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From: segal@morgan.com (Morris M. Siegel)
Date: Mon, 22 Jul 1996 15:26:46 -0400
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In-Reply-To: "Bart Schaefer" <schaefer@candle.brasslantern.com>
        "Re: Bug in case stmt with '('" (Jul 21, 11:31pm)
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	<9607211853.ZM979@morgan.com> 
	<960721233102.ZM22696@candle.brasslantern.com>
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To: schaefer@nbn.com, Zoltan Hidvegi <hzoli@cs.elte.hu>,
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Subject: Re: Bug in case stmt with '('
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> So your suggestion would amount to omitting the check for balanced
> parens, thus assuming (in the event that a closing paren is not found)
> that the glob pattern is correctly formed.  This doesn't simplify the
> parser in any significant way, and it delays detection of some other
> malformed glob patterns.

I'm ready to believe that my suggestion doesn't simplify the parser
significantly, but I'm _not_ suggesting to forego checking for balanced parens
-- on the contrary, I assume the parser would only accept well-formed glob
patterns.

	     | required paren
	     v
	"( x ) )"
	       ^
	       | optional paren
	       v
	 " x   )"

What I am suggesting is that the trailing ')' (which if present is UNbalanced)
not be required to be present.  I.e., each well-formed case-prefix pattern
(which may have internal parens or '|'s) is terminated by an [external]
'|', ')', or whitespace; if by whitespace, then the parser considers the
following token: if it is '|' or ')', then parsing of the case-prefix continues,
else the case-prefix is considered complete (the parser regards the whitespace
as equivalent to a trailing ')', if you will), and the token is taken to be
the initial token of the case-clause body.  Accordingly, I believe that
detection of malformed glob patterns would not at all be delayed.
Perhaps my approach might even make it easier to avoid the remaining problem
with Zoltan's current patch.