47 lines
750 B
Perl
47 lines
750 B
Perl
|
#! /usr/local/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
|