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=head1 NAME

Iterator::Misc - Miscellaneous iterator functions.

=head1 VERSION

This documentation describes version 0.03 of Iterator::Misc, August 26, 2005.

=cut

use strict;
use warnings;
package Iterator::Misc;
our $VERSION = '0.03';

use base 'Exporter';
use vars qw/@EXPORT @EXPORT_OK %EXPORT_TAGS/;

@EXPORT      = qw(ipermute igeometric inth irand_nth ifibonacci);
@EXPORT_OK   = @EXPORT;

use Iterator;

# Function name: ipermute
# Synopsis:      $iter = ipermute (@items);
# Description:   Generates permutations of a list.
# Created:       07/29/2005 by EJR
# Parameters:    @items - the items to be permuted.
# Returns:       Sequence iterator
# Exceptions:    Iterator::X::Am_Now_Exhausted
# Notes:         Algorithm from MJD's book.
sub ipermute
{
    my @items = @_;
    my @digits = (0) x @items;     # "Odometer".  See Dominus, pp 128-135.

    return Iterator->new (sub
    {
        unless (@digits)
        {
            Iterator::is_done;
        }

        # Use the existing state to create a new permutation
        my @perm = ();
        my @c_items = @items;
        push @perm, splice(@c_items, $_, 1)  for @digits;

        # Find the rightmost column that isn't already maximum
        my $column = $#digits;
        until ($digits[$column] < $#digits-$column || $column < 0)
            { $column-- }

        if ($column < 0)
        {
            # Last set. Generate no more.
            @digits = ();

Misc.pm  view on Meta::CPAN

that is, there are no more values in the sequence to return.

As a string, this exception is "Iterator is exhausted."

=item * User Code Exceptions

Class: C<Iterator::X::User_Code_Error>

This exception is thrown when the sequence generation code throws any
sort of error besides C<Am_Now_Exhausted>.  This could be because your
code explicitly threw an error (that is, C<die>d), or because it
otherwise encountered an exception (any runtime error).

This exception has one method, C<eval_error>, which returns the
original C<$@> that was trapped by the Iterator object.  This may be a
string or an object, depending on how C<die> was invoked.

As a string, this exception evaluates to the stringified C<$@>.

=item * Internal Errors

Class: C<Iterator::X::Internal_Error>

Something happened that I thought couldn't possibly happen.  I would
appreciate it if you could send me an email message detailing the
circumstances of the error.

=back

=head1 REQUIREMENTS

Requires the following additional modules:

L<Iterator>

=head1 SEE ALSO

I<Higher Order Perl>, Mark Jason Dominus, Morgan Kauffman 2005.

L<http://perl.plover.com/hop/>

=head1 THANKS

Much thanks to Will Coleda and Paul Lalli (and the RPI lily crowd in
general) for suggestions for the pre-release version.

=head1 AUTHOR / COPYRIGHT

Eric J. Roode, roode@cpan.org

Copyright (c) 2005 by Eric J. Roode.  All Rights Reserved.
This module is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.

To avoid my spam filter, please include "Perl", "module", or this
module's name in the message's subject line, and/or GPG-sign your
message.

=cut

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