pylint / pylint / checkers /

# Copyright (c) 2006-2010 LOGILAB S.A. (Paris, FRANCE).
# --
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation; either version 2 of the License, or (at your option) any later
# version.
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc.,
# 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
"""try to find more bugs in the code using astng inference capabilities

import re
import shlex

from logilab import astng
from logilab.astng import InferenceError, NotFoundError, YES, Instance

from pylint.interfaces import IASTNGChecker
from pylint.checkers import BaseChecker
from pylint.checkers.utils import safe_infer, is_super, check_messages

MSGS = {
    'E1101': ('%s %r has no %r member',
              'Used when a variable is accessed for an unexistent member.'),
    'E1102': ('%s is not callable',
              'Used when an object being called has been inferred to a non \
              callable object'),
    'E1103': ('%s %r has no %r member (but some types could not be inferred)',
              'Used when a variable is accessed for an unexistent member, but \
              astng was not able to interpret all possible types of this \
    'E1111': ('Assigning to function call which doesn\'t return',
              'Used when an assignment is done on a function call but the \
              inferred function doesn\'t return anything.'),
    'W1111': ('Assigning to function call which only returns None',
              'Used when an assignment is done on a function call but the \
              inferred function returns nothing but None.'),

    'E1120': ('No value passed for parameter %s in function call',
              'Used when a function call passes too few arguments.'),
    'E1121': ('Too many positional arguments for function call',
              'Used when a function call passes too many positional \
    'E1122': ('Duplicate keyword argument %r in function call',
              'Used when a function call passes the same keyword argument \
              multiple times.'),
    'E1123': ('Passing unexpected keyword argument %r in function call',
              'Used when a function call passes a keyword argument that \
              doesn\'t correspond to one of the function\'s parameter names.'),
    'E1124': ('Multiple values passed for parameter %r in function call',
              'Used when a function call would result in assigning multiple \
              values to a function parameter, one value from a positional \
              argument and one from a keyword argument.'),

class TypeChecker(BaseChecker):
    """try to find bugs in the code using type inference

    __implements__ = (IASTNGChecker,)

    # configuration section name
    name = 'typecheck'
    # messages
    msgs = MSGS
    priority = -1
    # configuration options
    options = (('ignore-mixin-members',
                {'default' : True, 'type' : 'yn', 'metavar': '<y_or_n>',
                 'help' : 'Tells whether missing members accessed in mixin \
class should be ignored. A mixin class is detected if its name ends with \
"mixin" (case insensitive).'}

                {'default' : ('SQLObject',),
                 'type' : 'csv',
                 'metavar' : '<members names>',
                 'help' : 'List of classes names for which member attributes \
should not be checked (useful for classes with attributes dynamically set).'}

                {'default' : False, 'type' : 'yn', 'metavar': '<y_or_n>',
                 'help' : 'When zope mode is activated, add a predefined set \
of Zope acquired attributes to generated-members.'}
                {'default' : (
        'REQUEST', 'acl_users', 'aq_parent'),
                 'type' : 'string',
                 'metavar' : '<members names>',
                 'help' : 'List of members which are set dynamically and \
missed by pylint inference system, and so shouldn\'t trigger E0201 when \
accessed. Python regular expressions are accepted.'}

    def open(self):
        # do this in open since config not fully initialized in __init__
        self.generated_members = list(self.config.generated_members)
        if self.config.zope:
            self.generated_members.extend(('REQUEST', 'acl_users', 'aq_parent'))

    def visit_assattr(self, node):
        if isinstance(node.ass_type(), astng.AugAssign):

    def visit_delattr(self, node):

    @check_messages('E1101', 'E1103')
    def visit_getattr(self, node):
        """check that the accessed attribute exists

        to avoid to much false positives for now, we'll consider the code as
        correct if a single of the inferred nodes has the accessed attribute.

        function/method, super call and metaclasses are ignored
        # generated_members may containt regular expressions
        # (surrounded by quote `"` and followed by a comma `,`)
        # REQUEST,aq_parent,"[a-zA-Z]+_set{1,2}"' =>
        # ('REQUEST', 'aq_parent', '[a-zA-Z]+_set{1,2}')
        if isinstance(self.config.generated_members, str):
            gen = shlex.shlex(self.config.generated_members)
            gen.whitespace += ','
            gen.wordchars += '[]-+'
            self.config.generated_members = tuple(tok.strip('"') for tok in gen)
        for pattern in self.config.generated_members:
            # attribute is marked as generated, stop here
            if re.match(pattern, node.attrname):
            infered = list(node.expr.infer())
        except InferenceError:
        # list of (node, nodename) which are missing the attribute
        missingattr = set()
        ignoremim = self.config.ignore_mixin_members
        inference_failure = False
        for owner in infered:
            # skip yes object
            if owner is YES:
                inference_failure = True
            # skip None anyway
            if isinstance(owner, astng.Const) and owner.value is None:
            # XXX "super" / metaclass call
            if is_super(owner) or getattr(owner, 'type', None) == 'metaclass':
            name = getattr(owner, 'name', 'None')
            if name in self.config.ignored_classes:
            if ignoremim and name[-5:].lower() == 'mixin':
                if not [n for n in owner.getattr(node.attrname)
                        if not isinstance(n.statement(), astng.AugAssign)]:
                    missingattr.add((owner, name))
            except AttributeError:
                # XXX method / function
            except NotFoundError:
                if isinstance(owner, astng.Function) and owner.decorators:
                if isinstance(owner, Instance) and owner.has_dynamic_getattr():
                # explicit skipping of optparse'Values class
                if == 'Values' and owner.root().name == 'optparse':
                missingattr.add((owner, name))
            # stop on the first found
            # we have not found any node with the attributes, display the
            # message for infered nodes
            done = set()
            for owner, name in missingattr:
                if isinstance(owner, Instance):
                    actual = owner._proxied
                    actual = owner
                if actual in done:
                if inference_failure:
                    msgid = 'E1103'
                    msgid = 'E1101'
                self.add_message(msgid, node=node,
                                 args=(owner.display_type(), name,

    def visit_assign(self, node):
        """check that if assigning to a function call, the function is
        possibly returning something valuable
        if not isinstance(node.value, astng.CallFunc):
        function_node = safe_infer(node.value.func)
        # skip class, generator and incomplete function definition
        if not (isinstance(function_node, astng.Function) and
        if function_node.is_generator() \
               or function_node.is_abstract(pass_is_abstract=False):
        returns = list(function_node.nodes_of_class(astng.Return,
        if len(returns) == 0:
            self.add_message('E1111', node=node)
            for rnode in returns:
                if not (isinstance(rnode.value, astng.Const)
                        and rnode.value.value is None):
                self.add_message('W1111', node=node)

    def visit_callfunc(self, node):
        """check that called functions/methods are inferred to callable objects,
        and that the arguments passed to the function match the parameters in
        the inferred function's definition

        # Build the set of keyword arguments, checking for duplicate keywords,
        # and count the positional arguments.
        keyword_args = set()
        num_positional_args = 0
        for arg in node.args:
            if isinstance(arg, astng.Keyword):
                keyword = arg.arg
                if keyword in keyword_args:
                    self.add_message('E1122', node=node, args=keyword)
                num_positional_args += 1

        called = safe_infer(node.func)
        # only function, generator and object defining __call__ are allowed
        if called is not None and not called.callable():
            self.add_message('E1102', node=node, args=node.func.as_string())

        # Note that BoundMethod is a subclass of UnboundMethod (huh?), so must
        # come first in this 'if..else'.
        if isinstance(called, astng.BoundMethod):
            # Bound methods have an extra implicit 'self' argument.
            num_positional_args += 1
        elif isinstance(called, astng.UnboundMethod):
            if called.decorators is not None:
                for d in called.decorators.nodes:
                    if isinstance(d, astng.Name) and (
                   in ['classmethod', 'classonlymethod']):
                        # Class methods have an extra implicit 'cls' argument.
                        num_positional_args += 1
        elif (isinstance(called, astng.Function) or
              isinstance(called, astng.Lambda)):

        if called.args.args is None:
            # Built-in functions have no argument information.

        if len( called.argnames() ) != len( set( called.argnames() ) ):
            # Duplicate parameter name (see E9801).  We can't really make sense
            # of the function call in this case, so just return.

        # Analyze the list of formal parameters.
        num_mandatory_parameters = len(called.args.args) - len(called.args.defaults)
        parameters = []
        parameter_name_to_index = {}
        for i, arg in enumerate(called.args.args):
            if isinstance(arg, astng.Tuple):
                name = None
                # Don't store any parameter names within the tuple, since those
                # are not assignable from keyword arguments.
                if isinstance(arg, astng.Keyword):
                    name = arg.arg
                    assert isinstance(arg, astng.AssName)
                    # This occurs with:
                    #    def f( (a), (b) ): pass
                    name =
                parameter_name_to_index[name] = i
            if i >= num_mandatory_parameters:
                defval = called.args.defaults[i - num_mandatory_parameters]
                defval = None
            parameters.append([(name, defval), False])

        # Match the supplied arguments against the function parameters.

        # 1. Match the positional arguments.
        for i in range(num_positional_args):
            if i < len(parameters):
                parameters[i][1] = True
            elif called.args.vararg is not None:
                # The remaining positional arguments get assigned to the *args
                # parameter.
                # Too many positional arguments.
                self.add_message('E1121', node=node)

        # 2. Match the keyword arguments.
        for keyword in keyword_args:
            if keyword in parameter_name_to_index:
                i = parameter_name_to_index[keyword]
                if parameters[i][1]:
                    # Duplicate definition of function parameter.
                    self.add_message('E1124', node=node, args=keyword)
                    parameters[i][1] = True
            elif called.args.kwarg is not None:
                # The keyword argument gets assigned to the **kwargs parameter.
                # Unexpected keyword argument.
                self.add_message('E1123', node=node, args=keyword)

        # 3. Match the *args, if any.  Note that Python actually processes
        #    *args _before_ any keyword arguments, but we wait until after
        #    looking at the keyword arguments so as to make a more conservative
        #    guess at how many values are in the *args sequence.
        if node.starargs is not None:
            for i in range(num_positional_args, len(parameters)):
                [(name, defval), assigned] = parameters[i]
                # Assume that *args provides just enough values for all
                # non-default parameters after the last parameter assigned by
                # the positional arguments but before the first parameter
                # assigned by the keyword arguments.  This is the best we can
                # get without generating any false positives.
                if (defval is not None) or assigned:
                parameters[i][1] = True

        # 4. Match the **kwargs, if any.
        if node.kwargs is not None:
            for i, [(name, defval), assigned] in enumerate(parameters):
                # Assume that *kwargs provides values for all remaining
                # unassigned named parameters.
                if name is not None:
                    parameters[i][1] = True
                    # **kwargs can't assign to tuples.

        # Check that any parameters without a default have been assigned
        # values.
        for [(name, defval), assigned] in parameters:
            if (defval is None) and not assigned:
                if name is None:
                    display = '<tuple>'
                    display_name = repr(name)
                self.add_message('E1120', node=node, args=display_name)

def register(linter):
    """required method to auto register this checker """