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1 package Parsers::SimpleCalcParser;
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2 #
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3 # $RCSfile: SimpleCalcParser.yy,v $
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4 # $Date: 2015/02/28 20:50:55 $
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5 # $Revision: 1.10 $
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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 # A WORD TO THE WISE:
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30 #
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31 # The parser package and token table files, SimpleCalcParser.pm and
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32 # SimpleCalcParser.tab.ph, are automatically generated from parser grammar
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33 # definition file, SimpleCalcParser.yy, using byacc available through perl-byacc1.8
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34 # modified with perl5-byacc-patches-0.5 for generation of object oriented parser:
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35 #
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36 # byacc -l -P -d -b SimpleCalcParser SimpleCalcParser.yy
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37 # mv SimpleCalcParser.tab.pl SimpleCalcParser.pm
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38 #
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39
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40 use Carp;
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41
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42 # Setup a hash map for mapping of words/letters to values...
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43 %LetterToValueMap = ();
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44
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45 $NUMBER=257;
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46 $LETTER=258;
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47 $YYERRCODE=256;
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48 @yylhs = ( -1,
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49 0, 0, 0, 1, 1, 2, 2, 2, 2, 2,
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50 2, 2, 2,
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51 );
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52 @yylen = ( 2,
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53 0, 3, 3, 1, 3, 3, 3, 3, 3, 3,
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54 3, 1, 1,
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55 );
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56 @yydefred = ( 1,
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57 0, 0, 12, 0, 0, 0, 0, 3, 0, 13,
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58 0, 2, 0, 0, 0, 0, 0, 0, 6, 0,
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59 0, 0, 0, 11,
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60 );
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61 @yydgoto = ( 1,
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62 6, 7,
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63 );
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64 @yysindex = ( 0,
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65 -40, -7, 0, -57, -38, -5, -18, 0, -38, 0,
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66 -31, 0, -38, -38, -38, -38, -38, -18, 0, -16,
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67 -16, -30, -30, 0,
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68 );
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69 @yyrindex = ( 0,
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70 0, 0, 0, -9, 0, 0, -1, 0, 0, 0,
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71 0, 0, 0, 0, 0, 0, 0, 3, 0, 8,
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72 13, -2, 5, 0,
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73 );
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74 @yygindex = ( 0,
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75 0, 50,
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76 );
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77 $YYTABLESIZE=220;
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78 @yytable = ( 5,
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79 13, 5, 8, 9, 12, 17, 17, 9, 4, 19,
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80 15, 13, 5, 14, 10, 16, 0, 7, 17, 0,
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81 17, 0, 8, 15, 13, 15, 14, 13, 16, 0,
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82 16, 0, 13, 13, 0, 13, 0, 13, 9, 9,
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83 9, 0, 9, 0, 9, 10, 10, 10, 7, 10,
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84 7, 10, 7, 8, 11, 8, 0, 8, 18, 0,
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85 0, 0, 20, 21, 22, 23, 24, 0, 0, 0,
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86 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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87 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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88 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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89 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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90 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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91 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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92 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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93 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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94 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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95 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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96 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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97 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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98 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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99 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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100 0, 0, 0, 0, 0, 2, 3, 4, 3, 10,
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101 );
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102 @yycheck = ( 40,
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103 10, 40, 10, 61, 10, 37, 37, 10, 10, 41,
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104 42, 43, 10, 45, 10, 47, -1, 10, 37, -1,
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105 37, -1, 10, 42, 43, 42, 45, 37, 47, -1,
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106 47, -1, 42, 43, -1, 45, -1, 47, 41, 42,
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107 43, -1, 45, -1, 47, 41, 42, 43, 41, 45,
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108 43, 47, 45, 41, 5, 43, -1, 45, 9, -1,
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109 -1, -1, 13, 14, 15, 16, 17, -1, -1, -1,
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110 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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111 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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112 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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113 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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114 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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115 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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116 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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117 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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118 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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119 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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120 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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121 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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122 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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123 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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124 -1, -1, -1, -1, -1, 256, 257, 258, 257, 258,
