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1 package Parsers::SimpleCalcYYLexer;
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2 #
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3 # $RCSfile: SimpleCalcYYLexer.pm,v $
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4 # $Date: 2015/02/28 20:50:55 $
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5 # $Revision: 1.9 $
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6 #
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7 # Author: Manish Sud <msud@san.rr.com>
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8 #
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9 # Copyright (C) 2015 Manish Sud. All rights reserved.
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10 #
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11 # This file is part of MayaChemTools.
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12 #
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13 # MayaChemTools is free software; you can redistribute it and/or modify it under
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14 # the terms of the GNU Lesser General Public License as published by the Free
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15 # Software Foundation; either version 3 of the License, or (at your option) any
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16 # later version.
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17 #
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18 # MayaChemTools is distributed in the hope that it will be useful, but without
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19 # any warranty; without even the implied warranty of merchantability of fitness
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20 # for a particular purpose. See the GNU Lesser General Public License for more
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21 # details.
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22 #
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23 # You should have received a copy of the GNU Lesser General Public License
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24 # along with MayaChemTools; if not, see <http://www.gnu.org/licenses/> or
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25 # write to the Free Software Foundation Inc., 59 Temple Place, Suite 330,
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26 # Boston, MA, 02111-1307, USA.
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27 #
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28
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29 use strict;
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30 use Carp;
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31 use Exporter;
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32 use Scalar::Util ();
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33 use Parsers::YYLexer;
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34
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35 use vars qw(@ISA @EXPORT @EXPORT_OK %EXPORT_TAGS);
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36
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37 @ISA = qw(Parsers::YYLexer Exporter);
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38 @EXPORT = qw();
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39 @EXPORT_OK = qw();
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40
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41 %EXPORT_TAGS = (all => [@EXPORT, @EXPORT_OK]);
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42
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43 # Setup class variables...
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44 my($ClassName, $YYTabFile, @YYLexerTokensSpec);
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45 _InitializeClass();
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46
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47 # Overload Perl functions...
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48 use overload '""' => 'StringifySimpleCalcYYLexer';
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49
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50 # Class constructor...
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51 sub new {
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52 my($Class, $Input) = @_;
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53 my(@TokensSpec);
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54
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55 # Initialize object...
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56 my $This = $Class->SUPER::new($Input, @YYLexerTokensSpec);
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57 bless $This, ref($Class) || $Class;
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58 $This->_InitializeYYLexer();
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59
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60 return $This;
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61 }
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62
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63 # Initialize object data...
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64 #
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65 sub _InitializeYYLexer {
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66 my($This) = @_;
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67
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68 # Setup default YYTabFile containing mapping of token names to numbers...
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69 $This->SetupYYTabFile($YYTabFile);
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70
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71 return $This;
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72 }
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73
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74 # Initialize class ...
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75 sub _InitializeClass {
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76 #Class name...
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77 $ClassName = __PACKAGE__;
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78
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79 # Setup default token table file...
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80 $YYTabFile = "Parsers/SimpleCalcParser.tab.ph";
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81
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82 # Setup default lexer tokens specs...
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83 @YYLexerTokensSpec = (
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84 [ 'LETTER', qr/[a-zA-Z]/ ],
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85 [ 'NUMBER', qr/\d+/ ],
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86 [ 'SPACE', qr/[ ]*/, sub { my($This, $TokenLabel, $MatchedText) = @_; return ''; } ],
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87 [ 'NEWLINE', qr/(?:\r\n|\r|\n)/, sub { my($This, $TokenLabel, $MatchedText) = @_; return "\n"; } ],
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88 [ 'CHAR', qr/./ ]
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89 );
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90 }
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91
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92 # Is it a lexer object?
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93 sub _IsSimpleCalcYYLexer {
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94 my($Object) = @_;
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95
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96 return (Scalar::Util::blessed($Object) && $Object->isa($ClassName)) ? 1 : 0;
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97 }
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98
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99 # Return a string containing information about lexer...
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100 sub StringifySimpleCalcYYLexer {
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101 my($This) = @_;
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102 my($SimleCalcYYLexerString);
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103
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104 $SimleCalcYYLexerString = "SimpleCalcYYLexer: PackageName: $ClassName; " . $This->_GetYYLexerInfoString();
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105
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106 return $SimleCalcYYLexerString;
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107 }
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108
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109 1;
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110
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111 __END__
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112
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113 =head1 NAME
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114
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115 Parsers::SimpleCalcYYLexer
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116
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117 =head1 SYNOPSIS
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118
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119 use Parsers::SimpleCalcYYLexer;
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120
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121 use Parsers::SimpleCalcYYLexer qw(:all);
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122
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123 =head1 DESCRIPTION
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124
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125 B<SimpleCalcYYLexer> class provides the following methods:
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126
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127 new, YYLex, GetYYLex, StringifySimpleCalcYYLexer
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128
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129 B<Parser::SimpleCalcYYLexer> class is derived from B<Parser::YYLexer> class, which in
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130 turn is derived from base class B<Parser::Lexer> that provides all the underlying
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131 lexer functionality. B<SimpleCalcYYLexer> class is designed to be used with
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132 B<yyparse> code generated by running B<byacc> on a parser defined using
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133 parser definition B<SimpleCalcParser.yy> file.
