match them in syntax pattern
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;; `syntax-parse` crabs if there are any duplicate ids, so remove them
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(map (λ (ids) (remove-duplicates ids bound-identifier=?)) (list bound-literals unbound-literals)))
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(define (all-...-follow-wildcards pats)
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(define prev-datum (box #f))
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(and
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(for*/and ([pat-arg (in-list (syntax-flatten pats))]
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[pat-datum (in-value (syntax->datum pat-arg))])
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;; OK if there's no previous datum,
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(and
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(when (eq? pat-datum '...)
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(wildcard-identifier? (unbox prev-datum)))
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(set-box! prev-datum pat-datum)))
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#true))
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(module+ test
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(require rackunit)
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(check-equal? (map syntax->datum (generate-literals #'(foo 42 BAR _ (... ...) bar <=> 3Bar 3bar))) '(foo bar <=> 3Bar 3bar))
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(test-case "wildcard-identifier?"
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(check-true (wildcard-identifier? 'FOO))
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(check-true (wildcard-identifier? 'TOPPING))
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(check-false (wildcard-identifier? 'piZZa))
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(check-false (wildcard-identifier? 'please)))
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(test-case "all-...-follow-wildcards"
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(check-true (all-...-follow-wildcards #'()))
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(check-true (all-...-follow-wildcards (datum->syntax #f '(a b))))
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(check-true (all-...-follow-wildcards (datum->syntax #f '(a b C ...))))
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(check-false (all-...-follow-wildcards (datum->syntax #f '(...))))
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(check-false (all-...-follow-wildcards (datum->syntax #f '(a ...))))
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(check-false (all-...-follow-wildcards (datum->syntax #f '(A ... b ...))))))
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