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# -*- Mode: Python -*-

#
# --- [ A port of the calculator example in Stroustrup's ]--------------
#

use Test::More 'no_plan';
use Acme::Pythonic debug => 0;

use strict
use warnings

use vars qw($cin $curr_tok $number_value $string_value %table)

use constant NAME   => 0
use constant NUMBER => 1
use constant STOP   => 2   # END is a Perl keyword
use constant PLUS   => '+'
use constant MINUS  => '-'
use constant MUL    => '*'
use constant DIV    => '/'
use constant PRINT  => ';'
use constant ASSIGN => '='
use constant LP     => '('
use constant RP     => ')'

%table = (pi => 3.1415926535897932385,
          e  => 2.7182818284590452354)

$curr_tok = PRINT

sub main:
    $cin = shift
    while $cin ne '':
        get_token()
        last if $curr_tok eq STOP
        next if $curr_tok eq PRINT
        return expr(0)

sub expr:
    my $get = shift
    my $left = term($get)
    while:
        $left += term(1), last if $curr_tok eq PLUS
        $left -= term(1), last if $curr_tok eq MINUS
        return $left

sub term:
    my $get = shift
    my $left = prim($get)
    while:
        $left *= prim(1), last if $curr_tok eq MUL
        if $curr_tok eq DIV:
            if my $d = prim(1):
                $left *= $d**(-1) # Filter::Simple eated too much with conventional notation
                last
            die
        return $left

sub prim:
    my $get = shift
    get_token() if $get

    if $curr_tok eq NUMBER:
        my $v = $number_value
        get_token()
        return $v
    if $curr_tok eq NAME: