Parse Python code and perform AST validation.
"""
import ast
+import platform
import sys
-from typing import Iterable, Iterator, List, Set, Union
+from typing import Any, Iterable, Iterator, List, Set, Tuple, Type, Union
-# lib2to3 fork
-from blib2to3.pytree import Node, Leaf
-from blib2to3 import pygram, pytree
+if sys.version_info < (3, 8):
+ from typing_extensions import Final
+else:
+ from typing import Final
+
+from black.mode import Feature, TargetVersion, supports_feature
+from black.nodes import syms
+from blib2to3 import pygram
from blib2to3.pgen2 import driver
from blib2to3.pgen2.grammar import Grammar
from blib2to3.pgen2.parse import ParseError
+from blib2to3.pgen2.tokenize import TokenError
+from blib2to3.pytree import Leaf, Node
-from black.mode import TargetVersion, Feature, supports_feature
-from black.nodes import syms
+ast3: Any
+
+_IS_PYPY = platform.python_implementation() == "PyPy"
try:
- from typed_ast import ast3, ast27
+ from typed_ast import ast3
except ImportError:
- if sys.version_info < (3, 8):
+ if sys.version_info < (3, 8) and not _IS_PYPY:
print(
"The typed_ast package is required but not installed.\n"
"You can upgrade to Python 3.8+ or install typed_ast with\n"
)
sys.exit(1)
else:
- ast3 = ast27 = ast
+ ast3 = ast
+
+
+PY2_HINT: Final = "Python 2 support was removed in version 22.0."
class InvalidInput(ValueError):
pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords,
# Python 3.0-3.6
pygram.python_grammar_no_print_statement_no_exec_statement,
- # Python 2.7 with future print_function import
- pygram.python_grammar_no_print_statement,
- # Python 2.7
- pygram.python_grammar,
- ]
-
- if all(version.is_python2() for version in target_versions):
- # Python 2-only code, so try Python 2 grammars.
- return [
- # Python 2.7 with future print_function import
- pygram.python_grammar_no_print_statement,
- # Python 2.7
- pygram.python_grammar,
+ # Python 3.10+
+ pygram.python_grammar_soft_keywords,
]
- # Python 3-compatible code, so only try Python 3 grammar.
grammars = []
# If we have to parse both, try to parse async as a keyword first
- if not supports_feature(target_versions, Feature.ASYNC_IDENTIFIERS):
- # Python 3.7+
+ if not supports_feature(
+ target_versions, Feature.ASYNC_IDENTIFIERS
+ ) and not supports_feature(target_versions, Feature.PATTERN_MATCHING):
+ # Python 3.7-3.9
grammars.append(
pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords
)
if not supports_feature(target_versions, Feature.ASYNC_KEYWORDS):
# Python 3.0-3.6
grammars.append(pygram.python_grammar_no_print_statement_no_exec_statement)
+ if supports_feature(target_versions, Feature.PATTERN_MATCHING):
+ # Python 3.10+
+ grammars.append(pygram.python_grammar_soft_keywords)
+
# At least one of the above branches must have been taken, because every Python
# version has exactly one of the two 'ASYNC_*' flags
return grammars
if not src_txt.endswith("\n"):
src_txt += "\n"
- for grammar in get_grammars(set(target_versions)):
- drv = driver.Driver(grammar, pytree.convert)
+ grammars = get_grammars(set(target_versions))
+ errors = {}
+ for grammar in grammars:
+ drv = driver.Driver(grammar)
try:
result = drv.parse_string(src_txt, True)
break
faulty_line = lines[lineno - 1]
except IndexError:
faulty_line = "<line number missing in source>"
- exc = InvalidInput(f"Cannot parse: {lineno}:{column}: {faulty_line}")
+ errors[grammar.version] = InvalidInput(
+ f"Cannot parse: {lineno}:{column}: {faulty_line}"
+ )
+
+ except TokenError as te:
+ # In edge cases these are raised; and typically don't have a "faulty_line".
+ lineno, column = te.args[1]
+ errors[grammar.version] = InvalidInput(
+ f"Cannot parse: {lineno}:{column}: {te.args[0]}"
+ )
+
else:
+ # Choose the latest version when raising the actual parsing error.
