NAME
    List::Flatten::Recursive - List::Flatten with recursion

VERSION
    version 0.103460

SYNOPSIS
        use List::Flatten::Recursive qw( flat );
        sub printlist { print '(' . join(', ', @_) . ")\n" }

        my $crazy_listref = [ 1, [ 2, 3 ], [ [ [ 4 ] ] ] ];
        my @flattened = flat($crazy_listref); # Yields (1,2,3,4)
        printlist(@flattened);
        push @$crazy_listref, $crazy_listref; # Now it contains itself!
        @flattened = flat($crazy_listref);    # Still yields (1,2,3,4)
        printlist(@flattened);
        @flattened = flat([ $crazy_listref ]); # Ditto.
        printlist(@flattened);
        # But don't do this for self-referential lists.
        @flattened = flat(@$crazy_listref); # Will not yield the same as above.
        printlist(@flattened);

DESCRIPTION
    If you think of nested lists as a tree structure (an in Lisp, for
    example), then "flat" basically returns all the leaf nodes from an
    inorder tree traversal, and leaves out the internal nodes (i.e.
    listrefs). If the nested list is a DAG instead of just a tree, it should
    still flatten correctly (based on my own definition of correctness, of
    course; see also t/flatten-dag.t).

    If the nested list is self-referential, then any cycles will be broken
    by replacing ancestor references with empty lists. However, the only
    behavior you should rely on when flattening a self-referential data
    structure is that infinite recursion should not occur, and each non-list
    element in the data structure should appear at least once in the output.

METHODS
  flat
    This method flattens a list (or listref) recursively. It takes a list
    that may contain other sublists, and replaces those sublists with their
    contents, recursively, until the list no longer contains any sublists.

    "flat" makes a best effort to break circular references (that is, lists
    that contain references to themselves), so it should not enter infinite
    recursion. If you find a case that causes it to recurse infinitely,
    please inform me.

    This method is exported by default.

  flatten_to_listref
    Same as "flat", but returns a single reference to the resulting list.

    This method is exported only by request. To use this method, put the
    following at the top of your program:

        use List::Flatten::Recursive qw( flatten_to_listref );

BUGS AND LIMITATIONS
  Self-referential lists should be flattened by reference
    If you are going to flatten a list which might contain references to
    itself, you should pass a reference to that list to "flat", or else
    things will not work the way you expect. You will end up with an extra
    instance of each item in the outermost list. However, this will not
    result in infinite recursion.

    This module should never cause infinite recursion. If it does, please
    submit a bug report.

  "flat" always returns a list
    Even if you call "flat" on a single scalar, it will still return a list
    with one element in it. If called in scalar context, it will return the
    length of that list. "flatten_to_listref" would return a reference to a
    list with one element. There is no case where the original scalar would
    be returned directly. This is by design. If you think this is wrong,
    email me and tell me why.

    Please report any bugs or feature requests to
    "rct+perlbug@thompsonclan.org". If you find a case where this module
    returns what you feel is a wrong result, please send an example that
    will cause it to do so, along with the actual and expected results.

SEE ALSO
    * List::Flatten The non-recursive insipiration for this module.

DISCLAIMER OF WARRANTY
    BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
    FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
    OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
    PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER
    EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
    ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH
    YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
    NECESSARY SERVICING, REPAIR, OR CORRECTION.

    IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
    WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
    REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE
    TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR
    CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE
    SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
    RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
    FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF
    SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
    DAMAGES.

AUTHOR
    Ryan C. Thompson <rct@thompsonclan.org>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2010 by Ryan C. Thompson.

    This is free software; you can redistribute it and/or modify it under
    the same terms as the Perl 5 programming language system itself.