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1 package Parsers::SimpleCalcParser;
2 #
3 # $RCSfile: SimpleCalcParser.yy,v $
4 # $Date: 2015/02/28 20:50:55 $
5 # $Revision: 1.10 $
6 #
7 # Author: Manish Sud <msud@san.rr.com>
8 #
9 # Copyright (C) 2015 Manish Sud. All rights reserved.
10 #
11 # This file is part of MayaChemTools.
12 #
13 # MayaChemTools is free software; you can redistribute it and/or modify it under
14 # the terms of the GNU Lesser General Public License as published by the Free
15 # Software Foundation; either version 3 of the License, or (at your option) any
16 # later version.
17 #
18 # MayaChemTools is distributed in the hope that it will be useful, but without
19 # any warranty; without even the implied warranty of merchantability of fitness
20 # for a particular purpose. See the GNU Lesser General Public License for more
21 # details.
22 #
23 # You should have received a copy of the GNU Lesser General Public License
24 # along with MayaChemTools; if not, see <http://www.gnu.org/licenses/> or
25 # write to the Free Software Foundation Inc., 59 Temple Place, Suite 330,
26 # Boston, MA, 02111-1307, USA.
27 #
28 #
29 # A WORD TO THE WISE:
30 #
31 # The parser package and token table files, SimpleCalcParser.pm and
32 # SimpleCalcParser.tab.ph, are automatically generated from parser grammar
33 # definition file, SimpleCalcParser.yy, using byacc available through perl-byacc1.8
34 # modified with perl5-byacc-patches-0.5 for generation of object oriented parser:
35 #
36 # byacc -l -P -d -b SimpleCalcParser SimpleCalcParser.yy
37 # mv SimpleCalcParser.tab.pl SimpleCalcParser.pm
38 #
39
40 use Carp;
41
42 # Setup a hash map for mapping of words/letters to values...
43 %LetterToValueMap = ();
44
45 $NUMBER=257;
46 $LETTER=258;
47 $YYERRCODE=256;
48 @yylhs = ( -1,
49 0, 0, 0, 1, 1, 2, 2, 2, 2, 2,
50 2, 2, 2,
51 );
52 @yylen = ( 2,
53 0, 3, 3, 1, 3, 3, 3, 3, 3, 3,
54 3, 1, 1,
55 );
56 @yydefred = ( 1,
57 0, 0, 12, 0, 0, 0, 0, 3, 0, 13,
58 0, 2, 0, 0, 0, 0, 0, 0, 6, 0,
59 0, 0, 0, 11,
60 );
61 @yydgoto = ( 1,
62 6, 7,
63 );
64 @yysindex = ( 0,
65 -40, -7, 0, -57, -38, -5, -18, 0, -38, 0,
66 -31, 0, -38, -38, -38, -38, -38, -18, 0, -16,
67 -16, -30, -30, 0,
68 );
69 @yyrindex = ( 0,
70 0, 0, 0, -9, 0, 0, -1, 0, 0, 0,
71 0, 0, 0, 0, 0, 0, 0, 3, 0, 8,
72 13, -2, 5, 0,
73 );
74 @yygindex = ( 0,
75 0, 50,
76 );
77 $YYTABLESIZE=220;
78 @yytable = ( 5,
79 13, 5, 8, 9, 12, 17, 17, 9, 4, 19,
80 15, 13, 5, 14, 10, 16, 0, 7, 17, 0,
81 17, 0, 8, 15, 13, 15, 14, 13, 16, 0,
82 16, 0, 13, 13, 0, 13, 0, 13, 9, 9,
83 9, 0, 9, 0, 9, 10, 10, 10, 7, 10,
84 7, 10, 7, 8, 11, 8, 0, 8, 18, 0,
85 0, 0, 20, 21, 22, 23, 24, 0, 0, 0,
86 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
87 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
88 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
89 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
90 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
91 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
92 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
93 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
94 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
95 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
96 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
97 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
98 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
99 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
100 0, 0, 0, 0, 0, 2, 3, 4, 3, 10,
