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27 lines
1.1 KiB
Racket
27 lines
1.1 KiB
Racket
#lang racket/base
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(provide (all-defined-out))
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(define (split-metas tree meta-key)
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(define matches null)
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(define (meta? x) ; meta has form (define-meta key value)
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(and (list? x) (>= (length x) 3) (eq? (car x) meta-key)))
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(define rest
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(let loop ([x (if (list? tree) tree (list tree))])
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(cond
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[(meta? x) (set! matches (cons x matches)) #f]
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[(list? x) (filter (λ(x) x) (map loop x))]
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[else x])))
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(values (apply hasheq (apply append (reverse (map cdr matches)))) rest))
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(module+ test
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(require rackunit)
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(let-values ([(metas rest) (split-metas '(root (div (define-meta foo "bar") "hi") "zim" (define-meta foo "boing") "zam") 'define-meta)])
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(check-equal? metas '#hasheq((foo . "boing")))
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(check-equal? rest '(root (div "hi") "zim" "zam")))
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(let-values ([(metas rest) (split-metas '(root (define-meta dog "Roxy") (define-meta dog "Lex")) 'define-meta)])
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(check-equal? metas '#hasheq((dog . "Lex"))))
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(let-values ([(metas rest) (split-metas '(root (define-meta dog "Roxy") (div (define-meta dog "Lex"))) 'define-meta)])
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(check-equal? metas '#hasheq((dog . "Lex"))))) |