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"""
Main module.
Implement the central Checker class.
Also, it models the Bindings and Scopes.
"""
import __future__
import builtins
import ast
import bisect
import collections
import contextlib
import doctest
import functools
import os
import re
import string
import sys
import tokenize
from pyflakes import messages
PY38_PLUS = sys.version_info >= (3, 8)
PYPY = hasattr(sys, 'pypy_version_info')
builtin_vars = dir(builtins)
parse_format_string = string.Formatter().parse
def getAlternatives(n):
if isinstance(n, ast.If):
return [n.body]
if isinstance(n, ast.Try):
return [n.body + n.orelse] + [[hdl] for hdl in n.handlers]
FOR_TYPES = (ast.For, ast.AsyncFor)
if PY38_PLUS:
def _is_singleton(node): # type: (ast.AST) -> bool
return (
isinstance(node, ast.Constant) and
isinstance(node.value, (bool, type(Ellipsis), type(None)))
)
else:
def _is_singleton(node): # type: (ast.AST) -> bool
return isinstance(node, (ast.NameConstant, ast.Ellipsis))
def _is_tuple_constant(node): # type: (ast.AST) -> bool
return (
isinstance(node, ast.Tuple) and
all(_is_constant(elt) for elt in node.elts)
)
if PY38_PLUS:
def _is_constant(node):
return isinstance(node, ast.Constant) or _is_tuple_constant(node)
else:
def _is_constant(node):
return (
isinstance(node, (ast.Str, ast.Num, ast.Bytes)) or
_is_singleton(node) or
_is_tuple_constant(node)
)
def _is_const_non_singleton(node): # type: (ast.AST) -> bool
return _is_constant(node) and not _is_singleton(node)
def _is_name_or_attr(node, name): # type: (ast.AST, str) -> bool
return (
(isinstance(node, ast.Name) and node.id == name) or
(isinstance(node, ast.Attribute) and node.attr == name)
)
# https://github.com/python/typed_ast/blob/1.4.0/ast27/Parser/tokenizer.c#L102-L104
TYPE_COMMENT_RE = re.compile(r'^#\s*type:\s*')
# https://github.com/python/typed_ast/blob/1.4.0/ast27/Parser/tokenizer.c#L1408-L1413
ASCII_NON_ALNUM = ''.join([chr(i) for i in range(128) if not chr(i).isalnum()])
TYPE_IGNORE_RE = re.compile(
TYPE_COMMENT_RE.pattern + fr'ignore([{ASCII_NON_ALNUM}]|$)')
# https://github.com/python/typed_ast/blob/1.4.0/ast27/Grammar/Grammar#L147
TYPE_FUNC_RE = re.compile(r'^(\(.*?\))\s*->\s*(.*)$')
MAPPING_KEY_RE = re.compile(r'\(([^()]*)\)')
CONVERSION_FLAG_RE = re.compile('[#0+ -]*')
WIDTH_RE = re.compile(r'(?:\*|\d*)')
PRECISION_RE = re.compile(r'(?:\.(?:\*|\d*))?')
LENGTH_RE = re.compile('[hlL]?')
# https://docs.python.org/3/library/stdtypes.html#old-string-formatting
VALID_CONVERSIONS = frozenset('diouxXeEfFgGcrsa%')
def _must_match(regex, string, pos):
match = regex.match(string, pos)
assert match is not None
return match
def parse_percent_format(s):
"""Parses the string component of a `'...' % ...` format call
Copied from https://github.com/asottile/pyupgrade at v1.20.1
"""
def _parse_inner():
string_start = 0
string_end = 0
in_fmt = False
i = 0
while i < len(s):
if not in_fmt:
try:
i = s.index('%', i)
except ValueError: # no more % fields!
yield s[string_start:], None
return
else:
string_end = i
i += 1
in_fmt = True
else:
key_match = MAPPING_KEY_RE.match(s, i)
if key_match:
key = key_match.group(1)
i = key_match.end()
else:
key = None
conversion_flag_match = _must_match(CONVERSION_FLAG_RE, s, i)
conversion_flag = conversion_flag_match.group() or None
i = conversion_flag_match.end()
width_match = _must_match(WIDTH_RE, s, i)
width = width_match.group() or None
i = width_match.end()
precision_match = _must_match(PRECISION_RE, s, i)
precision = precision_match.group() or None
i = precision_match.end()
# length modifier is ignored
i = _must_match(LENGTH_RE, s, i).end()
try:
conversion = s[i]
except IndexError:
raise ValueError('end-of-string while parsing format')
i += 1
fmt = (key, conversion_flag, width, precision, conversion)
yield s[string_start:string_end], fmt
in_fmt = False
string_start = i
if in_fmt:
raise ValueError('end-of-string while parsing format')
return tuple(_parse_inner())
class _FieldsOrder(dict):
"""Fix order of AST node fields."""
def _get_fields(self, node_class):
# handle iter before target, and generators before element
fields = node_class._fields
if 'iter' in fields:
key_first = 'iter'.find
elif 'generators' in fields:
key_first = 'generators'.find
else:
key_first = 'value'.find
return tuple(sorted(fields, key=key_first, reverse=True))
def __missing__(self, node_class):
self[node_class] = fields = self._get_fields(node_class)
return fields
def counter(items):
"""
Simplest required implementation of collections.Counter. Required as 2.6
does not have Counter in collections.
"""
results = {}
for item in items:
results[item] = results.get(item, 0) + 1
return results
def iter_child_nodes(node, omit=None, _fields_order=_FieldsOrder()):
"""
Yield all direct child nodes of *node*, that is, all fields that
are nodes and all items of fields that are lists of nodes.
:param node: AST node to be iterated upon
:param omit: String or tuple of strings denoting the
attributes of the node to be omitted from
further parsing
:param _fields_order: Order of AST node fields
"""
for name in _fields_order[node.__class__]:
if omit and name in omit:
continue
field = getattr(node, name, None)
if isinstance(field, ast.AST):
yield field
elif isinstance(field, list):
for item in field:
if isinstance(item, ast.AST):
yield item
def convert_to_value(item):
if isinstance(item, ast.Str):
return item.s
elif hasattr(ast, 'Bytes') and isinstance(item, ast.Bytes):
return item.s
elif isinstance(item, ast.Tuple):
return tuple(convert_to_value(i) for i in item.elts)
elif isinstance(item, ast.Num):
return item.n
elif isinstance(item, ast.Name):
result = VariableKey(item=item)
constants_lookup = {
'True': True,
'False': False,
'None': None,
}
return constants_lookup.get(
result.name,
result,
)
elif isinstance(item, ast.NameConstant):
return item.value
else:
return UnhandledKeyType()
def is_notimplemented_name_node(node):
return isinstance(node, ast.Name) and getNodeName(node) == 'NotImplemented'
class Binding:
"""
Represents the binding of a value to a name.
The checker uses this to keep track of which names have been bound and
which names have not. See L{Assignment} for a special type of binding that
is checked with stricter rules.
@ivar used: pair of (L{Scope}, node) indicating the scope and
the node that this binding was last used.
"""
def __init__(self, name, source):
self.name = name
self.source = source
self.used = False
def __str__(self):
return self.name
def __repr__(self):
return '<{} object {!r} from line {!r} at 0x{:x}>'.format(
self.__class__.__name__,
self.name,
self.source.lineno,
id(self),
)
def redefines(self, other):
return isinstance(other, Definition) and self.name == other.name
class Definition(Binding):
"""
A binding that defines a function or a class.
"""
class Builtin(Definition):
"""A definition created for all Python builtins."""
def __init__(self, name):
super().__init__(name, None)
def __repr__(self):
return '<{} object {!r} at 0x{:x}>'.format(
self.__class__.__name__,
self.name,
id(self)
)
class UnhandledKeyType:
"""
A dictionary key of a type that we cannot or do not check for duplicates.
"""
class VariableKey:
"""
A dictionary key which is a variable.
@ivar item: The variable AST object.
"""
def __init__(self, item):
self.name = item.id
def __eq__(self, compare):
return (
compare.__class__ == self.__class__ and
compare.name == self.name
)
def __hash__(self):
return hash(self.name)
class Importation(Definition):
"""
A binding created by an import statement.
@ivar fullName: The complete name given to the import statement,
possibly including multiple dotted components.
@type fullName: C{str}
"""
def __init__(self, name, source, full_name=None):
self.fullName = full_name or name
self.redefined = []
super().__init__(name, source)
def redefines(self, other):
if isinstance(other, SubmoduleImportation):
# See note in SubmoduleImportation about RedefinedWhileUnused
return self.fullName == other.fullName
return isinstance(other, Definition) and self.name == other.name
def _has_alias(self):
"""Return whether importation needs an as clause."""
return not self.fullName.split('.')[-1] == self.name
@property
def source_statement(self):
"""Generate a source statement equivalent to the import."""
if self._has_alias():
return f'import {self.fullName} as {self.name}'
else:
return 'import %s' % self.fullName
def __str__(self):
"""Return import full name with alias."""
if self._has_alias():
return self.fullName + ' as ' + self.name
else:
return self.fullName
class SubmoduleImportation(Importation):
"""
A binding created by a submodule import statement.
A submodule import is a special case where the root module is implicitly
imported, without an 'as' clause, and the submodule is also imported.
Python does not restrict which attributes of the root module may be used.
This class is only used when the submodule import is without an 'as' clause.
pyflakes handles this case by registering the root module name in the scope,
allowing any attribute of the root module to be accessed.
RedefinedWhileUnused is suppressed in `redefines` unless the submodule
name is also the same, to avoid false positives.
"""
def __init__(self, name, source):
# A dot should only appear in the name when it is a submodule import
assert '.' in name and (not source or isinstance(source, ast.Import))
package_name = name.split('.')[0]
super().__init__(package_name, source)
self.fullName = name
def redefines(self, other):
if isinstance(other, Importation):
return self.fullName == other.fullName
return super().redefines(other)
def __str__(self):
return self.fullName
@property
def source_statement(self):
return 'import ' + self.fullName
class ImportationFrom(Importation):
def __init__(self, name, source, module, real_name=None):
self.module = module
self.real_name = real_name or name
if module.endswith('.'):
full_name = module + self.real_name
else:
full_name = module + '.' + self.real_name
super().__init__(name, source, full_name)
def __str__(self):
"""Return import full name with alias."""
if self.real_name != self.name:
return self.fullName + ' as ' + self.name
else:
return self.fullName
@property
def source_statement(self):
if self.real_name != self.name:
return f'from {self.module} import {self.real_name} as {self.name}'
else:
return f'from {self.module} import {self.name}'
class StarImportation(Importation):
"""A binding created by a 'from x import *' statement."""
def __init__(self, name, source):
super().__init__('*', source)
# Each star importation needs a unique name, and
# may not be the module name otherwise it will be deemed imported
self.name = name + '.*'
self.fullName = name
@property
def source_statement(self):
return 'from ' + self.fullName + ' import *'
def __str__(self):
# When the module ends with a ., avoid the ambiguous '..*'
if self.fullName.endswith('.'):
return self.source_statement
else:
return self.name
class FutureImportation(ImportationFrom):
"""
A binding created by a from `__future__` import statement.
`__future__` imports are implicitly used.
"""
def __init__(self, name, source, scope):
super().__init__(name, source, '__future__')
self.used = (scope, source)
class Argument(Binding):
"""
Represents binding a name as an argument.
"""
class Assignment(Binding):
"""
Represents binding a name with an explicit assignment.
The checker will raise warnings for any Assignment that isn't used. Also,
the checker does not consider assignments in tuple/list unpacking to be
Assignments, rather it treats them as simple Bindings.
"""
class NamedExprAssignment(Assignment):
"""
Represents binding a name with an assignment expression.
"""
class Annotation(Binding):
"""
Represents binding a name to a type without an associated value.
As long as this name is not assigned a value in another binding, it is considered
undefined for most purposes. One notable exception is using the name as a type
annotation.
"""
def redefines(self, other):
"""An Annotation doesn't define any name, so it cannot redefine one."""
return False
class FunctionDefinition(Definition):
pass
class ClassDefinition(Definition):
pass
class ExportBinding(Binding):
"""
A binding created by an C{__all__} assignment. If the names in the list
can be determined statically, they will be treated as names for export and
additional checking applied to them.
The only recognized C{__all__} assignment via list/tuple concatenation is in the
following format:
__all__ = ['a'] + ['b'] + ['c']
Names which are imported and not otherwise used but appear in the value of
C{__all__} will not have an unused import warning reported for them.
"""
def __init__(self, name, source, scope):
if '__all__' in scope and isinstance(source, ast.AugAssign):
self.names = list(scope['__all__'].names)
else:
self.names = []
def _add_to_names(container):
for node in container.elts:
if isinstance(node, ast.Str):
self.names.append(node.s)
if isinstance(source.value, (ast.List, ast.Tuple)):
_add_to_names(source.value)
# If concatenating lists or tuples
elif isinstance(source.value, ast.BinOp):
currentValue = source.value
while isinstance(currentValue.right, (ast.List, ast.Tuple)):
left = currentValue.left
right = currentValue.right
_add_to_names(right)
# If more lists are being added
if isinstance(left, ast.BinOp):
currentValue = left
# If just two lists are being added
elif isinstance(left, (ast.List, ast.Tuple)):
_add_to_names(left)
# All lists accounted for - done
break
# If not list concatenation
else:
break
super().__init__(name, source)
class Scope(dict):
importStarred = False # set to True when import * is found
def __repr__(self):
scope_cls = self.__class__.__name__
return f'<{scope_cls} at 0x{id(self):x} {dict.__repr__(self)}>'
class ClassScope(Scope):
pass
class FunctionScope(Scope):
"""
I represent a name scope for a function.
@ivar globals: Names declared 'global' in this function.
"""
usesLocals = False
alwaysUsed = {'__tracebackhide__', '__traceback_info__',
'__traceback_supplement__'}
def __init__(self):
super().__init__()
# Simplify: manage the special locals as globals
self.globals = self.alwaysUsed.copy()
self.returnValue = None # First non-empty return
self.isGenerator = False # Detect a generator
def unusedAssignments(self):
"""
Return a generator for the assignments which have not been used.
"""
for name, binding in self.items():
if (not binding.used and
name != '_' and # see issue #202
name not in self.globals and
not self.usesLocals and
isinstance(binding, Assignment)):
yield name, binding
class GeneratorScope(Scope):
pass
class ModuleScope(Scope):
"""Scope for a module."""
_futures_allowed = True
_annotations_future_enabled = False
class DoctestScope(ModuleScope):
"""Scope for a doctest."""
class DummyNode:
"""Used in place of an `ast.AST` to set error message positions"""
def __init__(self, lineno, col_offset):
self.lineno = lineno
self.col_offset = col_offset
class DetectClassScopedMagic:
names = dir()
# Globally defined names which are not attributes of the builtins module, or
# are only present on some platforms.
_MAGIC_GLOBALS = ['__file__', '__builtins__', '__annotations__', 'WindowsError']
def getNodeName(node):
# Returns node.id, or node.name, or None
if hasattr(node, 'id'): # One of the many nodes with an id
return node.id
if hasattr(node, 'name'): # an ExceptHandler node
return node.name
if hasattr(node, 'rest'): # a MatchMapping node
return node.rest
TYPING_MODULES = frozenset(('typing', 'typing_extensions'))
def _is_typing_helper(node, is_name_match_fn, scope_stack):
"""
Internal helper to determine whether or not something is a member of a
typing module. This is used as part of working out whether we are within a
type annotation context.
Note: you probably don't want to use this function directly. Instead see the
utils below which wrap it (`_is_typing` and `_is_any_typing_member`).
"""
def _bare_name_is_attr(name):
for scope in reversed(scope_stack):
if name in scope:
return (
isinstance(scope[name], ImportationFrom) and
scope[name].module in TYPING_MODULES and
is_name_match_fn(scope[name].real_name)
)
return False
def _module_scope_is_typing(name):
for scope in reversed(scope_stack):
if name in scope:
return (
isinstance(scope[name], Importation) and
scope[name].fullName in TYPING_MODULES
)
return False
return (
(
isinstance(node, ast.Name) and
_bare_name_is_attr(node.id)
) or (
isinstance(node, ast.Attribute) and
isinstance(node.value, ast.Name) and
_module_scope_is_typing(node.value.id) and
is_name_match_fn(node.attr)
)
)
def _is_typing(node, typing_attr, scope_stack):
"""
Determine whether `node` represents the member of a typing module specified
by `typing_attr`.
This is used as part of working out whether we are within a type annotation
context.
"""
return _is_typing_helper(node, lambda x: x == typing_attr, scope_stack)
def _is_any_typing_member(node, scope_stack):
"""
Determine whether `node` represents any member of a typing module.
This is used as part of working out whether we are within a type annotation
context.
"""
return _is_typing_helper(node, lambda x: True, scope_stack)
def is_typing_overload(value, scope_stack):
return (
isinstance(value.source, (ast.FunctionDef, ast.AsyncFunctionDef)) and
any(
_is_typing(dec, 'overload', scope_stack)
for dec in value.source.decorator_list
)
)
class AnnotationState:
NONE = 0
STRING = 1
BARE = 2
def in_annotation(func):
@functools.wraps(func)
def in_annotation_func(self, *args, **kwargs):
with self._enter_annotation():
return func(self, *args, **kwargs)
return in_annotation_func
def in_string_annotation(func):
@functools.wraps(func)
def in_annotation_func(self, *args, **kwargs):
with self._enter_annotation(AnnotationState.STRING):
return func(self, *args, **kwargs)
return in_annotation_func
def make_tokens(code):
# PY3: tokenize.tokenize requires readline of bytes
if not isinstance(code, bytes):
code = code.encode('UTF-8')
lines = iter(code.splitlines(True))
# next(lines, b'') is to prevent an error in pypy3
return tuple(tokenize.tokenize(lambda: next(lines, b'')))
class _TypeableVisitor(ast.NodeVisitor):
"""Collect the line number and nodes which are deemed typeable by
PEP 484
https://www.python.org/dev/peps/pep-0484/#type-comments
"""
def __init__(self):
self.typeable_lines = []
self.typeable_nodes = {}
def _typeable(self, node):
# if there is more than one typeable thing on a line last one wins
self.typeable_lines.append(node.lineno)
self.typeable_nodes[node.lineno] = node
self.generic_visit(node)
visit_Assign = visit_For = visit_FunctionDef = visit_With = _typeable
visit_AsyncFor = visit_AsyncFunctionDef = visit_AsyncWith = _typeable
def _collect_type_comments(tree, tokens):
visitor = _TypeableVisitor()
visitor.visit(tree)
type_comments = collections.defaultdict(list)
for tp, text, start, _, _ in tokens:
if (
tp != tokenize.COMMENT or # skip non comments
not TYPE_COMMENT_RE.match(text) or # skip non-type comments
TYPE_IGNORE_RE.match(text) # skip ignores
):
continue
# search for the typeable node at or before the line number of the
# type comment.
# if the bisection insertion point is before any nodes this is an
# invalid type comment which is ignored.
lineno, _ = start
idx = bisect.bisect_right(visitor.typeable_lines, lineno)
if idx == 0:
continue
node = visitor.typeable_nodes[visitor.typeable_lines[idx - 1]]
type_comments[node].append((start, text))
return type_comments
class Checker:
"""
I check the cleanliness and sanity of Python code.
@ivar _deferredFunctions: Tracking list used by L{deferFunction}. Elements
of the list are two-tuples. The first element is the callable passed
to L{deferFunction}. The second element is a copy of the scope stack
at the time L{deferFunction} was called.
@ivar _deferredAssignments: Similar to C{_deferredFunctions}, but for
callables which are deferred assignment checks.
"""
_ast_node_scope = {
ast.Module: ModuleScope,
ast.ClassDef: ClassScope,
ast.FunctionDef: FunctionScope,
ast.AsyncFunctionDef: FunctionScope,
ast.Lambda: FunctionScope,
ast.ListComp: GeneratorScope,
ast.SetComp: GeneratorScope,
ast.GeneratorExp: GeneratorScope,
ast.DictComp: GeneratorScope,
}
nodeDepth = 0
offset = None
_in_annotation = AnnotationState.NONE
_in_deferred = False
builtIns = set(builtin_vars).union(_MAGIC_GLOBALS)
_customBuiltIns = os.environ.get('PYFLAKES_BUILTINS')
if _customBuiltIns:
builtIns.update(_customBuiltIns.split(','))
del _customBuiltIns
# TODO: file_tokens= is required to perform checks on type comments,
# eventually make this a required positional argument. For now it
# is defaulted to `()` for api compatibility.
def __init__(self, tree, filename='(none)', builtins=None,
withDoctest='PYFLAKES_DOCTEST' in os.environ, file_tokens=()):
self._nodeHandlers = {}
self._deferredFunctions = []
self._deferredAssignments = []
self.deadScopes = []
self.messages = []
self.filename = filename
if builtins:
self.builtIns = self.builtIns.union(builtins)
self.withDoctest = withDoctest
try:
self.scopeStack = [Checker._ast_node_scope[type(tree)]()]
except KeyError:
raise RuntimeError('No scope implemented for the node %r' % tree)
self.exceptHandlers = [()]
self.root = tree
self._type_comments = _collect_type_comments(tree, file_tokens)
for builtin in self.builtIns:
self.addBinding(None, Builtin(builtin))
self.handleChildren(tree)
self._in_deferred = True
self.runDeferred(self._deferredFunctions)
# Set _deferredFunctions to None so that deferFunction will fail
# noisily if called after we've run through the deferred functions.
self._deferredFunctions = None
self.runDeferred(self._deferredAssignments)
# Set _deferredAssignments to None so that deferAssignment will fail
# noisily if called after we've run through the deferred assignments.
self._deferredAssignments = None
del self.scopeStack[1:]
self.popScope()
self.checkDeadScopes()
def deferFunction(self, callable):
"""
Schedule a function handler to be called just before completion.
This is used for handling function bodies, which must be deferred
because code later in the file might modify the global scope. When
`callable` is called, the scope at the time this is called will be
restored, however it will contain any new bindings added to it.
"""
self._deferredFunctions.append((callable, self.scopeStack[:], self.offset))
def deferAssignment(self, callable):
"""
Schedule an assignment handler to be called just after deferred
function handlers.
"""
self._deferredAssignments.append((callable, self.scopeStack[:], self.offset))
def runDeferred(self, deferred):
"""
Run the callables in C{deferred} using their associated scope stack.
"""
for handler, scope, offset in deferred:
self.scopeStack = scope
self.offset = offset
handler()
def _in_doctest(self):
return (len(self.scopeStack) >= 2 and
isinstance(self.scopeStack[1], DoctestScope))
@property
def futuresAllowed(self):
if not all(isinstance(scope, ModuleScope)
for scope in self.scopeStack):
return False
return self.scope._futures_allowed
@futuresAllowed.setter
def futuresAllowed(self, value):
assert value is False
if isinstance(self.scope, ModuleScope):
self.scope._futures_allowed = False
@property
def annotationsFutureEnabled(self):
scope = self.scopeStack[0]
if not isinstance(scope, ModuleScope):
return False
return scope._annotations_future_enabled
@annotationsFutureEnabled.setter
def annotationsFutureEnabled(self, value):
assert value is True
assert isinstance(self.scope, ModuleScope)
self.scope._annotations_future_enabled = True
@property
def scope(self):
return self.scopeStack[-1]
def popScope(self):
self.deadScopes.append(self.scopeStack.pop())
def checkDeadScopes(self):
"""
Look at scopes which have been fully examined and report names in them
which were imported but unused.
"""
for scope in self.deadScopes:
# imports in classes are public members
if isinstance(scope, ClassScope):
continue
all_binding = scope.get('__all__')
if all_binding and not isinstance(all_binding, ExportBinding):
all_binding = None
if all_binding:
all_names = set(all_binding.names)
undefined = [
name for name in all_binding.names
if name not in scope
]
else:
all_names = undefined = []
if undefined:
if not scope.importStarred and \
os.path.basename(self.filename) != '__init__.py':
# Look for possible mistakes in the export list
for name in undefined:
self.report(messages.UndefinedExport,
scope['__all__'].source, name)
# mark all import '*' as used by the undefined in __all__
if scope.importStarred:
from_list = []
for binding in scope.values():
if isinstance(binding, StarImportation):
binding.used = all_binding
from_list.append(binding.fullName)
# report * usage, with a list of possible sources
from_list = ', '.join(sorted(from_list))
for name in undefined:
self.report(messages.ImportStarUsage,
scope['__all__'].source, name, from_list)
# Look for imported names that aren't used.
for value in scope.values():
if isinstance(value, Importation):
used = value.used or value.name in all_names
if not used:
messg = messages.UnusedImport
self.report(messg, value.source, str(value))
for node in value.redefined:
if isinstance(self.getParent(node), FOR_TYPES):
messg = messages.ImportShadowedByLoopVar
elif used:
continue
else:
messg = messages.RedefinedWhileUnused
self.report(messg, node, value.name, value.source)
def pushScope(self, scopeClass=FunctionScope):
self.scopeStack.append(scopeClass())
def report(self, messageClass, *args, **kwargs):
self.messages.append(messageClass(self.filename, *args, **kwargs))
def getParent(self, node):
# Lookup the first parent which is not Tuple, List or Starred
while True:
node = node._pyflakes_parent
if not hasattr(node, 'elts') and not hasattr(node, 'ctx'):
return node
def getCommonAncestor(self, lnode, rnode, stop):
if (
stop in (lnode, rnode) or
not (
hasattr(lnode, '_pyflakes_parent') and
hasattr(rnode, '_pyflakes_parent')
)
):
return None
if lnode is rnode:
return lnode
if (lnode._pyflakes_depth > rnode._pyflakes_depth):
return self.getCommonAncestor(lnode._pyflakes_parent, rnode, stop)
if (lnode._pyflakes_depth < rnode._pyflakes_depth):
return self.getCommonAncestor(lnode, rnode._pyflakes_parent, stop)
return self.getCommonAncestor(
lnode._pyflakes_parent,
rnode._pyflakes_parent,
stop,
)
def descendantOf(self, node, ancestors, stop):
for a in ancestors:
if self.getCommonAncestor(node, a, stop):
return True
return False
def _getAncestor(self, node, ancestor_type):
parent = node
while True:
if parent is self.root:
return None
parent = self.getParent(parent)
if isinstance(parent, ancestor_type):
return parent
def getScopeNode(self, node):
return self._getAncestor(node, tuple(Checker._ast_node_scope.keys()))
def differentForks(self, lnode, rnode):
"""True, if lnode and rnode are located on different forks of IF/TRY"""
ancestor = self.getCommonAncestor(lnode, rnode, self.root)
parts = getAlternatives(ancestor)
if parts:
for items in parts:
if self.descendantOf(lnode, items, ancestor) ^ \
self.descendantOf(rnode, items, ancestor):
return True
return False
def addBinding(self, node, value):
"""
Called when a binding is altered.
- `node` is the statement responsible for the change
- `value` is the new value, a Binding instance
"""
# assert value.source in (node, node._pyflakes_parent):
for scope in self.scopeStack[::-1]:
if value.name in scope:
break
existing = scope.get(value.name)
if (existing and not isinstance(existing, Builtin) and
not self.differentForks(node, existing.source)):
parent_stmt = self.getParent(value.source)
if isinstance(existing, Importation) and isinstance(parent_stmt, FOR_TYPES):
self.report(messages.ImportShadowedByLoopVar,
node, value.name, existing.source)
elif scope is self.scope:
if (
(not existing.used and value.redefines(existing)) and
(value.name != '_' or isinstance(existing, Importation)) and
not is_typing_overload(existing, self.scopeStack)
):
self.report(messages.RedefinedWhileUnused,
node, value.name, existing.source)
elif isinstance(existing, Importation) and value.redefines(existing):
existing.redefined.append(node)
if value.name in self.scope:
# then assume the rebound name is used as a global or within a loop
value.used = self.scope[value.name].used
# don't treat annotations as assignments if there is an existing value
# in scope
if value.name not in self.scope or not isinstance(value, Annotation):
cur_scope_pos = -1
# As per PEP 572, use scope in which outermost generator is defined
while (
isinstance(value, NamedExprAssignment) and
isinstance(self.scopeStack[cur_scope_pos], GeneratorScope)
):
cur_scope_pos -= 1
self.scopeStack[cur_scope_pos][value.name] = value
def _unknown_handler(self, node):
# this environment variable configures whether to error on unknown
# ast types.
#
# this is silent by default but the error is enabled for the pyflakes
# testsuite.
#
# this allows new syntax to be added to python without *requiring*
# changes from the pyflakes side. but will still produce an error
# in the pyflakes testsuite (so more specific handling can be added if
# needed).
if os.environ.get('PYFLAKES_ERROR_UNKNOWN'):
raise NotImplementedError(f'Unexpected type: {type(node)}')
else:
self.handleChildren(node)
def getNodeHandler(self, node_class):
try:
return self._nodeHandlers[node_class]
except KeyError:
nodeType = node_class.__name__.upper()
self._nodeHandlers[node_class] = handler = getattr(
self, nodeType, self._unknown_handler,
)
return handler
def handleNodeLoad(self, node):
name = getNodeName(node)
if not name:
return
in_generators = None
importStarred = None
# try enclosing function scopes and global scope
for scope in self.scopeStack[-1::-1]:
if isinstance(scope, ClassScope):
if name == '__class__':
return
elif in_generators is False:
# only generators used in a class scope can access the
# names of the class. this is skipped during the first
# iteration
continue
binding = scope.get(name, None)
if isinstance(binding, Annotation) and not self._in_postponed_annotation:
continue
if name == 'print' and isinstance(binding, Builtin):
parent = self.getParent(node)
if (isinstance(parent, ast.BinOp) and
isinstance(parent.op, ast.RShift)):
self.report(messages.InvalidPrintSyntax, node)
try:
scope[name].used = (self.scope, node)
# if the name of SubImportation is same as
# alias of other Importation and the alias
# is used, SubImportation also should be marked as used.
n = scope[name]
if isinstance(n, Importation) and n._has_alias():
try:
scope[n.fullName].used = (self.scope, node)
except KeyError:
pass
except KeyError:
pass
else:
return
importStarred = importStarred or scope.importStarred
if in_generators is not False:
in_generators = isinstance(scope, GeneratorScope)
if importStarred:
from_list = []
for scope in self.scopeStack[-1::-1]:
for binding in scope.values():
if isinstance(binding, StarImportation):
# mark '*' imports as used for each scope
binding.used = (self.scope, node)
from_list.append(binding.fullName)
# report * usage, with a list of possible sources
from_list = ', '.join(sorted(from_list))
self.report(messages.ImportStarUsage, node, name, from_list)
return
if name == '__path__' and os.path.basename(self.filename) == '__init__.py':
# the special name __path__ is valid only in packages
return
if name in DetectClassScopedMagic.names and isinstance(self.scope, ClassScope):
return
# protected with a NameError handler?
if 'NameError' not in self.exceptHandlers[-1]:
self.report(messages.UndefinedName, node, name)
def handleNodeStore(self, node):
name = getNodeName(node)
if not name:
return
# if the name hasn't already been defined in the current scope
if isinstance(self.scope, FunctionScope) and name not in self.scope:
# for each function or module scope above us
for scope in self.scopeStack[:-1]:
if not isinstance(scope, (FunctionScope, ModuleScope)):
continue
# if the name was defined in that scope, and the name has
# been accessed already in the current scope, and hasn't
# been declared global
used = name in scope and scope[name].used
if used and used[0] is self.scope and name not in self.scope.globals:
# then it's probably a mistake
self.report(messages.UndefinedLocal,
scope[name].used[1], name, scope[name].source)
break
parent_stmt = self.getParent(node)
if isinstance(parent_stmt, ast.AnnAssign) and parent_stmt.value is None:
binding = Annotation(name, node)
elif isinstance(parent_stmt, (FOR_TYPES, ast.comprehension)) or (
parent_stmt != node._pyflakes_parent and
not self.isLiteralTupleUnpacking(parent_stmt)):
binding = Binding(name, node)
elif (
name == '__all__' and
isinstance(self.scope, ModuleScope) and
isinstance(
node._pyflakes_parent,
(ast.Assign, ast.AugAssign, ast.AnnAssign)
)
):
binding = ExportBinding(name, node._pyflakes_parent, self.scope)
elif PY38_PLUS and isinstance(parent_stmt, ast.NamedExpr):
binding = NamedExprAssignment(name, node)
else:
binding = Assignment(name, node)
self.addBinding(node, binding)
def handleNodeDelete(self, node):
def on_conditional_branch():
"""
Return `True` if node is part of a conditional body.
"""
current = getattr(node, '_pyflakes_parent', None)
while current:
if isinstance(current, (ast.If, ast.While, ast.IfExp)):
return True
current = getattr(current, '_pyflakes_parent', None)
return False
name = getNodeName(node)
if not name:
return
if on_conditional_branch():
# We cannot predict if this conditional branch is going to
# be executed.
return
if isinstance(self.scope, FunctionScope) and name in self.scope.globals:
self.scope.globals.remove(name)
else:
try:
del self.scope[name]
except KeyError:
self.report(messages.UndefinedName, node, name)
@contextlib.contextmanager
def _enter_annotation(self, ann_type=AnnotationState.BARE):
orig, self._in_annotation = self._in_annotation, ann_type
try:
yield
finally:
self._in_annotation = orig
@property
def _in_postponed_annotation(self):
return (
self._in_annotation == AnnotationState.STRING or
self.annotationsFutureEnabled
)
def _handle_type_comments(self, node):
for (lineno, col_offset), comment in self._type_comments.get(node, ()):
comment = comment.split(':', 1)[1].strip()
func_match = TYPE_FUNC_RE.match(comment)
if func_match:
parts = (
func_match.group(1).replace('*', ''),
func_match.group(2).strip(),
)
else:
parts = (comment,)
for part in parts:
self.deferFunction(functools.partial(
self.handleStringAnnotation,
part, DummyNode(lineno, col_offset), lineno, col_offset,
messages.CommentAnnotationSyntaxError,
))
def handleChildren(self, tree, omit=None):
self._handle_type_comments(tree)
for node in iter_child_nodes(tree, omit=omit):
self.handleNode(node, tree)
def isLiteralTupleUnpacking(self, node):
if isinstance(node, ast.Assign):
for child in node.targets + [node.value]:
if not hasattr(child, 'elts'):
return False
return True
def isDocstring(self, node):
"""
Determine if the given node is a docstring, as long as it is at the
correct place in the node tree.
"""
return isinstance(node, ast.Str) or (isinstance(node, ast.Expr) and
isinstance(node.value, ast.Str))
def getDocstring(self, node):
if isinstance(node, ast.Expr):
node = node.value
if not isinstance(node, ast.Str):
return (None, None)
if PYPY or PY38_PLUS:
doctest_lineno = node.lineno - 1
else:
# Computed incorrectly if the docstring has backslash
doctest_lineno = node.lineno - node.s.count('\n') - 1
return (node.s, doctest_lineno)
def handleNode(self, node, parent):
if node is None:
return
if self.offset and getattr(node, 'lineno', None) is not None:
node.lineno += self.offset[0]
node.col_offset += self.offset[1]
if self.futuresAllowed and not (isinstance(node, ast.ImportFrom) or
self.isDocstring(node)):
self.futuresAllowed = False
self.nodeDepth += 1
node._pyflakes_depth = self.nodeDepth
node._pyflakes_parent = parent
try:
handler = self.getNodeHandler(node.__class__)
handler(node)
finally:
self.nodeDepth -= 1
_getDoctestExamples = doctest.DocTestParser().get_examples
def handleDoctests(self, node):
try:
(docstring, node_lineno) = self.getDocstring(node.body[0])
examples = docstring and self._getDoctestExamples(docstring)
except (ValueError, IndexError):
# e.g. line 6 of the docstring for <string> has inconsistent
# leading whitespace: ...
return
if not examples:
return
# Place doctest in module scope
saved_stack = self.scopeStack
self.scopeStack = [self.scopeStack[0]]
node_offset = self.offset or (0, 0)
self.pushScope(DoctestScope)
if '_' not in self.scopeStack[0]:
self.addBinding(None, Builtin('_'))
for example in examples:
try:
tree = ast.parse(example.source, "<doctest>")
except SyntaxError as e:
position = (node_lineno + example.lineno + e.lineno,
example.indent + 4 + (e.offset or 0))
self.report(messages.DoctestSyntaxError, node, position)
else:
self.offset = (node_offset[0] + node_lineno + example.lineno,
node_offset[1] + example.indent + 4)
self.handleChildren(tree)
self.offset = node_offset
self.popScope()
self.scopeStack = saved_stack
@in_string_annotation
def handleStringAnnotation(self, s, node, ref_lineno, ref_col_offset, err):
try:
tree = ast.parse(s)
except SyntaxError:
self.report(err, node, s)
return
body = tree.body
if len(body) != 1 or not isinstance(body[0], ast.Expr):
self.report(err, node, s)
return
parsed_annotation = tree.body[0].value
for descendant in ast.walk(parsed_annotation):
if (
'lineno' in descendant._attributes and
'col_offset' in descendant._attributes
):
descendant.lineno = ref_lineno
descendant.col_offset = ref_col_offset
self.handleNode(parsed_annotation, node)
@in_annotation
def handleAnnotation(self, annotation, node):
if isinstance(annotation, ast.Str):
# Defer handling forward annotation.
self.deferFunction(functools.partial(
self.handleStringAnnotation,
annotation.s,
node,
annotation.lineno,
annotation.col_offset,
messages.ForwardAnnotationSyntaxError,
))
elif self.annotationsFutureEnabled:
fn = in_annotation(Checker.handleNode)
self.deferFunction(lambda: fn(self, annotation, node))
else:
self.handleNode(annotation, node)
def ignore(self, node):
pass
# "stmt" type nodes
DELETE = FOR = ASYNCFOR = WHILE = WITH = WITHITEM = ASYNCWITH = \
EXPR = ASSIGN = handleChildren
PASS = ignore
# "expr" type nodes
BOOLOP = UNARYOP = SET = ATTRIBUTE = STARRED = NAMECONSTANT = \
NAMEDEXPR = handleChildren
def SUBSCRIPT(self, node):
if _is_name_or_attr(node.value, 'Literal'):
with self._enter_annotation(AnnotationState.NONE):
self.handleChildren(node)
elif _is_name_or_attr(node.value, 'Annotated'):
self.handleNode(node.value, node)
# py39+
if isinstance(node.slice, ast.Tuple):
slice_tuple = node.slice
# <py39
elif (
isinstance(node.slice, ast.Index) and
isinstance(node.slice.value, ast.Tuple)
):
slice_tuple = node.slice.value
else:
slice_tuple = None
# not a multi-arg `Annotated`
if slice_tuple is None or len(slice_tuple.elts) < 2:
self.handleNode(node.slice, node)
else:
# the first argument is the type
self.handleNode(slice_tuple.elts[0], node)
# the rest of the arguments are not
with self._enter_annotation(AnnotationState.NONE):
for arg in slice_tuple.elts[1:]:
self.handleNode(arg, node)
self.handleNode(node.ctx, node)
else:
if _is_any_typing_member(node.value, self.scopeStack):
with self._enter_annotation():
self.handleChildren(node)
else:
self.handleChildren(node)
def _handle_string_dot_format(self, node):
try:
placeholders = tuple(parse_format_string(node.func.value.s))
except ValueError as e:
self.report(messages.StringDotFormatInvalidFormat, node, e)
return
auto = None
next_auto = 0
placeholder_positional = set()
placeholder_named = set()
def _add_key(fmtkey):
"""Returns True if there is an error which should early-exit"""
nonlocal auto, next_auto
if fmtkey is None: # end of string or `{` / `}` escapes
return False
# attributes / indices are allowed in `.format(...)`
fmtkey, _, _ = fmtkey.partition('.')
fmtkey, _, _ = fmtkey.partition('[')
try:
fmtkey = int(fmtkey)
except ValueError:
pass
else: # fmtkey was an integer
if auto is True:
self.report(messages.StringDotFormatMixingAutomatic, node)
return True
else:
auto = False
if fmtkey == '':
if auto is False:
self.report(messages.StringDotFormatMixingAutomatic, node)
return True
else:
auto = True
fmtkey = next_auto
next_auto += 1
if isinstance(fmtkey, int):
placeholder_positional.add(fmtkey)
else:
placeholder_named.add(fmtkey)
return False
for _, fmtkey, spec, _ in placeholders:
if _add_key(fmtkey):
return
# spec can also contain format specifiers
if spec is not None:
try:
spec_placeholders = tuple(parse_format_string(spec))
except ValueError as e:
self.report(messages.StringDotFormatInvalidFormat, node, e)
return
for _, spec_fmtkey, spec_spec, _ in spec_placeholders:
# can't recurse again
if spec_spec is not None and '{' in spec_spec:
self.report(
messages.StringDotFormatInvalidFormat,
node,
'Max string recursion exceeded',
)
return
if _add_key(spec_fmtkey):
return
# bail early if there is *args or **kwargs
if (
# *args
any(isinstance(arg, ast.Starred) for arg in node.args) or
# **kwargs
any(kwd.arg is None for kwd in node.keywords)
):
return
substitution_positional = set(range(len(node.args)))
substitution_named = {kwd.arg for kwd in node.keywords}
extra_positional = substitution_positional - placeholder_positional
extra_named = substitution_named - placeholder_named
missing_arguments = (
(placeholder_positional | placeholder_named) -
(substitution_positional | substitution_named)
)
if extra_positional:
self.report(
messages.StringDotFormatExtraPositionalArguments,
node,
', '.join(sorted(str(x) for x in extra_positional)),
)
if extra_named:
self.report(
messages.StringDotFormatExtraNamedArguments,
node,
', '.join(sorted(extra_named)),
)
if missing_arguments:
self.report(
messages.StringDotFormatMissingArgument,
node,
', '.join(sorted(str(x) for x in missing_arguments)),
)
def CALL(self, node):
if (
isinstance(node.func, ast.Attribute) and
isinstance(node.func.value, ast.Str) and
node.func.attr == 'format'
):
self._handle_string_dot_format(node)
omit = []
annotated = []
not_annotated = []
if (
_is_typing(node.func, 'cast', self.scopeStack) and
len(node.args) >= 1
):
with self._enter_annotation():
self.handleNode(node.args[0], node)
elif _is_typing(node.func, 'TypeVar', self.scopeStack):
# TypeVar("T", "int", "str")
omit += ["args"]
annotated += [arg for arg in node.args[1:]]
# TypeVar("T", bound="str")
omit += ["keywords"]
annotated += [k.value for k in node.keywords if k.arg == "bound"]
not_annotated += [
(k, ["value"] if k.arg == "bound" else None)
for k in node.keywords
]
elif _is_typing(node.func, "TypedDict", self.scopeStack):
# TypedDict("a", {"a": int})
if len(node.args) > 1 and isinstance(node.args[1], ast.Dict):
omit += ["args"]
annotated += node.args[1].values
not_annotated += [
(arg, ["values"] if i == 1 else None)
for i, arg in enumerate(node.args)
]
# TypedDict("a", a=int)
omit += ["keywords"]
annotated += [k.value for k in node.keywords]
not_annotated += [(k, ["value"]) for k in node.keywords]
elif _is_typing(node.func, "NamedTuple", self.scopeStack):
# NamedTuple("a", [("a", int)])
if (
len(node.args) > 1 and
isinstance(node.args[1], (ast.Tuple, ast.List)) and
all(isinstance(x, (ast.Tuple, ast.List)) and
len(x.elts) == 2 for x in node.args[1].elts)
):
omit += ["args"]
annotated += [elt.elts[1] for elt in node.args[1].elts]
not_annotated += [(elt.elts[0], None) for elt in node.args[1].elts]
not_annotated += [
(arg, ["elts"] if i == 1 else None)
for i, arg in enumerate(node.args)
]
not_annotated += [(elt, "elts") for elt in node.args[1].elts]
# NamedTuple("a", a=int)
omit += ["keywords"]
annotated += [k.value for k in node.keywords]
not_annotated += [(k, ["value"]) for k in node.keywords]
if omit:
with self._enter_annotation(AnnotationState.NONE):
for na_node, na_omit in not_annotated:
self.handleChildren(na_node, omit=na_omit)
self.handleChildren(node, omit=omit)
with self._enter_annotation():
for annotated_node in annotated:
self.handleNode(annotated_node, node)
else:
self.handleChildren(node)
def _handle_percent_format(self, node):
try:
placeholders = parse_percent_format(node.left.s)
except ValueError:
self.report(
messages.PercentFormatInvalidFormat,
node,
'incomplete format',
)
return
named = set()
positional_count = 0
positional = None
for _, placeholder in placeholders:
if placeholder is None:
continue
name, _, width, precision, conversion = placeholder
if conversion == '%':
continue
if conversion not in VALID_CONVERSIONS:
self.report(
messages.PercentFormatUnsupportedFormatCharacter,
node,
conversion,
)
if positional is None and conversion:
positional = name is None
for part in (width, precision):
if part is not None and '*' in part:
if not positional:
self.report(
messages.PercentFormatStarRequiresSequence,
node,
)
else:
positional_count += 1
if positional and name is not None:
self.report(
messages.PercentFormatMixedPositionalAndNamed,
node,
)
return
elif not positional and name is None:
self.report(
messages.PercentFormatMixedPositionalAndNamed,
node,
)
return
if positional:
positional_count += 1
else:
named.add(name)
if (
isinstance(node.right, (ast.List, ast.Tuple)) and
# does not have any *splats (py35+ feature)
not any(
isinstance(elt, ast.Starred)
for elt in node.right.elts
)
):
substitution_count = len(node.right.elts)
if positional and positional_count != substitution_count:
self.report(
messages.PercentFormatPositionalCountMismatch,
node,
positional_count,
substitution_count,
)
elif not positional:
self.report(messages.PercentFormatExpectedMapping, node)
if (
isinstance(node.right, ast.Dict) and
all(isinstance(k, ast.Str) for k in node.right.keys)
):
if positional and positional_count > 1:
self.report(messages.PercentFormatExpectedSequence, node)
return
substitution_keys = {k.s for k in node.right.keys}
extra_keys = substitution_keys - named
missing_keys = named - substitution_keys
if not positional and extra_keys:
self.report(
messages.PercentFormatExtraNamedArguments,
node,
', '.join(sorted(extra_keys)),
)
if not positional and missing_keys:
self.report(
messages.PercentFormatMissingArgument,
node,
', '.join(sorted(missing_keys)),
)
def BINOP(self, node):
if (
isinstance(node.op, ast.Mod) and
isinstance(node.left, ast.Str)
):
self._handle_percent_format(node)
self.handleChildren(node)
def STR(self, node):
if self._in_annotation:
fn = functools.partial(
self.handleStringAnnotation,
node.s,
node,
node.lineno,
node.col_offset,
messages.ForwardAnnotationSyntaxError,
)
if self._in_deferred:
fn()
else:
self.deferFunction(fn)
if PY38_PLUS:
def CONSTANT(self, node):
if isinstance(node.value, str):
return self.STR(node)
else:
NUM = BYTES = ELLIPSIS = CONSTANT = ignore
# "slice" type nodes
SLICE = EXTSLICE = INDEX = handleChildren
# expression contexts are node instances too, though being constants
LOAD = STORE = DEL = AUGLOAD = AUGSTORE = PARAM = ignore
# same for operators
AND = OR = ADD = SUB = MULT = DIV = MOD = POW = LSHIFT = RSHIFT = \
BITOR = BITXOR = BITAND = FLOORDIV = INVERT = NOT = UADD = USUB = \
EQ = NOTEQ = LT = LTE = GT = GTE = IS = ISNOT = IN = NOTIN = \
MATMULT = ignore
def RAISE(self, node):
self.handleChildren(node)
arg = node.exc
if isinstance(arg, ast.Call):
if is_notimplemented_name_node(arg.func):
# Handle "raise NotImplemented(...)"
self.report(messages.RaiseNotImplemented, node)
elif is_notimplemented_name_node(arg):
# Handle "raise NotImplemented"
self.report(messages.RaiseNotImplemented, node)
# additional node types
COMPREHENSION = KEYWORD = FORMATTEDVALUE = handleChildren
_in_fstring = False
def JOINEDSTR(self, node):
if (
# the conversion / etc. flags are parsed as f-strings without
# placeholders
not self._in_fstring and
not any(isinstance(x, ast.FormattedValue) for x in node.values)
):
self.report(messages.FStringMissingPlaceholders, node)
self._in_fstring, orig = True, self._in_fstring
try:
self.handleChildren(node)
finally:
self._in_fstring = orig
def DICT(self, node):
# Complain if there are duplicate keys with different values
# If they have the same value it's not going to cause potentially
# unexpected behaviour so we'll not complain.
keys = [
convert_to_value(key) for key in node.keys
]
key_counts = counter(keys)
duplicate_keys = [
key for key, count in key_counts.items()
if count > 1
]
for key in duplicate_keys:
key_indices = [i for i, i_key in enumerate(keys) if i_key == key]
values = counter(
convert_to_value(node.values[index])
for index in key_indices
)
if any(count == 1 for value, count in values.items()):
for key_index in key_indices:
key_node = node.keys[key_index]
if isinstance(key, VariableKey):
self.report(messages.MultiValueRepeatedKeyVariable,
key_node,
key.name)
else:
self.report(
messages.MultiValueRepeatedKeyLiteral,
key_node,
key,
)
self.handleChildren(node)
def IF(self, node):
if isinstance(node.test, ast.Tuple) and node.test.elts != []:
self.report(messages.IfTuple, node)
self.handleChildren(node)
IFEXP = IF
def ASSERT(self, node):
if isinstance(node.test, ast.Tuple) and node.test.elts != []:
self.report(messages.AssertTuple, node)
self.handleChildren(node)
def GLOBAL(self, node):
"""
Keep track of globals declarations.
"""
global_scope_index = 1 if self._in_doctest() else 0
global_scope = self.scopeStack[global_scope_index]
# Ignore 'global' statement in global scope.
if self.scope is not global_scope:
# One 'global' statement can bind multiple (comma-delimited) names.
for node_name in node.names:
node_value = Assignment(node_name, node)
# Remove UndefinedName messages already reported for this name.
# TODO: if the global is not used in this scope, it does not
# become a globally defined name. See test_unused_global.
self.messages = [
m for m in self.messages if not
isinstance(m, messages.UndefinedName) or
m.message_args[0] != node_name]
# Bind name to global scope if it doesn't exist already.
global_scope.setdefault(node_name, node_value)
# Bind name to non-global scopes, but as already "used".
node_value.used = (global_scope, node)
for scope in self.scopeStack[global_scope_index + 1:]:
scope[node_name] = node_value
NONLOCAL = GLOBAL
def GENERATOREXP(self, node):
self.pushScope(GeneratorScope)
self.handleChildren(node)
self.popScope()
LISTCOMP = DICTCOMP = SETCOMP = GENERATOREXP
def NAME(self, node):
"""
Handle occurrence of Name (which can be a load/store/delete access.)
"""
# Locate the name in locals / function / globals scopes.
if isinstance(node.ctx, ast.Load):
self.handleNodeLoad(node)
if (node.id == 'locals' and isinstance(self.scope, FunctionScope) and
isinstance(node._pyflakes_parent, ast.Call)):
# we are doing locals() call in current scope
self.scope.usesLocals = True
elif isinstance(node.ctx, ast.Store):
self.handleNodeStore(node)
elif isinstance(node.ctx, ast.Del):
self.handleNodeDelete(node)
else:
# Unknown context
raise RuntimeError(f"Got impossible expression context: {node.ctx!r}")
def CONTINUE(self, node):
# Walk the tree up until we see a loop (OK), a function or class
# definition (not OK), for 'continue', a finally block (not OK), or
# the top module scope (not OK)
n = node
while hasattr(n, '_pyflakes_parent'):
n, n_child = n._pyflakes_parent, n
if isinstance(n, (ast.While, ast.For, ast.AsyncFor)):
# Doesn't apply unless it's in the loop itself
if n_child not in n.orelse:
return
if isinstance(n, (ast.FunctionDef, ast.ClassDef)):
break
# Handle Try/TryFinally difference in Python < and >= 3.3
if hasattr(n, 'finalbody') and isinstance(node, ast.Continue):
if n_child in n.finalbody and not PY38_PLUS:
self.report(messages.ContinueInFinally, node)
return
if isinstance(node, ast.Continue):
self.report(messages.ContinueOutsideLoop, node)
else: # ast.Break
self.report(messages.BreakOutsideLoop, node)
BREAK = CONTINUE
def RETURN(self, node):
if isinstance(self.scope, (ClassScope, ModuleScope)):
self.report(messages.ReturnOutsideFunction, node)
return
if (
node.value and
hasattr(self.scope, 'returnValue') and
not self.scope.returnValue
):
self.scope.returnValue = node.value
self.handleNode(node.value, node)
def YIELD(self, node):
if isinstance(self.scope, (ClassScope, ModuleScope)):
self.report(messages.YieldOutsideFunction, node)
return
self.scope.isGenerator = True
self.handleNode(node.value, node)
AWAIT = YIELDFROM = YIELD
def FUNCTIONDEF(self, node):
for deco in node.decorator_list:
self.handleNode(deco, node)
self.LAMBDA(node)
self.addBinding(node, FunctionDefinition(node.name, node))
# doctest does not process doctest within a doctest,
# or in nested functions.
if (self.withDoctest and
not self._in_doctest() and
not isinstance(self.scope, FunctionScope)):
self.deferFunction(lambda: self.handleDoctests(node))
ASYNCFUNCTIONDEF = FUNCTIONDEF
def LAMBDA(self, node):
args = []
annotations = []
if PY38_PLUS:
for arg in node.args.posonlyargs:
args.append(arg.arg)
annotations.append(arg.annotation)
for arg in node.args.args + node.args.kwonlyargs:
args.append(arg.arg)
annotations.append(arg.annotation)
defaults = node.args.defaults + node.args.kw_defaults
has_annotations = not isinstance(node, ast.Lambda)
for arg_name in ('vararg', 'kwarg'):
wildcard = getattr(node.args, arg_name)
if not wildcard:
continue
args.append(wildcard.arg)
if has_annotations:
annotations.append(wildcard.annotation)
if has_annotations:
annotations.append(node.returns)
if len(set(args)) < len(args):
for (idx, arg) in enumerate(args):
if arg in args[:idx]:
self.report(messages.DuplicateArgument, node, arg)
for annotation in annotations:
self.handleAnnotation(annotation, node)
for default in defaults:
self.handleNode(default, node)
def runFunction():
self.pushScope()
self.handleChildren(node, omit=['decorator_list', 'returns'])
def checkUnusedAssignments():
"""
Check to see if any assignments have not been used.
"""
for name, binding in self.scope.unusedAssignments():
self.report(messages.UnusedVariable, binding.source, name)
self.deferAssignment(checkUnusedAssignments)
self.popScope()
self.deferFunction(runFunction)
def ARGUMENTS(self, node):
self.handleChildren(node, omit=('defaults', 'kw_defaults'))
def ARG(self, node):
self.addBinding(node, Argument(node.arg, self.getScopeNode(node)))
def CLASSDEF(self, node):
"""
Check names used in a class definition, including its decorators, base
classes, and the body of its definition. Additionally, add its name to
the current scope.
"""
for deco in node.decorator_list:
self.handleNode(deco, node)
for baseNode in node.bases:
self.handleNode(baseNode, node)
for keywordNode in node.keywords:
self.handleNode(keywordNode, node)
self.pushScope(ClassScope)
# doctest does not process doctest within a doctest
# classes within classes are processed.
if (self.withDoctest and
not self._in_doctest() and
not isinstance(self.scope, FunctionScope)):
self.deferFunction(lambda: self.handleDoctests(node))
for stmt in node.body:
self.handleNode(stmt, node)
self.popScope()
self.addBinding(node, ClassDefinition(node.name, node))
def AUGASSIGN(self, node):
self.handleNodeLoad(node.target)
self.handleNode(node.value, node)
self.handleNode(node.target, node)
def TUPLE(self, node):
if isinstance(node.ctx, ast.Store):
# Python 3 advanced tuple unpacking: a, *b, c = d.
# Only one starred expression is allowed, and no more than 1<<8
# assignments are allowed before a stared expression. There is
# also a limit of 1<<24 expressions after the starred expression,
# which is impossible to test due to memory restrictions, but we
# add it here anyway
has_starred = False
star_loc = -1
for i, n in enumerate(node.elts):
if isinstance(n, ast.Starred):
if has_starred:
self.report(messages.TwoStarredExpressions, node)
# The SyntaxError doesn't distinguish two from more
# than two.
break
has_starred = True
star_loc = i
if star_loc >= 1 << 8 or len(node.elts) - star_loc - 1 >= 1 << 24:
self.report(messages.TooManyExpressionsInStarredAssignment, node)
self.handleChildren(node)
LIST = TUPLE
def IMPORT(self, node):
for alias in node.names:
if '.' in alias.name and not alias.asname:
importation = SubmoduleImportation(alias.name, node)
else:
name = alias.asname or alias.name
importation = Importation(name, node, alias.name)
self.addBinding(node, importation)
def IMPORTFROM(self, node):
if node.module == '__future__':
if not self.futuresAllowed:
self.report(messages.LateFutureImport, node)
else:
self.futuresAllowed = False
module = ('.' * node.level) + (node.module or '')
for alias in node.names:
name = alias.asname or alias.name
if node.module == '__future__':
importation = FutureImportation(name, node, self.scope)
if alias.name not in __future__.all_feature_names:
self.report(messages.FutureFeatureNotDefined,
node, alias.name)
if alias.name == 'annotations':
self.annotationsFutureEnabled = True
elif alias.name == '*':
if not isinstance(self.scope, ModuleScope):
self.report(messages.ImportStarNotPermitted,
node, module)
continue
self.scope.importStarred = True
self.report(messages.ImportStarUsed, node, module)
importation = StarImportation(module, node)
else:
importation = ImportationFrom(name, node,
module, alias.name)
self.addBinding(node, importation)
def TRY(self, node):
handler_names = []
# List the exception handlers
for i, handler in enumerate(node.handlers):
if isinstance(handler.type, ast.Tuple):
for exc_type in handler.type.elts:
handler_names.append(getNodeName(exc_type))
elif handler.type:
handler_names.append(getNodeName(handler.type))
if handler.type is None and i < len(node.handlers) - 1:
self.report(messages.DefaultExceptNotLast, handler)
# Memorize the except handlers and process the body
self.exceptHandlers.append(handler_names)
for child in node.body:
self.handleNode(child, node)
self.exceptHandlers.pop()
# Process the other nodes: "except:", "else:", "finally:"
self.handleChildren(node, omit='body')
TRYSTAR = TRY
def EXCEPTHANDLER(self, node):
if node.name is None:
self.handleChildren(node)
return
# If the name already exists in the scope, modify state of existing
# binding.
if node.name in self.scope:
self.handleNodeStore(node)
# 3.x: the name of the exception, which is not a Name node, but a
# simple string, creates a local that is only bound within the scope of
# the except: block. As such, temporarily remove the existing binding
# to more accurately determine if the name is used in the except:
# block.
try:
prev_definition = self.scope.pop(node.name)
except KeyError:
prev_definition = None
self.handleNodeStore(node)
self.handleChildren(node)
# See discussion on https://github.com/PyCQA/pyflakes/pull/59
# We're removing the local name since it's being unbound after leaving
# the except: block and it's always unbound if the except: block is
# never entered. This will cause an "undefined name" error raised if
# the checked code tries to use the name afterwards.
#
# Unless it's been removed already. Then do nothing.
try:
binding = self.scope.pop(node.name)
except KeyError:
pass
else:
if not binding.used:
self.report(messages.UnusedVariable, node, node.name)
# Restore.
if prev_definition:
self.scope[node.name] = prev_definition
def ANNASSIGN(self, node):
self.handleNode(node.target, node)
self.handleAnnotation(node.annotation, node)
# If the assignment has value, handle the *value* now.
if node.value:
# If the annotation is `TypeAlias`, handle the *value* as an annotation.
if _is_typing(node.annotation, 'TypeAlias', self.scopeStack):
self.handleAnnotation(node.value, node)
else:
self.handleNode(node.value, node)
def COMPARE(self, node):
left = node.left
for op, right in zip(node.ops, node.comparators):
if (
isinstance(op, (ast.Is, ast.IsNot)) and (
_is_const_non_singleton(left) or
_is_const_non_singleton(right)
)
):
self.report(messages.IsLiteral, node)
left = right
self.handleChildren(node)
MATCH = MATCH_CASE = MATCHCLASS = MATCHOR = MATCHSEQUENCE = handleChildren
MATCHSINGLETON = MATCHVALUE = handleChildren
def _match_target(self, node):
self.handleNodeStore(node)
self.handleChildren(node)
MATCHAS = MATCHMAPPING = MATCHSTAR = _match_target