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syntax/parse: add attribute-prefix check to template form

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(template x.y) raises an error if x an attribute but x.y is not.
This commit is contained in:
Ryan Culpepper 2012-02-27 04:02:24 -07:00
parent 4a8f447dae
commit 2a3d6d5c31
1 changed files with 12 additions and 1 deletions
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13
collects/syntax/parse/experimental/template.rkt
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@ -327,7 +327,18 @@ integers and integer vectors.
v]
[(template-metafunction? v)
v]
[else #f])))
[else
;; id is a literal; check that for all x s.t. id = x.y, x is not a pattern variable
(for ([pfx (in-list (dotted-prefixes id))])
(when (syntax-pattern-variable? (syntax-local-value pfx (lambda () #f)))
(wrong-syntax id "undefined nested attribute of attribute `~a'" (syntax-e pfx))))
#f])))
(define (dotted-prefixes id)
(let* ([id-string (symbol->string (syntax-e id))]
[dot-locations (map car (regexp-match-positions* #rx"\\.[^.]" id-string))])
(for/list ([loc (in-list dot-locations)])
(datum->syntax id (string->symbol (substring id-string 0 loc))))))
(define (index-hash->vector hash [f values])
(let ([vec (make-vector (hash-count hash))])