Implement JSON.Encoder protocol

Author: sabiwara

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Dev
 
+- Support the `JSON.Encode` protocol in Elixir 1.18+.
+
 ## v0.7.3 (2024-12-12)
 
 ### Enhancements

README.md

@@ -102,6 +102,7 @@ All data structures offer:
 - well-documented APIs that are consistent with the standard library
 - implementation of `Inspect`, `Enumerable` and `Collectable` protocols
 - implementation of the `Access` behaviour
+- implementation of the `JSON.Encoder` protocol (on Elixir 1.18+)
 - (optional if `Jason` is installed) implemention of the `Jason.Encoder`
   protocol
 

lib/ord_map.ex

@@ -15,6 +15,7 @@ defmodule Aja.OrdMap do
   `Aja.OrdMap`:
   - provides efficient (logarithmic) access: it is not a simple list of tuples
   - implements the `Access` behaviour, `Enum` / `Inspect` / `Collectable` protocols
+  - implements the `JSON.Encoder` protocol (on Elixir 1.18+)
   - optionally implements the `Jason.Encoder` protocol if `Jason` is installed
 
   ## Examples
@@ -98,7 +99,9 @@ defmodule Aja.OrdMap do
       true
 
 
-  ## With `Jason`
+  ## JSON encoding
+
+  Both `JSON.Encoder` and `Jason.Encoder` are supported.
 
       iex> Aja.OrdMap.new([{"un", 1}, {"deux", 2}, {"trois", 3}]) |> Jason.encode!()
       "{\"un\":1,\"deux\":2,\"trois\":3}"
@@ -1655,6 +1658,25 @@ defmodule Aja.OrdMap do
     end
   end
 
+  if Code.ensure_loaded?(JSON.Encoder) do
+    defimpl JSON.Encoder do
+      def encode(map, encoder) do
+        key_values =
+          Aja.Enum.map_intersperse(map, ?,, fn {key, value} ->
+            [key(key, encoder), ?:, encoder.(value, encoder)]
+          end)
+
+        [?{, key_values, ?}]
+      end
+
+      # ported from :json
+      defp key(key, encode) when is_binary(key), do: encode.(key, encode)
+      defp key(key, encode) when is_atom(key), do: encode.(Atom.to_string(key), encode)
+      defp key(key, _encode) when is_integer(key), do: [?", Integer.to_string(key), ?"]
+      defp key(key, _encode) when is_float(key), do: [?", Float.to_string(key), ?"]
+    end
+  end
+
   if Code.ensure_loaded?(Jason.Encoder) do
     defimpl Jason.Encoder do
       def encode(map, opts) do

lib/vector.ex

@@ -19,6 +19,7 @@ defmodule Aja.Vector do
   - is heavily optimized and should offer higher performance in most use cases, especially "loops" like `map/2` / `to_list/1` / `foldl/3`
   - mirrors most of the `Enum` module API (together with `Aja.Enum`) with highly optimized versions for vectors (`Aja.Enum.join/1`, `Aja.Enum.sum/1`, `Aja.Enum.random/1`...)
   - supports negative indexing (e.g. `-1` corresponds to the last element)
+  - implements the `JSON.Encoder` protocol (on Elixir 1.18+)
   - optionally implements the `Jason.Encoder` protocol if `Jason` is installed
 
   Note: most of the design is inspired by
@@ -2039,6 +2040,15 @@ defmodule Aja.Vector do
     end
   end
 
+  if Code.ensure_loaded?(JSON.Encoder) do
+    defimpl JSON.Encoder do
+      def encode(vector, encoder) do
+        values = Aja.Enum.map_intersperse(vector, ?,, fn value -> encoder.(value, encoder) end)
+        [?[, values, ?]]
+      end
+    end
+  end
+
   if Code.ensure_loaded?(Jason.Encoder) do
     defimpl Jason.Encoder do
       def encode(vector, opts) do

test/ord_map_test.exs

@@ -88,16 +88,15 @@ defmodule Aja.OrdMapTest do
                Aja.OrdMap.new([{:foo, :atom}, {5, :integer}]) |> inspect()
     end
 
-    if Version.compare(System.version(), "1.14.0") != :lt do
-      test "from_struct/1" do
-        ord_map = %User{name: "John", age: 44} |> Aja.OrdMap.from_struct()
-        expected = Aja.OrdMap.new(name: "John", age: 44)
-        assert ^expected = ord_map
-
-        ord_map = Aja.OrdMap.from_struct(User)
-        expected = Aja.OrdMap.new(name: nil, age: nil)
-        assert ^expected = ord_map
-      end
+    @tag skip: Version.compare(System.version(), "1.14.0") == :lt
+    test "from_struct/1" do
+      ord_map = %User{name: "John", age: 44} |> Aja.OrdMap.from_struct()
+      expected = Aja.OrdMap.new(name: "John", age: 44)
+      assert ^expected = ord_map
+
+      ord_map = Aja.OrdMap.from_struct(User)
+      expected = Aja.OrdMap.new(name: nil, age: nil)
+      assert ^expected = ord_map
     end
 
     test "get_and_update/3" do
@@ -117,5 +116,16 @@ defmodule Aja.OrdMapTest do
         Aja.OrdMap.get_and_update!(ord_map, :b, fn value -> value end)
       end
     end
+
+    @tag skip: Version.compare(System.version(), "1.18.0-rc.0") == :lt
+    test "JSON.encode!/1" do
+      result = Aja.OrdMap.new([{"un", 1}, {"deux", 2}, {"trois", 3}]) |> JSON.encode!()
+      assert result == "{\"un\":1,\"deux\":2,\"trois\":3}"
+    end
+
+    test "Jason.encode!/1" do
+      result = Aja.OrdMap.new([{"un", 1}, {"deux", 2}, {"trois", 3}]) |> Jason.encode!()
+      assert result == "{\"un\":1,\"deux\":2,\"trois\":3}"
+    end
   end
 end

test/vector_test.exs

@@ -542,5 +542,16 @@ defmodule Aja.VectorTest do
       assert [18, 19] == Aja.Vector.new(1..20) |> Enum.slice(-3, 2)
       assert Enum.to_list(2..99) == Aja.Vector.new(1..100) |> Enum.slice(1..98)
     end
+
+    @tag skip: Version.compare(System.version(), "1.18.0-rc.0") == :lt
+    test "JSON.encode!/1" do
+      result = Aja.Vector.new(["un", 2, :trois]) |> JSON.encode!()
+      assert result == "[\"un\",2,\"trois\"]"
+    end
+
+    test "Jason.encode!/1" do
+      result = Aja.Vector.new(["un", 2, :trois]) |> Jason.encode!()
+      assert result == "[\"un\",2,\"trois\"]"
+    end
   end
 end