Remove regex dependency (GH-2663)

We were no longer using it since GH-2644 and GH-2654. This should hopefully
make using Black easier to use as there's one less compiled dependency.
The core team also doesn't have to deal with the surprisingly frequent fires
the regex packaging setup goes through.

Co-authored-by: Richard Si <63936253+ichard26@users.noreply.github.com>

CHANGES.md

@@ -8,7 +8,7 @@
   cell magics were tokenized, leading to possible indentation errors e.g. with
   `%%writefile`. (#2630)
 - Fix Python 3.10 support on platforms without ProcessPoolExecutor (#2631)
-- Reduce usage of the `regex` dependency (#2644)
+- Remove dependency on `regex` (#2644) (#2663)
 - Fix `match` statements with open sequence subjects, like `match a, b:` or
   `match a, *b:` (#2639) (#2659)
 - Fix `match`/`case` statements that contain `match`/`case` soft keywords multiple

Pipfile

@@ -42,7 +42,6 @@ platformdirs= ">=2"
 click = ">=8.0.0"
 mypy_extensions = ">=0.4.3"
 pathspec = ">=0.8.1"
-regex = ">=2021.4.4"
 tomli = ">=0.2.6, <2.0.0"
 typed-ast = "==1.4.3"
 typing_extensions = {markers = "python_version < '3.10'", version = ">=3.10.0.0"}

docs/integrations/editors.md

@@ -204,30 +204,28 @@ Traceback (most recent call last):
 ImportError: /home/gui/.vim/black/lib/python3.7/site-packages/typed_ast/_ast3.cpython-37m-x86_64-linux-gnu.so: undefined symbool: PyExc_KeyboardInterrupt
 ```
 
-Then you need to install `typed_ast` and `regex` directly from the source code. The
-error happens because `pip` will download [Python wheels](https://pythonwheels.com/) if
-they are available. Python wheels are a new standard of distributing Python packages and
-packages that have Cython and extensions written in C are already compiled, so the
-installation is much more faster. The problem here is that somehow the Python
-environment inside Vim does not match with those already compiled C extensions and these
-kind of errors are the result. Luckily there is an easy fix: installing the packages
-from the source code.
-
-The two packages that cause the problem are:
-
-- [regex](https://pypi.org/project/regex/)
+Then you need to install `typed_ast` directly from the source code. The error happens
+because `pip` will download [Python wheels](https://pythonwheels.com/) if they are
+available. Python wheels are a new standard of distributing Python packages and packages
+that have Cython and extensions written in C are already compiled, so the installation
+is much more faster. The problem here is that somehow the Python environment inside Vim
+does not match with those already compiled C extensions and these kind of errors are the
+result. Luckily there is an easy fix: installing the packages from the source code.
+
+The package that causes problems is:
+
 - [typed-ast](https://pypi.org/project/typed-ast/)
 
 Now remove those two packages:
 
 ```console
-$ pip uninstall regex typed-ast -y
+$ pip uninstall typed-ast -y
 ```
 
 And now you can install them with:
 
 ```console
-$ pip install --no-binary :all: regex typed-ast
+$ pip install --no-binary :all: typed-ast
 ```
 
 The C extensions will be compiled and now Vim's Python environment will match. Note that
@@ -237,7 +235,7 @@ Ubuntu/Debian do `sudo apt-get install build-essential python3-dev`).
 If you later want to update _Black_, you should do it like this:
 
 ```console
-$ pip install -U black --no-binary regex,typed-ast
+$ pip install -U black --no-binary typed-ast
 ```
 
 ### With ALE

setup.py

@@ -101,7 +101,6 @@ def find_python_files(base: Path) -> List[Path]:
         "platformdirs>=2",
         "tomli>=0.2.6,<2.0.0",
         "typed-ast>=1.4.2; python_version < '3.8' and implementation_name == 'cpython'",
-        "regex>=2021.4.4",
         "pathspec>=0.9.0, <1",
         "dataclasses>=0.6; python_version < '3.7'",
         "typing_extensions>=3.10.0.0",

src/black/trans.py

@@ -4,7 +4,7 @@
 from abc import ABC, abstractmethod
 from collections import defaultdict
 from dataclasses import dataclass
-import regex as re  # We need recursive patterns here (?R)
+import re
 from typing import (
     Any,
     Callable,
@@ -453,7 +453,7 @@ def make_naked(string: str, string_prefix: str) -> str:
             # with 'f'...
             if "f" in prefix and "f" not in next_prefix:
                 # Then we must escape any braces contained in this substring.
-                SS = re.subf(r"(\{|\})", "{1}{1}", SS)
+                SS = re.sub(r"(\{|\})", r"\1\1", SS)
 
             NSS = make_naked(SS, next_prefix)