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125 );
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126 $YYFINAL=1;
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127 #ifndef YYDEBUG
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128 #define YYDEBUG 0
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129 #endif
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130 $YYMAXTOKEN=258;
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131 #if YYDEBUG
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132 @yyname = (
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133 "end-of-file",'','','','','','','','','',"'\\n'",'','','','','','','','','','','','','','','','','','','','',
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134 '','','','','','',"'%'",'','',"'('","')'","'*'","'+'",'',"'-'",'',"'/'",'','','','','','','','','',
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135 '','','','',"'='",'','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','',
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136 '','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','',
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137 '','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','',
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138 '','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','',
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139 '','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','','',
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140 '','',"NUMBER","LETTER",
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141 );
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142 @yyrule = (
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143 "\$accept : list",
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144 "list :",
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145 "list : list stat '\\n'",
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146 "list : list error '\\n'",
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147 "stat : expr",
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148 "stat : LETTER '=' expr",
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149 "expr : '(' expr ')'",
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150 "expr : expr '+' expr",
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151 "expr : expr '-' expr",
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152 "expr : expr '*' expr",
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153 "expr : expr '/' expr",
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154 "expr : expr '%' expr",
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155 "expr : NUMBER",
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156 "expr : LETTER",
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157 );
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158 #endif
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159
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160 sub yyclearin { $_[0]->{'yychar'} = -1; }
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161
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162 sub yyerrok { $_[0]->{'yyerrflag'} = 0; }
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163
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164 sub new {
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165 my $p = {'yylex' => $_[1], 'yyerror' => $_[2], 'yydebug' => $_[3]};
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166 bless $p, $_[0];
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167 }
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168
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169 sub YYERROR { ++$_[0]->{'yynerrs'}; $_[0]->yy_err_recover; }
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170
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171 sub yy_err_recover {
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172 #
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173 # msud@san.rr.com:
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174 #
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175 # Turn off "exiting" warning to suppress the following warning at "next yyloop":
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176 #
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177 # Exiting subroutine via next at <LineNum>
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178 #
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179 # The code does work as expected with or without turning off the warning.
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180 # This method is invoked in yyparse method directly or indirectly in another
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181 # method and Perl compilers ends up finding "yyloop" as the nearst enclosure
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182 # label.
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183 #
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184 no warnings qw(exiting);
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185
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186 my ($p) = @_;
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187 if ($p->{'yyerrflag'} < 3)
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188 {
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189 $p->{'yyerrflag'} = 3;
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190 while (1)
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191 {
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192 if (($p->{'yyn'} = $yysindex[$p->{'yyss'}->[$p->{'yyssp'}]]) &&
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193 ($p->{'yyn'} += $YYERRCODE) >= 0 &&
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194 $p->{'yyn'} < @yycheck &&
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195 $yycheck[$p->{'yyn'}] == $YYERRCODE)
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196 {
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197 warn("yydebug: state " .
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198 $p->{'yyss'}->[$p->{'yyssp'}] .
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199 ", error recovery shifting to state" .
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200 $yytable[$p->{'yyn'}] . "\n")
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201 if $p->{'yydebug'};
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202 $p->{'yyss'}->[++$p->{'yyssp'}] =
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203 $p->{'yystate'} = $yytable[$p->{'yyn'}];
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204 $p->{'yyvs'}->[++$p->{'yyvsp'}] = $p->{'yylval'};
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205 next yyloop;
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206 }
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207 else
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208 {
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209 warn("yydebug: error recovery discarding state ".
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210 $p->{'yyss'}->[$p->{'yyssp'}]. "\n")
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211 if $p->{'yydebug'};
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212 return(undef) if $p->{'yyssp'} <= 0;
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213 --$p->{'yyssp'};
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214 --$p->{'yyvsp'};
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215 }
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216 }
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217 }
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218 else
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219 {
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220 return (undef) if $p->{'yychar'} == 0;
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221 if ($p->{'yydebug'})
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222 {
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223 $p->{'yys'} = '';
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224 if ($p->{'yychar'} <= $YYMAXTOKEN) { $p->{'yys'} =
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225 $yyname[$p->{'yychar'}]; }
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226 if (!$p->{'yys'}) { $p->{'yys'} = 'illegal-symbol'; }
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227 warn("yydebug: state " . $p->{'yystate'} .
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228 ", error recovery discards " .
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229 "token " . $p->{'yychar'} . "(" .
