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package Iterator::Flex::Freeze;
# ABSTRACT:  Freeze an iterator after every next
use strict;
use warnings;
use experimental 'signatures';
our $VERSION = '0.18';
use Iterator::Flex::Factory;
use Iterator::Flex::Utils qw( RETURN EXHAUSTION :IterAttrs :Methods );
use parent 'Iterator::Flex::Base';
use Scalar::Util;
use Ref::Util;
use namespace::clean;
sub new ( $class, $code, $iterator, $pars = {} ) {
    $class->_throw( parameter => "'serialize' parameter is not a coderef" )
      unless Ref::Util::is_coderef( $code );
    $class->_throw( parameter => "iterator (@{[ $iterator->_name ]}) must provide a freeze method" )
      unless $class->_can_meth( $iterator, +FREEZE );
    $class->_throw(
        parameter => "iterator (@{[ $iterator->_name ]}) must provide set_exhausted/is_exhausted methods" )
      unless $class->_can_meth( $iterator, +SET_EXHAUSTED )
      && $class->_can_meth( $iterator, +IS_EXHAUSTED );
    $class->SUPER::new( { serialize => $code, src => $iterator }, $pars );
}
sub construct ( $class, $state ) {
    $class->_throw( parameter => "'state' parameter must be a HASH reference" )
      unless Ref::Util::is_hashref( $state );
    my ( $serialize, $src ) = @{$state}{qw( serialize src )};
    $class->_throw( parameter => "'serialize' must be a CODE reference" )
      unless Ref::Util::is_coderef( $serialize );
    # wrap the source iterator so that it returns undef on exhaustion.
    $src
      = Iterator::Flex::Factory->to_iterator( $src, { ( +EXHAUSTION ) => +RETURN } );
    my $self;
    my %params = (
        ( +_NAME ) => 'freeze',
        ( +_SELF ) => \$self,
        ( +_DEPENDS ) => $src,
        ( +NEXT )     => sub {
            my $value = $src->();
            local $_ = $src->freeze;
            &$serialize();
            $value = $self->signal_exhaustion if $src->is_exhausted;
            return $value;
        },
    );
    Scalar::Util::weaken $src;
    $params{ +_ROLES } = [];
    for my $meth ( +PREV, +CURRENT, +REWIND, +RESET ) {
        next unless $src->may( $meth );
        my $sub = $src->can( $meth );
        Scalar::Util::weaken $sub;
        $params{$meth} = sub {
            $src->$sub();
        };
        # figure out which role was used to describe the capability
        my $Umeth = ucfirst $meth;
        my $role;
        for my $suffix ( 'Closure', 'Method' ) {
            $role = eval { $class->_load_role( $suffix ? $Umeth . '::' . $suffix : $Umeth ); };
            next if $@ ne '';
            last if $src->does( $role );
            undef $role;
        }
        $class->_throw( class => "unable to find role for '$meth' capability for @{[ $src->_name ]}" )
          unless defined $role;
        # need '+' as role names are fully qualified
        push $params{ +_ROLES }->@*, '+' . $role;
    }
    return \%params;
}
__PACKAGE__->_add_roles( qw[
      State::Registry
      Next::ClosedSelf
] );
1;
#
# This file is part of Iterator-Flex
#
# This software is Copyright (c) 2018 by Smithsonian Astrophysical Observatory.
#
# This is free software, licensed under:
#
#   The GNU General Public License, Version 3, June 2007
#
__END__
HideShow 88 lines of Pod
=pod
=for :stopwords Diab Jerius Smithsonian Astrophysical Observatory
=head1 NAME
Iterator::Flex::Freeze - Freeze an iterator after every next
=head1 VERSION
version 0.18
=head1 METHODS
=head2 construct
  $iter = Iterator::Flex::Freeze->new( $coderef, $iterator, ?\%pars );
Construct a pass-through iterator which freezes the input iterator
after every call to C<next>.  C<$coderef> will be passed the frozen state
(generated by calling C<$iterator->freeze> via C<$_>, with which it
can do as it pleases.
<$coderef> I<is> executed when C<$iterator> is exhausted.
The optional C<%pars> hash may contain standard L<signal
parameters|Iterator::Flex::Manual::Overview/Signal Parameters>.
The returned iterator supports the following methods:
=over
=item next
=item prev
If C<$iterator> provides a C<prev> method.
=item rewind
=item freeze
=back
=head1 INTERNALS
=head1 SUPPORT
=head2 Bugs
Please report any bugs or feature requests to bug-iterator-flex@rt.cpan.org  or through the web interface at: L<https://rt.cpan.org/Public/Dist/Display.html?Name=Iterator-Flex>
=head2 Source
Source is available at
  https://gitlab.com/djerius/iterator-flex
and may be cloned from
  https://gitlab.com/djerius/iterator-flex.git
=head1 SEE ALSO
Please see those modules/websites for more information related to this module.
=over 4
=item *
L<Iterator::Flex|Iterator::Flex>
=back
=head1 AUTHOR
Diab Jerius <djerius@cpan.org>
=head1 COPYRIGHT AND LICENSE
This software is Copyright (c) 2018 by Smithsonian Astrophysical Observatory.
This is free software, licensed under:
  The GNU General Public License, Version 3, June 2007
=cut