in reply to Generating Hashes from arrays of arbitrary size

I'll ask a meta question. What is your assurance that a particular hash value won't have to do double duty as both a value and a nested hashref? In other words, are you sure you're never gonna have: 
A--B
A--B--X
A--B--Y

[download]
because that would require B to be both a terminal and a non-terminal.

-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.

Replies are listed 'Best First'.
Re^2: Generating Hashes from arrays of arbitrary size
by Anonymous Monk on Sep 30, 2004 at 17:11 UTC
    Yes, this is actually a possibility
[reply]
      This is how I deal with the leaf/node problem. Each level is an array ref, where the first element of the array is the hash ref for the next level, while the second element (if any) is the leaf value (if any). 
      use Data::Dumper;

my %shash;

foreach my $line (<DATA>) {
   # Get rid of end of line.
   chomp($line);

   # Build hash from line.
   my (@items) = split /--/, $line;
   @items or next;

   my $p = \%shash;       # Start at root node
   while (@items > 1) {
     my $i = shift @items;
     $p->{$i}[0] ||= {};  # Create new node if necessary
     $p = $p->{$i}[0];    # Point at new node
   }
   my $i = shift @items;  # Get last item
   $p->{$i}[1] = $i;      # Make it a leaf of the last node
}

print(Dumper(\%shash));

__DATA__
Item1--Item2--Item3
ItemX--Item2--ItemA
Item1--ItemV--Item3--Item4
Item1--Item2--Item3--Dup!
ItemX

      [download]
      Caution: Contents may have been coded under pressure.
[reply]
[d/l]

In Section Seekers of Perl Wisdom