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ea13bea8ab
LAC = lookahead correction. See discussion at
<http://lists.gnu.org/archive/html/bison-patches/2009-09/msg00034.html>.
However, one point there must be corrected: because of %nonassoc,
LAC is *not* always redundant for lr.type=canonical-lr.
* data/yacc.c: Accept values of "none" (default) or "full" for
parse.lac. Accept %define parse.lac.es-capacity to specify
capacity of LAC's temporary exploratory stack. It defaults to 20
and, for now, will not grow dynamically.
(b4_lac_flag, b4_lac_if): New m4 macros. Evaluate as true for
parse.lac!=none.
(YYBACKUP): Invoke YY_LAC_DISCARD.
(YY_LAC_ESTABLISH, YY_LAC_DISCARD): New cpp macros that invoke
yy_lac and track when it needs to be invoked
(yy_lac): New function that, given the current stack, determines
whether a token can eventually be shifted. Return status mimics
yyparse return status.
(yysyntax_error): Change yystate argument to yyssp so stack top
can be passed to yy_lac. If LAC is requested, build expected
token list by invoking yy_lac for every token instead of just
checking the current state for lookaheads. Return 2 if yy_lac
exhausts memory.
(yyparse, yypush_parse): Use local variable yy_lac_established and
cpp macros YY_LAC_ESTABLISH and YY_LAC_DISCARD to implement LAC.
Update yysyntax_error invocation. Add yyexhaustedlab code if LAC
is requested.
* tests/conflicts.at (%nonassoc and eof): Extend to check the
effect of each of -Dlr.type=canonical-lr and -Dparse.lac=full.
(%error-verbose and consistent errors): Likewise.
(LAC: %nonassoc requires splitting canonical LR states): New test
group demonstrating how LAC can fix canonical LR.
* tests/input.at (LAC: Errors for %define): New test group.
* tests/regression.at (LAC: Exploratory stack): New test group.
(LAC: Memory exhaustion): New test group.
(cherry picked from commit bf35c71c58)
Conflicts:
src/parse-gram.c
src/parse-gram.h
-*- outline -*- This directory contains data needed by Bison. * Skeletons Bison skeletons: the general shapes of the different parser kinds, that are specialized for specific grammars by the bison program. Currently, the supported skeletons are: - yacc.c It used to be named bison.simple: it corresponds to C Yacc compatible LALR(1) parsers. - lalr1.cc Produces a C++ parser class. - lalr1.java Produces a Java parser class. - glr.c A Generalized LR C parser based on Bison's LALR(1) tables. - glr.cc A Generalized LR C++ parser. Actually a C++ wrapper around glr.c. These skeletons are the only ones supported by the Bison team. Because the interface between skeletons and the bison program is not finished, *we are not bound to it*. In particular, Bison is not mature enough for us to consider that ``foreign skeletons'' are supported. * m4sugar This directory contains M4sugar, sort of an extended library for M4, which is used by Bison to instantiate the skeletons. * xslt This directory contains XSLT programs that transform Bison's XML output into various formats. - bison.xsl A library of routines used by the other XSLT programs. - xml2dot.xsl Conversion into GraphViz's dot format. - xml2text.xsl Conversion into text. - xml2xhtml.xsl Conversion into XHTML. ----- Copyright (C) 2002, 2008, 2009, 2010 Free Software Foundation, Inc. This file is part of GNU Bison. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>.