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1
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1 NAME
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2 Parsers::SimpleCalcYYLexer
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3
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4 SYNOPSIS
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5 use Parsers::SimpleCalcYYLexer;
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6
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7 use Parsers::SimpleCalcYYLexer qw(:all);
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8
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9 DESCRIPTION
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10 SimpleCalcYYLexer class provides the following methods:
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11
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12 new, YYLex, GetYYLex, StringifySimpleCalcYYLexer
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13
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14 Parser::SimpleCalcYYLexer class is derived from Parser::YYLexer class,
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15 which in turn is derived from base class Parser::Lexer that provides all
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16 the underlying lexer functionality. SimpleCalcYYLexer class is designed
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17 to be used with yyparse code generated by running byacc on a parser
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18 defined using parser definition SimpleCalcParser.yy file.
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19
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20 The parser package and token table files, SimpleCalcParser.pm and
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21 SimpleCalcParser.tab.ph, are automatically generated from parser grammar
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22 definition file, SimpleCalcParser.yy, using byacc available through
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23 perl-byacc1.8 modified with perl5-byacc-patches-0.5 for generation of
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24 object oriented parser:
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25
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26 byacc -l -P -d -b SimpleCalcParser SimpleCalcParser.yy
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27 mv SimpleCalcParser.tab.pl SimpleCalcParser.pm
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28
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29 SimpleCalcYYLexer.pm class implements a lexer for a simple calculator
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30 and is provided to highlight usasge of YYLex through yyparse.
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31
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32 The default specification of lexer tokens for SimpleCalcYYLexer.pm
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33 includes:
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34
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35 @YYLexerTokensSpec = (
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36 [ 'LETTER', qr/[a-zA-Z]/ ],
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37 [ 'NUMBER', qr/\d+/ ],
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38 [ 'SPACE', qr/[ ]*/,
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39 sub { my($This, $TokenLabel, $MatchedText) = @_; return ''; }
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40 ],
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41 [ 'NEWLINE', qr/(?:\r\n|\r|\n)/,
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42 sub { my($This, $TokenLabel, $MatchedText) = @_; return "\n"; }
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43 ],
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44 [ 'CHAR', qr/./ ]
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45 );
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46
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47 The default SimpleCalcParser.tab.ph file containing token identifiers
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48 for SimpleCalcParser.yy includes:
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49
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50 $NUMBER=257;
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51 $LETTER=258;
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52
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53 METHODS
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54 new
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55 $SimpleCalcYYLexer = new Parsers::SimpleCalcYYLexer($Input);
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56
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57 Using specified *Input*, new method generates a new
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58 SimpleCalcYYLexer and returns a reference to newly created
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59 SimpleCalcYYLexer object.
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60
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61 Examples:
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62
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63 # Input string...
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64 $InputText = "3 + 4 +6\nx=3\ny=5\nx+y\nx+z\n";
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65
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66 $YYLexer = new Parsers::SimpleCalcYYLexer($InputText);
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67 $YYLex = $YYLexer->GetYYLex();
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68
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69 $Debug = 0;
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70 $CalcParser = new Parsers::SimpleCalcParser($YYLex,
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71 \&Parsers::SimpleCalcParser::yyerror, $Debug);
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72 $Value = $SimpleCalcParser->yyparse();
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73 print "Value: $Value\n";
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74
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75 # Input file...
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76 $InputFile = "Input.txt";
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77 open INPUTFILE, "$InputFile" or die "Couldn't open $InputFile: $!\n";
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78 $YYLexer = new Parsers::SimpleCalcYYLexer($InputFile);
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79 $YYLex = $YYLexer->GetYYLex();
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80
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81 $CalcParser = new Parsers::SimpleCalcParser($YYLex,
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82 \&Parsers::SimpleCalcParser::yyerror);
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83 $Value = $SimpleCalcParser->yyparse();
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84 print "Value: $Value\n";
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85
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86 # Input file iterator...
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87 $InputFile = "TestSimpleCalcParser.txt";
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88 open INPUTFILE, "$InputFile" or die "Couldn't open $InputFile: $!\n";
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89 $InputIterator = sub { return <INPUTFILE>; };
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90 $YYLexer = new Parsers::SimpleCalcYYLexer($InputIterator);
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91 $YYLex = $YYLexer->GetYYLex();
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92
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93 $CalcParser = new Parsers::SimpleCalcParser($YYLex,
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94 \&Parsers::SimpleCalcParser::yyerror);
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95 $Value = $SimpleCalcParser->yyparse();
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96 print "Value: $Value\n";
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97
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98 StringifySimpleCalcYYLexer
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99 $YYLexerString = $YYLexer->StringifySimpleCalcYYLexer();
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100
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101 Returns a string containing information about *YYLexer* object.
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102
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103 AUTHOR
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104 Manish Sud <msud@san.rr.com>
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105
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106 SEE ALSO
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107 Lexer.pm, YYLexer.pm, SimpleCalcParser.yy
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108
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109 COPYRIGHT
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110 Copyright (C) 2015 Manish Sud. All rights reserved.
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111
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112 This file is part of MayaChemTools.
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113
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114 MayaChemTools is free software; you can redistribute it and/or modify it
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115 under the terms of the GNU Lesser General Public License as published by
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116 the Free Software Foundation; either version 3 of the License, or (at
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117 your option) any later version.
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118
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