diff mayachemtools/lib/Parsers/SimpleCalcParser.yy @ 0:73ae111cf86f draft

Uploaded

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mayachemtools/lib/Parsers/SimpleCalcParser.yy	Wed Jan 20 11:55:01 2016 -0500
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+%{
+package Parsers::SimpleCalcParser;
+#
+# $RCSfile: SimpleCalcParser.yy,v $
+# $Date: 2015/02/28 20:50:55 $
+# $Revision: 1.10 $
+#
+# Author: Manish Sud <[e-mail]>
+#
+# Copyright (C) 2015 Manish Sud. All rights reserved.
+#
+# This file is part of MayaChemTools.
+#
+# MayaChemTools is free software; you can redistribute it and/or modify it under
+# the terms of the GNU Lesser General Public License as published by the Free
+# Software Foundation; either version 3 of the License, or (at your option) any
+# later version.
+#
+# MayaChemTools is distributed in the hope that it will be useful, but without
+# any warranty; without even the implied warranty of merchantability of fitness
+# for a particular purpose.  See the GNU Lesser General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with MayaChemTools; if not, see <http://www.gnu.org/licenses/> or
+# write to the Free Software Foundation Inc., 59 Temple Place, Suite 330,
+# Boston, MA, 02111-1307, USA.
+#
+#
+# A WORD TO THE WISE:
+#
+# The parser package and token table files, SimpleCalcParser.pm and
+#  SimpleCalcParser.tab.ph, are automatically generated from parser grammar
+# definition file, SimpleCalcParser.yy, using byacc available through perl-byacc1.8
+# modified with perl5-byacc-patches-0.5 for generation of object oriented parser:
+#
+#    byacc -l -P -d -b SimpleCalcParser SimpleCalcParser.yy
+#    mv SimpleCalcParser.tab.pl SimpleCalcParser.pm
+#
+
+use Carp;
+
+# Setup a hash map for mapping of words/letters to values...
+%LetterToValueMap = ();
+
+%}
+
+%start list
+
+%token NUMBER LETTER
+
+%left '+' '-'
+%left '*' '/'
+%left '%'
+
+%%
+
+list    :
+        |       list  stat  '\n'
+                        {  $$ = $2; }
+        |       list  error  '\n'
+                        { $p->yyerrok; $p->yyclearin; }
+        ;
+
+
+stat    :       expr
+                        {  $ExprOut = sprintf "%5i", $1; print "$ExprOut\n"; $$ = $1; }
+        |       LETTER  '='  expr
+                        { $LetterToValueMap{$1} = $3; }
+        ;
+
+expr    :       '('  expr  ')'
+                        { $$ = $2; }
+        |       expr '+' expr
+                        { $$ = $1 + $3; }
+        |       expr '-' expr
+                        { $$ = $1 - $3; }
+        |       expr '*' expr
+                        { $$ = $1 * $3; }
+        |       expr '/' expr
+                        { $$ = $1 / $3; }
+        |       expr '%' expr
+                        { $$ = $1 % $3; }
+        |       NUMBER
+        |       LETTER
+                        {
+                          if (exists $LetterToValueMap{$1}) {
+                            $$ = $LetterToValueMap{$1};
+                          }
+                          else {
+                            $Letter = $1;
+                            print "Undefined variable $Letter encountered by SimpleCalcParser; Value set to 0\n";
+                            $$ = 0;
+                          }
+                        }
+        ;
+
+%%
+
+# yyerror function supplied to parser along with a lexer during initialization of
+# the parser...
+#
+sub yyerror {
+    my ($msg) = @_;
+    print "yyerror: $msg...\n";
+}
+
+1;
+
+__END__
+
+=head1 NAME
+
+Parsers::SimpleCalcParser
+
+=head1 SYNOPSIS
+
+use Parsers::SimpleCalcParser ;
+
+use Parsers::SimpleCalcParser qw(:all);
+
+=head1 DESCRIPTION
+
+B<Parsers::SimpleCalcParser> class provides the following methods:
+
+new, yyclearin, yyerrok, yyerror, yyparse
+
+B<Parsers::SimpleCalcParse.yy> parser grammer definition file implements a simple
+calculator and is provided to highlight usage of lexer capability available through
+B<Parsers::SimpleCalcYYLexer>, which in turn uses B<Parsers::YYLexer> and
+B<Parsers::Lexer> classes to procide underlying lexer functionality.
