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#!/usr/bin/perl
use strict;
#Stores the parser table. Its an array of hashes. Each index corresponds
#to ith state. Every key in hash corresponds to a token, value corresponds
#to next state. reduce key specifies the reduction of token and its
#value is an array consisting of number of elements to be reduced and a
#reference to a function to create a node.
my @table;
#Stores labels of nodes.
my @labels;
my $acceptstate = 0;
while( <> )
{
#Finding label word in the current line as every node and edge description
#contains label property. The value of label is extracted.
if( m/label=\"(.*)\"/ )
{
my $token = $1;
#Every edge is denoted as state_number -> state_number . The current
#line is searched for this and to and from state number are extracted.
if( m/(\d+) -> (\d+)/ )
{
# "$end" token is replaced with end.
if( $token eq "\$end" )
{
$table[ $1 ]{ end } = $2;
}
else
{
$table[ $1 ]{ $token } = $2;
}
}
#The line describing the node contains State word in its description
#followed by state number. The state number is extracted and its value
#is stored.
elsif( m/State (\d+)\\n/ )
{
$labels[ $1 ] = $token;
}
}
#Edges denoting reduction are represented as:
#state_number -> state_number R production_number.
#production_number denotes the production by which reduction is to happen.
#It is extracted from the label value of the specified state.
elsif( m/(\d+) -> "\d+R(\d+)"/ )
{
my $state_number = $1;
my $production_number = $2;
#The production is specified as:
#production_number left side: right side .\l
#If left side is $accept then acceptance state number is set to the
#current state number else a reduce key is inserted into current state
#with value equal to an array having number of words on right side and
#function with name of the value of left side.
$labels[$state_number] =~ m/$production_number (.+): (.+)\.\\l/;
if( $1 eq "\$accept" )
{
$table[ $state_number ] = {};
$acceptstate = $state_number;
}
else
{
$table[ $state_number ]{ reduce } = [scalar( split( /\s+/ , $2 )) , " \\&$1" ];
}
}
}
print "package ParserTable;\n\nuse Exporter;\nuse Tree;\n\nour \@ISA=qw(Exporter);\nour \@Export=qw(\@table \$accept);\n\nour \$accept=$acceptstate;\n\n";
#Prints the table.
my @data;
for my $href ( @table )
{
my @hashval;
for my $key ( keys %$href )
{
if( $key eq "reduce" )
{
push @hashval , sprintf( "$key => [%s]",join(", ",@{ $href -> { $key } }));
}
else
{
push @hashval, sprintf( "$key => %s",$href -> { $key });
}
}
push @data, sprintf( "{%s}" , join(", " , @hashval ));
}
print sprintf( "our \@table=(\n\t\t%s\n);" , join ( ",\n\t\t" , @data ));
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