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lib/freddy/utils/multikey_map.ex
defmodule Freddy.Utils.MultikeyMap do
@moduledoc false
# a map where values can be associated with multiple keys
@opaque t :: map
def new do
%{}
end
def put(map, [key | rest] = _keys, value) do
map
|> Map.put(key, {:value, value, rest})
|> associate(rest, key)
end
def pop(map, key, default \\ nil) do
case map do
%{^key => {:assoc, target}} ->
pop(map, target, default)
%{^key => {:value, value, associations}} ->
{value, Map.drop(map, [key | associations])}
_ ->
{default, map}
end
end
def has_key?(map, key) do
Map.has_key?(map, key)
end
defp associate(map, keys, target) do
Enum.reduce(keys, map, &Map.put(&2, &1, {:assoc, target}))
end
end