+
+The parser package and token table files, B<Parsers::SimpleCalcParser.pm> and
+B<SimpleCalcParser.tab.ph>, are automatically generated from parser grammar definition
+file, B<Parsers::SimpleCalcParser.yy>, using byacc available through perl-byacc1.8 modified
+with perl5-byacc-patches-0.5 for generation of object oriented parser:
+
+    byacc -l -P -d -b SimpleCalcParser SimpleCalcParser.yy
+    mv SimpleCalcParser.tab.pl SimpleCalcParser.pm
+
+=head2 METHODS
+
+=over 4
+
+=item B<new>
+
+    $SimpleCalcParser = new Parsers::SimpleCalcParser($YYLex,
+                                \&Parsers::SimpleCalcParser::yyerror);
+    $SimpleCalcParser = new Parsers::SimpleCalcParser($YYLex,
+                                \&Parsers::SimpleCalcParser::yyerror, $Debug);
+
+Using specified I<YYLex> I<YYError> functions, B<new> method generates a new
+B<SimpleCalcParser> and returns a reference to newly created B<SimpleCalcYYParser> object.
+
+Examples:
+
+    # Input string...
+    $InputText = "3 + 4 +6\nx=3\ny=5\nx+y\nx+z\n";
+    $YYLexer = new Parsers::SimpleCalcYYLexer($InputText);
+    $YYLex = $YYLexer->GetYYLex();
+
+    $Debug = 0;
+    $SimpleCalcParser = new Parsers::SimpleCalcParser($YYLex,
+                               \&Parsers::SimpleCalcParser::yyerror, $Debug);
+    $Value = $SimpleCalcParser->yyparse();
+    print "Value = " . (defined($Value) ? "$Value" : "Undefined") . "\n";
+
+    # Input file...
+    $InputFile = "TestSimpleCalcParser.txt";
+    open INPUTFILE, "$InputFile" or die "Couldn't open $InputFile: $!\n";
+
+    $YYLexer = new Parsers::SimpleCalcYYLexer(\*INPUTFILE);
+    $YYLex = $YYLexer->GetYYLex();
+
+    $Debug = 0;
+    $SimpleCalcParser = new Parsers::SimpleCalcParser($YYLex,
+                               \&Parsers::SimpleCalcParser::yyerror, $Debug);
+    $Value = $SimpleCalcParser->yyparse();
+    print "Value = " . (defined($Value) ? "$Value" : "Undefined") . "\n";
+
+    close INPUTFILE;
+
+    # Input iterator...
+    $InputFile = "TestSimpleCalcParser.txt";
+    open INPUTFILE, "$InputFile" or die "Couldn't open $InputFile: $!\n";
+    $InputIterator = sub { return <INPUTFILE>; };
+
+    $YYLexer = new Parsers::SimpleCalcYYLexer($InputIterator);
+    $YYLex = $YYLexer->GetYYLex();
+
+    $Debug = 0;
+    $SimpleCalcParser = new Parsers::SimpleCalcParser($YYLex,
+                               \&Parsers::SimpleCalcParser::yyerror, $Debug);
+    $Value = $SimpleCalcParser->yyparse();
+    print "Value = " . (defined($Value) ? "$Value" : "Undefined") . "\n";
+
+    close INPUTFILE;
+
+=item B<yyclearin>
+
+    $SimpleCalcParser->yyclearin();
+
+B<yyclearin> method clears any previous look-ahead token after encountering a syntax error
+during parsing. It can be used after B<yyerrok> in a grammer rule with the reserved word
+B<error>.
+
+=item B<yyerrok>
+
+    $SimpleCalcParser->yyerrok();
+
+B<yyerrok> method is used with the reserved word B<error> in grammer rule to indcate
+error recovery is complete after encountering a syntax error during parsing.
+
+=item B<yyerror>
+
+    $SimpleCalcParser->yyerror();
+
+B<yyerror> function is provided for the caller to use during initialization of a parser. It
+is used by B<yyparse> to print any error messages encountered during parsing of the
+input.
+
+=item B<yyparse>
+
+    $Value = $SimpleCalcParser->yyparse();
+
+Returns I<Value> after parsing all the input from a input stream using specified
+grammer rules.
+
+=back
+
+=head1 AUTHOR
+
+Manish Sud <[e-mail]>
+
+=head1 SEE ALSO
+
+Lexer.pm, YYLexer.pm, SimpleCalcYYLexer.pm
+
+=head1 COPYRIGHT
+
+Copyright (C) 2015 Manish Sud. All rights reserved.
+
+This file is part of MayaChemTools.
+
+MayaChemTools is free software; you can redistribute it and/or modify it under
+the terms of the GNU Lesser General Public License as published by the Free
+Software Foundation; either version 3 of the License, or (at your option)
+any later version.
+
+=cut
+