I thought extension of extension would be cool but it doesn't work ...

Author: lizziepaquette

lib/elixir.pb.ex

@@ -1,20 +1,6 @@
-defmodule Brex.Elixir.FieldOptions do
-  @moduledoc false
-  use Protobuf, syntax: :proto2
-
-  @type t :: %__MODULE__{
-          extype: String.t()
-        }
-  defstruct [:extype]
-
-  field :extype, 1, optional: true, type: :string
-end
-
 defmodule Brex.Elixir.PbExtension do
   @moduledoc false
   use Protobuf, syntax: :proto2
 
-  extend Google.Protobuf.FieldOptions, :field, 65_007,
-    optional: true,
-    type: Brex.Elixir.FieldOptions
+  extend Elixirpb.FieldOptions, :extype, 1000, optional: true, type: :string
 end

lib/elixirpb.pb.ex

@@ -3,16 +3,30 @@ defmodule Elixirpb.FileOptions do
   use Protobuf, syntax: :proto2
 
   @type t :: %__MODULE__{
-          module_prefix: String.t()
+          module_prefix: String.t(),
+          __pb_extensions__: map
         }
-  defstruct [:module_prefix]
+  defstruct [:module_prefix, :__pb_extensions__]
 
   field :module_prefix, 1, optional: true, type: :string
+
+  extensions [{1000, 536_870_912}]
+end
+
+defmodule Elixirpb.FieldOptions do
+  @moduledoc false
+  use Protobuf, syntax: :proto2
+
+  @type t :: %__MODULE__{__pb_extensions__: map}
+  defstruct [:__pb_extensions__]
+
+  extensions [{1000, 536_870_912}]
 end
 
 defmodule Elixirpb.PbExtension do
   @moduledoc false
   use Protobuf, syntax: :proto2
 
   extend Google.Protobuf.FileOptions, :file, 1047, optional: true, type: Elixirpb.FileOptions
+  extend Google.Protobuf.FieldOptions, :field, 65007, optional: true, type: Elixirpb.FieldOptions
 end

lib/protobuf/extension.ex

@@ -134,6 +134,7 @@ defmodule Protobuf.Extension do
         if GlobalStore.get(fnum_key, nil) do
           raise "Extension #{inspect(ext.extendee)}##{fnum} already exists"
         end
+          IO.inspect(:stderr, {fnum_key, mod}, label: :extensions)
 
         GlobalStore.put(fnum_key, mod)
       end)

lib/protobuf/protoc/generator/message.ex

@@ -11,6 +11,8 @@ defmodule Protobuf.Protoc.Generator.Message do
   end
 
   def generate(ctx, desc) do
+    IO.inspect(:stderr, desc, label: :desc)
+
     msg_struct = parse_desc(ctx, desc)
     IO.inspect(:stderr, msg_struct, label: :message_struct)
     ctx = %{ctx | namespace: msg_struct[:new_namespace]}
@@ -293,13 +295,32 @@ defmodule Protobuf.Protoc.Generator.Message do
   end
 
   defp merge_field_options(opts, f) do
-    extype_options = Google.Protobuf.FieldOptions.get_extension(f.options, Brex.Elixir.PbExtension, :field)
-
-    IO.inspect(:stderr, {opts, f.options, extype_options}, label: :together)
+    field_options =
+      f.options
+      |> Google.Protobuf.FieldOptions.get_extension(Elixirpb.PbExtension, :field)
+      |> case do
+        nil -> nil
+        elixir_field_options ->
+          elixir_field_options
+          # strips :__struct__
+          |> Map.from_struct()
+          |> Enum.flat_map(&get_custom_field_options/1)
+          |> case do
+            [] -> nil
+            custom_opts -> custom_opts
+          end
+      end
 
     opts
-    |> Map.put(:packed, f.options.packed)
-    |> Map.put(:deprecated, f.options.deprecated)
-    |> Map.put(:options, "#{inspect(extype_options)}")
+      |> Map.put(:packed, f.options.packed)
+      |> Map.put(:deprecated, f.options.deprecated)
+      |> Map.put(:options, field_options)
+  end
+
+  def get_custom_field_options({:__pb_extensions__, opts}) do
+    # For now if you want field options to show up in DSL you havee to extend Elixirpb.FieldOptions.
+    Enum.map(opts, fn {{_extending_message, field}, arg} -> {field, arg} end)
   end
+  # Collect existing Elixirpb.FieldOptions (right now no fields though).
+  def get_custom_field_options({k, v}), do: [{k, v}]
 end

