28 lines
823 B
Elixir
28 lines
823 B
Elixir
|
defmodule Allergies do
|
||
|
|
@allergens %{
|
||
|
|
"eggs" => 1,
|
||
|
|
"peanuts" => 2,
|
||
|
|
"shellfish" => 4,
|
||
|
|
"strawberries" => 8,
|
||
|
|
"tomatoes" => 16,
|
||
|
|
"chocolate" => 32,
|
||
|
|
"pollen" => 64,
|
||
|
|
"cats" => 128
|
||
|
|
}
|
||
|
|
|
||
|
|
@doc """
|
||
|
|
List the allergies for which the corresponding flag bit is true.
|
||
|
|
"""
|
||
|
|
@spec list(non_neg_integer) :: [String.t()]
|
||
|
|
def list(flags) do
|
||
|
|
for {allergen, mask} <- @allergens, allergic_to?(mask, flags), do: allergen
|
||
|
|
end
|
||
|
|
|
||
|
|
@doc """
|
||
|
|
Returns whether the corresponding flag bit in 'flags' is set for the item.
|
||
|
|
"""
|
||
|
|
@spec allergic_to?(non_neg_integer, String.t() | non_neg_integer) :: boolean
|
||
|
|
def allergic_to?(flags, mask) when is_integer(mask), do: Bitwise.band(mask, flags) > 0
|
||
|
|
def allergic_to?(flags, allergen) when is_binary(allergen), do: allergic_to?(@allergens[allergen], flags)
|
||
|
|
end
|