Merge pull request #48 from mykewould/deep_key_change

Recursive key change for Maps

lib/crutches/map.ex

@@ -0,0 +1,27 @@
+defmodule Crutches.Map do
+  @doc ~S"""
+  Recursively traverse a (nested) hash and change the keys based on
+  the function provided.
+  
+  ## Examples
+  
+  iex> map = %{"hello" => %{"goodbye" => 1}, "akuna" => "matata"}
+  iex> Map.dkeys_update(map, fn (key) -> String.to_atom(key) end)
+  %{:hello => %{:goodbye => 1}, :akuna => "matata"}
+  
+  iex> map = %{"hello" => %{"goodbye" => 1, "akuna" => "matata", "hello" => %{"goodbye" => 1, "akuna" => "matata"}}, "akuna" => "matata"}
+  iex> Map.dkeys_update(map, fn (key) -> String.to_atom(key) end)
+  %{hello: %{akuna: "matata", goodbye: 1, hello: %{akuna: "matata", goodbye: 1}}, akuna: "matata"}
+  
+  """
+  def dkeys_update(map, fun), do: dkeys_update(map, fun, %{})
+  def dkeys_update(map, _, acc) when map == %{}, do: acc
+  def dkeys_update(map, fun, acc) do
+    key = Map.keys(map) |> List.first
+    case is_map(map[key]) do
+      true -> value = dkeys_update(map[key], fun)
+         _ -> value = map[key]
+    end
+    dkeys_update(Map.delete(map, key), fun, Map.put(acc, fun.(key), value))
+  end
+end

test/crutches/map_test.exs

@@ -0,0 +1,5 @@
+defmodule Crutches.MapTest do
+  alias Crutches.Map
+  use ExUnit.Case, async: true
+  doctest Crutches.Map
+end