/usr/share/pyshared/pychecker2/VariableChecks.py is in pychecker 0.8.19-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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from pychecker2.Options import Opt, BoolOpt
from pychecker2.Warning import Warning
from pychecker2.util import *
from pychecker2 import symbols
from compiler import ast, walk
def _is_method(scope):
return scope.__class__ is symbols.FunctionScope and \
scope.parent.__class__ is symbols.ClassScope
def _is_self(scope, name):
return _is_method(scope) and name in scope.node.argnames[:1]
def is_arg_and_defaulted_to_same_name(name, scope):
if isinstance(scope, symbols.FunctionScope):
if name in scope.node.argnames and scope.node.defaults:
# compute default args
args = scope.node.argnames[:]
# knock off kwargs
if scope.node.kwargs:
args = args[:-1]
# knock off varags
if scope.node.varargs:
args = args[:-1]
# take the last args as the defaults
args = args[-len(scope.node.defaults):]
try:
# get the corresponding default arg value
default = scope.node.defaults[args.index(name)]
# must be a Name node of the same name
if isinstance(default, ast.Name) and \
default.name == name:
return 1
except ValueError:
pass
return None
class ShadowCheck(Check):
"""Use symbol information to check that no scope defines a name
already known to a parent scope"""
defineNone = Warning('Report any redefinition of None',
'Do not redefine None')
shadowBuiltins = Warning('Report names that shadow builtins',
'Identifier (%s) shadows builtin', 0)
shadowIdentifier = Warning('Report names already defined in outer scopes',
'Identifier (%s) shadows definition in scope %s')
def check(self, file, unused_checker):
# warn if any name defined in a scope is defined in a parent scope
# or even the builtins
for node, scope in file.not_class_scopes():
for name in scope.defs:
if name == 'None':
file.warning(scope.defs[name], self.defineNone)
continue
if name in scope.globals:
continue
if is_arg_and_defaulted_to_same_name(name, scope):
continue
if _is_self(scope, name):
continue
if __builtins__.has_key(name):
file.warning(scope.defs[name], self.shadowBuiltins, name)
for p in parents(scope):
if p.defs.has_key(name) and \
not isinstance(p, symbols.ClassScope):
file.warning(scope.defs[name], \
self.shadowIdentifier, name, `p`)
def _str_value(s):
if type(s) == type(''):
return eval(s)
return s
def _empty_function(stmts):
if not stmts:
return 1
stmt = stmts[0]
# functions which only raise exceptions
if isinstance(stmt, ast.Raise):
return 1
# functions which do nothing
if len(stmts) == 1 and isinstance(stmt, ast.Pass):
return 1
# functions which just return a constant
if len(stmts) == 1 and \
isinstance(stmt, ast.Return) and isinstance(stmt.value, ast.Const):
return 1
# functions which only assert falsehood
if isinstance(stmt, ast.Assert):
if (isinstance(stmt.test, ast.Const) and not stmt.test.value) or \
(isinstance(stmt.test, ast.Name) and stmt.test.name == 'None'):
return 1
return 0
class UnusedCheck(Check):
"""Use symbol information to check that no scope defines a name
not used in this or any child scope"""
unused = Warning('Report names not used', 'Identifier (%s) not used')
def __init__(self):
self.reportUnusedSelf = None
self.unusedPrefixes = None
def get_options(self, options):
desc = 'Ignore unused identifiers that start with these values'
default = ['unused', 'empty', 'dummy',
'__pychecker__', '__all__', '__version__', 'ignored']
options.add(Opt(self, 'unusedPrefixes', desc, default))
desc = 'Ignore unused method "self" parameter'
options.add(BoolOpt(self, 'reportUnusedSelf', desc))
def check(self, file, unused_checker):
self.unusedPrefixes = _str_value(self.unusedPrefixes)
def used(name, parent_scope):
if parent_scope.uses.has_key(name):
return 1
for c in parent_scope.get_children():
if used(name, c):
return 1
return 0
for nodes, scope in file.not_class_scopes():
if isinstance(nodes, ast.Function):
if _empty_function(nodes.code.nodes):
continue
# ensure that every defined variable is used in some scope
for var in scope.defs:
# ignore '_'... just because
if var == '_':
continue
# check for method self
if not self.reportUnusedSelf and _is_self(scope, var):
continue
# ignore names in the root scope which are not imported:
# class defs, function defs, variables, etc, unless
# they start with '_'
if scope == file.root_scope:
if not scope.imports.has_key(var):
if not var.startswith('_'):
continue
for prefix in self.unusedPrefixes:
if var.startswith(prefix):
break
else:
if not used(var, scope) and not scope.globals.has_key(var):
file.warning(scope.defs[var], self.unused, var)
def _importedName(scope, name):
if scope.imports.has_key(name):
return 1
if scope.parent:
return _importedName(scope.parent, name)
return None
class UnknownCheck(Check):
"""Use symbol information to check that no scope uses a name
not defined in a parent scope"""
unknown = Warning('Report names that are not defined',
'Unknown identifier: %s')
builtins = {}
