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03c07b0394
Its value describes the states that are permitted to contain default rules: "all", "consistent", or "accepting". * src/reader.c (reader): Default lr.default_rules to "all". Check for a valid lr.default_rules value. * src/lalr.c (state_lookahead_tokens_count): If lr.default_rules is "accepting", then only mark the accepting state as consistent. (initialize_LA): Tell state_lookahead_tokens_count whether lr.default_rules is "accepting". * src/tables.c (action_row): If lr.default_rules is not "all", then disable default rules in inconsistent states. * src/print.c (print_reductions): Use this opportunity to perform some assertions about whether lr.default_rules was obeyed correctly. * tests/local.at (AT_TEST_TABLES_AND_PARSE): New macro that helps with checking the parser tables for a grammar. * tests/input.at (%define lr.default_rules invalid values): New test group. * tests/reduce.at (AT_TEST_LR_DEFAULT_RULES): New macro using AT_TEST_TABLES_AND_PARSE. (`no %define lr.default_rules'): New test group generated by AT_TEST_LR_DEFAULT_RULES. (`%define lr.default_rules "all"'): Likewise. (`%define lr.default_rules "consistent"'): Likewise. (`%define lr.default_rules "accepting"'): Likewise.
503 lines
12 KiB
Plaintext
503 lines
12 KiB
Plaintext
# Exercising Bison Grammar Reduction. -*- Autotest -*-
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# Copyright (C) 2001, 2002, 2007, 2008, 2009 Free Software Foundation,
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# Inc.
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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AT_BANNER([[Grammar Reduction.]])
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## ------------------- ##
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## Useless Terminals. ##
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## ------------------- ##
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AT_SETUP([Useless Terminals])
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AT_DATA([[input.y]],
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[[%verbose
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%output "input.c"
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%token useless1
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%token useless2
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%token useless3
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%token useless4
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%token useless5
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%token useless6
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%token useless7
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%token useless8
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%token useless9
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%token useful
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%%
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exp: useful;
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]])
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AT_BISON_CHECK([[input.y]])
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AT_CHECK([[sed -n '/^Grammar/q;/^$/!p' input.output]], 0,
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[[Terminals unused in grammar
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useless1
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useless2
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useless3
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useless4
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useless5
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useless6
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useless7
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useless8
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useless9
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]])
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AT_CLEANUP
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## ---------------------- ##
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## Useless Nonterminals. ##
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## ---------------------- ##
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AT_SETUP([Useless Nonterminals])
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AT_DATA([[input.y]],
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[[%verbose
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%output "input.c"
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%nterm useless1
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%nterm useless2
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%nterm useless3
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%nterm useless4
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%nterm useless5
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%nterm useless6
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%nterm useless7
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%nterm useless8
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%nterm useless9
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%token useful
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%%
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exp: useful;
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]])
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AT_BISON_CHECK([[input.y]], 0, [],
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[[input.y: warning: 9 nonterminals useless in grammar
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input.y:4.8-15: warning: nonterminal useless in grammar: useless1
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input.y:5.8-15: warning: nonterminal useless in grammar: useless2
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input.y:6.8-15: warning: nonterminal useless in grammar: useless3
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input.y:7.8-15: warning: nonterminal useless in grammar: useless4
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input.y:8.8-15: warning: nonterminal useless in grammar: useless5
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input.y:9.8-15: warning: nonterminal useless in grammar: useless6
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input.y:10.8-15: warning: nonterminal useless in grammar: useless7
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input.y:11.8-15: warning: nonterminal useless in grammar: useless8
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input.y:12.8-15: warning: nonterminal useless in grammar: useless9
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]])
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AT_CHECK([[sed -n '/^Grammar/q;/^$/!p' input.output]], 0,
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[[Nonterminals useless in grammar
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useless1
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useless2
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useless3
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useless4
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useless5
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useless6
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useless7
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useless8
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useless9
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]])
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AT_CLEANUP
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## --------------- ##
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## Useless Rules. ##
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## --------------- ##
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AT_SETUP([Useless Rules])
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AT_KEYWORDS([report])
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AT_DATA([[input.y]],
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[[%verbose
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%output "input.c"
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%token useful
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%%
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exp: useful;
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useless1: '1';
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useless2: '2';
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useless3: '3';
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useless4: '4';
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useless5: '5';
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useless6: '6';
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useless7: '7';
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useless8: '8';
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useless9: '9';
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]])
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AT_BISON_CHECK([[input.y]], 0, [],
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[[input.y: warning: 9 nonterminals useless in grammar
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input.y: warning: 9 rules useless in grammar
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input.y:6.1-8: warning: nonterminal useless in grammar: useless1
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input.y:7.1-8: warning: nonterminal useless in grammar: useless2
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input.y:8.1-8: warning: nonterminal useless in grammar: useless3
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input.y:9.1-8: warning: nonterminal useless in grammar: useless4
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input.y:10.1-8: warning: nonterminal useless in grammar: useless5
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input.y:11.1-8: warning: nonterminal useless in grammar: useless6
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input.y:12.1-8: warning: nonterminal useless in grammar: useless7
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input.y:13.1-8: warning: nonterminal useless in grammar: useless8
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input.y:14.1-8: warning: nonterminal useless in grammar: useless9
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input.y:6.11-13: warning: rule useless in grammar: useless1: '1'
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input.y:7.11-13: warning: rule useless in grammar: useless2: '2'
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input.y:8.11-13: warning: rule useless in grammar: useless3: '3'
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input.y:9.11-13: warning: rule useless in grammar: useless4: '4'
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input.y:10.11-13: warning: rule useless in grammar: useless5: '5'
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input.y:11.11-13: warning: rule useless in grammar: useless6: '6'
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input.y:12.11-13: warning: rule useless in grammar: useless7: '7'
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input.y:13.11-13: warning: rule useless in grammar: useless8: '8'
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input.y:14.11-13: warning: rule useless in grammar: useless9: '9'
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]])
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AT_CHECK([[sed -n '/^Grammar/q;/^$/!p' input.output]], 0,
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[[Nonterminals useless in grammar
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useless1
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useless2
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useless3
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useless4
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useless5
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useless6
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useless7
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useless8
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useless9
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Terminals unused in grammar
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'1'
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'2'
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'3'
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'4'
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'5'
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'6'
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'7'
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'8'
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'9'
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Rules useless in grammar
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2 useless1: '1'
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3 useless2: '2'
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4 useless3: '3'
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5 useless4: '4'
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6 useless5: '5'
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7 useless6: '6'
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8 useless7: '7'
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9 useless8: '8'
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10 useless9: '9'
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]])
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AT_CLEANUP
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## ------------------- ##
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## Reduced Automaton. ##
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## ------------------- ##
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# Check that the automaton is that as the for the grammar reduced by
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# hand.
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AT_SETUP([Reduced Automaton])
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AT_KEYWORDS([report])
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# The non reduced grammar.
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# ------------------------
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AT_DATA([[not-reduced.y]],
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[[/* A useless token. */
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%token useless_token
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/* A useful one. */
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%token useful
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%verbose
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%output "not-reduced.c"
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%%
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exp: useful { /* A useful action. */ }
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| non_productive { /* A non productive action. */ }
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;
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not_reachable: useful { /* A not reachable action. */ }
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;
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non_productive: non_productive useless_token
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{ /* Another non productive action. */ }
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;
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%%
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]])
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AT_BISON_CHECK([[not-reduced.y]], 0, [],
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[[not-reduced.y: warning: 2 nonterminals useless in grammar
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not-reduced.y: warning: 3 rules useless in grammar
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not-reduced.y:14.1-13: warning: nonterminal useless in grammar: not_reachable
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not-reduced.y:11.6-19: warning: nonterminal useless in grammar: non_productive
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not-reduced.y:11.6-57: warning: rule useless in grammar: exp: non_productive
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not-reduced.y:14.16-56: warning: rule useless in grammar: not_reachable: useful
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not-reduced.y:17.17-18.63: warning: rule useless in grammar: non_productive: non_productive useless_token
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]])
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AT_CHECK([[sed -n '/^Grammar/q;/^$/!p' not-reduced.output]], 0,
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[[Nonterminals useless in grammar
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not_reachable
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non_productive
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Terminals unused in grammar
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useless_token
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Rules useless in grammar
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2 exp: non_productive
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3 not_reachable: useful
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4 non_productive: non_productive useless_token
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]])
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# The reduced grammar.
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# --------------------
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AT_DATA([[reduced.y]],
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[[/* A useless token. */
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%token useless_token
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/* A useful one. */
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%token useful
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%verbose
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%output "reduced.c"
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%%
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exp: useful { /* A useful action. */ }
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// | non_productive { /* A non productive action. */ } */
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;
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//not_reachable: useful { /* A not reachable action. */ }
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// ;
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//non_productive: non_productive useless_token
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// { /* Another non productive action. */ }
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// ;
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%%
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]])
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AT_BISON_CHECK([[reduced.y]])
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# Comparing the parsers.
