#!/usr/bin/perl
use strict;
use warnings;

my $spaces=0;
while (chomp(my $line=<DATA>)) {
    $line =~ s/^\s+|\s+$//g;
    if ($line =~ /}/) {
        $spaces-=4;
    }
    my $padded = ' ' x $spaces . $line;
    print "$spaces:$padded\n";
    if ($line =~ /{/) {
        $spaces+=4;
    }
}