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230 $p->{'yys'} . ")\n");
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231 }
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232 $p->{'yychar'} = -1;
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233 next yyloop;
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234 }
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235 0;
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236 } # yy_err_recover
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237
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238 sub yyparse {
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239 my ($p, $s) = @_;
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240 if ($p->{'yys'} = $ENV{'YYDEBUG'})
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241 {
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242 $p->{'yydebug'} = int($1) if $p->{'yys'} =~ /^(\d)/;
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243 }
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244
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245 $p->{'yynerrs'} = 0;
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246 $p->{'yyerrflag'} = 0;
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247 $p->{'yychar'} = (-1);
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248
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249 $p->{'yyssp'} = 0;
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250 $p->{'yyvsp'} = 0;
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251 $p->{'yyss'}->[$p->{'yyssp'}] = $p->{'yystate'} = 0;
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252
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253 yyloop: while(1)
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254 {
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255 yyreduce: {
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256 last yyreduce if ($p->{'yyn'} = $yydefred[$p->{'yystate'}]);
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257 if ($p->{'yychar'} < 0)
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258 {
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259 if ((($p->{'yychar'}, $p->{'yylval'}) =
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260 &{$p->{'yylex'}}($s)) < 0) { $p->{'yychar'} = 0; }
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261 if ($p->{'yydebug'})
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262 {
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263 $p->{'yys'} = '';
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264 if ($p->{'yychar'} <= $#yyname)
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265 { $p->{'yys'} = $yyname[$p->{'yychar'}]; }
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266 if (!$p->{'yys'}) { $p->{'yys'} = 'illegal-symbol'; };
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267 warn("yydebug: state " . $p->{'yystate'} .
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268 ", reading " . $p->{'yychar'} . " (" .
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269 $p->{'yys'} . ")\n");
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270 }
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271 }
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272 if (($p->{'yyn'} = $yysindex[$p->{'yystate'}]) &&
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273 ($p->{'yyn'} += $p->{'yychar'}) >= 0 &&
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274 $yycheck[$p->{'yyn'}] == $p->{'yychar'})
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275 {
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276 warn("yydebug: state " . $p->{'yystate'} .
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277 ", shifting to state " .
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278 $yytable[$p->{'yyn'}] . "\n") if $p->{'yydebug'};
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279 $p->{'yyss'}->[++$p->{'yyssp'}] = $p->{'yystate'} =
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280 $yytable[$p->{'yyn'}];
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281 $p->{'yyvs'}->[++$p->{'yyvsp'}] = $p->{'yylval'};
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282 $p->{'yychar'} = (-1);
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283 --$p->{'yyerrflag'} if $p->{'yyerrflag'} > 0;
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284 next yyloop;
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285 }
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286 if (($p->{'yyn'} = $yyrindex[$p->{'yystate'}]) &&
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287 ($p->{'yyn'} += $p->{'yychar'}) >= 0 &&
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288 $yycheck[$p->{'yyn'}] == $p->{'yychar'})
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289 {
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290 $p->{'yyn'} = $yytable[$p->{'yyn'}];
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291 last yyreduce;
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292 }
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293 if (! $p->{'yyerrflag'}) {
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294 if ( (defined($EOI) && $p->{'yychar'} == $EOI) || ($p->{'yychar'} == 0) ) {
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295 &{$p->{'yyerror'}}("syntax error at or near the end of input text", $s);
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296 }
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297 else {
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298 &{$p->{'yyerror'}}("syntax error at or near input text: '$p->{'yylval'}'", $s);
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299 }
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300 ++$p->{'yynerrs'};
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301 }
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302 return(undef) if $p->yy_err_recover;
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303 } # yyreduce
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304 warn("yydebug: state " . $p->{'yystate'} .
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305 ", reducing by rule " .
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306 $p->{'yyn'} . " (" . $yyrule[$p->{'yyn'}] .
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307 ")\n") if $p->{'yydebug'};
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308 $p->{'yym'} = $yylen[$p->{'yyn'}];
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309 $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}+1-$p->{'yym'}];
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310
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311 if ($p->{'yyn'} == 2) {
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312 { $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}-1]; }
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313 }
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314
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315 if ($p->{'yyn'} == 3) {
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316 { $p->yyerrok; $p->yyclearin; }
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317 }
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318
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319 if ($p->{'yyn'} == 4) {
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320 { $ExprOut = sprintf "%5i", $p->{'yyvs'}->[$p->{'yyvsp'}-0]; print "$ExprOut\n"; $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}-0]; }
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321 }
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322
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323 if ($p->{'yyn'} == 5) {
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324 { $LetterToValueMap{$p->{'yyvs'}->[$p->{'yyvsp'}-2]} = $p->{'yyvs'}->[$p->{'yyvsp'}-0]; }
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325 }
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326
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327 if ($p->{'yyn'} == 6) {
