gh-138281: Run ruff on Tools/peg_generator

.pre-commit-config.yaml

@@ -22,6 +22,10 @@ repos:
         name: Run Ruff (lint) on Argument Clinic
         args: [--exit-non-zero-on-fix, --config=Tools/clinic/.ruff.toml]
         files: ^Tools/clinic/|Lib/test/test_clinic.py
+      - id: ruff
+        name: Run Ruff (lint) on Tools/peg_generator/
+        args: [--exit-non-zero-on-fix, --config=Tools/peg_generator/.ruff.toml]
+        files: ^Tools/peg_generator/
       - id: ruff-format
         name: Run Ruff (format) on Doc/
         args: [--check]

Tools/peg_generator/.ruff.toml

@@ -0,0 +1,35 @@
+extend = "../../.ruff.toml"  # Inherit the project-wide settings
+extend-exclude = [
+    # Generated files:
+    "Tools/peg_generator/pegen/grammar_parser.py",
+]
+
+[lint]
+select = [
+    "F",  # Enable all pyflakes rules
+    "I",  # Enable all isort rules
+    "UP",  # Enable all pyupgrade rules by default
+    "RUF100",  # Ban unused `# noqa` comments
+    "PGH004",  # Ban blanket `# noqa` comments (only ignore specific error codes)
+]
+ignore = [
+    # Unnecessary parentheses to functools.lru_cache: just leads to unnecessary churn.
+    # https://github.com/python/cpython/pull/104684#discussion_r1199653347.
+    "UP011",
+    # Use format specifiers instead of %-style formatting.
+    # Doesn't always make code more readable.
+    "UP031",
+    # Use f-strings instead of format specifiers.
+    # Doesn't always make code more readable.
+    "UP032",
+    # Use PEP-604 unions rather than tuples for isinstance() checks.
+    # Makes code slower and more verbose. https://github.com/astral-sh/ruff/issues/7871.
+    "UP038",
+]
+unfixable = [
+    # The autofixes sometimes do the wrong things for these;
+    # it's better to have to manually look at the code and see how it needs fixing
+    "F841",  # Detects unused variables
+    "F601",  # Detects dictionaries that have duplicate keys
+    "F602",  # Also detects dictionaries that have duplicate keys
+]

Tools/peg_generator/pegen/__main__.py

@@ -10,7 +10,6 @@
 import time
 import token
 import traceback
-from typing import Tuple
 
 from pegen.grammar import Grammar
 from pegen.parser import Parser
@@ -21,7 +20,7 @@
 
 def generate_c_code(
     args: argparse.Namespace,
-) -> Tuple[Grammar, Parser, Tokenizer, ParserGenerator]:
+) -> tuple[Grammar, Parser, Tokenizer, ParserGenerator]:
     from pegen.build import build_c_parser_and_generator
 
     verbose = args.verbose
@@ -50,7 +49,7 @@ def generate_c_code(
 
 def generate_python_code(
     args: argparse.Namespace,
-) -> Tuple[Grammar, Parser, Tokenizer, ParserGenerator]:
+) -> tuple[Grammar, Parser, Tokenizer, ParserGenerator]:
     from pegen.build import build_python_parser_and_generator
 
     verbose = args.verbose
@@ -188,7 +187,7 @@ def main() -> None:
 
 
 if __name__ == "__main__":
-    if sys.version_info < (3, 8):
+    if sys.version_info < (3, 8):  # noqa: UP036
         print("ERROR: using pegen requires at least Python 3.8!", file=sys.stderr)
         sys.exit(1)
     main()

Tools/peg_generator/pegen/ast_dump.py

@@ -6,17 +6,17 @@
 TODO: Remove the above-described hack.
 """
 
-from typing import Any, Optional, Tuple
+from typing import Any
 
 
 def ast_dump(
     node: Any,
     annotate_fields: bool = True,
     include_attributes: bool = False,
     *,
-    indent: Optional[str] = None,
+    indent: str | None = None,
 ) -> str:
-    def _format(node: Any, level: int = 0) -> Tuple[str, bool]:
+    def _format(node: Any, level: int = 0) -> tuple[str, bool]:
         if indent is not None:
             level += 1
             prefix = "\n" + indent * level
@@ -41,7 +41,7 @@ def _format(node: Any, level: int = 0) -> Tuple[str, bool]:
                 value, simple = _format(value, level)
                 allsimple = allsimple and simple
                 if keywords:
-                    args.append("%s=%s" % (name, value))
+                    args.append(f"{name}={value}")
                 else:
                     args.append(value)
             if include_attributes and node._attributes:
@@ -54,14 +54,14 @@ def _format(node: Any, level: int = 0) -> Tuple[str, bool]:
                         continue
                     value, simple = _format(value, level)
                     allsimple = allsimple and simple
-                    args.append("%s=%s" % (name, value))
+                    args.append(f"{name}={value}")
             if allsimple and len(args) <= 3:
-                return "%s(%s)" % (node.__class__.__name__, ", ".join(args)), not args
-            return "%s(%s%s)" % (node.__class__.__name__, prefix, sep.join(args)), False
+                return "{}({})".format(node.__class__.__name__, ", ".join(args)), not args
+            return f"{node.__class__.__name__}({prefix}{sep.join(args)})", False
         elif isinstance(node, list):
             if not node:
                 return "[]", True
-            return "[%s%s]" % (prefix, sep.join(_format(x, level)[0] for x in node)), False
+            return f"[{prefix}{sep.join(_format(x, level)[0] for x in node)}]", False
         return repr(node), True
 