+ assert len(errors) >= 1
+ exc = errors[max(errors)]
+
+ if matches_grammar(src_txt, pygram.python_grammar) or matches_grammar(
+ src_txt, pygram.python_grammar_no_print_statement
+ ):
+ original_msg = exc.args[0]
+ msg = f"{original_msg}\n{PY2_HINT}"
+ raise InvalidInput(msg) from None
+
raise exc from None
if isinstance(result, Leaf):
return result
+def matches_grammar(src_txt: str, grammar: Grammar) -> bool:
+ drv = driver.Driver(grammar)
+ try:
+ drv.parse_string(src_txt, True)
+ except (ParseError, TokenError, IndentationError):
+ return False
+ else:
+ return True
+
+
def lib2to3_unparse(node: Node) -> str:
"""Given a lib2to3 node, return its string representation."""
code = str(node)
return code
-def parse_ast(src: str) -> Union[ast.AST, ast3.AST, ast27.AST]:
+def parse_single_version(
+ src: str, version: Tuple[int, int]
+) -> Union[ast.AST, ast3.AST]:
filename = "<unknown>"
- if sys.version_info >= (3, 8):
- # TODO: support Python 4+ ;)
- for minor_version in range(sys.version_info[1], 4, -1):
- try:
- return ast.parse(src, filename, feature_version=(3, minor_version))
- except SyntaxError:
- continue
+ # typed-ast is needed because of feature version limitations in the builtin ast 3.8>
+ if sys.version_info >= (3, 8) and version >= (3,):
+ return ast.parse(src, filename, feature_version=version, type_comments=True)
+
+ if _IS_PYPY:
+ # PyPy 3.7 doesn't support type comment tracking which is not ideal, but there's
+ # not much we can do as typed-ast won't work either.
+ if sys.version_info >= (3, 8):
+ return ast3.parse(src, filename, type_comments=True)
+ else:
+ return ast3.parse(src, filename)
else:
- for feature_version in (7, 6):
- try:
- return ast3.parse(src, filename, feature_version=feature_version)
- except SyntaxError:
- continue
- if ast27.__name__ == "ast":
- raise SyntaxError(
- "The requested source code has invalid Python 3 syntax.\n"
- "If you are trying to format Python 2 files please reinstall Black"
- " with the 'python2' extra: `python3 -m pip install black[python2]`."
- )
- return ast27.parse(src)
+ # Typed-ast is guaranteed to be used here and automatically tracks type
+ # comments separately.
+ return ast3.parse(src, filename, feature_version=version[1])
+
+def parse_ast(src: str) -> Union[ast.AST, ast3.AST]:
+ # TODO: support Python 4+ ;)
+ versions = [(3, minor) for minor in range(3, sys.version_info[1] + 1)]
+
+ first_error = ""
+ for version in sorted(versions, reverse=True):
+ try:
+ return parse_single_version(src, version)
+ except SyntaxError as e:
+ if not first_error:
+ first_error = str(e)
-def stringify_ast(
- node: Union[ast.AST, ast3.AST, ast27.AST], depth: int = 0
-) -> Iterator[str]:
+ raise SyntaxError(first_error)
+
+
+ast3_AST: Final[Type[ast3.AST]] = ast3.AST
+
+
+def _normalize(lineend: str, value: str) -> str:
+ # To normalize, we strip any leading and trailing space from
+ # each line...
+ stripped: List[str] = [i.strip() for i in value.splitlines()]
+ normalized = lineend.join(stripped)
+ # ...and remove any blank lines at the beginning and end of
+ # the whole string
+ return normalized.strip()
+
+
+def stringify_ast(node: Union[ast.AST, ast3.AST], depth: int = 0) -> Iterator[str]:
"""Simple visitor generating strings to compare ASTs by content."""
node = fixup_ast_constants(node)
yield f"{' ' * depth}{node.__class__.__name__}("
+ type_ignore_classes: Tuple[Type[Any], ...]
