Actually add trailing commas to collection literals even if there are terminating...

Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>
Co-authored-by: Richard Si <sichard26@gmail.com>

diff --git a/CHANGES.md b/CHANGES.md
index 2071eb3f80000aeca667153b500869296a374215..a8b556cb7e8692c241f4566e7e5c4bf08d5cafd5 100644 (file)
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -14,6 +14,9 @@
 
 <!-- Changes that affect Black's preview style -->
 
 
 <!-- Changes that affect Black's preview style -->
 

+- Add trailing commas to collection literals even if there's a comment after the last
+  entry (#3393)
+

 ### 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 7afb1733939d6d0472663b371c88f8a5cc435bda..c582b2d6dff18a9ac6c1f4a79cfde8a5f428cd73 100644 (file)
--- a/src/black/linegen.py
+++ b/src/black/linegen.py
@@ -520,7 +520,7 @@ def transform_line(
     else:
 
         def _rhs(
     else:
 
         def _rhs(

-            self: object, line: Line, features: Collection[Feature]
+            self: object, line: Line, features: Collection[Feature], mode: Mode

         ) -> Iterator[Line]:
             """Wraps calls to `right_hand_split`.
 
         ) -> Iterator[Line]:
             """Wraps calls to `right_hand_split`.
 


@@ -604,7 +604,9 @@ class _BracketSplitComponent(Enum):
     tail = auto()
 
 
     tail = auto()
 
 

-def left_hand_split(line: Line, _features: Collection[Feature] = ()) -> Iterator[Line]:
+def left_hand_split(
+    line: Line, _features: Collection[Feature], mode: Mode
+) -> Iterator[Line]:

     """Split line into many lines, starting with the first matching bracket pair.
 
     Note: this usually looks weird, only use this for function definitions.
     """Split line into many lines, starting with the first matching bracket pair.
 
     Note: this usually looks weird, only use this for function definitions.


@@ -940,16 +942,39 @@ def dont_increase_indentation(split_func: Transformer) -> Transformer:
     """
 
     @wraps(split_func)
     """
 
     @wraps(split_func)

-    def split_wrapper(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]:
-        for split_line in split_func(line, features):
+    def split_wrapper(
+        line: Line, features: Collection[Feature], mode: Mode
+    ) -> Iterator[Line]:
+        for split_line in split_func(line, features, mode):

             normalize_prefix(split_line.leaves[0], inside_brackets=True)
             yield split_line
 
     return split_wrapper
 
 
             normalize_prefix(split_line.leaves[0], inside_brackets=True)
             yield split_line
 
     return split_wrapper
 
 

+def _get_last_non_comment_leaf(line: Line) -> Optional[int]:
+    for leaf_idx in range(len(line.leaves) - 1, 0, -1):
+        if line.leaves[leaf_idx].type != STANDALONE_COMMENT:
+            return leaf_idx
+    return None
+
+
+def _safe_add_trailing_comma(safe: bool, delimiter_priority: int, line: Line) -> Line:
+    if (
+        safe
+        and delimiter_priority == COMMA_PRIORITY
+        and line.leaves[-1].type != token.COMMA
+        and line.leaves[-1].type != STANDALONE_COMMENT
+    ):
+        new_comma = Leaf(token.COMMA, ",")
+        line.append(new_comma)
+    return line
+
+

 @dont_increase_indentation
 @dont_increase_indentation

-def delimiter_split(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]:
+def delimiter_split(
+    line: Line, features: Collection[Feature], mode: Mode
+) -> Iterator[Line]:

     """Split according to delimiters of the highest priority.
 
     If the appropriate Features are given, the split will add trailing commas
     """Split according to delimiters of the highest priority.
 
