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From: hammond@steinmetz.UUCP (Steve Hammond)
Newsgroups: net.unix
Subject: Re: Re: comments in lex
Message-ID: <190@steinmetz.UUCP>
Date: Mon, 22-Jul-85 18:24:47 EDT
Article-I.D.: steinmet.190
Posted: Mon Jul 22 18:24:47 1985
Date-Received: Fri, 26-Jul-85 02:34:02 EDT
References: <114@emacs.uucp> <193@jendeh.UUCP> <1614@orca.UUCP>
Organization: GE CRD, Schenectady, NY
Lines: 21

> >> How do you recognise a PL/1 style comment?
> >
> > "/*"([^*]|"*"[^/])*"*/"
> 
> Two problems:
> 
> 1) This pattern will incorrectly recognize "/***/ */" as a comment.
> 
> 2) This approach to comment skipping is a bad idea in lex, because the
>    generated lexer will try to accumulate the entire comment in the
>    "yytext" buffer, which has a fixed size.  (On our system, the size
>    is 1024 bytes.)  If ever a comment with more bytes than the buffer
>    size is found, the lex driver will merrily overwrite the memory
>    following the buffer and blow away your compile.
> 

I get around #1 it by switching modes when I encounter a /*
and switching back when I encounter a */.  To date I
have not overflowed the yytext buffer (I hope).
-- 
  Steve Hammond   arpa: hammond@GE   uucp: {...edison!}steinmetz!hammond