     if all(cls.__name__ != "AST" for cls in node.__class__.__mro__):

Tools/peg_generator/pegen/build.py

@@ -6,7 +6,7 @@
 import sysconfig
 import tempfile
 import tokenize
-from typing import IO, Any, Dict, List, Optional, Set, Tuple
+from typing import IO, Any
 
 from pegen.c_generator import CParserGenerator
 from pegen.grammar import Grammar
@@ -18,11 +18,11 @@
 
 MOD_DIR = pathlib.Path(__file__).resolve().parent
 
-TokenDefinitions = Tuple[Dict[int, str], Dict[str, int], Set[str]]
+TokenDefinitions = tuple[dict[int, str], dict[str, int], set[str]]
 Incomplete = Any  # TODO: install `types-setuptools` and remove this alias
 
 
-def get_extra_flags(compiler_flags: str, compiler_py_flags_nodist: str) -> List[str]:
+def get_extra_flags(compiler_flags: str, compiler_py_flags_nodist: str) -> list[str]:
     flags = sysconfig.get_config_var(compiler_flags)
     py_flags_nodist = sysconfig.get_config_var(compiler_py_flags_nodist)
     if flags is None or py_flags_nodist is None:
@@ -71,11 +71,11 @@ def fixup_build_ext(cmd: Incomplete) -> None:
 
 def compile_c_extension(
     generated_source_path: str,
-    build_dir: Optional[str] = None,
+    build_dir: str | None = None,
     verbose: bool = False,
     keep_asserts: bool = True,
     disable_optimization: bool = False,
-    library_dir: Optional[str] = None,
+    library_dir: str | None = None,
 ) -> pathlib.Path:
     """Compile the generated source for a parser generator into an extension module.
 
@@ -93,11 +93,10 @@ def compile_c_extension(
     """
     import setuptools.command.build_ext
     import setuptools.logging
-
-    from setuptools import Extension, Distribution
-    from setuptools.modified import newer_group
+    from setuptools import Distribution, Extension
     from setuptools._distutils.ccompiler import new_compiler
     from setuptools._distutils.sysconfig import customize_compiler
+    from setuptools.modified import newer_group
 
     if verbose:
         setuptools.logging.set_threshold(logging.DEBUG)
@@ -241,7 +240,7 @@ def compile_c_extension(
 
 def build_parser(
     grammar_file: str, verbose_tokenizer: bool = False, verbose_parser: bool = False
-) -> Tuple[Grammar, Parser, Tokenizer]:
+) -> tuple[Grammar, Parser, Tokenizer]:
     with open(grammar_file) as file:
         tokenizer = Tokenizer(tokenize.generate_tokens(file.readline), verbose=verbose_tokenizer)
         parser = GrammarParser(tokenizer, verbose=verbose_parser)
@@ -292,7 +291,7 @@ def build_c_generator(
     keep_asserts_in_extension: bool = True,
     skip_actions: bool = False,
 ) -> ParserGenerator:
-    with open(tokens_file, "r") as tok_file:
+    with open(tokens_file) as tok_file:
         all_tokens, exact_tok, non_exact_tok = generate_token_definitions(tok_file)
     with open(output_file, "w") as file:
         gen: ParserGenerator = CParserGenerator(
@@ -333,7 +332,7 @@ def build_c_parser_and_generator(
     verbose_c_extension: bool = False,
     keep_asserts_in_extension: bool = True,
     skip_actions: bool = False,
-) -> Tuple[Grammar, Parser, Tokenizer, ParserGenerator]:
+) -> tuple[Grammar, Parser, Tokenizer, ParserGenerator]:
     """Generate rules, C parser, tokenizer, parser generator for a given grammar
 
     Args:
@@ -373,7 +372,7 @@ def build_python_parser_and_generator(
     verbose_tokenizer: bool = False,
     verbose_parser: bool = False,
     skip_actions: bool = False,
-) -> Tuple[Grammar, Parser, Tokenizer, ParserGenerator]:
+) -> tuple[Grammar, Parser, Tokenizer, ParserGenerator]:
     """Generate rules, python parser, tokenizer, parser generator for a given grammar
 
     Args: