TIMTOWTDI

NOTE that this example iterates over HoH not AoAs (which is a bit silly b/c order matters) since I have only 5.10 installed.

With >=5.12 each should also work with ARRAYs! (testing appreciated)

It might not be the most elegant solution but

a) it's really lazy - not only for the programmer - and

b) it can iterate nested Arrays and Hashes alike for >=5.12.

c) it's quite fast.

d) I can tell the recursion "depth" of each iteration. NOTE I'm only returning 3 values for better visualization/debugging. Only $v matters for this task. 

use Data::Dump 'dd';
use strict;
use warnings;

dd my $h1 = { a => {b => {c => 1}, d=> 2}, e=>3,f=>4 };
dd my $h2 = { a => {b => {c => 1}, d=> 2}, e=>3,f=>4 };

sub gen {
  my $ref=shift;
  my @path=();
  return sub {
    while (1) {
      while (my ($k,$v) = each %$ref) {
        if ( ref $v eq "HASH") {
          push @path,$ref;
          $ref =$v;
          next;
        } else {
          return $k,$v,scalar @path;
        }
      }
      return unless  $ref = pop @path;
    }
  }
}

my $iter1=gen($h1);
my $iter2=gen($h2);

while ((my ($k1,$v1,$l1) = $iter1->()) + (my ($k2,$v2,$l2) = $iter2->(
+)) ) {
  die "error $v1 != $v2" if $v1 ne $v2; 
  print "$l1: $k1=> $v1\n";
}

[download]

out

/usr/bin/perl -w /tmp/lanx_fringe.pl 
{ a => { b => { c => 1 }, d => 2 }, e => 3, f => 4 }
{ a => { b => { c => 1 }, d => 2 }, e => 3, f => 4 }
0: e=> 3
2: c=> 1
1: d=> 2
0: f=> 4

[download]
a more functional solution on Monday.

Cheers Rolf

( addicted to the Perl Programming Language)

UPDATE

I just realized that it's about binary trees and that the representation of them is free.

So when choosing nested hashes with keys L and R , this algorithm already delivers the needed features. =)

UPDATE

Limitations see Re^3: Challenge: Perl 5: lazy sameFringe()?

In reply to Re: Challenge: Perl 5: lazy sameFringe()? by LanX
in thread Challenge: Perl 5: lazy sameFringe()? by BrowserUk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.