101 );
102 @yycheck = ( 40,
103 10, 40, 10, 61, 10, 37, 37, 10, 10, 41,
104 42, 43, 10, 45, 10, 47, -1, 10, 37, -1,
105 37, -1, 10, 42, 43, 42, 45, 37, 47, -1,
106 47, -1, 42, 43, -1, 45, -1, 47, 41, 42,
107 43, -1, 45, -1, 47, 41, 42, 43, 41, 45,
108 43, 47, 45, 41, 5, 43, -1, 45, 9, -1,
109 -1, -1, 13, 14, 15, 16, 17, -1, -1, -1,
110 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
111 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
112 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
113 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
114 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
115 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
116 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
117 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
118 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
119 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
120 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
121 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
122 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
123 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
124 -1, -1, -1, -1, -1, 256, 257, 258, 257, 258,
125 );
126 $YYFINAL=1;
127 #ifndef YYDEBUG
128 #define YYDEBUG 0
129 #endif
130 $YYMAXTOKEN=258;
131 #if YYDEBUG
132 @yyname = (
133 "end-of-file",'','','','','','','','','',"'\\n'",'','','','','','','','','','','','','','','','','','','','',
134 '','','','','','',"'%'",'','',"'('","')'","'*'","'+'",'',"'-'",'',"'/'",'','','','','','','','','',
135 '','','','',"'='",'','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','',
136 '','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','',
137 '','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','',
138 '','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','',
139 '','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','',
140 '','',"NUMBER","LETTER",
141 );
142 @yyrule = (
143 "\$accept : list",
144 "list :",
145 "list : list stat '\\n'",
146 "list : list error '\\n'",
147 "stat : expr",
148 "stat : LETTER '=' expr",
149 "expr : '(' expr ')'",
150 "expr : expr '+' expr",
151 "expr : expr '-' expr",
152 "expr : expr '*' expr",
153 "expr : expr '/' expr",
154 "expr : expr '%' expr",
155 "expr : NUMBER",
156 "expr : LETTER",
157 );
158 #endif
159
160 sub yyclearin { $_[0]->{'yychar'} = -1; }
161
162 sub yyerrok { $_[0]->{'yyerrflag'} = 0; }
163
164 sub new {
165 my $p = {'yylex' => $_[1], 'yyerror' => $_[2], 'yydebug' => $_[3]};
166 bless $p, $_[0];
167 }
168
169 sub YYERROR { ++$_[0]->{'yynerrs'}; $_[0]->yy_err_recover; }
170
171 sub yy_err_recover {
172 #
173 # msud@san.rr.com:
174 #
175 # Turn off "exiting" warning to suppress the following warning at "next yyloop":
176 #
177 # Exiting subroutine via next at <LineNum>
178 #
179 # The code does work as expected with or without turning off the warning.
180 # This method is invoked in yyparse method directly or indirectly in another
181 # method and Perl compilers ends up finding "yyloop" as the nearst enclosure
182 # label.
183 #
184 no warnings qw(exiting);
185
186 my ($p) = @_;
187 if ($p->{'yyerrflag'} < 3)
188 {
189 $p->{'yyerrflag'} = 3;
190 while (1)
191 {
192 if (($p->{'yyn'} = $yysindex[$p->{'yyss'}->[$p->{'yyssp'}]]) &&
193 ($p->{'yyn'} += $YYERRCODE) >= 0 &&
194 $p->{'yyn'} < @yycheck &&
195 $yycheck[$p->{'yyn'}] == $YYERRCODE)
196 {
197 warn("yydebug: state " .
198 $p->{'yyss'}->[$p->{'yyssp'}] .
199 ", error recovery shifting to state" .
