More concise formatting for dummy implementations (#3796)

diff --git a/CHANGES.md b/CHANGES.md
index 1de08792f7532b783db469fe7c97341a836f8028..d084498f404ab4696847adbd93be0e550d2c7de5 100644 (file)
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -14,6 +14,8 @@
 
 <!-- Changes that affect Black's preview style -->
 
 
 <!-- Changes that affect Black's preview style -->
 

+- More concise formatting for dummy implementations (#3796)
+

 ### Configuration
 
 <!-- Changes to how Black can be configured -->
 ### Configuration
 
 <!-- Changes to how Black can be configured -->

diff --git a/src/black/linegen.py b/src/black/linegen.py
index 5ef3bbd170578159249eb9f850676767a9bc1f56..507e860190f0c8a31701f5a316e46fa8099ac1e7 100644 (file)
--- a/src/black/linegen.py
+++ b/src/black/linegen.py
@@ -281,7 +281,9 @@ class LineGenerator(Visitor[Line]):
 
     def visit_suite(self, node: Node) -> Iterator[Line]:
         """Visit a suite."""
 
     def visit_suite(self, node: Node) -> Iterator[Line]:
         """Visit a suite."""

-        if self.mode.is_pyi and is_stub_suite(node):
+        if (
+            self.mode.is_pyi or Preview.dummy_implementations in self.mode
+        ) and is_stub_suite(node):

             yield from self.visit(node.children[2])
         else:
             yield from self.visit_default(node)
             yield from self.visit(node.children[2])
         else:
             yield from self.visit_default(node)


@@ -296,7 +298,9 @@ class LineGenerator(Visitor[Line]):
 
         is_suite_like = node.parent and node.parent.type in STATEMENT
         if is_suite_like:
 
         is_suite_like = node.parent and node.parent.type in STATEMENT
         if is_suite_like:

-            if self.mode.is_pyi and is_stub_body(node):
+            if (
+                self.mode.is_pyi or Preview.dummy_implementations in self.mode
+            ) and is_stub_body(node):

                 yield from self.visit_default(node)
             else:
                 yield from self.line(+1)
                 yield from self.visit_default(node)
             else:
                 yield from self.line(+1)


@@ -305,7 +309,7 @@ class LineGenerator(Visitor[Line]):
 
         else:
             if (
 
         else:
             if (

-                not self.mode.is_pyi
+                not (self.mode.is_pyi or Preview.dummy_implementations in self.mode)

                 or not node.parent
                 or not is_stub_suite(node.parent)
             ):
                 or not node.parent
                 or not is_stub_suite(node.parent)
             ):

diff --git a/src/black/lines.py b/src/black/lines.py
index 016a489310d492cb2d19aecc68720aa23c832e4d..0a307b45efff745ab07b744f1f99068c1b81c37c 100644 (file)
--- a/src/black/lines.py
+++ b/src/black/lines.py
@@ -165,6 +165,13 @@ class Line:
             and second_leaf.value == "def"
         )
 
             and second_leaf.value == "def"
         )
 

+    @property
+    def is_stub_def(self) -> bool:
+        """Is this line a function definition with a body consisting only of "..."?"""
+        return self.is_def and self.leaves[-4:] == [Leaf(token.COLON, ":")] + [
+            Leaf(token.DOT, ".") for _ in range(3)
+        ]
+

     @property
     def is_class_paren_empty(self) -> bool:
         """Is this a class with no base classes but using parentheses?
     @property
     def is_class_paren_empty(self) -> bool:
         """Is this a class with no base classes but using parentheses?


@@ -578,6 +585,8 @@ class EmptyLineTracker:
             first_leaf.prefix = ""
         else:
             before = 0
             first_leaf.prefix = ""
         else:
             before = 0

+
+        user_had_newline = bool(before)

         depth = current_line.depth
 
         previous_def = None
         depth = current_line.depth
 
         previous_def = None


@@ -589,7 +598,7 @@ class EmptyLineTracker:
             if self.mode.is_pyi:
                 if depth and not current_line.is_def and self.previous_line.is_def:
                     # Empty lines between attributes and methods should be preserved.
             if self.mode.is_pyi:
                 if depth and not current_line.is_def and self.previous_line.is_def:
                     # Empty lines between attributes and methods should be preserved.

