Memory Optimizations

src/black/brackets.py

@@ -56,7 +56,7 @@ class BracketMatchError(Exception):
     """Raised when an opening bracket is unable to be matched to a closing bracket."""
 
 
-@dataclass
+@dataclass(slots=True, eq=False)
 class BracketTracker:
     """Keeps track of brackets on a line."""
 
@@ -156,7 +156,7 @@ def delimiter_count_with_priority(self, priority: Priority = 0) -> int:
             return 0
 
         priority = priority or self.max_delimiter_priority()
-        return sum(1 for p in self.delimiters.values() if p == priority)
+        return sum(p == priority for p in self.delimiters.values())
 
     def maybe_increment_for_loop_variable(self, leaf: Leaf) -> bool:
         """In a for loop, or comprehension, the variables are often unpacks.

src/black/comments.py

@@ -2,7 +2,7 @@
 from collections.abc import Collection, Iterator
 from dataclasses import dataclass
 from functools import lru_cache
-from typing import Final, Union
+from typing import Final
 
 from black.mode import Mode
 from black.nodes import (
@@ -22,7 +22,7 @@
 from blib2to3.pytree import Leaf, Node
 
 # types
-LN = Union[Leaf, Node]
+LN = Leaf | Node
 
 FMT_OFF: Final = {"# fmt: off", "# fmt:off", "# yapf: disable"}
 FMT_SKIP: Final = {"# fmt: skip", "# fmt:skip"}
@@ -37,7 +37,7 @@
 _COMMENT_LIST_SEPARATOR = ";"
 
 
-@dataclass
+@dataclass(slots=True, eq=False, repr=False)
 class ProtoComment:
     """Describes a piece of syntax that is a comment.
 

src/black/handle_ipynb_magics.py

@@ -460,9 +460,7 @@ def visit_Assign(self, node: ast.Assign) -> None:
             if node.value.func.attr == "getoutput":
                 src = f"!{args[0]}"
             elif node.value.func.attr == "run_line_magic":
-                src = f"%{args[0]}"
-                if args[1]:
-                    src += f" {args[1]}"
+                src = "%" + " ".join(filter(None, args))
             else:
                 raise AssertionError(
                     f"Unexpected IPython magic {node.value.func.attr!r} found. "
@@ -500,9 +498,7 @@ def visit_Expr(self, node: ast.Expr) -> None:
                 elif args[0] == "pinfo2":
                     src = f"??{args[1]}"
                 else:
-                    src = f"%{args[0]}"
-                    if args[1]:
-                        src += f" {args[1]}"
+                    src = "%" + " ".join(filter(None, args))
             elif node.value.func.attr == "system":
                 src = f"!{args[0]}"
             elif node.value.func.attr == "getoutput":

src/black/linegen.py

@@ -1054,13 +1054,12 @@ def _first_right_hand_split(
                     len(str(leaf))
                     for leaf in hugged_opening_leaves + hugged_closing_leaves
                 )
-                if is_line_short_enough(
+
+                # Do not hug if it fits on a single line.
+                should_hug = not is_line_short_enough(
                     inner_body, mode=replace(line.mode, line_length=line_length)
-                ):
-                    # Do not hug if it fits on a single line.
-                    should_hug = False
-                else:
-                    should_hug = True
+                )
+
             if should_hug:
                 body_leaves = inner_body_leaves
                 head_leaves.extend(hugged_opening_leaves)

src/black/lines.py

@@ -38,7 +38,7 @@
 LN = Union[Leaf, Node]
 
 
-@dataclass
+@dataclass(slots=True, eq=False)
 class Line:
     """Holds leaves and comments. Can be printed with `str(line)`."""
 
