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3 <title>MayaChemTools:Documentation:Parsers::SimpleCalcParser.pm</title>
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12 <br/>
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13 <div class="DocNav">
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14 <table width="100%" border=0 cellpadding=0 cellspacing=2>
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15 <tr align="left" valign="top"><td width="33%" align="left"><a href="./Lexer.html" title="Lexer.html">Previous</a> <a href="./index.html" title="Table of Contents">TOC</a> <a href="./SimpleCalcYYLexer.html" title="SimpleCalcYYLexer.html">Next</a></td><td width="34%" align="middle"><strong>Parsers::SimpleCalcParser.pm</strong></td><td width="33%" align="right"><a href="././code/SimpleCalcParser.html" title="View source code">Code</a> | <a href="./../pdf/SimpleCalcParser.pdf" title="PDF US Letter Size">PDF</a> | <a href="./../pdfgreen/SimpleCalcParser.pdf" title="PDF US Letter Size with narrow margins: www.changethemargins.com">PDFGreen</a> | <a href="./../pdfa4/SimpleCalcParser.pdf" title="PDF A4 Size">PDFA4</a> | <a href="./../pdfa4green/SimpleCalcParser.pdf" title="PDF A4 Size with narrow margins: www.changethemargins.com">PDFA4Green</a></td></tr>
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16 </table>
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17 </div>
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18 <p>
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19 </p>
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20 <h2>NAME</h2>
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21 <p>Parsers::SimpleCalcParser</p>
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22 <p>
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23 </p>
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24 <h2>SYNOPSIS</h2>
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25 <p>use Parsers::SimpleCalcParser ;</p>
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26 <p>use Parsers::SimpleCalcParser qw(:all);</p>
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27 <p>
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28 </p>
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29 <h2>DESCRIPTION</h2>
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30 <p><strong>Parsers::SimpleCalcParser</strong> class provides the following methods:</p>
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31 <p> <a href="#new">new</a>, <a href="#yyclearin">yyclearin</a>, <a href="#yyerrok">yyerrok</a>, <a href="#yyerror">yyerror</a>, <a href="#yyparse">yyparse</a>
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32 </p><p><strong>Parsers::SimpleCalcParse.yy</strong> parser grammer definition file implements a simple
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33 calculator and is provided to highlight usage of lexer capability available through
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34 <strong>Parsers::SimpleCalcYYLexer</strong>, which in turn uses <strong>Parsers::YYLexer</strong> and
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35 <strong>Parsers::Lexer</strong> classes to procide underlying lexer functionality.</p>
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36 <p>The parser package and token table files, <strong>Parsers::SimpleCalcParser.pm</strong> and
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37 <strong>SimpleCalcParser.tab.ph</strong>, are automatically generated from parser grammar definition
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38 file, <strong>Parsers::SimpleCalcParser.yy</strong>, using byacc available through perl-byacc1.8 modified
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39 with perl5-byacc-patches-0.5 for generation of object oriented parser:</p>
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40 <div class="OptionsBox">
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41 byacc -l -P -d -b SimpleCalcParser SimpleCalcParser.yy
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42 <br/> mv SimpleCalcParser.tab.pl SimpleCalcParser.pm</div>
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43 <p>
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44 </p>
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45 <h2>METHODS</h2>
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46 <dl>
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47 <dt><strong><a name="new" class="item"><strong>new</strong></a></strong></dt>
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48 <dd>
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49 <div class="OptionsBox">
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50 $SimpleCalcParser = new Parsers::SimpleCalcParser($YYLex,
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51 \&Parsers::SimpleCalcParser::yyerror);
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52 <br/> $SimpleCalcParser = new Parsers::SimpleCalcParser($YYLex,
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53 \&Parsers::SimpleCalcParser::yyerror, $Debug);</div>
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54 <p>Using specified <em>YYLex</em> <em>YYError</em> functions, <strong>new</strong> method generates a new
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55 <strong>SimpleCalcParser</strong> and returns a reference to newly created <strong>SimpleCalcYYParser</strong> object.</p>
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56 <p>Examples:</p>
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57 <div class="OptionsBox">
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58 # Input string...
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59 <br/> $InputText = "3 + 4 +6\nx=3\ny=5\nx+y\nx+z\n";
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60 <br/> $YYLexer = new Parsers::SimpleCalcYYLexer($InputText);
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61 <br/> $YYLex = $YYLexer->GetYYLex();</div>
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62 <div class="OptionsBox">
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63 $Debug = 0;
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64 <br/> $SimpleCalcParser = new Parsers::SimpleCalcParser($YYLex,
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65 \&Parsers::SimpleCalcParser::yyerror, $Debug);
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66 <br/> $Value = $SimpleCalcParser->yyparse();
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67 <br/> print "Value = " . (defined($Value) ? "$Value" : "Undefined") . "\n";</div>
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68 <div class="OptionsBox">
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69 # Input file...
