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Adds a check to the define/extend language parser

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This commit is contained in:
Casey Klein 2011-01-14 05:55:04 -06:00
parent f742479d8d
commit 61607c4da1
2 changed files with 17 additions and 1 deletions
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12
collects/redex/private/reduction-semantics.rkt
View File

@ -1743,7 +1743,17 @@
stx (or delim (car left))))
(check-each prods delim? "expected production")
(cons names prods))
(map parse-non-terminal (syntax->list nt-defs)))
(define parsed (map parse-non-terminal (syntax->list nt-defs)))
(define defs (make-hash))
(for ([p parsed])
(define ns (car p))
(for ([n ns])
(define m (hash-ref defs (syntax-e n) #f))
(if m
(raise-syntax-error #f "same non-terminal defined twice"
stx n (list m))
(hash-set! defs (syntax-e n) n))))
parsed)
(define-syntax (define-language stx)
(syntax-case stx ()

6
collects/redex/tests/tl-test.rkt
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@ -1468,6 +1468,12 @@
(define-language good-lang (a 1 2))
(define-extended-language bad-lang5 good-lang (a) (b 2)))
#rx"at least one production")
(test-syn-err (define-language bad-lang5 (x 1) (x 2)) #rx"same non-terminal" 2)
(test-syn-err (define-language bad-lang6 ((x x) 1)) #rx"same non-terminal" 2)
(test-syn-err (let ()
(define-language good-lang)
(define-extended-language bad-lang7 good-lang ((x x) 1)))
#rx"same non-terminal" 2)
(test-syn-err (redex-match grammar m_1) #rx"before underscore")
(test-syn-err (redex-match grammar (variable-except a 2 c)) #rx"expected an identifier")