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Date: Mon, 23 Aug 2004 21:42:00 -0000
From: Michael Chastain <mec.gnu@mindspring.com>
To: gdb@sources.redhat.com, drow@false.org
Subject: Re: GDB/MI Output Syntax ambiguity
Message-ID: <412A64E9.nailD781GRTXW@mindspring.com>
References: <20040823210314.GA15374@white>
 <20040823210924.GA22417@nevyn.them.org>
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X-SW-Source: 2004-08/txt/msg00303.txt.bz2

It's been a while since I wrote a yacc grammar, but my inclination
would be to enhance the lexer and distinguish some new terminals:

  TOKEN-UPARROW
  TOKEN-STAR
  TOKEN-PLUS
  TOKEN-EQUALS

Then the grammar goes from LALR(2) to LALR(1), because
result-record can start with TOKEN-UPARROW, which is just
one symbol, rather than token "^", which is two symbols.
That ought to make it yacc-parseable.

That keeps the token numbers in the natural place.

With drow's rule:

 output     -> [token] ( out-of-band-record-1 [token] )* [ result-record ] "(gdb)" nl

This is also LALR(1), but the token symbol is not bundled with
the wrong out-of-band-record-1, so the tree-value-constructing
code gets a little skewed.

But I'm rusty on all this.