200 $yytable[$p->{'yyn'}] . "\n")
201 if $p->{'yydebug'};
202 $p->{'yyss'}->[++$p->{'yyssp'}] =
203 $p->{'yystate'} = $yytable[$p->{'yyn'}];
204 $p->{'yyvs'}->[++$p->{'yyvsp'}] = $p->{'yylval'};
205 next yyloop;
206 }
207 else
208 {
209 warn("yydebug: error recovery discarding state ".
210 $p->{'yyss'}->[$p->{'yyssp'}]. "\n")
211 if $p->{'yydebug'};
212 return(undef) if $p->{'yyssp'} <= 0;
213 --$p->{'yyssp'};
214 --$p->{'yyvsp'};
215 }
216 }
217 }
218 else
219 {
220 return (undef) if $p->{'yychar'} == 0;
221 if ($p->{'yydebug'})
222 {
223 $p->{'yys'} = '';
224 if ($p->{'yychar'} <= $YYMAXTOKEN) { $p->{'yys'} =
225 $yyname[$p->{'yychar'}]; }
226 if (!$p->{'yys'}) { $p->{'yys'} = 'illegal-symbol'; }
227 warn("yydebug: state " . $p->{'yystate'} .
228 ", error recovery discards " .
229 "token " . $p->{'yychar'} . "(" .
230 $p->{'yys'} . ")\n");
231 }
232 $p->{'yychar'} = -1;
233 next yyloop;
234 }
235 0;
236 } # yy_err_recover
237
238 sub yyparse {
239 my ($p, $s) = @_;
240 if ($p->{'yys'} = $ENV{'YYDEBUG'})
241 {
242 $p->{'yydebug'} = int($1) if $p->{'yys'} =~ /^(\d)/;
243 }
244
245 $p->{'yynerrs'} = 0;
246 $p->{'yyerrflag'} = 0;
247 $p->{'yychar'} = (-1);
248
249 $p->{'yyssp'} = 0;
250 $p->{'yyvsp'} = 0;
251 $p->{'yyss'}->[$p->{'yyssp'}] = $p->{'yystate'} = 0;
252
253 yyloop: while(1)
254 {
255 yyreduce: {
256 last yyreduce if ($p->{'yyn'} = $yydefred[$p->{'yystate'}]);
257 if ($p->{'yychar'} < 0)
258 {
259 if ((($p->{'yychar'}, $p->{'yylval'}) =
260 &{$p->{'yylex'}}($s)) < 0) { $p->{'yychar'} = 0; }
261 if ($p->{'yydebug'})
262 {
263 $p->{'yys'} = '';
264 if ($p->{'yychar'} <= $#yyname)
265 { $p->{'yys'} = $yyname[$p->{'yychar'}]; }
266 if (!$p->{'yys'}) { $p->{'yys'} = 'illegal-symbol'; };
267 warn("yydebug: state " . $p->{'yystate'} .
268 ", reading " . $p->{'yychar'} . " (" .
269 $p->{'yys'} . ")\n");
270 }
271 }
272 if (($p->{'yyn'} = $yysindex[$p->{'yystate'}]) &&
273 ($p->{'yyn'} += $p->{'yychar'}) >= 0 &&
274 $yycheck[$p->{'yyn'}] == $p->{'yychar'})
275 {
276 warn("yydebug: state " . $p->{'yystate'} .
277 ", shifting to state " .