     If the appropriate Features are given, the split will add trailing commas


@@ -989,7 +1014,8 @@ def delimiter_split(line: Line, features: Collection[Feature] = ()) -> Iterator[
             )
             current_line.append(leaf)
 
             )
             current_line.append(leaf)
 

-    for leaf in line.leaves:
+    last_non_comment_leaf = _get_last_non_comment_leaf(line)
+    for leaf_idx, leaf in enumerate(line.leaves):

         yield from append_to_line(leaf)
 
         for comment_after in line.comments_after(leaf):
         yield from append_to_line(leaf)
 
         for comment_after in line.comments_after(leaf):


@@ -1006,6 +1032,15 @@ def delimiter_split(line: Line, features: Collection[Feature] = ()) -> Iterator[
                     trailing_comma_safe and Feature.TRAILING_COMMA_IN_CALL in features
                 )
 
                     trailing_comma_safe and Feature.TRAILING_COMMA_IN_CALL in features
                 )
 

+        if (
+            Preview.add_trailing_comma_consistently in mode
+            and last_leaf.type == STANDALONE_COMMENT
+            and leaf_idx == last_non_comment_leaf
+        ):
+            current_line = _safe_add_trailing_comma(
+                trailing_comma_safe, delimiter_priority, current_line
+            )
+

         leaf_priority = bt.delimiters.get(id(leaf))
         if leaf_priority == delimiter_priority:
             yield current_line
         leaf_priority = bt.delimiters.get(id(leaf))
         if leaf_priority == delimiter_priority:
             yield current_line


@@ -1014,20 +1049,15 @@ def delimiter_split(line: Line, features: Collection[Feature] = ()) -> Iterator[
                 mode=line.mode, depth=line.depth, inside_brackets=line.inside_brackets
             )
     if current_line:
                 mode=line.mode, depth=line.depth, inside_brackets=line.inside_brackets
             )
     if current_line:

-        if (
-            trailing_comma_safe
-            and delimiter_priority == COMMA_PRIORITY
-            and current_line.leaves[-1].type != token.COMMA
-            and current_line.leaves[-1].type != STANDALONE_COMMENT
-        ):
-            new_comma = Leaf(token.COMMA, ",")
-            current_line.append(new_comma)
+        current_line = _safe_add_trailing_comma(
+            trailing_comma_safe, delimiter_priority, current_line
+        )

         yield current_line
 
 
 @dont_increase_indentation
 def standalone_comment_split(
         yield current_line
 
 
 @dont_increase_indentation
 def standalone_comment_split(

-    line: Line, features: Collection[Feature] = ()
+    line: Line, features: Collection[Feature], mode: Mode

 ) -> Iterator[Line]:
     """Split standalone comments from the rest of the line."""
     if not line.contains_standalone_comments(0):
 ) -> Iterator[Line]:
     """Split standalone comments from the rest of the line."""
     if not line.contains_standalone_comments(0):


@@ -1480,7 +1510,7 @@ def run_transformer(
     if not line_str:
         line_str = line_to_string(line)
     result: List[Line] = []
     if not line_str:
         line_str = line_to_string(line)
     result: List[Line] = []

-    for transformed_line in transform(line, features):
+    for transformed_line in transform(line, features, mode):

         if str(transformed_line).strip("\n") == line_str:
             raise CannotTransform("Line transformer returned an unchanged result")
 
         if str(transformed_line).strip("\n") == line_str:
             raise CannotTransform("Line transformer returned an unchanged result")
 

diff --git a/src/black/mode.py b/src/black/mode.py
index 1af160700738bbc30157ce627c6f7881f82ba851..c9a4c2b080c7c8d2b7159ecbde403fc188e1abdc 100644 (file)
--- a/src/black/mode.py
+++ b/src/black/mode.py
@@ -153,6 +153,7 @@ def supports_feature(target_versions: Set[TargetVersion], feature: Feature) -> b
 class Preview(Enum):
     """Individual preview style features."""
 
 class Preview(Enum):
     """Individual preview style features."""
 

+    add_trailing_comma_consistently = auto()

     hex_codes_in_unicode_sequences = auto()
     prefer_splitting_right_hand_side_of_assignments = auto()
     # NOTE: string_processing requires wrap_long_dict_values_in_parens
     hex_codes_in_unicode_sequences = auto()
     prefer_splitting_right_hand_side_of_assignments = auto()
     # NOTE: string_processing requires wrap_long_dict_values_in_parens

diff --git a/src/black/trans.py b/src/black/trans.py
index 2360c13f06a249e17c340a684d9f8a3e9eba02ce..a6a416e71bc4c4e484e1a74c0949341e5908d67a 100644 (file)
--- a/src/black/trans.py
+++ b/src/black/trans.py
@@ -32,7 +32,7 @@ from mypy_extensions import trait
 
 from black.comments import contains_pragma_comment
 from black.lines import Line, append_leaves
 
 from black.comments import contains_pragma_comment
 from black.lines import Line, append_leaves

