Dmitry E. Oboukhov

NAME

DR::Tarantool::Iterator - an iterator and a container class for DR::Tarantool

SYNOPSIS

    use DR::Tarantool::Iterator;

    my $iter = DR::Tarantool::Iterator->new([1, 2, 3]);

    my $item0 = $iter->item(0);

    my @all = $iter->all;
    my $all = $iter->all;

    while(my $item = $iter->next) {
        do_something_with_item( $item );
    }

METHODS

new

A constructor.

Arguments

  • An array of tuples to iterate over.

  • A list of named arguments:

    item_class

    Name of the class to bless each tuple in the iterator with. If the field is 'ARRAYREF' then the first element of the array is item_class, and the second element is item_constructor.

    item_constructor

    Name of a constructor to invoke for each tuple. If this value is undefined and item_class is defined, the iterator blesses each tuple but does not invoke a constructor on it.

    The constructor is invoked on with three arguments: item, item_index and iterator, for example:

        my $iter = DR::Tarantool::Iterator->new(
            [ [1], [2], [3] ],
            item_class => 'MyClass',
            item_constructor => 'new'
        );
    
        my $iter = DR::Tarantool::Iterator->new(    # the same
            [ [1], [2], [3] ],
            item_class => [ 'MyClass', 'new' ]
        );
    
    
        my $item = $iter->item(0);
        my $item = MyClass->new( [1], 0, $iter );  # the same
    
        my $item = $iter->item(2);
        my $item = MyClass->new( [3], 2, $iter );  # the same
    data

    Application state to store in the iterator. Is useful if additional state needs to be passed into tuple constructor.

clone(%opt)

Clone the iterator object, but do not clone the tuples. This method can be used to create an iterator that has a different item_class and (or) item_constructor.

If clone_items argument is true, the function clones the tuple list as well.

    my $iter1 = $old_iter->clone(item_class => [ 'MyClass', 'new' ]);
    my $iter2 = $old_iter->clone(item_class => [ 'MyClass', 'new' ],
        clone_items => 1);

    $old_iter->sort(sub { $_[0]->name cmp $_[1]->name });
    # $iter1 is sorted, too, but $iter2 is not

count

Return the number of tuples available through the iterator.

item

Return one tuple from the iterator by its index (or croak an error if the index is out of range).

raw_item

Return one raw tuple from the iterator by its index (or croak error if the index is out of range).

In other words, this method ignores item_class and item_constructor.

raw_sort(&)

Sort the contents referred to by the iterator (changes the current iterator object). The compare function receives two raw objects:

    $iter->raw_sort(sub { $_[0]->field cmp $_[1]->field });

sort(&)

Sort the contents referred to by the iterator (changes the current object). The compare function receives two constructed objects:

    $iter->sort(sub { $_[0]->field <=> $_[1]->field });

grep(&)

Find all objects in the set referred to by the iterator that match a given search criteria (linear search).

    my $admins = $users->grep(sub { $_[0]->is_admin });

raw_grep(&)

Same as grep, but works on raw objects.

    my $admins = $users->raw_grep(sub { $_[0]->is_admin });

get

An alias for item method.

exists

Return true if the iterator contains a tuple with the given index.

    my $item = $iter->exists(10) ? $iter->get(10) : somethig_else();

next

Return the next tuple, or undef in case of eof.

    while(my $item = $iter->next) {
        do_something_with( $item );
    }

Index of the current tuple can be queried with function 'iter'.

iter

Return index of the tuple at the current iterator position.

reset

Reset iteration index, return the previous value of the index.

all

Return all tuples available through the iterator.

    my @list = $iter->all;
    my $list_aref = $iter->all;

    my @abc_list = map { $_->abc } $iter->all;
    my @abc_list = $iter->all('abc');               # the same


    my @list = map { [ $_->abc, $_->cde ] } $iter->all;
    my @list = $iter->all('abc', 'cde');                # the same


    my @list = map { $_->abc + $_->cde } $iter->all;
    my @list = $iter->all(sub { $_[0]->abc + $_->cde }); # the same

item_class

Set/return the tuple class. If the value is defined, the iterator blesses tuples with it (and also calls item_constructor if it is set).

item_constructor

Set/return the tuple constructor. The value is used only if item_class is defined.

push

Push a tuple into the iterator.

data

Return/set an application-specific context maintained in the iterator object. This can be useful to pass additional state to item_constructor.