builtins.update(__builtins__)
builtins['__builtins__'] = __builtins__
builtins['WindowsError'] = getattr(__builtins__, 'WindowsError', None)
def check(self, file, unused_checker):
# if a name used is not found in the defined variables, complain
for scope in file.scopes.values():
unknown = dict_minus(scope.uses, scope.defs)
unknown = dict_minus(unknown, self.builtins)
for var in unknown:
for p in parents(scope):
if p.defs.has_key(var):
break
else:
if not _importedName(scope, var):
file.warning(scope.uses[var], self.unknown, var)
def _first_arg_defaulted(function_node):
count = len(function_node.argnames)
if function_node.varargs:
count -= 1
if function_node.kwargs:
count -= 1
if count > 0 and len(function_node.defaults) == count:
return 1
return None
class SelfCheck(Check):
'Check for simple self parameter'
selfName = Warning('Report any methods whose first argument is not self',
'First argument to method %s (%s) is not in %s')
selfDefault = Warning('Report a self parameter with a default value',
'First argument to method %s (%s) has a default value')
functionSelf = Warning('Report functions (not methods) with '
'arguments named "self"',
'Argument to function (%s) is "%s"')
missingSelf = Warning('Report methods without "self"',
'Method %s is missing self parameter')
def get_options(self, options):
desc = 'Name of self parameter'
default = ["self", "this", "s"]
options.add(Opt(self, 'selfNames', desc, default))
desc = 'Suspicious self parameters'
self.selfSuspicious = ["self"]
options.add(Opt(self, 'selfSuspicious', desc, self.selfSuspicious))
def check(self, file, unused_checker):
self.selfNames = _str_value(self.selfNames)
self.selfSuspicious = _str_value(self.selfSuspicious)
for node, scope in file.function_scopes():
args = node.argnames
name = getattr(scope.node, 'name', 'lambda')
if _is_method(scope):
if not args:
file.warning(scope.node, self.missingSelf, name)
else:
if args[0] not in self.selfNames:
file.warning(scope.node, self.selfName,
name, args[0], `self.selfNames`)
if _first_arg_defaulted(scope.node):
file.warning(scope.node, self.selfDefault,
name, args[0])
else:
for arg in args:
if arg in self.selfSuspicious:
file.warning(scope.defs[arg], self.functionSelf,
name, arg)
class UnpackCheck(Check):
'Mark all unpacked variables as used'
def __init__(self):
self.unpackedUsed = None
def get_options(self, options):
desc = 'Do not treat variables used in tuple assignment as used'
options.add(BoolOpt(self, 'unpackedUsed', desc, 1))
def check(self, file, unused_checker):
if not self.unpackedUsed:
return
class Visitor:
def visitAssTuple(self, node):
for c in node.getChildNodes():
for n in parents(c):
try:
file.scopes[n].uses[c.name] = node
break
except (KeyError, AttributeError):
pass
visitAssList = visitAssTuple
# local args unpacked on the `def' line are used, too
for scope_node, scope in file.function_scopes():
for arg in type_filter(scope_node.argnames, tuple):
for unpacked in ast.flatten(arg):
scope.uses[unpacked] = scope.uses.get(unpacked, scope_node)
if file.root_scope:
walk(file.root_scope.node, Visitor())
def intersect2(a, b):
return [i for i in a if i in b]
def intersect(items):
result = items[0]
for item in items[1:]:
result = intersect2(result, item)
return result
class UsedBeforeSetCheck(Check):
usedBeforeDefined = \
Warning('Report variables that may be used before they are defined',
'The local %s may be used before defined')
def check(self, file, unused_checker):
class Visitor(BaseVisitor):
def __init__(self, defines = None, uses = None):
# list of vars defined
self.defines = []
# name->node vars used before defined
self.uses = {}
if defines is not None:
self.defines = defines[:]
if uses is not None:
self.uses = uses.copy()
def visitFunction(self, n):
self.defines.append(n.name)
visitClass = visitFunction
visitAssName = visitFunction
def visitGlobal(self, node):
for name in node.names:
self.defines.append(name)
def visitListComp(self, n):
# visit qualifiers before expression
children = ast.flatten_nodes(n.quals) + [n.expr]
for c in children:
self.visit(c)
def visitName(self, n):
if n.name not in self.defines:
self.uses[n.name] = self.uses.get(n.name, n)
def visitIf(self, n):
if not n.else_:
return
visits = []
for test, code in n.tests:
visits.append(walk(code, Visitor(self.defines, self.uses)))
visits.append(walk(n.else_, Visitor(self.defines, self.uses)))
# compute the intersection of defines
self.defines = intersect([v.defines for v in visits])
# compute the union of uses, perserving first occurances
union = {}
visits.reverse()
for v in visits:
union.update(v.uses)
union.update(self.uses)
self.uses = union
for node, scope in file.function_scopes():
predefined = ast.flatten(scope.params) + scope.imports.keys()
visitor = walk(node.code, Visitor(predefined))
usedBefore = dict_intersect(visitor.uses, scope.defs)
for name, use_node in usedBefore.items():
file.warning(use_node, self.usedBeforeDefined, name)
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