NAME

Iterator::GroupedRange - Iterates retrieving a set of specified number rows

SYNOPSIS

  use Iterator::GroupedRange;

  my @ds = (
    [ 1 .. 6 ],
    [ 7 .. 11 ],
    [ 11 .. 25 ],
  );

  my $i1 = Iterator::GroupedRange->new( sub { shift @ds; }, 10 );
  $i1->next; # [ 1 .. 10 ]
  $i1->next; # [ 11 .. 20 ]
  $i1->next; # [ 21 .. 25 ]

  my $i2 = Iterator::GroupedRange->new( [ 1 .. 25 ], 10 );
  $i2->next; # [ 1 .. 10 ]
  $i2->next; # [ 11 .. 20 ]
  $i2->next; # [ 21 .. 25 ]

DESCRIPTION

Iterator::GroupedRange is module to iterate retrieving a set of specified number rows. Code reference or list reference becomes provider of sets.

It accepts other iterator to get rows, or list.

METHODS

new( \&provider[, $range, \%opts] )

new( \@list[, $range, \%opts] )

Return new instance. Arguments details are:

&provider

The code reference must be taking a list reference or undef. If the return value is undef or empty array reference, #has_next() will return false value.

@list

This list reference will be code reference that will be return a set of specified number rows.

$range

Most number of retrieving rows by each iteration. Default value is 1000.

%opts

range

Grouped size.

rows

Number of rows. For example, using DBI's statement handle:

  my $sth = $dbh->prepare('SELECT blah FROM example');
  $sth->execute;
  my $iter; $iter = Iterator::GroupedRange->new(sub {
      if ( my $ids = $sth->fetchrow_arrayref( undef, $iter->range ) ) {
          return [ map { $_->[0] } @$ids ];
      }
      else {
          return;
      }
  }, { rows => $sth->rows, range => 1000 });

has_next()

Return which the iterator has next rows or not.

next()

Return next rows.

is_last()

Return which the iterator becomes ended of iteration or not.

append(@items)

append(\@items)

Append new items.

range()

Return grouped size.

rows()

Return total rows.

AUTHOR

Toru Yamaguchi <zigorou@cpan.org>

SEE ALSO

List::MoreUtils

List::MoreUtils has natatime subroutine looks like this module. The natatime subroutine can treat only list.

DBI

DBI's fetchall_arrayref can accepts max_rows argument. This feature is similar to this module. For example:

  use DBI;
  use Data::Dumper;

  my $sth = $dbh->prepare('SELECT id FROM people');
  while ( my $ids = $sth->fetchall_arrayref(undef, 100) ) {
      $ids = [ map { $_->[0] } @$ids ];
      warn Dumper($ids);
  }

LICENSE

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

cpanm Iterator::GroupedRange

perl -MCPAN -e shell
install Iterator::GroupedRange