-                    before = min(1, before)
+                    before = 1 if user_had_newline else 0

                 elif (
                     Preview.blank_line_after_nested_stub_class in self.mode
                     and previous_def.is_class
                 elif (
                     Preview.blank_line_after_nested_stub_class in self.mode
                     and previous_def.is_class


@@ -624,7 +633,9 @@ class EmptyLineTracker:
                     before = 2
 
         if current_line.is_decorator or current_line.is_def or current_line.is_class:
                     before = 2
 
         if current_line.is_decorator or current_line.is_def or current_line.is_class:

-            return self._maybe_empty_lines_for_class_or_def(current_line, before)
+            return self._maybe_empty_lines_for_class_or_def(
+                current_line, before, user_had_newline
+            )

 
         if (
             self.previous_line
 
         if (
             self.previous_line


@@ -648,8 +659,8 @@ class EmptyLineTracker:
             return 0, 0
         return before, 0
 
             return 0, 0
         return before, 0
 

-    def _maybe_empty_lines_for_class_or_def(
-        self, current_line: Line, before: int
+    def _maybe_empty_lines_for_class_or_def(  # noqa: C901
+        self, current_line: Line, before: int, user_had_newline: bool

     ) -> Tuple[int, int]:
         if not current_line.is_decorator:
             self.previous_defs.append(current_line)
     ) -> Tuple[int, int]:
         if not current_line.is_decorator:
             self.previous_defs.append(current_line)


@@ -715,6 +726,14 @@ class EmptyLineTracker:
                 newlines = 0
         else:
             newlines = 1 if current_line.depth else 2
                 newlines = 0
         else:
             newlines = 1 if current_line.depth else 2

+            # If a user has left no space after a dummy implementation, don't insert
+            # new lines. This is useful for instance for @overload or Protocols.
+            if (
+                Preview.dummy_implementations in self.mode
+                and self.previous_line.is_stub_def
+                and not user_had_newline
+            ):
+                newlines = 0

         if comment_to_add_newlines is not None:
             previous_block = comment_to_add_newlines.previous_block
             if previous_block is not None:
         if comment_to_add_newlines is not None:
             previous_block = comment_to_add_newlines.previous_block
             if previous_block is not None:

diff --git a/src/black/mode.py b/src/black/mode.py
index 4d979afd84de332135ac0052c494e9be842e8352..282c1669da74f5275b818befeed14634eb186a51 100644 (file)
--- a/src/black/mode.py
+++ b/src/black/mode.py
@@ -182,6 +182,7 @@ class Preview(Enum):
     skip_magic_trailing_comma_in_subscript = auto()
     wrap_long_dict_values_in_parens = auto()
     wrap_multiple_context_managers_in_parens = auto()
     skip_magic_trailing_comma_in_subscript = auto()
     wrap_long_dict_values_in_parens = auto()
     wrap_multiple_context_managers_in_parens = auto()

+    dummy_implementations = auto()

 
 
 class Deprecated(UserWarning):
 
 
 class Deprecated(UserWarning):

diff --git a/tests/data/miscellaneous/force_py36.py b/tests/data/miscellaneous/force_py36.py
index cad935e525a46057349becfcc1845ba37b2b28e3..4c9b70336e748ecc7c0384338ee7606b6496c95f 100644 (file)
--- a/tests/data/miscellaneous/force_py36.py
+++ b/tests/data/miscellaneous/force_py36.py
@@ -1,6 +1,6 @@
 # The input source must not contain any Py36-specific syntax (e.g. argument type
 # annotations, trailing comma after *rest) or this test becomes invalid.
 # The input source must not contain any Py36-specific syntax (e.g. argument type
 # annotations, trailing comma after *rest) or this test becomes invalid.

