#!/usr/bin/perl

use strict;
use warnings;
use Term::ReadLine;

my $name = '#perl.br calc';
print $name.$/;
my $term = Term::ReadLine->new($name);
$term->Features()->{'autohistory'} = 1;
my $prompt = "> ";
my $OUT = $term->OUT || \*STDOUT;

my $___eval_str___;
my $M = 0;
my $scale = 2;

sub ler {
        my $a = $term->readline($prompt);
        unless (defined $a) {
                print $/;
                exit(0);
        }
        return $a;
}

sub substituir {
        my $a = shift;
        $a =~ s/^(.+)(\*\*)$/\$M $2 $1/;
        $a =~ s/^(.+)(\+|\-|\*|\/)$/\$M $2 $1/;
        $a =~ s/\;\s*$//;
        if ($a =~ /^\s*do {\s*$/) {
                my $block = '';
                my $count = 1;
                while (defined($_=$term->readline(' '.('.'x$count).' '))) {
                        while ($_ =~ m/\{/g) {
                                $count++;
                        }
                        while ($_ =~ m/\}/g) {
                                $count--;
                        }
                        last if $count < 1;
                        $block .= $_;
                }
                $a = 'do {'.$block.'}';
        }
        return $a;
}

sub falar {
        my $a = shift;
        if ($@) {
                print "! ".$@;
        } else {
                if (defined $a && $a =~ /^[\d\.]$/) {
                        $M=sprintf("%.".$scale."f",$a);
                } elsif ($a) {
                        $M=$a;
                }
                print $OUT "= ".$M.$/ if defined $M;
        }
}

sub doit {
        $___eval_str___ = '
eval("
   falar(".substituir(ler()).");
   $___eval_str___;
");
if($@){
   print "! ".$@;
   eval($___eval_str___)
}
';
        eval $___eval_str___;
}

doit();