278 $yytable[$p->{'yyn'}] . "\n") if $p->{'yydebug'};
279 $p->{'yyss'}->[++$p->{'yyssp'}] = $p->{'yystate'} =
280 $yytable[$p->{'yyn'}];
281 $p->{'yyvs'}->[++$p->{'yyvsp'}] = $p->{'yylval'};
282 $p->{'yychar'} = (-1);
283 --$p->{'yyerrflag'} if $p->{'yyerrflag'} > 0;
284 next yyloop;
285 }
286 if (($p->{'yyn'} = $yyrindex[$p->{'yystate'}]) &&
287 ($p->{'yyn'} += $p->{'yychar'}) >= 0 &&
288 $yycheck[$p->{'yyn'}] == $p->{'yychar'})
289 {
290 $p->{'yyn'} = $yytable[$p->{'yyn'}];
291 last yyreduce;
292 }
293 if (! $p->{'yyerrflag'}) {
294 if ( (defined($EOI) && $p->{'yychar'} == $EOI) || ($p->{'yychar'} == 0) ) {
295 &{$p->{'yyerror'}}("syntax error at or near the end of input text", $s);
296 }
297 else {
298 &{$p->{'yyerror'}}("syntax error at or near input text: '$p->{'yylval'}'", $s);
299 }
300 ++$p->{'yynerrs'};
301 }
302 return(undef) if $p->yy_err_recover;
303 } # yyreduce
304 warn("yydebug: state " . $p->{'yystate'} .
305 ", reducing by rule " .
306 $p->{'yyn'} . " (" . $yyrule[$p->{'yyn'}] .
307 ")\n") if $p->{'yydebug'};
308 $p->{'yym'} = $yylen[$p->{'yyn'}];
309 $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}+1-$p->{'yym'}];
310
311 if ($p->{'yyn'} == 2) {
312 { $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}-1]; }
313 }
314
315 if ($p->{'yyn'} == 3) {
316 { $p->yyerrok; $p->yyclearin; }
317 }
318
319 if ($p->{'yyn'} == 4) {
320 { $ExprOut = sprintf "%5i", $p->{'yyvs'}->[$p->{'yyvsp'}-0]; print "$ExprOut\n"; $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}-0]; }
321 }
322
323 if ($p->{'yyn'} == 5) {
324 { $LetterToValueMap{$p->{'yyvs'}->[$p->{'yyvsp'}-2]} = $p->{'yyvs'}->[$p->{'yyvsp'}-0]; }
325 }
326
327 if ($p->{'yyn'} == 6) {
328 { $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}-1]; }
329 }
330
331 if ($p->{'yyn'} == 7) {
332 { $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}-2] + $p->{'yyvs'}->[$p->{'yyvsp'}-0]; }
333 }
334
335 if ($p->{'yyn'} == 8) {
336 { $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}-2] - $p->{'yyvs'}->[$p->{'yyvsp'}-0]; }
337 }
338
339 if ($p->{'yyn'} == 9) {
340 { $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}-2] * $p->{'yyvs'}->[$p->{'yyvsp'}-0]; }
341 }
342
343 if ($p->{'yyn'} == 10) {
344 { $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}-2] / $p->{'yyvs'}->[$p->{'yyvsp'}-0]; }
345 }
346
347 if ($p->{'yyn'} == 11) {
348 { $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}-2] % $p->{'yyvs'}->[$p->{'yyvsp'}-0]; }
349 }
350
351 if ($p->{'yyn'} == 13) {
352 {
353 if (exists $LetterToValueMap{$p->{'yyvs'}->[$p->{'yyvsp'}-0]}) {
354 $p->{'yyval'} = $LetterToValueMap{$p->{'yyvs'}->[$p->{'yyvsp'}-0]};
355 }
356 else {
357 $Letter = $p->{'yyvs'}->[$p->{'yyvsp'}-0];
358 print "Undefined variable $Letter encountered by SimpleCalcParser; Value set to 0\n";
359 $p->{'yyval'} = 0;
360 }
361 }
362 }
363 $p->{'yyssp'} -= $p->{'yym'};
364 $p->{'yystate'} = $p->{'yyss'}->[$p->{'yyssp'}];
365 $p->{'yyvsp'} -= $p->{'yym'};
366 $p->{'yym'} = $yylhs[$p->{'yyn'}];
367 if ($p->{'yystate'} == 0 && $p->{'yym'} == 0)
368 {
369 warn("yydebug: after reduction, shifting from state 0 ",
370 "to state $YYFINAL\n") if $p->{'yydebug'};
371 $p->{'yystate'} = $YYFINAL;
372 $p->{'yyss'}->[++$p->{'yyssp'}] = $YYFINAL;
373 $p->{'yyvs'}->[++$p->{'yyvsp'}] = $p->{'yyval'};
374 if ($p->{'yychar'} < 0)
375 {
376 if ((($p->{'yychar'}, $p->{'yylval'}) =
377 &{$p->{'yylex'}}($s)) < 0) { $p->{'yychar'} = 0; }
378 if ($p->{'yydebug'})
379 {
380 $p->{'yys'} = '';
381 if ($p->{'yychar'} <= $#yyname)
382 { $p->{'yys'} = $yyname[$p->{'yychar'}]; }
383 if (!$p->{'yys'}) { $p->{'yys'} = 'illegal-symbol'; }
384 warn("yydebug: state $YYFINAL, reading " .
