Support @abstract functions

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",
@@ -110,6 +111,16 @@
 ]
 
 
+def is_abstract_annotation_for_statement(statement: Tree, next_statement: Tree) -> bool:
+    """Check if this is an @abstract annotation that should be combined with the next statement."""
+    if statement.data != "annotation":
+        return False
+    name = statement.children[0].value
+    if name != "abstract":
+        return False
+    return next_statement.data in ["abstract_func_def", "classname_stmt", "class_def"]
+
+
 def is_non_standalone_annotation(statement: Tree) -> bool:
     if statement.data != "annotation":
         return False
@@ -135,9 +146,26 @@ def prepend_annotations_to_formatted_line(
     single_line_length = (
         context.indent + len(annotations_string) + len(whitelineless_line)
     )
-    standalone_formatting_enforced = whitelineless_line.startswith(
-        "func"
-    ) or whitelineless_line.startswith("static func")
+    # Check if this is an abstract function or class_name annotation
+    is_abstract_func = (
+        len(context.annotations) == 1 and
+        context.annotations[0].children[0].value == "abstract" and
+        whitelineless_line.startswith("func")
+    )
+    is_abstract_class_name = (
+        len(context.annotations) == 1 and
+        context.annotations[0].children[0].value == "abstract" and
+        whitelineless_line.startswith("class_name")
+    )
+    is_abstract_class = (
+        len(context.annotations) == 1 and
+        context.annotations[0].children[0].value == "abstract" and
+        whitelineless_line.startswith("class ")
+    )
+    standalone_formatting_enforced = (
+        whitelineless_line.startswith("func") or 
+        whitelineless_line.startswith("static func")
+    ) and not is_abstract_func and not is_abstract_class_name
     if (
         not _annotations_have_standalone_comments(
             context.annotations, context.standalone_comments, line_to_prepend_to[0]

gdtoolkit/formatter/block.py

@@ -14,6 +14,7 @@
 from .annotation import (
     is_non_standalone_annotation,
     prepend_annotations_to_formatted_line,
+    is_abstract_annotation_for_statement,
 )
 
 
@@ -26,8 +27,15 @@ def format_block(
     previous_statement_name = None
     formatted_lines = []  # type: FormattedLines
     previously_processed_line_number = context.previously_processed_line_number
-    for statement in statements:
-        if is_non_standalone_annotation(statement):
+    for i, statement in enumerate(statements):
+        # Check if this is an abstract annotation followed by an abstract function or class_name
+        next_statement = statements[i + 1] if i + 1 < len(statements) else None
+        is_abstract_for_statement = (
+            next_statement is not None and
+            is_abstract_annotation_for_statement(statement, next_statement)
+        )
+
+        if is_non_standalone_annotation(statement) or is_abstract_for_statement:
             context.annotations.append(statement)
             is_first_annotation = len(context.annotations) == 1
             if not is_first_annotation:
@@ -47,7 +55,7 @@ def format_block(
                 blank_lines, statement.data, surrounding_empty_lines_table
             )
         is_first_annotation = len(context.annotations) == 1
-        if is_non_standalone_annotation(statement) and is_first_annotation:
+        if (is_non_standalone_annotation(statement) or is_abstract_for_statement) and is_first_annotation:
             formatted_lines += blank_lines
             continue
         if len(context.annotations) == 0:

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/gd2py/__init__.py

@@ -64,6 +64,7 @@ def _convert_statement(statement: Tree, context: Context) -> List[str]:
             )
         ],
         "static_func_def": _convert_first_child_as_statement,
+        "abstract_func_def": _convert_abstract_func_def,
         "docstr_stmt": _pass,
         # func statements:
         "func_var_stmt": _convert_first_child_as_statement,
@@ -164,6 +165,16 @@ def _convert_func_def(statement: Tree, context: Context) -> List[str]:
     ] + _convert_block(statement.children[1:], context.create_child_context(-1))
 
 
+def _convert_abstract_func_def(statement: Tree, context: Context) -> List[str]:
+    # Abstract functions don't have a body, so we create a function that raises NotImplementedError
+    func_header = statement.children[0]
+    func_name = func_header.children[0].value
+    return [
+        f"{context.indent_string}def {func_name}():",
+        f"{context.indent_string}    raise NotImplementedError('Abstract method not implemented')",
+    ]
+
+
 def _convert_branch_with_expression(
     prefix: str, statement: Tree, context: Context
 ) -> List[str]:

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 +1,22 @@
+@abstract
+class_name BaseClass
+
+@abstract
+class TestClass:
+	@abstract
+	func test_func()
+
+@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 +1,17 @@
+@abstract class_name BaseClass
+
+@abstract class TestClass:
+	@abstract func test_func()
+
+
+@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