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70 <br/> $InputFile = "TestSimpleCalcParser.txt";
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71 <br/> open INPUTFILE, "$InputFile" or die "Couldn't open $InputFile: $!\n";</div>
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72 <div class="OptionsBox">
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73 $YYLexer = new Parsers::SimpleCalcYYLexer(\*INPUTFILE);
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74 <br/> $YYLex = $YYLexer->GetYYLex();</div>
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75 <div class="OptionsBox">
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76 $Debug = 0;
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77 <br/> $SimpleCalcParser = new Parsers::SimpleCalcParser($YYLex,
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78 \&Parsers::SimpleCalcParser::yyerror, $Debug);
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79 <br/> $Value = $SimpleCalcParser->yyparse();
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80 <br/> print "Value = " . (defined($Value) ? "$Value" : "Undefined") . "\n";</div>
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81 <div class="OptionsBox">
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82 close INPUTFILE;</div>
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83 <div class="OptionsBox">
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84 # Input iterator...
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85 <br/> $InputFile = "TestSimpleCalcParser.txt";
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86 <br/> open INPUTFILE, "$InputFile" or die "Couldn't open $InputFile: $!\n";
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87 <br/> $InputIterator = sub { return <INPUTFILE>; };</div>
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88 <div class="OptionsBox">
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89 $YYLexer = new Parsers::SimpleCalcYYLexer($InputIterator);
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90 <br/> $YYLex = $YYLexer->GetYYLex();</div>
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91 <div class="OptionsBox">
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92 $Debug = 0;
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93 <br/> $SimpleCalcParser = new Parsers::SimpleCalcParser($YYLex,
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94 \&Parsers::SimpleCalcParser::yyerror, $Debug);
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95 <br/> $Value = $SimpleCalcParser->yyparse();
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96 <br/> print "Value = " . (defined($Value) ? "$Value" : "Undefined") . "\n";</div>
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97 <div class="OptionsBox">
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98 close INPUTFILE;</div>
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99 </dd>
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100 <dt><strong><a name="yyclearin" class="item"><strong>yyclearin</strong></a></strong></dt>
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101 <dd>
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102 <div class="OptionsBox">
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103 $SimpleCalcParser->yyclearin();</div>
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104 <p><strong>yyclearin</strong> method clears any previous look-ahead token after encountering a syntax error
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105 during parsing. It can be used after <strong>yyerrok</strong> in a grammer rule with the reserved word
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106 <strong>error</strong>.</p>
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107 </dd>
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108 <dt><strong><a name="yyerrok" class="item"><strong>yyerrok</strong></a></strong></dt>
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109 <dd>
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110 <div class="OptionsBox">
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111 $SimpleCalcParser->yyerrok();</div>
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112 <p><strong>yyerrok</strong> method is used with the reserved word <strong>error</strong> in grammer rule to indcate
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113 error recovery is complete after encountering a syntax error during parsing.</p>
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114 </dd>
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115 <dt><strong><a name="yyerror" class="item"><strong>yyerror</strong></a></strong></dt>
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116 <dd>
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117 <div class="OptionsBox">
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118 $SimpleCalcParser->yyerror();</div>
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119 <p><strong>yyerror</strong> function is provided for the caller to use during initialization of a parser. It
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120 is used by <strong>yyparse</strong> to print any error messages encountered during parsing of the
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121 input.</p>
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122 </dd>
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123 <dt><strong><a name="yyparse" class="item"><strong>yyparse</strong></a></strong></dt>
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124 <dd>
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125 <div class="OptionsBox">
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126 $Value = $SimpleCalcParser->yyparse();</div>
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127 <p>Returns <em>Value</em> after parsing all the input from a input stream using specified
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128 grammer rules.</p>
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129 </dd>
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130 </dl>
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131 <p>
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132 </p>
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133 <h2>AUTHOR</h2>
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134 <p><a href="mailto:msud@san.rr.com">Manish Sud</a></p>
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135 <p>
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136 </p>
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137 <h2>SEE ALSO</h2>
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138 <p><a href="./Lexer.html">Lexer.pm</a>, <a href="./YYLexer.html">YYLexer.pm</a>, <a href="./SimpleCalcYYLexer.html">SimpleCalcYYLexer.pm</a>
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139 </p>
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140 <p>
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141 </p>
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142 <h2>COPYRIGHT</h2>
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143 <p>Copyright (C) 2015 Manish Sud. All rights reserved.</p>
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144 <p>This file is part of MayaChemTools.</p>
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145 <p>MayaChemTools is free software; you can redistribute it and/or modify it under
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146 the terms of the GNU Lesser General Public License as published by the Free
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147 Software Foundation; either version 3 of the License, or (at your option)
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148 any later version.</p>
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149 <p> </p><p> </p><div class="DocNav">
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150 <table width="100%" border=0 cellpadding=0 cellspacing=2>
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151 <tr align="left" valign="top"><td width="33%" align="left"><a href="./Lexer.html" title="Lexer.html">Previous</a> <a href="./index.html" title="Table of Contents">TOC</a> <a href="./SimpleCalcYYLexer.html" title="SimpleCalcYYLexer.html">Next</a></td><td width="34%" align="middle"><strong>March 29, 2015</strong></td><td width="33%" align="right"><strong>Parsers::SimpleCalcParser.pm</strong></td></tr>
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152 </table>
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153 </div>
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154 <br />
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