385 $p->{'yychar'} . " (" . $p->{'yys'} . ")\n");
386 }
387 }
388 return ($p->{'yyvs'}->[1]) if $p->{'yychar'} == 0;
389 next yyloop;
390 }
391 if (($p->{'yyn'} = $yygindex[$p->{'yym'}]) &&
392 ($p->{'yyn'} += $p->{'yystate'}) >= 0 &&
393 $p->{'yyn'} <= $#yycheck &&
394 $yycheck[$p->{'yyn'}] == $p->{'yystate'})
395 {
396 $p->{'yystate'} = $yytable[$p->{'yyn'}];
397 } else {
398 $p->{'yystate'} = $yydgoto[$p->{'yym'}];
399 }
400 warn("yydebug: after reduction, shifting from state " .
401 $p->{'yyss'}->[$p->{'yyssp'}] . " to state " .
402 $p->{'yystate'} . "\n") if $p->{'yydebug'};
403 $p->{'yyss'}[++$p->{'yyssp'}] = $p->{'yystate'};
404 $p->{'yyvs'}[++$p->{'yyvsp'}] = $p->{'yyval'};
405 } # yyloop
406 } # yyparse
407
408
409 # yyerror function supplied to parser along with a lexer during initialization of
410 # the parser...
411 #
412
413 sub yyerror {
414 my ($msg) = @_;
415 print "yyerror: $msg...\n";
416 }
417
418 1;
419
420 __END__
421
422 =head1 NAME
423
424 Parsers::SimpleCalcParser
425
426 =head1 SYNOPSIS
427
428 use Parsers::SimpleCalcParser ;
429
430 use Parsers::SimpleCalcParser qw(:all);
431
432 =head1 DESCRIPTION
433
434 B<Parsers::SimpleCalcParser> class provides the following methods:
435
436 new, yyclearin, yyerrok, yyerror, yyparse
437
438 B<Parsers::SimpleCalcParse.yy> parser grammer definition file implements a simple
439 calculator and is provided to highlight usage of lexer capability available through
440 B<Parsers::SimpleCalcYYLexer>, which in turn uses B<Parsers::YYLexer> and
441 B<Parsers::Lexer> classes to procide underlying lexer functionality.
442
443 The parser package and token table files, B<Parsers::SimpleCalcParser.pm> and
444 B<SimpleCalcParser.tab.ph>, are automatically generated from parser grammar definition
445 file, B<Parsers::SimpleCalcParser.yy>, using byacc available through perl-byacc1.8 modified
446 with perl5-byacc-patches-0.5 for generation of object oriented parser:
447
448 byacc -l -P -d -b SimpleCalcParser SimpleCalcParser.yy
449 mv SimpleCalcParser.tab.pl SimpleCalcParser.pm
450
451 =head2 METHODS
452
453 =over 4
454
455 =item B<new>
456
457 $SimpleCalcParser = new Parsers::SimpleCalcParser($YYLex,
458 \&Parsers::SimpleCalcParser::yyerror);
459 $SimpleCalcParser = new Parsers::SimpleCalcParser($YYLex,
460 \&Parsers::SimpleCalcParser::yyerror, $Debug);
461
462 Using specified I<YYLex> I<YYError> functions, B<new> method generates a new
463 B<SimpleCalcParser> and returns a reference to newly created B<SimpleCalcYYParser> object.
464
465 Examples:
466
467 # Input string...
