/usr/share/pyshared/pocketlint/contrib/pyflakes/checker.py is in python-pocket-lint 0.5.31-0ubuntu1.
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# (c) 2005-2010 Divmod, Inc.
# See LICENSE file for details
import __builtin__
import os.path
import _ast
# XXX sinzui 2012-01-03: Import the contrib version of message.
#from pyflakes import messages
from pocketlint.contrib.pyflakes import messages
# utility function to iterate over an AST node's children, adapted
# from Python 2.6's standard ast module
try:
import ast
iter_child_nodes = ast.iter_child_nodes
except (ImportError, AttributeError):
def iter_child_nodes(node, astcls=_ast.AST):
"""
Yield all direct child nodes of *node*, that is, all fields that are nodes
and all items of fields that are lists of nodes.
"""
for name in node._fields:
field = getattr(node, name, None)
if isinstance(field, astcls):
yield field
elif isinstance(field, list):
for item in field:
yield item
class Binding(object):
"""
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}, line-number) indicating the scope and
line number 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 '<%s object %r from line %r at 0x%x>' % (self.__class__.__name__,
self.name,
self.source.lineno,
id(self))
class UnBinding(Binding):
'''Created by the 'del' operator.'''
class Importation(Binding):
"""
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):
self.fullName = name
name = name.split('.')[0]
super(Importation, self).__init__(name, 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 FunctionDefinition(Binding):
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 C{__all__} assignment that can be recognized is one which takes
the value of a literal list containing literal strings. For example::
__all__ = ["foo", "bar"]
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 names(self):
"""
Return a list of the names referenced by this binding.
"""
names = []
if isinstance(self.source, _ast.List):
for node in self.source.elts:
if isinstance(node, _ast.Str):
names.append(node.s)
return names
class Scope(dict):
importStarred = False # set to True when import * is found
def __repr__(self):
return '<%s at 0x%x %s>' % (self.__class__.__name__, id(self), dict.__repr__(self))
def __init__(self):
super(Scope, self).__init__()
class ClassScope(Scope):
pass
class FunctionScope(Scope):
"""
I represent a name scope for a function.
@ivar globals: Names declared 'global' in this function.
"""
def __init__(self):
super(FunctionScope, self).__init__()
self.globals = {}
class ModuleScope(Scope):
pass
# Globally defined names which are not attributes of the __builtin__ module.
_MAGIC_GLOBALS = ['__file__', '__builtins__']
class Checker(object):
"""
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.
"""
nodeDepth = 0
traceTree = False
def __init__(self, tree, filename='(none)'):
self._deferredFunctions = []
self._deferredAssignments = []
self.dead_scopes = []
self.messages = []
self.filename = filename
self.scopeStack = [ModuleScope()]
self.futuresAllowed = True
self.handleChildren(tree)
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
# noisly if called after we've run through the deferred assignments.
self._deferredAssignments = None
del self.scopeStack[1:]
self.popScope()
self.check_dead_scopes()
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[:]))
def deferAssignment(self, callable):
"""
Schedule an assignment handler to be called just after deferred
function handlers.
"""
self._deferredAssignments.append((callable, self.scopeStack[:]))
def _runDeferred(self, deferred):
"""
Run the callables in C{deferred} using their associated scope stack.
"""
for handler, scope in deferred:
self.scopeStack = scope
handler()
def scope(self):
return self.scopeStack[-1]
scope = property(scope)
def popScope(self):
self.dead_scopes.append(self.scopeStack.pop())
def check_dead_scopes(self):
"""
Look at scopes which have been fully examined and report names in them
which were imported but unused.
