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Modify the src-pos error reporting in parser-tools to better show the token context.

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Addresses PR 9924.
This commit is contained in:
Danny Yoo 2013-02-26 12:56:34 -07:00
parent bc479b41c5
commit 9b86d4452f
1 changed files with 14 additions and 2 deletions
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16
collects/parser-tools/yacc.rkt
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@ -228,17 +228,29 @@
"(or/c symbol? token?)"
0
tok))))
;; well-formed-position-token?: any -> boolean
;; Returns true if pt is a position token whose position-token-token
;; is itself a token or a symbol.
;; This is meant to help raise more precise error messages when
;; a tokenizer produces an erroneous position-token wrapped twice.
;; (as often happens when omitting return-without-pos).
(define (well-formed-position-token? pt)
(and (position-token? pt)
(let ([t (position-token-token pt)])
(or (symbol? t)
(token? t)))))
;; extract-src-pos : position-token -> symbol any any any
(define (extract-src-pos ip)
(cond
((position-token? ip)
((well-formed-position-token? ip)
(extract-helper (position-token-token ip)
(position-token-start-pos ip)
(position-token-end-pos ip)))
(else
(raise-argument-error 'parser
"position-token?"
"well-formed-position-token?"
0
ip))))