MultiEnumerator

Simultaneously process multiple enumerators.

Installation

Add this line to your application's Gemfile:

gem 'multi_enumerator'

And then execute:

$ bundle

Or install it yourself as:

$ gem install multi_enumerator

Usage

Main goal of MultiEnumerator is to reduce Array#zip abuse and simplify IO streams handling.

a = [1, 2, 3].each
b = [10, 20].each
c = [30].each
MultiEnumerator.build([a, b, c]).each do |*slice|
  puts slice.inspect
end

=>
[1, 10, 30]
[2, 20, #<StopIteration: iteration reached an end>]
[3, #<StopIteration: iteration reached an end>, #<StopIteration: iteration reached an end>]

Instead of getting tons of StopIteration you may wish to specify a replacement.

a = [1, 2, 3].each
b = [10, 20].each
c = [30].each
MultiEnumerator.build(a, b, c, :ljust_with => nil).each do |*slice|
  puts slice.inspect
end

=>
[1, 10, 30]
[2, 20, nil]
[3, nil, nil]

By default all enumerators are rewound on before the iterating. This may be prevented by passing :rewind option.

enum = [1, 2, 3].each
enum.next  # skip first elem
puts MultiEnumerator.build(enum, :rewind => false).each.to_a.inspect

=>
[2, 3]

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request