"""
for scope in self.dead_scopes:
export = isinstance(scope.get('__all__'), ExportBinding)
if export:
all = scope['__all__'].names()
if os.path.split(self.filename)[1] != '__init__.py':
# Look for possible mistakes in the export list
undefined = set(all) - set(scope)
for name in undefined:
self.report(
messages.UndefinedExport,
scope['__all__'].source.lineno,
name)
else:
all = []
# Look for imported names that aren't used.
for importation in scope.itervalues():
if isinstance(importation, Importation):
if not importation.used and importation.name not in all:
self.report(
messages.UnusedImport,
importation.source.lineno,
importation.name)
def pushFunctionScope(self):
self.scopeStack.append(FunctionScope())
def pushClassScope(self):
self.scopeStack.append(ClassScope())
def report(self, messageClass, *args, **kwargs):
self.messages.append(messageClass(self.filename, *args, **kwargs))
def handleChildren(self, tree):
for node in iter_child_nodes(tree):
self.handleNode(node, tree)
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 handleNode(self, node, parent):
node.parent = parent
if self.traceTree:
print ' ' * self.nodeDepth + node.__class__.__name__
self.nodeDepth += 1
if self.futuresAllowed and not \
(isinstance(node, _ast.ImportFrom) or self.isDocstring(node)):
self.futuresAllowed = False
nodeType = node.__class__.__name__.upper()
try:
handler = getattr(self, nodeType)
handler(node)
finally:
self.nodeDepth -= 1
if self.traceTree:
print ' ' * self.nodeDepth + 'end ' + node.__class__.__name__
def ignore(self, node):
pass
# "stmt" type nodes
RETURN = DELETE = PRINT = WHILE = IF = WITH = RAISE = TRYEXCEPT = \
TRYFINALLY = ASSERT = EXEC = EXPR = handleChildren
CONTINUE = BREAK = PASS = ignore
# "expr" type nodes
BOOLOP = BINOP = UNARYOP = IFEXP = DICT = SET = YIELD = COMPARE = \
CALL = REPR = ATTRIBUTE = SUBSCRIPT = LIST = TUPLE = handleChildren
NUM = STR = ELLIPSIS = 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 = ignore
# additional node types
COMPREHENSION = EXCEPTHANDLER = KEYWORD = handleChildren
def addBinding(self, lineno, value, reportRedef=True):
'''Called when a binding is altered.
- `lineno` is the line of the statement responsible for the change
- `value` is the optional new value, a Binding instance, associated
with the binding; if None, the binding is deleted if it exists.
- if `reportRedef` is True (default), rebinding while unused will be
reported.
'''
if (isinstance(self.scope.get(value.name), FunctionDefinition)
and isinstance(value, FunctionDefinition)):
self.report(messages.RedefinedFunction,
lineno, value.name, self.scope[value.name].source.lineno)
if not isinstance(self.scope, ClassScope):
for scope in self.scopeStack[::-1]:
existing = scope.get(value.name)
if (isinstance(existing, Importation)
and not existing.used
and (not isinstance(value, Importation) or value.fullName == existing.fullName)
and reportRedef):
self.report(messages.RedefinedWhileUnused,
lineno, value.name, scope[value.name].source.lineno)
if isinstance(value, UnBinding):
try:
del self.scope[value.name]
except KeyError:
self.report(messages.UndefinedName, lineno, value.name)
else:
self.scope[value.name] = value
def GLOBAL(self, node):
"""
Keep track of globals declarations.
"""
if isinstance(self.scope, FunctionScope):
self.scope.globals.update(dict.fromkeys(node.names))
def LISTCOMP(self, node):
# handle generators before element
for gen in node.generators:
self.handleNode(gen, node)
self.handleNode(node.elt, node)
GENERATOREXP = SETCOMP = LISTCOMP
# dictionary comprehensions; introduced in Python 2.7
def DICTCOMP(self, node):
for gen in node.generators:
self.handleNode(gen, node)
self.handleNode(node.key, node)
self.handleNode(node.value, node)
def FOR(self, node):
"""
Process bindings for loop variables.
