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Re: Problems with bison creating a GLR parser
From: |
Paul N. Hilfinger |
Subject: |
Re: Problems with bison creating a GLR parser |
Date: |
Tue, 28 Jan 2003 02:06:39 -0800 |
OK. The problem is that support for semantic references with non-
positive indices (e.g., $-1 or $0) is currently missing in GLR mode
(that is, when a GLR parser has multiple stacks). Even when programs
do not explicitly use $0, etc., they are implicitly present in
embedded semantic actions, since, for example,
X: Y Z { f ($1); } Q
gets converted into something like
X: Y Z @1 Q
@1: { f ($-1); }
In a day or two, I will provide the necessary changes to glr.c, plus a
regression test.
Paul