@@ -199,9 +199,7 @@ def _is_triple_quoted_string(self) -> bool:
         value = self.leaves[0].value
         if value.startswith(('"""', "'''")):
             return True
-        if value.startswith(("r'''", 'r"""', "R'''", 'R"""')):
-            return True
-        return False
+        return value.startswith(("r'''", 'r"""', "R'''", 'R"""'))
 
     @property
     def is_docstring(self) -> bool:
@@ -483,22 +481,21 @@ def __str__(self) -> str:
             return "\n"
 
         indent = "    " * self.depth
-        leaves = iter(self.leaves)
-        first = next(leaves)
-        res = f"{first.prefix}{indent}{first.value}"
-        res += "".join(str(leaf) for leaf in leaves)
-        comments_iter = itertools.chain.from_iterable(self.comments.values())
-        comments = [str(comment) for comment in comments_iter]
-        res += "".join(comments)
+        first, *rest = self.leaves
+
+        rest_str = "".join(map(str, rest))
+        comments_str = "".join(
+            str(comment) for group in self.comments.values() for comment in group
+        )
 
-        return res + "\n"
+        return f"{first.prefix}{indent}{first.value}{rest_str}{comments_str}\n"
 
     def __bool__(self) -> bool:
         """Return True if the line has leaves or comments."""
         return bool(self.leaves or self.comments)
 
 
-@dataclass
+@dataclass(slots=True, eq=False, repr=False)
 class RHSResult:
     """Intermediate split result from a right hand split."""
 
@@ -509,7 +506,7 @@ class RHSResult:
     closing_bracket: Leaf
 
 
-@dataclass
+@dataclass(slots=True, eq=False, repr=False)
 class LinesBlock:
     """Class that holds information about a block of formatted lines.
 
@@ -549,7 +546,7 @@ class _DecoratedFuncInfo(NamedTuple):
     is_multi: bool
 
 
-@dataclass
+@dataclass(slots=True, eq=False, repr=False)
 class EmptyLineTracker:
     """Provides a stateful method that returns the number of potential extra
     empty lines needed before and after the currently processed line.
@@ -1610,7 +1607,6 @@ def can_omit_invisible_parens(
         # a leading opening bracket and a trailing closing bracket.  If the
         # opening bracket doesn't match our rule, maybe the closing will.
 
-    penultimate = line.leaves[-2]
     last = line.leaves[-1]
 
     if (
@@ -1624,6 +1620,7 @@ def can_omit_invisible_parens(
             and last.parent.type != syms.trailer
         )
     ):
+        penultimate = line.leaves[-2]
         if penultimate.type in OPENING_BRACKETS:
             # Empty brackets don't help.
             return False

src/black/output.py

@@ -89,8 +89,7 @@ def diff(a: str, b: str, a_name: str, b_name: str) -> str:
         if line[-1] == "\n":
             diff_lines.append(line)
         else:
-            diff_lines.append(line + "\n")
-            diff_lines.append("\\ No newline at end of file\n")
+            diff_lines.extend((line + "\n", "\\ No newline at end of file\n"))
     return "".join(diff_lines)
 
 
@@ -113,9 +112,7 @@ def color_diff(contents: str) -> str:
 
 
 def style_output(message: str, **styles: Any) -> str:
-    if not _color_enabled():
-        return message
-    return style(message, **styles)
+    return style(message, **styles) if _color_enabled() else message
 
 
 def _color_enabled() -> bool:

src/black/ranges.py

@@ -525,7 +525,7 @@ def _get_line_range(node_or_nodes: LN | list[LN]) -> set[int]:
                 return set()
 
 
-@dataclass
+@dataclass(slots=True, eq=False, repr=False)
 class _LinesMapping:
     """1-based lines mapping from original source to modified source.
 

src/black/trans.py

@@ -360,7 +360,7 @@ def _get_key(string: str) -> CustomSplitMapKey:
             A unique identifier that is used internally to map @string to a
             group of custom splits.
         """
-        return (id(string), string)
+        return id(string), string
 
     def add_custom_splits(
         self, string: str, custom_splits: Iterable[CustomSplit]
@@ -422,6 +422,8 @@ class StringMerger(StringTransformer, CustomSplitMapMixin):
         StringMerger provides custom split information to StringSplitter.
     """
 
+    __slots__ = ()
+
     def do_match(self, line: Line) -> TMatchResult:
         LL = line.leaves
 
@@ -1016,13 +1018,11 @@ def do_transform(
             string_parser = StringParser()
             rpar_idx = string_parser.parse(LL, string_idx)
 
