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#!/usr/bin/perl -ws
BEGIN
{
unless (-f "Calc.pm")
{
print "You first need to build Calc.pm.\n\n",
"Try: perl -MParse::RecDescent - calc_grammar Calc\n",
" or: demo_buildcalc.pl\n\n";
exit;
}
}
use Parse::RecDescent;
use Calc;
sub evalop
{
# my (@list) = @{[@{$_[0]}]};
my (@list) = @{$_[0]};
my $val = shift(@list)->();
while (@list)
{
my ($op, $arg2) = splice @list, 0, 2;
$op->($val,$arg2->());
}
return $val;
}
my $parse = Calc->new() or die "bad grammar";
print "> ";
while (<DATA>) { # FOR DEMO CHANGE TO: while (<DATA>)
print $parse->main($_), "\n\n> ";
}
__DATA__
$x = 2
$y = 3
+1-1+1-1+1-1+1-1+1
7*7-6*8
121/(121/11)/121*11
1/(10-1/(1/(10-1)))
$x * $y
foreach $i (1..$y) $x = $x * 2 + $i
$x