-def long_function_name(argument_one, argument_two, argument_three, argument_four, argument_five, argument_six, *rest): ...
+def long_function_name(argument_one, argument_two, argument_three, argument_four, argument_five, argument_six, *rest): pass

 # output
 # The input source must not contain any Py36-specific syntax (e.g. argument type
 # annotations, trailing comma after *rest) or this test becomes invalid.
 # output
 # The input source must not contain any Py36-specific syntax (e.g. argument type
 # annotations, trailing comma after *rest) or this test becomes invalid.


@@ -13,4 +13,4 @@ def long_function_name(
     argument_six,
     *rest,
 ):
     argument_six,
     *rest,
 ):

-    ...
+    pass

diff --git a/tests/data/preview/comments7.py b/tests/data/preview/comments7.py
index ec2dc501d8ef8382e132ed9b9bbd497ddaebe36a..8b1224017e5208878cd7ef51dad87df81bc85eef 100644 (file)
--- a/tests/data/preview/comments7.py
+++ b/tests/data/preview/comments7.py
@@ -278,8 +278,7 @@ class C:
     )
     def test_fails_invalid_post_data(
         self, pyramid_config, db_request, post_data, message
     )
     def test_fails_invalid_post_data(
         self, pyramid_config, db_request, post_data, message

-    ):
-        ...
+    ): ...

 
 
 square = Square(4)  # type: Optional[Square]
 
 
 square = Square(4)  # type: Optional[Square]

diff --git a/tests/data/preview/dummy_implementations.py b/tests/data/preview/dummy_implementations.py
new file mode 100644 (file)
index 0000000..e07c25e
--- /dev/null
+++ b/tests/data/preview/dummy_implementations.py
@@ -0,0 +1,99 @@
+from typing import NoReturn, Protocol, Union, overload
+
+
+def dummy(a): ...
+def other(b): ...
+
+
+@overload
+def a(arg: int) -> int: ...
+@overload
+def a(arg: str) -> str: ...
+@overload
+def a(arg: object) -> NoReturn: ...
+def a(arg: Union[int, str, object]) -> Union[int, str]:
+    if not isinstance(arg, (int, str)):
+        raise TypeError
+    return arg
+
+class Proto(Protocol):
+    def foo(self, a: int) -> int:
+        ...
+
+    def bar(self, b: str) -> str: ...
+    def baz(self, c: bytes) -> str:
+        ...
+
+
+def dummy_two():
+    ...
+@dummy
+def dummy_three():
+    ...
+
+def dummy_four():
+    ...
+
+@overload
+def b(arg: int) -> int: ...
+
+@overload
+def b(arg: str) -> str: ...
+@overload
+def b(arg: object) -> NoReturn: ...
+
+def b(arg: Union[int, str, object]) -> Union[int, str]:
+    if not isinstance(arg, (int, str)):
+        raise TypeError
+    return arg
+
+# output
+
+from typing import NoReturn, Protocol, Union, overload
+
+
+def dummy(a): ...
+def other(b): ...
+
+
+@overload
+def a(arg: int) -> int: ...
+@overload
+def a(arg: str) -> str: ...
+@overload
+def a(arg: object) -> NoReturn: ...
+def a(arg: Union[int, str, object]) -> Union[int, str]:
+    if not isinstance(arg, (int, str)):
+        raise TypeError
+    return arg
+
+
+class Proto(Protocol):
+    def foo(self, a: int) -> int: ...
+
+    def bar(self, b: str) -> str: ...
+    def baz(self, c: bytes) -> str: ...
+
+
+def dummy_two(): ...
+@dummy
+def dummy_three(): ...
+
+
+def dummy_four(): ...
+
+
+@overload
+def b(arg: int) -> int: ...
+
+
+@overload
+def b(arg: str) -> str: ...
+@overload
+def b(arg: object) -> NoReturn: ...
+
+
+def b(arg: Union[int, str, object]) -> Union[int, str]:
+    if not isinstance(arg, (int, str)):
+        raise TypeError
+    return arg