Stripped out pop from ErlangArray.

TODO: Think about how to deal with difference w.r.t. handling of `default`.

lib/arrays.ex

@@ -141,11 +141,11 @@ contents = quote do
 
       iex> arr = Arrays.new([1, -4, 33, 5])
       iex> {33, arr} = pop_in(arr[-2])
-      ** (ArgumentError) There is no efficient implementation possible to remove an element from a random location in an array, so `Access.pop/2` (and returning `:pop` from `Access.get_and_update/3` ) are not supported by Elixir.Arrays.Implementations.MapArray. If you want to remove the last element, use `Arrays.extract/1`.
+      ** (ArgumentError) There is no efficient implementation possible to remove an element from a random location in an array, so `Access.pop/2` (and returning `:pop` from `Access.get_and_update/3` ) are not supported by #{@current_default_array}. If you want to remove the last element, use `Arrays.extract/1`.
 
       iex> arr2 = Arrays.new([10, 20, 30])
       iex> {20, arr2} = get_and_update_in(arr2[1], fn _ -> :pop end)
-      ** (ArgumentError) There is no efficient implementation possible to remove an element from a random location in an array, so `Access.pop/2` (and returning `:pop` from `Access.get_and_update/3` ) are not supported by Elixir.Arrays.Implementations.MapArray. If you want to remove the last element, use `Arrays.extract/1`.
+      ** (ArgumentError) There is no efficient implementation possible to remove an element from a random location in an array, so `Access.pop/2` (and returning `:pop` from `Access.get_and_update/3` ) are not supported by #{@current_default_array}. If you want to remove the last element, use `Arrays.extract/1`.
 
       iex> arr2 = Arrays.new([10, 20, 30])
       iex> {:ok, {value, arr2}} = Arrays.extract(arr2)

lib/arrays/implementations/erlang_array.ex

@@ -88,22 +88,22 @@ defmodule Arrays.Implementations.ErlangArray do
     end
   end
 
+  @undefined_pop_message """
+  There is no efficient implementation possible to remove an element from a random location in an array, so `Access.pop/2` (and returning `:pop` from `Access.get_and_update/3` ) are not supported by #{inspect(__MODULE__)}. If you want to remove the last element, use `Arrays.extract/1`.
+  """ |> String.trim
+
   @impl Access
   def get_and_update(array = %ErlangArray{contents: contents}, index, function) when index >= 0 do
     if index >= :array.size(contents) do
       raise ArgumentError
     else
       value = :array.get(index, contents)
-
       case function.(value) do
-        :pop ->
-          value = :array.get(index, contents)
-          new_contents = fix_contents_after_pop(contents, index, :array.default(contents))
-          {value, %ErlangArray{array | contents: new_contents}}
-
         {get, new_value} ->
           new_contents = :array.set(index, new_value, contents)
           {get, %ErlangArray{array | contents: new_contents}}
+        :pop ->
+          raise ArgumentError, @undefined_pop_message
       end
     end
   end
@@ -118,49 +118,8 @@ defmodule Arrays.Implementations.ErlangArray do
   end
 
   @impl Access
-  def pop(array = %ErlangArray{contents: contents}, index) when index >= 0 do
-    cond do
-      (index >= :array.size(contents)) ->
-        raise ArgumentError
-      (index == :array.size(contents) - 1) ->
-        # Fast implementation
-        value = :array.get(index, contents)
-        new_contents = :array.resize(index, contents)
-        {value, %ErlangArray{array | contents: new_contents}}
-      true ->
-        # Slow implementation
-        value = :array.get(index, contents)
-        new_contents = fix_contents_after_pop(contents, index, :array.default(contents))
-        {value, %ErlangArray{array | contents: new_contents}}
-    end
-  end
-
-  def pop(array = %ErlangArray{contents: contents}, index) when index < 0 do
-    if (index < (-:array.size(contents))) do
-      raise ArgumentError
-    else
-      pop(array, index + :array.size(contents))
-    end
-  end
-
-  defp fix_contents_after_pop(contents, index, default) do
-    contents
-    |> do_foldl([], fn key, value, acc ->
-      cond do
-        key > index ->
-          [{key - 1, value} | acc]
-        key == index ->
-          acc # Leave out popped element
-        key < index ->
-          [{key, value} | acc]
-      end
-    end)
-    |> Enum.reverse()
-    |> :array.from_orddict(default)
-  end
-
-  defp do_foldl(arr, acc, fun) do
-    :array.foldl(fun, acc, arr)
+  def pop(%ErlangArray{}, _index) do
+    raise ArgumentError, @undefined_pop_message
   end
 
   @doc false
@@ -239,11 +198,25 @@ defmodule Arrays.Implementations.ErlangArray do
     end
 
     @impl true
-    def resize(array = %ErlangArray{contents: contents}, new_size) do
-      new_contents = :array.resize(new_size, contents)
+    def resize(array = %ErlangArray{contents: contents}, new_size, default) do
+      IO.inspect(contents)
+      changed = change_default(contents, default)
+      IO.inspect(changed)
+      new_contents = :array.resize(new_size, changed)
+      IO.inspect(new_contents)
       %ErlangArray{array | contents: new_contents}
     end
 
+    defp change_default(raw_array, new_default) do
+      sparse_size = :array.sparse_size(raw_array)
+      size = :array.size(raw_array)
+      {:array, a, b, _old_default, vals} = raw_array
+      new_array = {:array, a, b, new_default, vals}
+      Enum.reduce(sparse_size..(size - 1), new_array, fn index, arr ->
+        :array.reset(index, arr)
+      end)
+    end
+
     @impl true
     def extract(array = %ErlangArray{contents: contents}) do
       case :array.size(contents) do

lib/arrays/implementations/map_array.ex

@@ -61,7 +61,7 @@ defmodule Arrays.Implementations.MapArray do
   def fetch(%MapArray{}, _index), do: :error
 
   @undefined_pop_message """
-  There is no efficient implementation possible to remove an element from a random location in an array, so `Access.pop/2` (and returning `:pop` from `Access.get_and_update/3` ) are not supported by #{__MODULE__}. If you want to remove the last element, use `Arrays.extract/1`.
+  There is no efficient implementation possible to remove an element from a random location in an array, so `Access.pop/2` (and returning `:pop` from `Access.get_and_update/3` ) are not supported by #{inspect(__MODULE__)}. If you want to remove the last element, use `Arrays.extract/1`.
   """ |> String.trim
 
   @impl Access