lib/protobuf/protoc/generator/util.ex

@@ -49,5 +49,6 @@ defmodule Protobuf.Protoc.Generator.Util do
   end
 
   def print(v) when is_atom(v), do: inspect(v)
+  def print(v) when is_list(v), do: inspect(v)
   def print(v), do: v
 end

src/elixir.proto

@@ -1,24 +1,22 @@
+// This is not working, remove
+
 syntax = "proto2";
 
 // we should call just elixirpb and merge with Tony's
 // https://github.com/tony612/protobuf-elixir/blob/e1d4a23baa1f51c2da58db24f58a26dc4d6511b2/src/elixirpb.proto
 package brex.elixir;
 
-import "google/protobuf/descriptor.proto";
+import "elixirpb.proto";
 
 // Define an extension to specify the elixir type generated for the given field.
 
 // Field level options
 //
 // For example,
-// google.protobuf.StringValue my_string = 1 [(brex.elixirpb.field).extype="String.t"];
-
-message FieldOptions {
-  // Specify an elixir type to generate for this field. This will override usual type.
-  optional string extype = 1;
-}
+// google.protobuf.StringValue my_string = 1 [(elixirpb.field).extype="String.t"];
 
-extend google.protobuf.FieldOptions {
+extend elixirpb.FieldOptions {
   // number to change
-  optional FieldOptions field = 65007;
+  optional string extype = 1000;
+  //optional boolean lowercase = 1001;
 }

src/elixirpb.proto

@@ -23,9 +23,20 @@ message FileOptions {
   // will be "Hello.Request". But with module_prefix "Foo", the message will be
   // "Foo.Request"
   optional string module_prefix = 1;
+  extensions 1000 to max;
 }
 
 extend google.protobuf.FileOptions {
   optional FileOptions file = 1047;
 }
 
+message FieldOptions {
+  // optional string extype = 1;
+  extensions 1000 to max;
+}
+
+extend google.protobuf.FieldOptions {
+  // TODO: determine appropriate number
+  optional FieldOptions field = 65007;
+}
+

test/protobuf/protoc/generator/message_test.exs

@@ -176,11 +176,12 @@ defmodule Protobuf.Protoc.Generator.MessageTest do
   test "generate/2 supports extensions on field options" do
     ctx = %Context{package: ""}
 
-    opts = Google.Protobuf.FieldOptions.new()
-    custom_opts = Brex.Elixir.FieldOptions.new(extype: "String.t")
+    field_opts = Google.Protobuf.FieldOptions.new()
+    elixir_opts = Elixirpb.FieldOptions.new()
+    custom_opts = Elixirpb.FieldOptions.put_extension(elixir_opts, Brex.Elixir.PbExtension, :extype, "String.t")
 
     opts =
-      Google.Protobuf.FieldOptions.put_extension(opts, Brex.Elixir.PbExtension, :field, custom_opts)
+      Google.Protobuf.FieldOptions.put_extension(field_opts, Elixirpb.PbExtension, :field, custom_opts)
 
     desc =
       Google.Protobuf.DescriptorProto.new(
@@ -190,15 +191,15 @@ defmodule Protobuf.Protoc.Generator.MessageTest do
             name: "my_string",
             number: 1,
             type: :TYPE_MESSAGE,
-            # type_name: ".google.protobuf.StringValue",
+            # type_name: ".google.protodescbuf.StringValue",
             label: :LABEL_OPTIONAL,
             options: opts
           )
         ]
       )
 
     {[], [msg]} = Generator.generate(ctx, desc)
-    assert msg =~ "field :my_string, 1, optional: true, type: :message, options: %Brex.Elixir.FieldOptions{extype: \"String.t\"}\n"
+    assert msg =~ "field :my_string, 1, optional: true, type: :message, options: [extype: \"String.t\"]\n"
   end
 
   test "generate/2 supports message type field" do