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