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134
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135 The parser package and token table files, B<SimpleCalcParser.pm> and B<SimpleCalcParser.tab.ph>,
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136 are automatically generated from parser grammar definition file, B<SimpleCalcParser.yy>, using
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137 byacc available through perl-byacc1.8 modified with perl5-byacc-patches-0.5 for generation
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138 of object oriented parser:
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139
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140 byacc -l -P -d -b SimpleCalcParser SimpleCalcParser.yy
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141 mv SimpleCalcParser.tab.pl SimpleCalcParser.pm
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142
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143 B<SimpleCalcYYLexer.pm> class implements a lexer for a simple calculator and is provided
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144 to highlight usasge of B<YYLex> through B<yyparse>.
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145
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146 The default specification of lexer tokens for B<SimpleCalcYYLexer.pm> includes:
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147
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148 @YYLexerTokensSpec = (
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149 [ 'LETTER', qr/[a-zA-Z]/ ],
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150 [ 'NUMBER', qr/\d+/ ],
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151 [ 'SPACE', qr/[ ]*/,
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152 sub { my($This, $TokenLabel, $MatchedText) = @_; return ''; }
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153 ],
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154 [ 'NEWLINE', qr/(?:\r\n|\r|\n)/,
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155 sub { my($This, $TokenLabel, $MatchedText) = @_; return "\n"; }
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156 ],
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157 [ 'CHAR', qr/./ ]
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158 );
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159
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160 The default B<SimpleCalcParser.tab.ph> file containing token identifiers for
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161 B<SimpleCalcParser.yy> includes:
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162
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163 $NUMBER=257;
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164 $LETTER=258;
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165
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166 =head2 METHODS
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167
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168 =over 4
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169
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170 =item B<new>
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171
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172 $SimpleCalcYYLexer = new Parsers::SimpleCalcYYLexer($Input);
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173
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174 Using specified I<Input>, B<new> method generates a new B<SimpleCalcYYLexer>
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175 and returns a reference to newly created B<SimpleCalcYYLexer> object.
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176
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177 Examples:
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178
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179 # Input string...
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180 $InputText = "3 + 4 +6\nx=3\ny=5\nx+y\nx+z\n";
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181
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182 $YYLexer = new Parsers::SimpleCalcYYLexer($InputText);
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183 $YYLex = $YYLexer->GetYYLex();
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184
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185 $Debug = 0;
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186 $CalcParser = new Parsers::SimpleCalcParser($YYLex,
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187 \&Parsers::SimpleCalcParser::yyerror, $Debug);
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188 $Value = $SimpleCalcParser->yyparse();
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189 print "Value: $Value\n";
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190
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191 # Input file...
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192 $InputFile = "Input.txt";
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193 open INPUTFILE, "$InputFile" or die "Couldn't open $InputFile: $!\n";
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194 $YYLexer = new Parsers::SimpleCalcYYLexer($InputFile);
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195 $YYLex = $YYLexer->GetYYLex();
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196
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197 $CalcParser = new Parsers::SimpleCalcParser($YYLex,
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198 \&Parsers::SimpleCalcParser::yyerror);
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199 $Value = $SimpleCalcParser->yyparse();
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200 print "Value: $Value\n";
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201
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202 # Input file iterator...
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203 $InputFile = "TestSimpleCalcParser.txt";
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204 open INPUTFILE, "$InputFile" or die "Couldn't open $InputFile: $!\n";
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205 $InputIterator = sub { return <INPUTFILE>; };
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206 $YYLexer = new Parsers::SimpleCalcYYLexer($InputIterator);
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207 $YYLex = $YYLexer->GetYYLex();
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208
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209 $CalcParser = new Parsers::SimpleCalcParser($YYLex,
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210 \&Parsers::SimpleCalcParser::yyerror);
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211 $Value = $SimpleCalcParser->yyparse();
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212 print "Value: $Value\n";
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213
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214 =item B<StringifySimpleCalcYYLexer>
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215
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216 $YYLexerString = $YYLexer->StringifySimpleCalcYYLexer();
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217
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218 Returns a string containing information about I<YYLexer> object.
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219
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220 =back
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221
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222 =head1 AUTHOR
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223
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224 Manish Sud <msud@san.rr.com>
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225
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226 =head1 SEE ALSO
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227
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228 Lexer.pm, YYLexer.pm, SimpleCalcParser.yy
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229
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230 =head1 COPYRIGHT
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231
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232 Copyright (C) 2015 Manish Sud. All rights reserved.
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233
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234 This file is part of MayaChemTools.
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235
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236 MayaChemTools is free software; you can redistribute it and/or modify it under
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237 the terms of the GNU Lesser General Public License as published by the Free
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238 Software Foundation; either version 3 of the License, or (at your option)
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239 any later version.
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240
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241 =cut
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