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328 { $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}-1]; }
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329 }
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330
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331 if ($p->{'yyn'} == 7) {
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332 { $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}-2] + $p->{'yyvs'}->[$p->{'yyvsp'}-0]; }
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333 }
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334
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335 if ($p->{'yyn'} == 8) {
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336 { $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}-2] - $p->{'yyvs'}->[$p->{'yyvsp'}-0]; }
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337 }
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338
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339 if ($p->{'yyn'} == 9) {
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340 { $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}-2] * $p->{'yyvs'}->[$p->{'yyvsp'}-0]; }
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341 }
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342
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343 if ($p->{'yyn'} == 10) {
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344 { $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}-2] / $p->{'yyvs'}->[$p->{'yyvsp'}-0]; }
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345 }
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346
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347 if ($p->{'yyn'} == 11) {
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348 { $p->{'yyval'} = $p->{'yyvs'}->[$p->{'yyvsp'}-2] % $p->{'yyvs'}->[$p->{'yyvsp'}-0]; }
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349 }
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350
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351 if ($p->{'yyn'} == 13) {
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352 {
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353 if (exists $LetterToValueMap{$p->{'yyvs'}->[$p->{'yyvsp'}-0]}) {
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354 $p->{'yyval'} = $LetterToValueMap{$p->{'yyvs'}->[$p->{'yyvsp'}-0]};
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355 }
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356 else {
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357 $Letter = $p->{'yyvs'}->[$p->{'yyvsp'}-0];
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358 print "Undefined variable $Letter encountered by SimpleCalcParser; Value set to 0\n";
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359 $p->{'yyval'} = 0;
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360 }
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361 }
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362 }
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363 $p->{'yyssp'} -= $p->{'yym'};
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364 $p->{'yystate'} = $p->{'yyss'}->[$p->{'yyssp'}];
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365 $p->{'yyvsp'} -= $p->{'yym'};
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366 $p->{'yym'} = $yylhs[$p->{'yyn'}];
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367 if ($p->{'yystate'} == 0 && $p->{'yym'} == 0)
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368 {
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369 warn("yydebug: after reduction, shifting from state 0 ",
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370 "to state $YYFINAL\n") if $p->{'yydebug'};
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371 $p->{'yystate'} = $YYFINAL;
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372 $p->{'yyss'}->[++$p->{'yyssp'}] = $YYFINAL;
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373 $p->{'yyvs'}->[++$p->{'yyvsp'}] = $p->{'yyval'};
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374 if ($p->{'yychar'} < 0)
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375 {
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376 if ((($p->{'yychar'}, $p->{'yylval'}) =
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377 &{$p->{'yylex'}}($s)) < 0) { $p->{'yychar'} = 0; }
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378 if ($p->{'yydebug'})
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379 {
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380 $p->{'yys'} = '';
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381 if ($p->{'yychar'} <= $#yyname)
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382 { $p->{'yys'} = $yyname[$p->{'yychar'}]; }
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383 if (!$p->{'yys'}) { $p->{'yys'} = 'illegal-symbol'; }
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384 warn("yydebug: state $YYFINAL, reading " .
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385 $p->{'yychar'} . " (" . $p->{'yys'} . ")\n");
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386 }
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387 }
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388 return ($p->{'yyvs'}->[1]) if $p->{'yychar'} == 0;
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389 next yyloop;
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390 }
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391 if (($p->{'yyn'} = $yygindex[$p->{'yym'}]) &&
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392 ($p->{'yyn'} += $p->{'yystate'}) >= 0 &&
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393 $p->{'yyn'} <= $#yycheck &&
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394 $yycheck[$p->{'yyn'}] == $p->{'yystate'})
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395 {
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396 $p->{'yystate'} = $yytable[$p->{'yyn'}];
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397 } else {
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398 $p->{'yystate'} = $yydgoto[$p->{'yym'}];
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399 }
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400 warn("yydebug: after reduction, shifting from state " .
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401 $p->{'yyss'}->[$p->{'yyssp'}] . " to state " .
|
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402 $p->{'yystate'} . "\n") if $p->{'yydebug'};
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403 $p->{'yyss'}[++$p->{'yyssp'}] = $p->{'yystate'};
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404 $p->{'yyvs'}[++$p->{'yyvsp'}] = $p->{'yyval'};
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405 } # yyloop
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406 } # yyparse
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407
|
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408
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409 # yyerror function supplied to parser along with a lexer during initialization of
|
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|
410 # the parser...
|
|
|
411 #
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412
|
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413 sub yyerror {
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414 my ($msg) = @_;
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|
|
415 print "yyerror: $msg...\n";
|
|
|
416 }
|
|
|
417
|
|
|
418 1;
|
|
|
419
|
|
|
420 __END__
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421
|
|
|
422 =head1 NAME
|
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423
|
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424 Parsers::SimpleCalcParser
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425
|
|
|
426 =head1 SYNOPSIS
|
|
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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:
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|
|
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
|
