Refactor access impl

lib/vix/vips/image.ex

@@ -1,8 +1,4 @@
 defmodule Vix.Vips.Image do
-  defstruct [:ref]
-
-  alias __MODULE__
-
   @moduledoc """
   Functions for reading and writing images as well as
   accessing and updating image metadata.
@@ -99,6 +95,9 @@ defmodule Vix.Vips.Image do
       %Vix.Vips.Image{ref: #Reference<0.2448791511.2685009949.153742>}
   """
 
+  defstruct [:ref]
+
+  alias __MODULE__
   alias Vix.Nif
   alias Vix.Type
   alias Vix.Vips.MutableImage
@@ -152,7 +151,7 @@ defmodule Vix.Vips.Image do
 
   # Extract band when the band number is positive or zero
   def fetch(image, band) when is_integer(band) and band >= 0 do
-    case Vix.Vips.Operation.extract_band(image, band) do
+    case Operation.extract_band(image, band) do
       {:ok, band} -> {:ok, band}
       {:error, _reason} -> raise ArgumentError, "Invalid band requested. Found #{inspect(band)}"
     end
@@ -179,9 +178,13 @@ defmodule Vix.Vips.Image do
     with {:ok, args} <- normalize_access_args(args),
          {:ok, left, width} <- validate_dimension(args[:width], width(image)),
          {:ok, top, height} <- validate_dimension(args[:height], height(image)),
-         {:ok, first_band, bands} <- validate_dimension(args[:band], bands(image)),
-         {:ok, area} <- extract_area(image, left, top, width, height) do
-      extract_band(area, first_band, n: bands)
+         {:ok, first_band, bands} <- validate_dimension(args[:band], bands(image)) do
+      extracted_image =
+        image
+        |> extract_area!(left, top, width, height)
+        |> extract_band!(first_band, n: bands)
+
+      {:ok, extracted_image}
     else
       {:error, _} ->
         raise ArgumentError, "Argument must be list of integers or ranges or keyword list"
@@ -190,19 +193,19 @@ defmodule Vix.Vips.Image do
 
   @impl Access
   def get_and_update(_image, _key, _fun) do
-    raise "get_and_update/3 for Vix.Vips.Image is not supported."
+    raise ArgumentError, "get_and_update/3 for Vix.Vips.Image is not supported."
   end
 
   @impl Access
   def pop(_image, _band, _default \\ nil) do
-    raise "pop/3 for Vix.Vips.Image is not supported."
+    raise ArgumentError, "pop/3 for Vix.Vips.Image is not supported."
   end
 
   # Extract a range of bands
   defp fetch_range(image, %Range{first: first, last: last}) when first >= 0 and last >= first do
-    case Vix.Vips.Operation.extract_band(image, first, n: last - first + 1) do
+    case Operation.extract_band(image, first, n: last - first + 1) do
       {:ok, band} -> {:ok, band}
-      {:error, _reason} -> raise "Invalid band range #{inspect(first..last)}"
+      {:error, _reason} -> raise Error, "Invalid band range #{inspect(first..last)}"
     end
   end
 
@@ -281,17 +284,25 @@ defmodule Vix.Vips.Image do
     Map.get(range, :step) == 1 || !Map.has_key?(range, :step)
   end
 
-  defp extract_area(image, left, top, width, height) do
+  @spec extract_area!(
+          Image.t(),
+          non_neg_integer,
+          non_neg_integer,
+          non_neg_integer,
+          non_neg_integer
+        ) :: Image.t() | no_return
+  defp extract_area!(image, left, top, width, height) do
     case Operation.extract_area(image, left, top, width, height) do
-      {:ok, image} -> {:ok, image}
-      _other -> raise "Requested area could not be extracted"
+      {:ok, image} -> image
+      {:error, _} = _error -> raise Error, "Requested area could not be extracted"
     end
   end
 
-  defp extract_band(area, first_band, options) do
+  @spec extract_band!(Image.t(), non_neg_integer, keyword) :: Image.t() | no_return
+  defp extract_band!(area, first_band, options) do
     case Operation.extract_band(area, first_band, options) do
-      {:ok, image} -> {:ok, image}
-      _other -> raise "Requested band(s) could not be extracted"
+      {:ok, image} -> image
+      {:error, _} = _error -> raise Error, "Requested band(s) could not be extracted"
     end
   end
 
@@ -380,7 +391,7 @@ defmodule Vix.Vips.Image do
   @spec new_from_buffer(binary(), keyword()) :: {:ok, t()} | {:error, term()}
   def new_from_buffer(bin, opts \\ []) do
     with {:ok, loader} <- Vix.Vips.Foreign.find_load_buffer(bin),
-         {:ok, {ref, _optional}} <- Vix.Vips.Operation.Helper.operation_call(loader, [bin], opts) do
+         {:ok, {ref, _optional}} <- Operation.Helper.operation_call(loader, [bin], opts) do
       {:ok, wrap_type(ref)}
     end
   end

test/vix/vips/access_test.exs

@@ -24,7 +24,7 @@ defmodule Vix.Vips.AccessTest do
   test "Access behaviour for Vix.Vips.Image with invalid range band" do
     {:ok, im} = Image.new_from_file(img_path("puppies.jpg"))
 
-    assert_raise RuntimeError, "Invalid band range 1..5", fn ->
+    assert_raise Image.Error, "Invalid band range 1..5", fn ->
       im[1..5]
     end