You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
32 lines
1.6 KiB
Racket
32 lines
1.6 KiB
Racket
#lang racket/base
|
|
(require racket/match
|
|
racket/list)
|
|
(provide (all-defined-out))
|
|
|
|
(define (split-metas x [meta-key 'define-meta])
|
|
(apply hasheq
|
|
(let loop ([x ((if (syntax? x) syntax->datum values) x)])
|
|
(match x
|
|
[(list (== meta-key eq?) kvs ...)
|
|
(unless (>= (length kvs) 2)
|
|
(raise-argument-error meta-key "at least one key-value pair" kvs))
|
|
(unless (even? (length kvs))
|
|
(raise-argument-error meta-key "equal number of keys and values" kvs))
|
|
(for ([(key idx) (in-indexed kvs)]
|
|
#:when (even? idx))
|
|
(unless (symbol? key)
|
|
(raise-argument-error meta-key "valid meta key" key)))
|
|
kvs]
|
|
[(? list? xs) (append-map loop xs)]
|
|
[_ null]))))
|
|
|
|
(module+ test
|
|
(require rackunit)
|
|
(check-equal? (split-metas 'root) (hasheq))
|
|
(check-equal? (split-metas '(root)) (hasheq))
|
|
(check-exn exn:fail:contract? (λ () (split-metas '(root (define-meta 42 "bar")))))
|
|
(check-exn exn:fail:contract? (λ () (split-metas '(root (define-meta foo "bar" zim)))))
|
|
(check-equal? (split-metas '(root (div #:kw #f (define-meta foo "bar") "hi") "zim" (define-meta foo "boing") "zam")) '#hasheq((foo . "boing")))
|
|
(check-equal? (split-metas '(root (div #:kw #f (define-meta foo 'bar) "hi") "zim" (define-meta foo 'boing) "zam")) '#hasheq((foo . 'boing)))
|
|
(check-equal? (split-metas #'(root (define-meta dog "Roxy") (define-meta dog "Lex"))) '#hasheq((dog . "Lex")))
|
|
(check-equal? (split-metas #'(root (define-meta dog "Roxy") (div (define-meta dog "Lex")))) '#hasheq((dog . "Lex")))) |