#! /usr/bin/perl

use strict;
use warnings;

my %data;
my @columns;
my $current;

my $line;
while (<DATA>)
{
  chomp;
  $line = $_;
  if ($line =~ /:$/)
  {
    push @columns, $line;
    $current = $line;
    $data{$current} = ();
  }
  else
  {
    push @{$data{$current}}, $line;
  }
}

print join (",", @columns), "\n";

my $count = @{$data{$columns[0]}};
for my $i (0 .. $count - 1)
{
  for my $c (0 .. $#columns)
  {
    print $data{$columns[$c]}[$i];
    print "," if $c < $#columns;
  }

  print "\n";
}

__DATA__
heading1:
text1
text2
text3
heading2:
text1
text2
text3