468 $InputText = "3 + 4 +6\nx=3\ny=5\nx+y\nx+z\n";
469 $YYLexer = new Parsers::SimpleCalcYYLexer($InputText);
470 $YYLex = $YYLexer->GetYYLex();
471
472 $Debug = 0;
473 $SimpleCalcParser = new Parsers::SimpleCalcParser($YYLex,
474 \&Parsers::SimpleCalcParser::yyerror, $Debug);
475 $Value = $SimpleCalcParser->yyparse();
476 print "Value = " . (defined($Value) ? "$Value" : "Undefined") . "\n";
477
478 # Input file...
479 $InputFile = "TestSimpleCalcParser.txt";
480 open INPUTFILE, "$InputFile" or die "Couldn't open $InputFile: $!\n";
481
482 $YYLexer = new Parsers::SimpleCalcYYLexer(\*INPUTFILE);
483 $YYLex = $YYLexer->GetYYLex();
484
485 $Debug = 0;
486 $SimpleCalcParser = new Parsers::SimpleCalcParser($YYLex,
487 \&Parsers::SimpleCalcParser::yyerror, $Debug);
488 $Value = $SimpleCalcParser->yyparse();
489 print "Value = " . (defined($Value) ? "$Value" : "Undefined") . "\n";
490
491 close INPUTFILE;
492
493 # Input iterator...
494 $InputFile = "TestSimpleCalcParser.txt";
495 open INPUTFILE, "$InputFile" or die "Couldn't open $InputFile: $!\n";
496 $InputIterator = sub { return <INPUTFILE>; };
497
498 $YYLexer = new Parsers::SimpleCalcYYLexer($InputIterator);
499 $YYLex = $YYLexer->GetYYLex();
500
501 $Debug = 0;
502 $SimpleCalcParser = new Parsers::SimpleCalcParser($YYLex,
503 \&Parsers::SimpleCalcParser::yyerror, $Debug);
504 $Value = $SimpleCalcParser->yyparse();
505 print "Value = " . (defined($Value) ? "$Value" : "Undefined") . "\n";
506
507 close INPUTFILE;
508
509 =item B<yyclearin>
510
511 $SimpleCalcParser->yyclearin();
512
513 B<yyclearin> method clears any previous look-ahead token after encountering a syntax error
514 during parsing. It can be used after B<yyerrok> in a grammer rule with the reserved word
515 B<error>.
516
517 =item B<yyerrok>
518
519 $SimpleCalcParser->yyerrok();
520
521 B<yyerrok> method is used with the reserved word B<error> in grammer rule to indcate
522 error recovery is complete after encountering a syntax error during parsing.
523
524 =item B<yyerror>
525
526 $SimpleCalcParser->yyerror();
527
528 B<yyerror> function is provided for the caller to use during initialization of a parser. It
529 is used by B<yyparse> to print any error messages encountered during parsing of the
530 input.
531
532 =item B<yyparse>
533
534 $Value = $SimpleCalcParser->yyparse();
535
536 Returns I<Value> after parsing all the input from a input stream using specified
537 grammer rules.
538
539 =back
540
541 =head1 AUTHOR
542
543 Manish Sud <msud@san.rr.com>
544
545 =head1 SEE ALSO
546
547 Lexer.pm, YYLexer.pm, SimpleCalcYYLexer.pm
548
549 =head1 COPYRIGHT
550
551 Copyright (C) 2015 Manish Sud. All rights reserved.
552
553 This file is part of MayaChemTools.
554
555 MayaChemTools is free software; you can redistribute it and/or modify it under
556 the terms of the GNU Lesser General Public License as published by the Free
557 Software Foundation; either version 3 of the License, or (at your option)
558 any later version.
559
560 =cut
561