An unreachable error

by aaron792 :: Rate this Message:

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Hi, all!

I am writing a .jj file. The function is:

void Start():{}{

(

LOOKAHEAD(3)

// Only do someting when sequence <A><D> and <A><C><D> appear

<A>{do something} {do something} <D>{do something}

<A>{do something} <C>{do something} <D>{do something}

{do nothing}

<C>{do nothing}

<D>{do nothing}

<A>{do nothing}

}

JavaCC compiler reports an error that <A> is unreachable.

But I can't see why it is unreachable, because there are obvious other combinations of <A>, , <C> and <D> other than <A><D> and <A><C><D>.

Can anyone give some hint?

Thanks!

Aaron

aaron792

2008-06-25

发件人： Paul Cager

发送时间： 2008-06-16 22:27:00

收件人： dev@...; Stefan Hong

抄送： users@...

主题： [JavaCC] Re: [JavaCC-Dev] Wrong line/column number reported in javacc errormessage

On Mon, June 16, 2008 10:40, Stefan Hong wrote:

> Hi,

> I am using JavaCC with JJTree, it seems that the grammar errors

> reported by JavaCC frequently points to the wrong position in the

> source code. I am aware that the line/column numbers refer to the

> original *.jjt file instead of *.jj file generated by JJTree, but in

> my grammar, it is completely off (points to empty line etc). I can't

> reproduce this problem in smaller grammar file, but it happens

> regularly in grammar that I am working on, making it very hard to

> debug. A quick search through the issue database doesn't find

> anything related... am I doing anything wrong? Has anyone encountered

> similar problems?

> Thanks,

> Stefan

Hi Stefan,

Thanks for your email.

This is a known problem in JavaCC 4.0 (see issue

https://javacc.dev.java.net/issues/show_bug.cgi?id=80), and has been fixed

in release 4.1. (By default the "Issue List" does not display issues that

have been fixed in CVS).

There is a beta version of 4.1 available for download (see

https://javacc.dev.java.net/servlets/ProjectDocumentList). I'd be

interested to know if 4.1 fixes your problem.

Thanks,

Paul

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