Support maps in typespecs

Author: José Valim

lib/elixir/lib/kernel/typespec.ex

@@ -640,6 +640,21 @@ defmodule Kernel.Typespec do
     for arg <- args, do: typespec_to_ast(arg)
   end
 
+  defp typespec_to_ast({ :type, line, :map, fields }) do
+    fields = Enum.map fields, fn { :type, _, :map_field_assoc, k, v } ->
+      { typespec_to_ast(k), typespec_to_ast(v) }
+    end
+
+    { struct, fields } = Keyword.pop(fields, :__struct__)
+    map = { :%{}, [line: line], fields }
+
+    if struct do
+      { :%, [line: line], [struct, map] }
+    else
+      map
+    end
+  end
+
   defp typespec_to_ast({ :type, line, :binary, [arg1, arg2] }) do
     [arg1, arg2] = for arg <- [arg1, arg2], do: typespec_to_ast(arg)
     cond do
@@ -764,6 +779,18 @@ defmodule Kernel.Typespec do
     {:type, line(meta), :binary, [{:integer, line(meta1), base}, {:integer, line(meta2), 0}]}
   end
 
+  ## Handle maps and structs
+  defp typespec({:%{}, meta, fields}, vars, caller) do
+    fields = Enum.map(fields, fn { k, v } ->
+      {:type, line(meta), :map_field_assoc, typespec(k, vars, caller), typespec(v, vars, caller)}
+    end)
+    {:type, line(meta), :map, fields}
+  end
+
+  defp typespec({:%, _, [name, {:%{}, meta, fields}]}, vars, caller) do
+    typespec({:%{}, meta, [{:__struct__, name}|fields]}, vars, caller)
+  end
+
   # Handle ranges
   defp typespec({:.., meta, args}, vars, caller) do
     typespec({:range, meta, args}, vars, caller)

lib/elixir/test/elixir/kernel/typespec_test.exs

@@ -122,6 +122,29 @@ defmodule Kernel.TypespecTest do
     assert {:mytype, {:type, _, :range, [{:integer, _, 1}, {:integer, _, 10}]}, []} = spec
   end
 
+  test "@type with a map" do
+    spec = test_module do
+      @type mytype :: %{hello: :world}
+    end
+    assert {:mytype,
+             {:type, _, :map, [
+               {:type, _, :map_field_assoc, {:atom, _, :hello}, {:atom, _, :world}}
+             ]},
+            []} = spec
+  end
+
+  test "@type with a struct" do
+    spec = test_module do
+      @type mytype :: %User{hello: :world}
+    end
+    assert {:mytype,
+             {:type, _, :map, [
+               {:type, _, :map_field_assoc, {:atom, _, :__struct__}, {:atom, _, User}},
+               {:type, _, :map_field_assoc, {:atom, _, :hello}, {:atom, _, :world}}
+             ]},
+            []} = spec
+  end
+
   test "@type with a tuple" do
     {spec1, spec2, spec3} = test_module do
       t1 = @type mytype :: tuple
@@ -252,7 +275,7 @@ defmodule Kernel.TypespecTest do
       @type
     end
 
-    assert [{:t, {:type, 251, :map, []}, []}] = types
+    assert [{:t, {:type, _, :map, []}, []}] = types
   end
 
   test "@type unquote fragment" do
@@ -380,6 +403,8 @@ defmodule Kernel.TypespecTest do
       (quote do: @type rng() :: 1 .. 10),
       (quote do: @type opts() :: [first: integer(), step: integer(), last: integer()]),
       (quote do: @type ops() :: {+1,-1}),
+      (quote do: @type my_map() :: %{hello: :world}),
+      (quote do: @type my_struct() :: %User{hello: :world}),
     ]
 
     types = test_module do