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cp reduced.c expout
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AT_CHECK([sed 's/not-reduced/reduced/g' not-reduced.c], 0, [expout])
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AT_CLEANUP
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## ------------------- ##
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## Underivable Rules. ##
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## ------------------- ##
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AT_SETUP([Underivable Rules])
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AT_KEYWORDS([report])
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AT_DATA([[input.y]],
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[[%verbose
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%output "input.c"
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%token useful
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%%
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exp: useful | underivable;
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underivable: indirection;
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indirection: underivable;
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]])
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AT_BISON_CHECK([[input.y]], 0, [],
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[[input.y: warning: 2 nonterminals useless in grammar
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input.y: warning: 3 rules useless in grammar
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input.y:5.15-25: warning: nonterminal useless in grammar: underivable
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input.y:6.14-24: warning: nonterminal useless in grammar: indirection
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input.y:5.15-25: warning: rule useless in grammar: exp: underivable
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input.y:6.14-24: warning: rule useless in grammar: underivable: indirection
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input.y:7.14-24: warning: rule useless in grammar: indirection: underivable
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]])
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AT_CHECK([[sed -n '/^Grammar/q;/^$/!p' input.output]], 0,
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[[Nonterminals useless in grammar
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underivable
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indirection
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Rules useless in grammar
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2 exp: underivable
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3 underivable: indirection
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4 indirection: underivable
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]])
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AT_CLEANUP
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## ---------------- ##
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## Empty Language. ##
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## ---------------- ##
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AT_SETUP([Empty Language])
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AT_DATA([[input.y]],
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[[%output "input.c"
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%%
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exp: exp;
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]])
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AT_BISON_CHECK([[input.y]], 1, [],
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[[input.y: warning: 2 nonterminals useless in grammar
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input.y: warning: 2 rules useless in grammar
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input.y:3.1-3: fatal error: start symbol exp does not derive any sentence
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]])
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AT_CLEANUP
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## -------------------------- ##
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## %define lr.default_rules. ##
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## -------------------------- ##
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# AT_TEST_LR_DEFAULT_RULES(GRAMMAR, INPUT, TABLES)
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# ------------------------------------------------
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m4_define([AT_TEST_LR_DEFAULT_RULES],
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[
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AT_TEST_TABLES_AND_PARSE([[no %define lr.default_rules]],
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[[all]], [[]],
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[[]],
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[$1], [$2], [[]], [$3])
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AT_TEST_TABLES_AND_PARSE([[%define lr.default_rules "all"]],
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[[all]], [[]],
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[[%define lr.default_rules "all"]],
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[$1], [$2], [[]], [$3])
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AT_TEST_TABLES_AND_PARSE([[%define lr.default_rules "consistent"]],
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[[consistent]], [[]],
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[[%define lr.default_rules "consistent"]],
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[$1], [$2], [[]], [$3])
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AT_TEST_TABLES_AND_PARSE([[%define lr.default_rules "accepting"]],
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[[accepting]], [[]],
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[[%define lr.default_rules "accepting"]],
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[$1], [$2], [[]], [$3])
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])
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AT_TEST_LR_DEFAULT_RULES([[
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/* The start state is consistent and has a shift on 'a' and no reductions.
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After pushing the b below, enter an inconsistent state that has a shift and
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one reduction with one lookahead. */
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start:
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a b
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| a b 'a'
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| a c 'b'
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;
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/* After shifting this 'a', enter a consistent state that has no shift and 1
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reduction with multiple lookaheads. */
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a: 'a' ;
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/* After the previous reduction, enter an inconsistent state that has no shift
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and multiple reductions. The first reduction has more lookaheads than the
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second, so the first should always be preferred as the default rule if
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enabled. The second reduction has one lookahead. */
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b: ;
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c: ;
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]],
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dnl Visit each state mentioned above.
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[['a', 'a']],
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[[state 0
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0 $accept: . start $end
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1 start: . a b
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2 | . a b 'a'
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3 | . a c 'b'
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4 a: . 'a'
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'a' shift, and go to state 1
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start go to state 2
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a go to state 3
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state 1
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4 a: 'a' .]AT_COND_CASE([[accepting]], [[ [$end, 'a', 'b']
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$end reduce using rule 4 (a)
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'a' reduce using rule 4 (a)
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'b' reduce using rule 4 (a)]], [[
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$default reduce using rule 4 (a)]])[
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state 2
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0 $accept: start . $end
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$end shift, and go to state 4
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state 3
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1 start: a . b
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2 | a . b 'a'
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3 | a . c 'b'
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5 b: . [$end, 'a']
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6 c: . ['b']]AT_COND_CASE([[all]], [[
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'b' reduce using rule 6 (c)
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$default reduce using rule 5 (b)]], [[
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$end reduce using rule 5 (b)
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'a' reduce using rule 5 (b)
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'b' reduce using rule 6 (c)]])[
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b go to state 5
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c go to state 6
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state 4
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0 $accept: start $end .
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$default accept
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state 5
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1 start: a b . [$end]
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2 | a b . 'a'
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'a' shift, and go to state 7
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]AT_COND_CASE([[all]], [[$default]], [[$end]])[ reduce using rule 1 (start)
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state 6
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3 start: a c . 'b'
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'b' shift, and go to state 8
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state 7
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2 start: a b 'a' .]AT_COND_CASE([[accepting]], [[ [$end]
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$end reduce using rule 2 (start)]], [[
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$default reduce using rule 2 (start)]])[
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state 8
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3 start: a c 'b' .]AT_COND_CASE([[accepting]], [[ [$end]
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$end reduce using rule 3 (start)]], [[
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$default reduce using rule 3 (start)]])[
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]])
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