Parse Python code and perform AST validation.
"""
import ast
-import platform
import sys
-from typing import Iterable, Iterator, List, Set, Union, Tuple
+from typing import Final, Iterable, Iterator, List, Set, Tuple
-# lib2to3 fork
-from blib2to3.pytree import Node, Leaf
-from blib2to3 import pygram, pytree
+from black.mode import VERSION_TO_FEATURES, 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
-
-_IS_PYPY = platform.python_implementation() == "PyPy"
-
-try:
- from typed_ast import ast3, ast27
-except ImportError:
- # Either our python version is too low, or we're on pypy
- if sys.version_info < (3, 7) or (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"
- "`python3 -m pip install typed-ast`.",
- file=sys.stderr,
- )
- sys.exit(1)
- else:
- ast3 = ast27 = ast
+PY2_HINT: Final = "Python 2 support was removed in version 22.0."
class InvalidInput(ValueError):
if not target_versions:
# No target_version specified, so try all grammars.
return [
- # Python 3.7+
+ # Python 3.7-3.9
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,
+ # Python 3.10+
+ pygram.python_grammar_soft_keywords,
]
- 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-compatible code, so only try Python 3 grammar.
grammars = []
- if supports_feature(target_versions, Feature.PATTERN_MATCHING):
- # Python 3.10+
- grammars.append(pygram.python_grammar_soft_keywords)
# 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 any(Feature.PATTERN_MATCHING in VERSION_TO_FEATURES[v] for v in target_versions):
+ # 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)
def parse_single_version(
- src: str, version: Tuple[int, int]
-) -> Union[ast.AST, ast3.AST, ast27.AST]:
+ src: str, version: Tuple[int, int], *, type_comments: bool
+) -> ast.AST:
filename = "<unknown>"
- # typed_ast is needed because of feature version limitations in the builtin ast
- if sys.version_info >= (3, 8) and version >= (3,):
- return ast.parse(src, filename, feature_version=version)
- elif version >= (3,):
- if _IS_PYPY:
- return ast3.parse(src, filename)
- else:
- return ast3.parse(src, filename, feature_version=version[1])
- elif version == (2, 7):
- return ast27.parse(src)
- raise AssertionError("INTERNAL ERROR: Tried parsing unsupported Python version!")
+ return ast.parse(
+ src, filename, feature_version=version, type_comments=type_comments
+ )
-def parse_ast(src: str) -> Union[ast.AST, ast3.AST, ast27.AST]:
+def parse_ast(src: str) -> ast.AST:
# TODO: support Python 4+ ;)
versions = [(3, minor) for minor in range(3, sys.version_info[1] + 1)]
- if ast27.__name__ != "ast":
- versions.append((2, 7))
-
first_error = ""
for version in sorted(versions, reverse=True):
try:
- return parse_single_version(src, version)
+ return parse_single_version(src, version, type_comments=True)
except SyntaxError as e:
if not first_error:
first_error = str(e)
+ # Try to parse without type comments
+ for version in sorted(versions, reverse=True):
+ try:
+ return parse_single_version(src, version, type_comments=False)
+ except SyntaxError:
+ pass
+
raise SyntaxError(first_error)
-def stringify_ast(
- node: Union[ast.AST, ast3.AST, ast27.AST], depth: int = 0
-) -> Iterator[str]:
+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: ast.AST, depth: int = 0) -> Iterator[str]:
"""Simple visitor generating strings to compare ASTs by content."""
- node = fixup_ast_constants(node)
+ if (
+ isinstance(node, ast.Constant)
+ and isinstance(node.value, str)
+ and node.kind == "u"
+ ):
+ # It's a quirk of history that we strip the u prefix over here. We used to
+ # rewrite the AST nodes for Python version compatibility and we never copied
+ # over the kind
+ node.kind = None
yield f"{' ' * depth}{node.__class__.__name__}("
for field in sorted(node._fields): # noqa: F402
- # 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, ast27.TypeIgnore)
- if sys.version_info >= (3, 8):
- type_ignore_classes += (ast.TypeIgnore,)
- if isinstance(node, type_ignore_classes):
- break
+ # TypeIgnore has only one field 'lineno' which breaks this comparison
+ if isinstance(node, ast.TypeIgnore):
+ 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)
+ and isinstance(item, ast.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):
yield from stringify_ast(item, depth + 2)
- elif isinstance(value, (ast.AST, ast3.AST, ast27.AST)):
+ elif isinstance(value, ast.AST):
yield from stringify_ast(value, depth + 2)
else:
- # 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.
+ normalized: object
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()
+ # 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.
+ normalized = _normalize("\n", value)
+ elif field == "type_comment" and isinstance(value, str):
+ # Trailing whitespace in type comments is removed.
+ normalized = value.rstrip()
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]:
- """Map ast nodes deprecated in 3.8 to Constant."""
- if isinstance(node, (ast.Str, ast3.Str, ast27.Str, ast.Bytes, ast3.Bytes)):
- return ast.Constant(value=node.s)
-
- if isinstance(node, (ast.Num, ast3.Num, ast27.Num)):
- return ast.Constant(value=node.n)
-
- if isinstance(node, (ast.NameConstant, ast3.NameConstant)):
- return ast.Constant(value=node.value)
-
- return node
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