# Triad

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A Triad is like a Set, or a collection of three-part arrays.

A Triad is a collection of items each with a `key`, `descriptor`, and `value`.

Each `key` must be a unique symbol.
Each `descriptor` must be a string.
Each `value` must not be a symbol nor a string.

```ruby
user = Object.new

map = Triad.new
map << [:admin, 'Admin', user]

map.keys('Admin') #=> [:admin]
map.values('Admin') #=> [user]
map.descriptors('Admin') #=> ['Admin']
# or raise Triad::ItemNotPresent

map.descriptors(user) #=> ['Admin']
map.keys(user) #=> [:admin]
map.values(user) #=> [user]
# or raise Triad::ItemNotPresent

map.values(:admin) #=> [user]
map.descriptors(:admin) #=> ['Admin']
map.keys(:admin) #=> [:admin]
# or raise Triad::ItemNotPresent

map.each do |key, descriptor, value|
  #...
end
```

## Installation

Add this line to your application's Gemfile:

```ruby
gem 'triad'
```

And then execute:

    $ bundle

Or install it yourself as:

    $ gem install triad

## 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