LimitedMapSet is an extension of Elixir’s MapSet that keeps insertion order (FIFO) and automatically evicts the oldest elements when the limit is reached.

Examples

• Creating a limited set

  iex> s = LimitedMapSet.new(3)
  #LimitedMapSet<limit: 3, size: 0>
  
  iex> s = LimitedMapSet.put(s, :a)
  iex> s = LimitedMapSet.put(s, :b)
  iex> s = LimitedMapSet.put(s, :c)
  iex> LimitedMapSet.to_list(s)
  [:a, :b, :c]

• Automatic eviction when full

  iex> s = LimitedMapSet.put(s, :d)
  iex> LimitedMapSet.to_list(s)
  [:b, :c, :d]   # :a was evicted

• Membership and deletion

  iex> LimitedMapSet.member?(s, :b)
  true
  
  iex> s = LimitedMapSet.delete(s, :b)
  iex> LimitedMapSet.member?(s, :b)
  false

• Creating from a list

  iex> s = LimitedMapSet.new([1, 2, 3, 4], 3)
  iex> LimitedMapSet.to_list(s)
  [2, 3, 4]

• Checking size

  iex> LimitedMapSet.size(s)
  3

• Using Enum

  iex> s = LimitedMapSet.new([:a, :b, :c], 3)
  iex> Enum.member?(s, :b)
  true
  iex> Enum.to_list(s)
  [:a, :b, :c]

Add to your mix.exs:

def deps do
  [
    {:limited_map_set, "~> 0.1.0"}
  ]
end