"""
vars = []
def collectLoopVars(n):
if isinstance(n, _ast.Name):
vars.append(n.id)
elif isinstance(n, _ast.expr_context):
return
else:
for c in iter_child_nodes(n):
collectLoopVars(c)
collectLoopVars(node.target)
for varn in vars:
if (isinstance(self.scope.get(varn), Importation)
# unused ones will get an unused import warning
and self.scope[varn].used):
self.report(messages.ImportShadowedByLoopVar,
node.lineno, varn, self.scope[varn].source.lineno)
self.handleChildren(node)
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, _ast.AugLoad)):
# try local scope
importStarred = self.scope.importStarred
try:
self.scope[node.id].used = (self.scope, node.lineno)
except KeyError:
pass
else:
return
# try enclosing function scopes
for scope in self.scopeStack[-2:0:-1]:
importStarred = importStarred or scope.importStarred
if not isinstance(scope, FunctionScope):
continue
try:
scope[node.id].used = (self.scope, node.lineno)
except KeyError:
pass
else:
return
# try global scope
importStarred = importStarred or self.scopeStack[0].importStarred
try:
self.scopeStack[0][node.id].used = (self.scope, node.lineno)
except KeyError:
if ((not hasattr(__builtin__, node.id))
and node.id not in _MAGIC_GLOBALS
and not importStarred):
if (os.path.basename(self.filename) == '__init__.py' and
node.id == '__path__'):
# the special name __path__ is valid only in packages
pass
else:
self.report(messages.UndefinedName, node.lineno, node.id)
elif isinstance(node.ctx, (_ast.Store, _ast.AugStore)):
# if the name hasn't already been defined in the current scope
if isinstance(self.scope, FunctionScope) and node.id 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
if (node.id in scope
and scope[node.id].used
and scope[node.id].used[0] is self.scope
and node.id not in self.scope.globals):
# then it's probably a mistake
self.report(messages.UndefinedLocal,
scope[node.id].used[1],
node.id,
scope[node.id].source.lineno)
break
if isinstance(node.parent,
(_ast.For, _ast.comprehension, _ast.Tuple, _ast.List)):
binding = Binding(node.id, node)
elif (node.id == '__all__' and
isinstance(self.scope, ModuleScope)):
binding = ExportBinding(node.id, node.parent.value)
else:
binding = Assignment(node.id, node)
if node.id in self.scope:
binding.used = self.scope[node.id].used
self.addBinding(node.lineno, binding)
elif isinstance(node.ctx, _ast.Del):
if isinstance(self.scope, FunctionScope) and \
node.id in self.scope.globals:
del self.scope.globals[node.id]
else:
self.addBinding(node.lineno, UnBinding(node.id, node))
else:
# must be a Param context -- this only happens for names in function
# arguments, but these aren't dispatched through here
raise RuntimeError(
"Got impossible expression context: %r" % (node.ctx,))
def FUNCTIONDEF(self, node):
# the decorators attribute is called decorator_list as of Python 2.6
if hasattr(node, 'decorators'):
for deco in node.decorators:
self.handleNode(deco, node)
else:
for deco in node.decorator_list:
self.handleNode(deco, node)
self.addBinding(node.lineno, FunctionDefinition(node.name, node))
self.LAMBDA(node)
def LAMBDA(self, node):
for default in node.args.defaults:
self.handleNode(default, node)
def runFunction():
args = []
def addArgs(arglist):
for arg in arglist:
if isinstance(arg, _ast.Tuple):
addArgs(arg.elts)
else:
if arg.id in args:
self.report(messages.DuplicateArgument,
node.lineno, arg.id)
args.append(arg.id)
self.pushFunctionScope()
addArgs(node.args.args)
# vararg/kwarg identifiers are not Name nodes
if node.args.vararg:
args.append(node.args.vararg)
if node.args.kwarg:
args.append(node.args.kwarg)
for name in args:
self.addBinding(node.lineno, Argument(name, node), reportRedef=False)
if isinstance(node.body, list):
# case for FunctionDefs
for stmt in node.body:
self.handleNode(stmt, node)
else:
# case for Lambdas
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)
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