Fix parsing tuples (#164)

* Fix parsing tuples

* Add regression test for `tuple` parsing

* Apply suggestions

lib/abi/function_selector.ex

@@ -311,34 +311,28 @@ defmodule ABI.FunctionSelector do
     end
   end
 
-  @doc false
-  def parse_specification_type(%{"type" => "tuple", "components" => components}) do
-    sub_types = for component <- components, do: parse_specification_type(component)
-    {:tuple, sub_types}
+  defp replace_tuple({:array, inner}, sub_types) do
+    {:array, replace_tuple(inner, sub_types)}
   end
 
-  def parse_specification_type(%{"type" => "tuple[]", "components" => components}) do
-    sub_types = for component <- components, do: parse_specification_type(component)
-    {:array, {:tuple, sub_types}}
+  defp replace_tuple({:array, inner, size}, sub_types) do
+    {:array, replace_tuple(inner, sub_types), size}
   end
 
-  def parse_specification_type(%{"type" => "tuple[][]", "components" => components}) do
-    sub_types = for component <- components, do: parse_specification_type(component)
-    {:array, {:array, {:tuple, sub_types}}}
+  defp replace_tuple(:tuple, sub_types) do
+    {:tuple, sub_types}
   end
 
-  def parse_specification_type(%{
-        "type" => "tuple[" <> tail,
-        "components" => components
-      }) do
-    sub_types = for component <- components, do: parse_specification_type(component)
+  defp replace_tuple(other, _) do
+    other
+  end
 
-    size =
-      tail
-      |> String.replace("]", "")
-      |> String.to_integer()
+  def parse_specification_type(%{"type" => "tuple" <> _ = type, "components" => components}) do
+    sub_types = for component <- components, do: parse_specification_type(component)
 
-    {:array, {:tuple, sub_types}, size}
+    type
+    |> decode_type()
+    |> replace_tuple(sub_types)
   end
 
   def parse_specification_type(%{"type" => type}), do: decode_type(type)

test/abi/function_selector_test.exs

@@ -345,6 +345,38 @@ defmodule ABI.FunctionSelectorTest do
       assert expected_type == selector.types
     end
 
+    test "parses fixed 2D array of tuples" do
+      function = %{
+        "inputs" => [],
+        "name" => "createTupleArray",
+        "outputs" => [
+          %{
+            "components" => [
+              %{
+                "internalType" => "uint256",
+                "name" => "element1",
+                "type" => "uint256"
+              },
+              %{"internalType" => "bool", "name" => "element2", "type" => "bool"}
+            ],
+            "internalType" => "struct StorageB.MyTuple[2][]",
+            "name" => "",
+            "type" => "tuple[2][]"
+          }
+        ],
+        "stateMutability" => "pure",
+        "type" => "function"
+      }
+
+      expected = [
+        array: {:array, {:tuple, [{:uint, 256}, :bool]}, 2}
+      ]
+
+      selector = FunctionSelector.parse_specification_item(function)
+
+      assert expected == selector.returns
+    end
+
     test "with stateMutability set" do
       ~w(pure view nonpayable payable)
       |> Enum.zip(~w(pure view non_payable payable)a)