Reduce usage of regex (#2644)

[etc/vim.git] / src / black / trans.py

diff --git a/src/black/trans.py b/src/black/trans.py
index 023dcd3618a5c0edb6b6f5e7e91e09bb6d3add30..a4d1e6fbc7990f3813dfcc469a906af519252eb7 100644 (file)
--- a/src/black/trans.py
+++ b/src/black/trans.py
@@ -4,10 +4,11 @@ String transformers that can split and merge strings.
 from abc import ABC, abstractmethod
 from collections import defaultdict
 from dataclasses import dataclass
-import regex as re
+import regex as re  # We need recursive patterns here (?R)
 from typing import (
     Any,
     Callable,
+    ClassVar,
     Collection,
     Dict,
     Iterable,
@@ -20,6 +21,14 @@ from typing import (
     TypeVar,
     Union,
 )
+import sys
+
+if sys.version_info < (3, 8):
+    from typing_extensions import Final
+else:
+    from typing import Final
+
+from mypy_extensions import trait
 
 from black.rusty import Result, Ok, Err
 
@@ -62,7 +71,6 @@ def TErr(err_msg: str) -> Err[CannotTransform]:
     return Err(cant_transform)
 
 
-@dataclass  # type: ignore
 class StringTransformer(ABC):
     """
     An implementation of the Transformer protocol that relies on its
@@ -90,9 +98,13 @@ class StringTransformer(ABC):
         as much as possible.
     """
 
-    line_length: int
-    normalize_strings: bool
-    __name__ = "StringTransformer"
+    __name__: Final = "StringTransformer"
+
+    # Ideally this would be a dataclass, but unfortunately mypyc breaks when used with
+    # `abc.ABC`.
+    def __init__(self, line_length: int, normalize_strings: bool) -> None:
+        self.line_length = line_length
+        self.normalize_strings = normalize_strings
 
     @abstractmethod
     def do_match(self, line: Line) -> TMatchResult:
@@ -184,6 +196,7 @@ class CustomSplit:
     break_idx: int
 
 
+@trait
 class CustomSplitMapMixin:
     """
     This mixin class is used to map merged strings to a sequence of
@@ -191,8 +204,10 @@ class CustomSplitMapMixin:
     the resultant substrings go over the configured max line length.
     """
 
-    _Key = Tuple[StringID, str]
-    _CUSTOM_SPLIT_MAP: Dict[_Key, Tuple[CustomSplit, ...]] = defaultdict(tuple)
+    _Key: ClassVar = Tuple[StringID, str]
+    _CUSTOM_SPLIT_MAP: ClassVar[Dict[_Key, Tuple[CustomSplit, ...]]] = defaultdict(
+        tuple
+    )
 
     @staticmethod
     def _get_key(string: str) -> "CustomSplitMapMixin._Key":
@@ -243,7 +258,7 @@ class CustomSplitMapMixin:
         return key in self._CUSTOM_SPLIT_MAP
 
 
-class StringMerger(CustomSplitMapMixin, StringTransformer):
+class StringMerger(StringTransformer, CustomSplitMapMixin):
     """StringTransformer that merges strings together.
 
     Requirements:
@@ -739,7 +754,7 @@ class BaseStringSplitter(StringTransformer):
         * The target string is not a multiline (i.e. triple-quote) string.
     """
 
-    STRING_OPERATORS = [
+    STRING_OPERATORS: Final = [
         token.EQEQUAL,
         token.GREATER,
         token.GREATEREQUAL,
@@ -927,7 +942,7 @@ class BaseStringSplitter(StringTransformer):
         return max_string_length
 
 
-class StringSplitter(CustomSplitMapMixin, BaseStringSplitter):
+class StringSplitter(BaseStringSplitter, CustomSplitMapMixin):
     """
     StringTransformer that splits "atom" strings (i.e. strings which exist on
     lines by themselves).
@@ -965,9 +980,9 @@ class StringSplitter(CustomSplitMapMixin, BaseStringSplitter):
         CustomSplit objects and add them to the custom split map.
     """
 
-    MIN_SUBSTR_SIZE = 6
+    MIN_SUBSTR_SIZE: Final = 6
     # Matches an "f-expression" (e.g. {var}) that might be found in an f-string.
-    RE_FEXPR = r"""
+    RE_FEXPR: Final = r"""
     (?<!\{) (?:\{\{)* \{ (?!\{)
         (?:
             [^\{\}]
@@ -1426,7 +1441,7 @@ class StringSplitter(CustomSplitMapMixin, BaseStringSplitter):
         return string_op_leaves
 
 
-class StringParenWrapper(CustomSplitMapMixin, BaseStringSplitter):
+class StringParenWrapper(BaseStringSplitter, CustomSplitMapMixin):
     """
     StringTransformer that splits non-"atom" strings (i.e. strings that do not
     exist on lines by themselves).
@@ -1811,20 +1826,20 @@ class StringParser:
         ```
     """
 
-    DEFAULT_TOKEN = -1
+    DEFAULT_TOKEN: Final = 20210605
 
     # String Parser States
-    START = 1
-    DOT = 2
-    NAME = 3
-    PERCENT = 4
-    SINGLE_FMT_ARG = 5
-    LPAR = 6
-    RPAR = 7
-    DONE = 8
+    START: Final = 1
+    DOT: Final = 2
+    NAME: Final = 3
+    PERCENT: Final = 4
+    SINGLE_FMT_ARG: Final = 5
+    LPAR: Final = 6
+    RPAR: Final = 7
+    DONE: Final = 8
 
     # Lookup Table for Next State
-    _goto: Dict[Tuple[ParserState, NodeType], ParserState] = {
+    _goto: Final[Dict[Tuple[ParserState, NodeType], ParserState]] = {
         # A string trailer may start with '.' OR '%'.
         (START, token.DOT): DOT,
         (START, token.PERCENT): PERCENT,