-from black.mode import Feature
+from black.mode import Feature, Mode

 from black.nodes import (
     CLOSING_BRACKETS,
     OPENING_BRACKETS,
 from black.nodes import (
     CLOSING_BRACKETS,
     OPENING_BRACKETS,


@@ -63,7 +63,7 @@ class CannotTransform(Exception):
 # types
 T = TypeVar("T")
 LN = Union[Leaf, Node]
 # types
 T = TypeVar("T")
 LN = Union[Leaf, Node]

-Transformer = Callable[[Line, Collection[Feature]], Iterator[Line]]
+Transformer = Callable[[Line, Collection[Feature], Mode], Iterator[Line]]

 Index = int
 NodeType = int
 ParserState = int
 Index = int
 NodeType = int
 ParserState = int


@@ -81,7 +81,9 @@ def TErr(err_msg: str) -> Err[CannotTransform]:
     return Err(cant_transform)
 
 
     return Err(cant_transform)
 
 

-def hug_power_op(line: Line, features: Collection[Feature]) -> Iterator[Line]:
+def hug_power_op(
+    line: Line, features: Collection[Feature], mode: Mode
+) -> Iterator[Line]:

     """A transformer which normalizes spacing around power operators."""
 
     # Performance optimization to avoid unnecessary Leaf clones and other ops.
     """A transformer which normalizes spacing around power operators."""
 
     # Performance optimization to avoid unnecessary Leaf clones and other ops.


@@ -228,7 +230,9 @@ class StringTransformer(ABC):
             yield an CannotTransform after that point.)
         """
 
             yield an CannotTransform after that point.)
         """
 

-    def __call__(self, line: Line, _features: Collection[Feature]) -> Iterator[Line]:
+    def __call__(
+        self, line: Line, _features: Collection[Feature], _mode: Mode
+    ) -> Iterator[Line]:

         """
         StringTransformer instances have a call signature that mirrors that of
         the Transformer type.
         """
         StringTransformer instances have a call signature that mirrors that of
         the Transformer type.

diff --git a/tests/data/preview/trailing_comma.py b/tests/data/preview/trailing_comma.py
new file mode 100644 (file)
index 0000000..5b09c66
--- /dev/null
+++ b/tests/data/preview/trailing_comma.py
@@ -0,0 +1,55 @@
+e = {
+    "a": fun(msg, "ts"),
+    "longggggggggggggggid": ...,
+    "longgggggggggggggggggggkey": ..., "created": ...
+    # "longkey": ...
+}
+f = [
+    arg1,
+    arg2,
+    arg3, arg4
+    # comment
+]
+g = (
+    arg1,
+    arg2,
+    arg3, arg4
+    # comment
+)
+h = {
+    arg1,
+    arg2,
+    arg3, arg4
+    # comment
+}
+
+# output
+
+e = {
+    "a": fun(msg, "ts"),
+    "longggggggggggggggid": ...,
+    "longgggggggggggggggggggkey": ...,
+    "created": ...,
+    # "longkey": ...
+}
+f = [
+    arg1,
+    arg2,
+    arg3,
+    arg4,
+    # comment
+]
+g = (
+    arg1,
+    arg2,
+    arg3,
+    arg4,
+    # comment
+)
+h = {
+    arg1,
+    arg2,
+    arg3,
+    arg4,
+    # comment
+}

diff --git a/tests/data/preview_context_managers/targeting_py39.py b/tests/data/preview_context_managers/targeting_py39.py
index 5cb8763040a2e49d28bdeb750abb5b3f8affb5de..64f5d09bbe8e94d263b0ae110f3902461fad4b5a 100644 (file)
--- a/tests/data/preview_context_managers/targeting_py39.py
+++ b/tests/data/preview_context_managers/targeting_py39.py
@@ -84,7 +84,7 @@ with (
     # First comment.
     new_new_new1() as cm1,
     # Second comment.
     # First comment.
     new_new_new1() as cm1,
     # Second comment.

-    new_new_new2()
+    new_new_new2(),

     # Last comment.
 ):
     pass
     # Last comment.
 ):
     pass