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lib/Iterator/Flex/Gather.pm  view on Meta::CPAN

package Iterator::Flex::Gather;

# ABSTRACT: Gather Iterator Class

use v5.28;
use strict;
use warnings;
use experimental 'signatures';

our $VERSION = '0.34';

use Iterator::Flex::Factory 'to_iterator';
use Iterator::Flex::Utils qw[ THROW STATE EXHAUSTION :IterAttrs :IterStates throw_failure];
use Ref::Util;
use parent 'Iterator::Flex::Base';

use Iterator::Flex::Gather::Constants ':all';


use namespace::clean;

lib/Iterator/Flex/Gather.pm  view on Meta::CPAN

sub new ( $class, $code, $iterable, $pars = {} ) {

    throw_failure( parameter => q{'code' parameter is not a coderef} )
      unless Ref::Util::is_coderef( $code );

    my %pars = $pars->%*;

    my %state = (
        code                => $code,
        cycle_on_exhaustion => delete( $pars{cycle_on_exhaustion} ) // GATHER_CYCLE_STOP,
        src                 => $iterable,
    );

    throw_failure( parameter => q{'cycle_on_exhaustion': illegal value} )
      if defined $pars{cycle_on_exhaustion}
      and $pars{cycle_on_exhaustion} != GATHER_CYCLE_CHOOSE
      and !$pars{cycle_on_exhaustion} & ( GATHER_CYCLE_STOP | GATHER_CYCLE_ABORT );

    $class->SUPER::new( \%state, \%pars );
}


sub construct ( $class, $state ) {

    throw_failure( parameter => q{'state' parameter must be a HASH reference} )
      unless Ref::Util::is_hashref( $state );

    my ( $code, $src, $cycle_on_exhaustion ) = @{$state}{qw[ code src cycle_on_exhaustion ]};

    $src
      = to_iterator( $src, { ( +EXHAUSTION ) => THROW } );

    my $self;

    # cached value if current element should be in
    # next cycle
    my $has_cache = !!0;
    my $cache;

    my $iterator_state;

    # This iterator may have to delay signalling exhaustion for one cycle if the
    # input iterator is exhausted, and it needs to return the last group of elements.
    # exhaustion.
    my $next_is_exhausted = !!0;

    return {
        ( +_NAME ) => 'igather',

        ( +_SELF ) => \$self,

        ( +STATE ) => \$iterator_state,

        ( +NEXT ) => sub {
            return $self->signal_exhaustion
              if $iterator_state == IterState_EXHAUSTED || $next_is_exhausted;

            my $cycle;
            my @gathered;
            my $ret = eval {
                while ( 1 ) {

                    my $rv = $has_cache ? $cache : $src->();
                    $has_cache = !!0;

                    local $_ = $rv;
                    my $result = $code->( \@gathered, GATHER_GATHERING );
                    $cycle = $result & GATHER_CYCLE_MASK;

                    throw_failure( parameter => 'cycle action (continue, stop, abort, restart) was not specified' )
                      unless $cycle;

                    if ( ( $result & GATHER_ELEMENT_MASK ) == GATHER_ELEMENT_INCLUDE ) {
                        push @gathered, $rv;
                    }
                    elsif ( ( $result & GATHER_ELEMENT_MASK ) == GATHER_ELEMENT_CACHE ) {
                        throw_failure( parameter =>
                              'inconsistent return: element action GATHER_ELEMENT_CACHE requires cycle action GATHER_CYCLE_STOP',
                        ) unless $cycle & GATHER_CYCLE_RESTART;
                        $cache     = $rv;
                        $has_cache = !!1;
                    }

                    last if $cycle & ( GATHER_CYCLE_RESTART | GATHER_CYCLE_STOP | GATHER_CYCLE_ABORT );
                }
                1;
            };
            if ( !$ret && length $@ ) {

                die $@
                  unless Ref::Util::is_blessed_ref( $@ )
                  && $@->isa( 'Iterator::Flex::Failure::Exhausted' );

                local $_ = undef;
                my $result
                  = $cycle_on_exhaustion == GATHER_CYCLE_CHOOSE
                  ? $code->( \@gathered, GATHER_SRC_EXHAUSTED )
                  : $cycle_on_exhaustion;
                return $self->signal_exhaustion
                  if ( $result & GATHER_CYCLE_ABORT )
                  || ( $result & GATHER_CYCLE_STOP && !@gathered );

                $next_is_exhausted = !!1;
            }

            return \@gathered;
        },
        (
            map { ( ( +RESET ) => $_, ( +REWIND ) => $_, ) } sub {
                $next_is_exhausted = $has_cache = !!0;
            },
        ),
        ( +_DEPENDS ) => $src,
    };
}

__PACKAGE__->_add_roles( qw[
      State::Closure
      Next::ClosedSelf
      Rewind::Closure
      Reset::Closure
      Current::Closure
] );

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__

=pod

=for :stopwords Diab Jerius Smithsonian Astrophysical Observatory

=head1 NAME

Iterator::Flex::Gather - Gather Iterator Class

=head1 VERSION

version 0.34

=head1 METHODS