Support @abstract functions

Author: TranquilMarmot

gdtoolkit/common/ast.py

@@ -39,6 +39,9 @@ def _load_sub_statements(self):
             raise NotImplementedError
         if self.kind in ["func_def", "static_func_def"]:
             self.sub_statements = [Statement(n) for n in self.lark_node.children[1:]]
+        elif self.kind == "abstract_func_def":
+            # Abstract functions don't have a body, so no sub-statements
+            pass
         elif self.kind == "if_stmt":
             for branch in self.lark_node.children:
                 if branch.data in ["if_branch", "elif_branch"]:
@@ -141,6 +144,10 @@ def _load_data_from_node_children(self, node: Tree) -> None:
                 function = Function(stmt)
                 self.functions.append(function)
                 self.all_functions.append(function)
+            if stmt.data == "abstract_func_def":
+                function = Function(stmt)
+                self.functions.append(function)
+                self.all_functions.append(function)
 
     def _load_data_from_class_def(self, class_def: Tree) -> None:
         name_token = find_name_token_among_children(class_def)

gdtoolkit/formatter/annotation.py

@@ -9,6 +9,7 @@
 from .expression_to_str import expression_to_str
 
 _STANDALONE_ANNOTATIONS = [
+    "abstract",
     "export_category",
     "export_group",
     "export_subgroup",

gdtoolkit/formatter/class_statement.py

@@ -40,6 +40,7 @@ def format_class_statement(statement: Tree, context: Context) -> Outcome:
         "static_func_def": lambda s, c: _format_func_statement(
             s.children[0], c, "static "
         ),
+        "abstract_func_def": _format_abstract_func_statement,
         "annotation": format_standalone_annotation,
         "property_body_def": format_property_body,
     }  # type: Dict[str, Callable]
@@ -203,3 +204,21 @@ def _format_enum_statement(statement: Tree, context: Context) -> Outcome:
     )
     enum_body = actual_enum.children[-1]
     return format_concrete_expression(enum_body, expression_context, context)
+
+
+def _format_abstract_func_statement(statement: Tree, context: Context) -> Outcome:
+    abstract_func_header = statement.children[0]
+    return _format_abstract_func_header(abstract_func_header, context)
+
+
+def _format_abstract_func_header(statement: Tree, context: Context) -> Outcome:
+    name = statement.children[0].value
+    has_return_type = len(statement.children) > 2
+    expression_context = ExpressionContext(
+        f"func {name}",
+        get_line(statement),
+        f" -> {statement.children[2].value}" if has_return_type else "",
+        get_end_line(statement),
+    )
+    func_args = statement.children[1]
+    return format_concrete_expression(func_args, expression_context, context)

gdtoolkit/linter/class_checks.py

@@ -122,6 +122,8 @@ def _map_statement_to_section(statement: Statement) -> str:
         return "others"
     if statement.kind == "static_func_def":
         return "others"
+    if statement.kind == "abstract_func_def":
+        return "others"
     if statement.kind == "docstr_stmt":
         return "docstrings"
     if statement.kind == "static_class_var_stmt":

gdtoolkit/parser/gdscript.lark

@@ -18,6 +18,7 @@ _simple_class_stmt: annotation* single_class_stmt (";" annotation* single_class_
                     | property_body_def
                     | func_def
                     | "static" func_def -> static_func_def
+                    | abstract_func_def
 annotation: "@" NAME [annotation_args]
 annotation_args: "(" [test_expr ("," test_expr)* [trailing_comma]] ")"
 
@@ -71,7 +72,9 @@ _property_delegates: property_delegate_set ["," [_NL] property_delegate_get]
 property_custom_getter_args: "(" ")"
 
 func_def: func_header _func_suite
+abstract_func_def: abstract_func_header
 func_header: "func" NAME func_args ["->" TYPE_HINT] ":"
+abstract_func_header: "func" NAME func_args ["->" TYPE_HINT]
 func_args: "(" [func_arg ("," func_arg)* [trailing_comma]] ")"
 ?func_arg: func_arg_regular
          | func_arg_inf

tests/formatter/input-output-pairs/abstract_functions.in.gd

@@ -0,0 +1,12 @@
+@abstract class_name BaseClass
+
+@abstract func simple_abstract()
+
+@abstract func abstract_with_params(param1: String, param2: int)
+
+@abstract func abstract_with_return_type() -> String
+
+@abstract func abstract_with_params_and_return(input: String) -> int
+
+func concrete_method():
+	pass

tests/formatter/input-output-pairs/abstract_functions.out.gd

@@ -0,0 +1,18 @@
+@abstract
+class_name BaseClass
+
+@abstract
+func simple_abstract()
+
+@abstract
+func abstract_with_params(param1: String, param2: int)
+
+@abstract
+func abstract_with_return_type() -> String
+
+@abstract
+func abstract_with_params_and_return(input: String) -> int
+
+
+func concrete_method():
+	pass