for field in sorted(node._fields): # noqa: F402
- # TypeIgnore has only one field 'lineno' which breaks this comparison
- type_ignore_classes = (ast3.TypeIgnore, ast27.TypeIgnore)
- if sys.version_info >= (3, 8):
- type_ignore_classes += (ast.TypeIgnore,)
- if isinstance(node, type_ignore_classes):
- break
+ # TypeIgnore will not be present using pypy < 3.8, so need for this
+ if not (_IS_PYPY and sys.version_info < (3, 8)):
+ # TypeIgnore has only one field 'lineno' which breaks this comparison
+ type_ignore_classes = (ast3.TypeIgnore,)
+ if sys.version_info >= (3, 8):
+ type_ignore_classes += (ast.TypeIgnore,)
+ if isinstance(node, type_ignore_classes):
+ break
try:
- value = getattr(node, field)
+ value: object = getattr(node, field)
except AttributeError:
continue
# parentheses and they change the AST.
if (
field == "targets"
- and isinstance(node, (ast.Delete, ast3.Delete, ast27.Delete))
- and isinstance(item, (ast.Tuple, ast3.Tuple, ast27.Tuple))
+ and isinstance(node, (ast.Delete, ast3.Delete))
+ and isinstance(item, (ast.Tuple, ast3.Tuple))
):
- for item in item.elts:
- yield from stringify_ast(item, depth + 2)
+ for elt in item.elts:
+ yield from stringify_ast(elt, depth + 2)
- elif isinstance(item, (ast.AST, ast3.AST, ast27.AST)):
+ elif isinstance(item, (ast.AST, ast3.AST)):
yield from stringify_ast(item, depth + 2)
- elif isinstance(value, (ast.AST, ast3.AST, ast27.AST)):
+ # Note that we are referencing the typed-ast ASTs via global variables and not
+ # direct module attribute accesses because that breaks mypyc. It's probably
+ # something to do with the ast3 variables being marked as Any leading
+ # mypy to think this branch is always taken, leaving the rest of the code
+ # unanalyzed. Tighting up the types for the typed-ast AST types avoids the
+ # mypyc crash.
+ elif isinstance(value, (ast.AST, ast3_AST)):
yield from stringify_ast(value, depth + 2)
else:
+ normalized: object
# Constant strings may be indented across newlines, if they are
# docstrings; fold spaces after newlines when comparing. Similarly,
# trailing and leading space may be removed.
- # Note that when formatting Python 2 code, at least with Windows
- # line-endings, docstrings can end up here as bytes instead of
- # str so make sure that we handle both cases.
if (
isinstance(node, ast.Constant)
and field == "value"
- and isinstance(value, (str, bytes))
+ and isinstance(value, str)
):
- lineend = "\n" if isinstance(value, str) else b"\n"
- # To normalize, we strip any leading and trailing space from
- # each line...
- stripped = [line.strip() for line in value.splitlines()]
- normalized = lineend.join(stripped) # type: ignore[attr-defined]
- # ...and remove any blank lines at the beginning and end of
- # the whole string
- normalized = normalized.strip()
+ normalized = _normalize("\n", value)
else:
normalized = value
yield f"{' ' * (depth+2)}{normalized!r}, # {value.__class__.__name__}"
yield f"{' ' * depth}) # /{node.__class__.__name__}"
-def fixup_ast_constants(
- node: Union[ast.AST, ast3.AST, ast27.AST]
-) -> Union[ast.AST, ast3.AST, ast27.AST]:
+def fixup_ast_constants(node: Union[ast.AST, ast3.AST]) -> Union[ast.AST, ast3.AST]:
"""Map ast nodes deprecated in 3.8 to Constant."""
- if isinstance(node, (ast.Str, ast3.Str, ast27.Str, ast.Bytes, ast3.Bytes)):
+ if isinstance(node, (ast.Str, ast3.Str, ast.Bytes, ast3.Bytes)):
return ast.Constant(value=node.s)
- if isinstance(node, (ast.Num, ast3.Num, ast27.Num)):
+ if isinstance(node, (ast.Num, ast3.Num)):
return ast.Constant(value=node.n)
if isinstance(node, (ast.NameConstant, ast3.NameConstant)):
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