Add direct support for dataclasses (#26)

* WIP support dataclasses

* Ignore stubs/ directory

* Also test KW_ONLY and InitVar in dataclasses

Author: lagru

.gitignore

@@ -1,3 +1,6 @@
+# Project specific folders
+stubs/
+
 # Byte-compiled / optimized / DLL files
 __pycache__/
 *.py[cod]

src/docstub/_stubs.py

@@ -119,30 +119,42 @@ class ScopeType(enum.StrEnum):
     # docstub: on
 
 
+# TODO use `libcst.metadata.ScopeProvider` instead
 @dataclass(slots=True, frozen=True)
 class _Scope:
     """"""
 
     type: ScopeType
-    node: cst.CSTNode = None
+    node: cst.CSTNode | None = None
 
     @property
-    def has_self_or_cls(self):
+    def has_self_or_cls(self) -> bool:
         return self.type in {ScopeType.METHOD, ScopeType.CLASSMETHOD}
 
     @property
-    def is_method(self):
+    def is_method(self) -> bool:
         return self.type in {
             ScopeType.METHOD,
             ScopeType.CLASSMETHOD,
             ScopeType.STATICMETHOD,
         }
 
     @property
-    def is_class_init(self):
+    def is_class_init(self) -> bool:
         out = self.is_method and self.node.name.value == "__init__"
         return out
 
+    @property
+    def is_dataclass(self) -> bool:
+        if cstm.matches(self.node, cstm.ClassDef()):
+            # Determine if dataclass
+            decorators = cstm.findall(self.node, cstm.Decorator())
+            is_dataclass = any(
+                cstm.findall(d, cstm.Name("dataclass")) for d in decorators
+            )
+            return is_dataclass
+        return False
+
 
 def _get_docstring_node(node):
     """Extract the node with the docstring from a definition.
@@ -672,16 +684,27 @@ def leave_AnnAssign(self, original_node, updated_node):
         updated_node : cst.AnnAssign
         """
         name = updated_node.target.value
-        is_type_alias = cstm.matches(
-            updated_node.annotation, cstm.Annotation(cstm.Name("TypeAlias"))
-        )
-        is__all__ = cstm.matches(updated_node.target, cstm.Name("__all__"))
 
-        # Remove value if not type alias or __all__
-        if updated_node.value is not None and not is_type_alias and not is__all__:
-            updated_node = updated_node.with_changes(
-                value=None, equal=cst.MaybeSentinel.DEFAULT
+        if updated_node.value is not None:
+            is_type_alias = cstm.matches(
+                updated_node.annotation, cstm.Annotation(cstm.Name("TypeAlias"))
             )
+            is__all__ = cstm.matches(updated_node.target, cstm.Name("__all__"))
+            is_dataclass = self._scope_stack[-1].is_dataclass
+            is_classvar = any(
+                cstm.findall(updated_node.annotation, cstm.Name("ClassVar"))
+            )
+
+            # Replace with ellipses if dataclass
+            if is_dataclass and not is_classvar:
+                updated_node = updated_node.with_changes(
+                    value=cst.Ellipsis(), equal=cst.MaybeSentinel.DEFAULT
+                )
+            # Remove value if not type alias or __all__
+            elif not is_type_alias and not is__all__:
+                updated_node = updated_node.with_changes(
+                    value=None, equal=cst.MaybeSentinel.DEFAULT
+                )
 
         # Replace with type annotation from docstring, if available
         pytypes = self._pytypes_stack[-1]

stubtest_allow.txt

@@ -2,6 +2,3 @@ docstub\._version\..*
 docstub\..*\.__match_args__$
 docstub._cache.FuncSerializer.__type_params__
 docstub._cli.main
-docstub._config.Config.__init__
-docstub._docstrings.Annotation.__init__
-docstub._stubs._Scope.__init__

tests/test_stubs.py

@@ -394,3 +394,39 @@ class Foo:
         # remove these empty lines from the result too
         result = dedent(result)
         assert expected == result
+
+    @pytest.mark.parametrize("decorator", ["dataclass", "dataclasses.dataclass"])
+    def test_dataclass(self, decorator):
+        source = dedent(
+            f"""
+            @{decorator}
+            class Foo:
+                a: float
+                b: int = 3
+                c: str = None
+                _: KW_ONLY
+                d: dict[str, Any] = field(default_factory=dict)
+                e: InitVar[tuple] = tuple()
+                f: ClassVar
+                g: ClassVar[float]
+                h: Final[ClassVar[int]] = 1
+            """
+        )
+        expected = dedent(
+            f"""
+            @{decorator}
+            class Foo:
+                a: float
+                b: int = ...
+                c: str = ...
+                _: KW_ONLY
+                d: dict[str, Any] = ...
+                e: InitVar[tuple] = ...
+                f: ClassVar
+                g: ClassVar[float]
+                h: Final[ClassVar[int]]
+            """
+        )
+        transformer = Py2StubTransformer()
+        result = transformer.python_to_stub(source)
+        assert expected == result