Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!husc6!hao!oddjob!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.lang.c
Subject: Re: whats wrong with this lex grammer? (help)
Message-ID: <8765@mimsy.UUCP>
Date: Fri, 25-Sep-87 09:07:27 EDT
Article-I.D.: mimsy.8765
Posted: Fri Sep 25 09:07:27 1987
Date-Received: Sat, 26-Sep-87 19:59:21 EDT
References: <443@aucs.UUCP>
Distribution: na
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 26

In article <443@aucs.UUCP> 820785gm@aucs.UUCP (ANDREW MACLEOD) writes:
>... For recognizing comments (ie (*...*) ) I have this horrible long
>statement that works.  However, I have a much nicer one that I don't
>understand why it doesn't work. ...  Here is  the short lex program:
> 
>"(*"([^*]|("*"/[^)]))*"*)"     printf("&%s&\n", yytext);

>(*andrew*) macleod (*was*) here
>&(*andrew*&
>) macleod &(*was*&
>) here

Your `/' (right context) causes lex to back up one character after
matching a string that contains one `*)'.  In general, right context
does not work; it should be used sparingly, if at all.

The expression

	\(\*(\*[^)]|[^*])*\*+\)

should work.  You should be aware that this stores the entire
comment in the array `yytext'---whether it fits or not.  Comments
can easily overrun lex's token buffer.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris