625 lines
22 KiB
Python
625 lines
22 KiB
Python
# -*- test-case-name: pyflakes -*-
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# (c) 2005-2010 Divmod, Inc.
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# See LICENSE file for details
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import __builtin__
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import os.path
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import _ast
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from pyflakes import messages
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# utility function to iterate over an AST node's children, adapted
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# from Python 2.6's standard ast module
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try:
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import ast
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iter_child_nodes = ast.iter_child_nodes
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except (ImportError, AttributeError):
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def iter_child_nodes(node, astcls=_ast.AST):
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"""
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Yield all direct child nodes of *node*, that is, all fields that are nodes
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and all items of fields that are lists of nodes.
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"""
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for name in node._fields:
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field = getattr(node, name, None)
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if isinstance(field, astcls):
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yield field
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elif isinstance(field, list):
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for item in field:
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yield item
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class Binding(object):
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"""
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Represents the binding of a value to a name.
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The checker uses this to keep track of which names have been bound and
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which names have not. See L{Assignment} for a special type of binding that
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is checked with stricter rules.
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@ivar used: pair of (L{Scope}, line-number) indicating the scope and
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line number that this binding was last used
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"""
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def __init__(self, name, source):
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self.name = name
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self.source = source
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self.used = False
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def __str__(self):
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return self.name
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def __repr__(self):
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return '<%s object %r from line %r at 0x%x>' % (self.__class__.__name__,
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self.name,
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self.source.lineno,
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id(self))
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class UnBinding(Binding):
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'''Created by the 'del' operator.'''
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class Importation(Binding):
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"""
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A binding created by an import statement.
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@ivar fullName: The complete name given to the import statement,
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possibly including multiple dotted components.
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@type fullName: C{str}
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"""
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def __init__(self, name, source):
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self.fullName = name
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name = name.split('.')[0]
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super(Importation, self).__init__(name, source)
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class Argument(Binding):
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"""
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Represents binding a name as an argument.
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"""
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class Assignment(Binding):
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"""
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Represents binding a name with an explicit assignment.
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The checker will raise warnings for any Assignment that isn't used. Also,
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the checker does not consider assignments in tuple/list unpacking to be
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Assignments, rather it treats them as simple Bindings.
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"""
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class FunctionDefinition(Binding):
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pass
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class ExportBinding(Binding):
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"""
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A binding created by an C{__all__} assignment. If the names in the list
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can be determined statically, they will be treated as names for export and
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additional checking applied to them.
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The only C{__all__} assignment that can be recognized is one which takes
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the value of a literal list containing literal strings. For example::
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__all__ = ["foo", "bar"]
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Names which are imported and not otherwise used but appear in the value of
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C{__all__} will not have an unused import warning reported for them.
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"""
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def names(self):
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"""
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Return a list of the names referenced by this binding.
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"""
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names = []
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if isinstance(self.source, _ast.List):
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for node in self.source.elts:
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if isinstance(node, _ast.Str):
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names.append(node.s)
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return names
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class Scope(dict):
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importStarred = False # set to True when import * is found
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def __repr__(self):
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return '<%s at 0x%x %s>' % (self.__class__.__name__, id(self), dict.__repr__(self))
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def __init__(self):
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super(Scope, self).__init__()
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class ClassScope(Scope):
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pass
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class FunctionScope(Scope):
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"""
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I represent a name scope for a function.
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@ivar globals: Names declared 'global' in this function.
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"""
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def __init__(self):
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super(FunctionScope, self).__init__()
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self.globals = {}
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class ModuleScope(Scope):
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pass
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# Globally defined names which are not attributes of the __builtin__ module.
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_MAGIC_GLOBALS = ['__file__', '__builtins__']
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class Checker(object):
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"""
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I check the cleanliness and sanity of Python code.
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@ivar _deferredFunctions: Tracking list used by L{deferFunction}. Elements
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of the list are two-tuples. The first element is the callable passed
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to L{deferFunction}. The second element is a copy of the scope stack
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at the time L{deferFunction} was called.
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@ivar _deferredAssignments: Similar to C{_deferredFunctions}, but for
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callables which are deferred assignment checks.
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"""
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nodeDepth = 0
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traceTree = False
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def __init__(self, tree, filename='(none)'):
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self._deferredFunctions = []
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self._deferredAssignments = []
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self.dead_scopes = []
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self.messages = []
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self.filename = filename
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self.scopeStack = [ModuleScope()]
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self.futuresAllowed = True
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self.handleChildren(tree)
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self._runDeferred(self._deferredFunctions)
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# Set _deferredFunctions to None so that deferFunction will fail
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# noisily if called after we've run through the deferred functions.
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self._deferredFunctions = None
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self._runDeferred(self._deferredAssignments)
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# Set _deferredAssignments to None so that deferAssignment will fail
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# noisly if called after we've run through the deferred assignments.
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self._deferredAssignments = None
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del self.scopeStack[1:]
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self.popScope()
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self.check_dead_scopes()
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def deferFunction(self, callable):
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'''
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Schedule a function handler to be called just before completion.
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This is used for handling function bodies, which must be deferred
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because code later in the file might modify the global scope. When
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`callable` is called, the scope at the time this is called will be
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restored, however it will contain any new bindings added to it.
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'''
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self._deferredFunctions.append((callable, self.scopeStack[:]))
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def deferAssignment(self, callable):
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"""
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Schedule an assignment handler to be called just after deferred
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function handlers.
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"""
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self._deferredAssignments.append((callable, self.scopeStack[:]))
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def _runDeferred(self, deferred):
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"""
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Run the callables in C{deferred} using their associated scope stack.
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"""
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for handler, scope in deferred:
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self.scopeStack = scope
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handler()
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def scope(self):
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return self.scopeStack[-1]
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scope = property(scope)
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def popScope(self):
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self.dead_scopes.append(self.scopeStack.pop())
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def check_dead_scopes(self):
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"""
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Look at scopes which have been fully examined and report names in them
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which were imported but unused.
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"""
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for scope in self.dead_scopes:
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export = isinstance(scope.get('__all__'), ExportBinding)
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if export:
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all = scope['__all__'].names()
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if os.path.split(self.filename)[1] != '__init__.py':
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# Look for possible mistakes in the export list
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undefined = set(all) - set(scope)
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for name in undefined:
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self.report(
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messages.UndefinedExport,
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scope['__all__'].source.lineno,
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name)
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else:
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all = []
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# Look for imported names that aren't used.
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for importation in scope.itervalues():
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if isinstance(importation, Importation):
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if not importation.used and importation.name not in all:
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self.report(
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messages.UnusedImport,
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importation.source.lineno,
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importation.name)
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def pushFunctionScope(self):
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self.scopeStack.append(FunctionScope())
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def pushClassScope(self):
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self.scopeStack.append(ClassScope())
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def report(self, messageClass, *args, **kwargs):
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self.messages.append(messageClass(self.filename, *args, **kwargs))
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def handleChildren(self, tree):
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for node in iter_child_nodes(tree):
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self.handleNode(node, tree)
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def isDocstring(self, node):
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"""
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Determine if the given node is a docstring, as long as it is at the
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correct place in the node tree.
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"""
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return isinstance(node, _ast.Str) or \
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(isinstance(node, _ast.Expr) and
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isinstance(node.value, _ast.Str))
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def handleNode(self, node, parent):
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node.parent = parent
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if self.traceTree:
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print ' ' * self.nodeDepth + node.__class__.__name__
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self.nodeDepth += 1
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if self.futuresAllowed and not \
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(isinstance(node, _ast.ImportFrom) or self.isDocstring(node)):
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self.futuresAllowed = False
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nodeType = node.__class__.__name__.upper()
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try:
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handler = getattr(self, nodeType)
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handler(node)
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finally:
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self.nodeDepth -= 1
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if self.traceTree:
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print ' ' * self.nodeDepth + 'end ' + node.__class__.__name__
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def ignore(self, node):
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pass
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# "stmt" type nodes
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RETURN = DELETE = PRINT = WHILE = IF = WITH = RAISE = TRYEXCEPT = \
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TRYFINALLY = ASSERT = EXEC = EXPR = handleChildren
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CONTINUE = BREAK = PASS = ignore
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# "expr" type nodes
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BOOLOP = BINOP = UNARYOP = IFEXP = DICT = SET = YIELD = COMPARE = \
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CALL = REPR = ATTRIBUTE = SUBSCRIPT = LIST = TUPLE = handleChildren
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NUM = STR = ELLIPSIS = ignore
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# "slice" type nodes
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SLICE = EXTSLICE = INDEX = handleChildren
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# expression contexts are node instances too, though being constants
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LOAD = STORE = DEL = AUGLOAD = AUGSTORE = PARAM = ignore
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# same for operators
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AND = OR = ADD = SUB = MULT = DIV = MOD = POW = LSHIFT = RSHIFT = \
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BITOR = BITXOR = BITAND = FLOORDIV = INVERT = NOT = UADD = USUB = \
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EQ = NOTEQ = LT = LTE = GT = GTE = IS = ISNOT = IN = NOTIN = ignore
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# additional node types
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COMPREHENSION = EXCEPTHANDLER = KEYWORD = handleChildren
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def addBinding(self, lineno, value, reportRedef=True):
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'''Called when a binding is altered.
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- `lineno` is the line of the statement responsible for the change
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- `value` is the optional new value, a Binding instance, associated
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with the binding; if None, the binding is deleted if it exists.
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- if `reportRedef` is True (default), rebinding while unused will be
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reported.
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'''
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if (isinstance(self.scope.get(value.name), FunctionDefinition)
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and isinstance(value, FunctionDefinition)):
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self.report(messages.RedefinedFunction,
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lineno, value.name, self.scope[value.name].source.lineno)
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if not isinstance(self.scope, ClassScope):
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for scope in self.scopeStack[::-1]:
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existing = scope.get(value.name)
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if (isinstance(existing, Importation)
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and not existing.used
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and (not isinstance(value, Importation) or value.fullName == existing.fullName)
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and reportRedef):
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self.report(messages.RedefinedWhileUnused,
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lineno, value.name, scope[value.name].source.lineno)
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if isinstance(value, UnBinding):
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try:
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del self.scope[value.name]
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except KeyError:
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self.report(messages.UndefinedName, lineno, value.name)
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else:
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self.scope[value.name] = value
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def GLOBAL(self, node):
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"""
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Keep track of globals declarations.
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"""
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if isinstance(self.scope, FunctionScope):
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self.scope.globals.update(dict.fromkeys(node.names))
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def LISTCOMP(self, node):
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# handle generators before element
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for gen in node.generators:
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self.handleNode(gen, node)
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self.handleNode(node.elt, node)
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GENERATOREXP = SETCOMP = LISTCOMP
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# dictionary comprehensions; introduced in Python 2.7
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def DICTCOMP(self, node):
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for gen in node.generators:
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self.handleNode(gen, node)
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self.handleNode(node.key, node)
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self.handleNode(node.value, node)
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def FOR(self, node):
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"""
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Process bindings for loop variables.
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"""
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vars = []
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def collectLoopVars(n):
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if isinstance(n, _ast.Name):
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vars.append(n.id)
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elif isinstance(n, _ast.expr_context):
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return
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else:
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for c in iter_child_nodes(n):
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collectLoopVars(c)
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collectLoopVars(node.target)
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for varn in vars:
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if (isinstance(self.scope.get(varn), Importation)
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# unused ones will get an unused import warning
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and self.scope[varn].used):
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self.report(messages.ImportShadowedByLoopVar,
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node.lineno, varn, self.scope[varn].source.lineno)
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self.handleChildren(node)
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def NAME(self, node):
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"""
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Handle occurrence of Name (which can be a load/store/delete access.)
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"""
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# Locate the name in locals / function / globals scopes.
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if isinstance(node.ctx, (_ast.Load, _ast.AugLoad)):
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# try local scope
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importStarred = self.scope.importStarred
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try:
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self.scope[node.id].used = (self.scope, node.lineno)
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except KeyError:
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pass
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else:
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return
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# try enclosing function scopes
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for scope in self.scopeStack[-2:0:-1]:
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importStarred = importStarred or scope.importStarred
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if not isinstance(scope, FunctionScope):
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continue
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try:
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scope[node.id].used = (self.scope, node.lineno)
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except KeyError:
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pass
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else:
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return
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# try global scope
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importStarred = importStarred or self.scopeStack[0].importStarred
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try:
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self.scopeStack[0][node.id].used = (self.scope, node.lineno)
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except KeyError:
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if ((not hasattr(__builtin__, node.id))
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and node.id not in _MAGIC_GLOBALS
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and not importStarred):
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if (os.path.basename(self.filename) == '__init__.py' and
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node.id == '__path__'):
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# the special name __path__ is valid only in packages
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pass
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else:
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self.report(messages.UndefinedName, node.lineno, node.id)
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elif isinstance(node.ctx, (_ast.Store, _ast.AugStore)):
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# if the name hasn't already been defined in the current scope
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if isinstance(self.scope, FunctionScope) and node.id not in self.scope:
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# for each function or module scope above us
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for scope in self.scopeStack[:-1]:
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if not isinstance(scope, (FunctionScope, ModuleScope)):
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continue
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# if the name was defined in that scope, and the name has
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# been accessed already in the current scope, and hasn't
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# been declared global
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if (node.id in scope
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and scope[node.id].used
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and scope[node.id].used[0] is self.scope
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and node.id not in self.scope.globals):
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# then it's probably a mistake
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self.report(messages.UndefinedLocal,
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scope[node.id].used[1],
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node.id,
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scope[node.id].source.lineno)
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break
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if isinstance(node.parent,
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(_ast.For, _ast.comprehension, _ast.Tuple, _ast.List)):
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binding = Binding(node.id, node)
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elif (node.id == '__all__' and
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isinstance(self.scope, ModuleScope)):
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binding = ExportBinding(node.id, node.parent.value)
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else:
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binding = Assignment(node.id, node)
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if node.id in self.scope:
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binding.used = self.scope[node.id].used
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self.addBinding(node.lineno, binding)
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elif isinstance(node.ctx, _ast.Del):
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if isinstance(self.scope, FunctionScope) and \
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node.id in self.scope.globals:
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del self.scope.globals[node.id]
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else:
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self.addBinding(node.lineno, UnBinding(node.id, node))
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else:
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# must be a Param context -- this only happens for names in function
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# arguments, but these aren't dispatched through here
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raise RuntimeError(
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"Got impossible expression context: %r" % (node.ctx,))
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def FUNCTIONDEF(self, node):
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# the decorators attribute is called decorator_list as of Python 2.6
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if hasattr(node, 'decorators'):
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for deco in node.decorators:
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self.handleNode(deco, node)
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else:
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for deco in node.decorator_list:
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self.handleNode(deco, node)
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self.addBinding(node.lineno, FunctionDefinition(node.name, node))
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self.LAMBDA(node)
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def LAMBDA(self, node):
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for default in node.args.defaults:
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self.handleNode(default, node)
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def runFunction():
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args = []
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def addArgs(arglist):
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for arg in arglist:
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if isinstance(arg, _ast.Tuple):
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addArgs(arg.elts)
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else:
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if arg.id in args:
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self.report(messages.DuplicateArgument,
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node.lineno, arg.id)
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args.append(arg.id)
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self.pushFunctionScope()
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addArgs(node.args.args)
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# vararg/kwarg identifiers are not Name nodes
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if node.args.vararg:
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args.append(node.args.vararg)
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if node.args.kwarg:
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args.append(node.args.kwarg)
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for name in args:
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self.addBinding(node.lineno, Argument(name, node), reportRedef=False)
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if isinstance(node.body, list):
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# case for FunctionDefs
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for stmt in node.body:
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self.handleNode(stmt, node)
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else:
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# case for Lambdas
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|
self.handleNode(node.body, node)
|
|
def checkUnusedAssignments():
|
|
"""
|
|
Check to see if any assignments have not been used.
|
|
"""
|
|
for name, binding in self.scope.iteritems():
|
|
if (not binding.used and not name in self.scope.globals
|
|
and isinstance(binding, Assignment)):
|
|
self.report(messages.UnusedVariable,
|
|
binding.source.lineno, name)
|
|
self.deferAssignment(checkUnusedAssignments)
|
|
self.popScope()
|
|
|
|
self.deferFunction(runFunction)
|
|
|
|
|
|
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.
|
|
"""
|
|
# decorator_list is present as of Python 2.6
|
|
for deco in getattr(node, 'decorator_list', []):
|
|
self.handleNode(deco, node)
|
|
for baseNode in node.bases:
|
|
self.handleNode(baseNode, node)
|
|
self.pushClassScope()
|
|
for stmt in node.body:
|
|
self.handleNode(stmt, node)
|
|
self.popScope()
|
|
self.addBinding(node.lineno, Binding(node.name, node))
|
|
|
|
def ASSIGN(self, node):
|
|
self.handleNode(node.value, node)
|
|
for target in node.targets:
|
|
self.handleNode(target, node)
|
|
|
|
def AUGASSIGN(self, node):
|
|
# AugAssign is awkward: must set the context explicitly and visit twice,
|
|
# once with AugLoad context, once with AugStore context
|
|
node.target.ctx = _ast.AugLoad()
|
|
self.handleNode(node.target, node)
|
|
self.handleNode(node.value, node)
|
|
node.target.ctx = _ast.AugStore()
|
|
self.handleNode(node.target, node)
|
|
|
|
def IMPORT(self, node):
|
|
for alias in node.names:
|
|
name = alias.asname or alias.name
|
|
importation = Importation(name, node)
|
|
self.addBinding(node.lineno, importation)
|
|
|
|
def IMPORTFROM(self, node):
|
|
if node.module == '__future__':
|
|
if not self.futuresAllowed:
|
|
self.report(messages.LateFutureImport, node.lineno,
|
|
[n.name for n in node.names])
|
|
else:
|
|
self.futuresAllowed = False
|
|
|
|
for alias in node.names:
|
|
if alias.name == '*':
|
|
self.scope.importStarred = True
|
|
self.report(messages.ImportStarUsed, node.lineno, node.module)
|
|
continue
|
|
name = alias.asname or alias.name
|
|
importation = Importation(name, node)
|
|
if node.module == '__future__':
|
|
importation.used = (self.scope, node.lineno)
|
|
self.addBinding(node.lineno, importation)
|