Implement ERC-165 support

lib/ethers/contracts/erc1155.ex

@@ -2,8 +2,16 @@ defmodule Ethers.Contracts.ERC1155 do
   @moduledoc """
   ERC1155 token interface
 
-  More info: https://ethereum.org/en/developers/docs/standards/tokens/erc-1155/
+  More info: https://eips.ethereum.org/EIPS/eip-1155
   """
 
   use Ethers.Contract, abi: :erc1155
+
+  @behaviour Ethers.Contracts.ERC165
+
+  # ERC-165 Interface ID
+  @interface_id Ethers.Utils.hex_decode!("0xd9b67a26")
+
+  @impl Ethers.Contracts.ERC165
+  def erc165_interface_id, do: @interface_id
 end

lib/ethers/contracts/erc165.ex

@@ -0,0 +1,30 @@
+defmodule Ethers.Contracts.ERC165 do
+  @moduledoc """
+  ERC-165 Standard Interface Detection
+
+  More info: https://eips.ethereum.org/EIPS/eip-165
+  """
+  use Ethers.Contract, abi: :erc165
+
+  @behaviour __MODULE__
+
+  @callback erc165_interface_id() :: <<_::32>>
+
+  @interface_id Ethers.Utils.hex_decode!("0x01ffc9a7")
+
+  defmodule NotERC165CompatibleError do
+    defexception [:message]
+  end
+
+  @impl __MODULE__
+  def erc165_interface_id, do: @interface_id
+
+  def supports_interface(iface) when is_atom(iface) do
+    supports_interface(iface.erc165_interface_id())
+  rescue
+    UndefinedFunctionError ->
+      reraise NotERC165CompatibleError,
+              "module #{iface} does not implement ERC165 behaviour",
+              __STACKTRACE__
+  end
+end

lib/ethers/contracts/erc721.ex

@@ -2,8 +2,16 @@ defmodule Ethers.Contracts.ERC721 do
   @moduledoc """
   ERC721 token interface
 
-  More info: https://ethereum.org/en/developers/docs/standards/tokens/erc-721/
+  More info: https://eips.ethereum.org/EIPS/eip-721
   """
 
   use Ethers.Contract, abi: :erc721
+
+  @behaviour Ethers.Contracts.ERC165
+
+  # Interface ID
+  @interface_id Ethers.Utils.hex_decode!("0x80ac58cd")
+
+  @impl Ethers.Contracts.ERC165
+  def erc165_interface_id, do: @interface_id
 end

priv/abi/erc165.json

@@ -0,0 +1,23 @@
+[
+  {
+    "inputs":
+    [
+      {
+        "internalType": "bytes4",
+        "name": "interfaceId",
+        "type": "bytes4"
+      }
+    ],
+    "name": "supportsInterface",
+    "outputs":
+    [
+      {
+        "internalType": "bool",
+        "name": "",
+        "type": "bool"
+      }
+    ],
+    "stateMutability": "view",
+    "type": "function"
+  }
+]