Add struct support as the builder entries

lib/macros/guarded_struct/derive/parser.ex

@@ -107,6 +107,12 @@ defmodule MishkaDeveloperTools.Macros.GuardedStruct.Derive.Parser do
 
   def convert_to_atom_map({:ok, map}) when is_map(map), do: convert_to_atom_map(map)
 
+  def convert_to_atom_map(map) when is_struct(map) do
+    for {key, value} <- Map.from_struct(map),
+        into: %{},
+        do: {convert_key(key), convert_value(value)}
+  end
+
   def convert_to_atom_map(map) when is_map(map) do
     for {key, value} <- map, into: %{}, do: {convert_key(key), convert_value(value)}
   end

lib/macros/guarded_struct/guarded_struct.ex

@@ -1317,7 +1317,10 @@ defmodule GuardedStruct do
       def builder(attrs, error \\ false)
 
       def builder({key, attrs} = input, error)
-          when is_tuple(input) and is_map(attrs) and (is_list(key) or is_atom(key)) do
+          when is_tuple(input) and (is_map(attrs) or is_struct(attrs)) and
+                 (is_list(key) or is_atom(key)) do
+        attrs = if(is_struct(attrs), do: Map.from_struct(attrs), else: attrs)
+
         GuardedStruct.builder(
           %{attrs: attrs, module: unquote(module), revaluation: unquote(escaped_list)},
           key,
@@ -1327,7 +1330,10 @@ defmodule GuardedStruct do
       end
 
       def builder({key, attrs, type} = input, error)
-          when is_tuple(input) and is_map(attrs) and (is_list(key) or is_atom(key)) do
+          when is_tuple(input) and (is_map(attrs) or is_struct(attrs)) and
+                 (is_list(key) or is_atom(key)) do
+        attrs = if(is_struct(attrs), do: Map.from_struct(attrs), else: attrs)
+
         GuardedStruct.builder(
           %{attrs: attrs, module: unquote(module), revaluation: unquote(escaped_list)},
           key,
@@ -1336,7 +1342,9 @@ defmodule GuardedStruct do
         )
       end
 
-      def builder(attrs, error) when is_map(attrs) do
+      def builder(attrs, error) when is_map(attrs) or is_struct(attrs) do
+        attrs = if(is_struct(attrs), do: Map.from_struct(attrs), else: attrs)
+
         GuardedStruct.builder(
           %{attrs: attrs, module: unquote(module), revaluation: unquote(escaped_list)},
           :root,