-            should_transform = True
-            for leaf in (LL[string_idx - 1], LL[rpar_idx]):
-                if line.comments_after(leaf):
-                    # Should not strip parentheses which have comments attached
-                    # to them.
-                    should_transform = False
-                    break
+            # Should not strip parentheses which have comments attached
+            # to them.
+            should_transform = not any(
+                line.comments_after(leaf) for leaf in (LL[string_idx - 1], LL[rpar_idx])
+            )
             if should_transform:
                 string_and_rpar_indices.extend((string_idx, rpar_idx))
 
@@ -1358,7 +1358,7 @@ def iter_fexpr_spans(s: str) -> Iterator[tuple[int, int]]:
             j = stack.pop()
             # we've made it back out of the expression! yield the span
             if not stack:
-                yield (j, i + 1)
+                yield j, i + 1
             i += 1
             continue
 
@@ -1397,11 +1397,13 @@ def _toggle_fexpr_quotes(fstring: str, old_quote: str) -> str:
     escaping, once Black figures out how to parse the new grammar.
     """
     new_quote = "'" if old_quote == '"' else '"'
-    parts = []
+    parts: list[str] = []
     previous_index = 0
     for start, end in iter_fexpr_spans(fstring):
-        parts.append(fstring[previous_index:start])
-        parts.append(fstring[start:end].replace(old_quote, new_quote))
+        parts.extend((
+            fstring[previous_index:start],
+            fstring[start:end].replace(old_quote, new_quote),
+        ))
         previous_index = end
     parts.append(fstring[previous_index:])
     return "".join(parts)
@@ -2257,10 +2259,7 @@ def do_transform(
         insert_str_child = insert_str_child_factory(LL[string_idx])
 
         comma_idx = -1
-        ends_with_comma = False
-        if LL[comma_idx].type == token.COMMA:
-            ends_with_comma = True
-
+        ends_with_comma = LL[comma_idx].type == token.COMMA
         leaves_to_steal_comments_from = [LL[string_idx]]
         if ends_with_comma:
             leaves_to_steal_comments_from.append(LL[comma_idx])

src/blib2to3/pgen2/conv.py

@@ -168,7 +168,7 @@ def parse_graminit_c(self, filename):
         mo = re.match(r"static dfa dfas\[(\d+)\] = {$", line)
         assert mo, (lineno, line)
         ndfas = int(mo.group(1))
-        for i in range(ndfas):
+        for _ in range(ndfas):
             lineno, line = lineno + 1, next(f)
             mo = re.match(r'\s+{(\d+), "(\w+)", (\d+), (\d+), states_(\d+),$', line)
             assert mo, (lineno, line)

src/blib2to3/pgen2/driver.py

@@ -16,7 +16,6 @@
 __all__ = ["Driver", "load_grammar"]
 
 # Python imports
-import io
 import logging
 import os
 import pkgutil
@@ -37,7 +36,7 @@
 Path = Union[str, "os.PathLike[str]"]
 
 
-@dataclass
+@dataclass(slots=True, eq=False, repr=False)
 class ReleaseRange:
     start: int
     end: int | None = None
@@ -49,6 +48,8 @@ def lock(self) -> None:
 
 
 class TokenProxy:
+    __slots__ = ("_tokens", "_counter", "_release_ranges", "logger")
+
     def __init__(self, generator: Any) -> None:
         self._tokens = generator
         self._counter = 0

src/blib2to3/pgen2/parse.py

@@ -157,6 +157,17 @@ class Parser:
 
     """
 
+    __slots__ = (
+        "convert",
+        "grammar",
+        "is_backtracking",
+        "last_token",
+        "proxy",
+        "rootnode",
+        "stack",
+        "used_names",
+    )
+
     def __init__(self, grammar: Grammar, convert: Convert | None = None) -> None:
         """Constructor.
 
@@ -392,4 +403,3 @@ def pop(self) -> None:
                 node[-1].append(newnode)
             else:
                 self.rootnode = newnode
-                self.rootnode.used_names = self.used_names