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