forget the past.

forget the past.

1 files changed, 428 insertions, 0 deletions

diff --git a/checkers/variables.py b/checkers/variables.py
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+# Copyright (c) 2003-2006 LOGILAB S.A. (Paris, FRANCE).
+# http://www.logilab.fr/ -- mailto:contact@logilab.fr
+#
+# 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.
+"""variables checkers for Python code
+"""
+
+__revision__ = "$Id: variables.py,v 1.69 2006-04-19 09:17:40 syt Exp $"
+
+from copy import copy
+
+from logilab.common.compat import enumerate
+from logilab import astng
+from logilab.astng.lookup import builtin_lookup
+
+from pylint.interfaces import IASTNGChecker
+from pylint.checkers import BaseChecker
+from pylint.checkers.utils import is_error, is_builtin, is_func_default, \
+     is_ancestor_name, assign_parent, are_exclusive, \
+     is_defined_before #, is_parent, FOR_NODE_TYPES
+
+
+    
+MSGS = {
+    'E0601': ('Using variable %r before assignment',
+              'Used when a local variable is accessed before it\'s \
+              assignment.'),
+    'E0602': ('Undefined variable %r',
+              'Used when an undefined variable is accessed.'),
+
+    'E0611': ('No name %r in module %r',
+              'Used when a name cannot be found in a module.'),
+    
+    'W0601': ('Global variable %r undefined at the module level',
+              'Used when a variable is defined through the "global" statement \
+              but the variable is not defined in the module scope.'),
+    'W0602': ('Using global for %r but no assigment is done',
+              'Used when a variable is defined through the "global" statement \
+              but no assigment to this variable is done.'),
+    'W0603': ('Using the global statement', # W0121
+              'Used when you use the "global" statement to update a global \
+              variable. PyLint just try to discourage this \
+              usage. That doesn\'t mean you can not use it !'),
+    'W0604': ('Using the global statement at the module level', # W0103
+              'Used when you use the "global" statement at the module level \
+              since it has no effect'),
+    'W0611': ('Unused import %s',
+              'Used when an imported module or variable is not used.'),
+    'W0612': ('Unused variable %r',
+              'Used when a variable is defined but not used.'),
+    'W0613': ('Unused argument %r',
+              'Used when a function or method argument is not used.'),
+    
+    'W0621': ('Redefining name %r from outer scope (line %s)',
+              'Used when a variable\'s name hide a name defined in the outer \
+              scope.'),
+    'W0622': ('Redefining built-in %r',
+              'Used when a variable or function override a built-in.'),
+
+    'W0631': ('Using possibly undefined loop variable %r',
+              'Used when an loop variable (i.e. defined by a for loop or \
+              a list comprehension or a generator expression) is used outside \
+              the loop.'),
+    }
+
+class VariablesChecker(BaseChecker):
+    """checks for                                                              
+    * unused variables / imports                                               
+    * undefined variables                                                      
+    * redefinition of variable from builtins or from an outer scope            
+    * use of variable before assigment                                         
+    """
+    
+    __implements__ = IASTNGChecker
+
+    name = 'variables'
+    msgs = MSGS
+    priority = -1
+    options = (
+               ("init-import",
+                {'default': 0, 'type' : 'yn', 'metavar' : '<y_or_n>',
+                 'help' : 'Tells wether we should check for unused import in \
+__init__ files.'}),
+               ("dummy-variables-rgx",
+                {'default': ('_|dummy'), 
+                 'type' :'regexp', 'metavar' : '<regexp>',
+                 'help' : 'A regular expression matching names used \
+                 for dummy variables (i.e. not used).'}),
+               ("additional-builtins",
+                {'default': (), 'type' : 'csv',
+                 'metavar' : '<comma separated list>',
+                 'help' : 'List of additional names supposed to be defined in \
+builtins. Remember that you should avoid to define new builtins when possible.'
+                 }),
+               )
+    def __init__(self, linter=None):
+        BaseChecker.__init__(self, linter)
+        self._to_consume = None
+        self._checking_mod_attr = None
+        self._vars = None
+        
+    def visit_module(self, node):
+        """visit module : update consumption analysis variable
+        checks globals doesn't overrides builtins
+        """
+        self._to_consume = [(copy(node.locals), {}, 'module')]
+        self._vars = []
+        for name, stmts in node.locals.items():
+            if name in ('__name__', '__doc__', '__file__', '__path__') \
+                   and len(stmts) == 1:
+                # only the definition added by the astng builder, continue
+                continue
+            if self._is_builtin(name):
+                self.add_message('W0622', args=name, node=stmts[0])
+        
+    def leave_module(self, node):
+        """leave module: check globals
+        """
+        assert len(self._to_consume) == 1
+        not_consumed = self._to_consume.pop()[0]
+        # don't check unused imports in __init__ files
+        if not self.config.init_import and node.package:
+            return
+        for name, stmts in not_consumed.items():
+            stmt = stmts[0]
+            if isinstance(stmt, astng.Import) or (
+                isinstance(stmt, astng.From) and stmt.modname != '__future__'):
+                self.add_message('W0611', args=name, node=stmt)
+        del self._to_consume
+        del self._vars
+
+    def visit_class(self, node):
+        """visit class: update consumption analysis variable
+        """
+        self._to_consume.append((copy(node.locals), {}, 'class'))
+            
+    def leave_class(self, _):
+        """leave class: update consumption analysis variable
+        """
+        # do not check for not used locals here (no sense)
+        self._to_consume.pop()
+
+    def visit_lambda(self, node):
+        """visit lambda: update consumption analysis variable
+        """
+        self._to_consume.append((copy(node.locals), {}, 'lambda'))
+            
+    def leave_lambda(self, _):
+        """leave lambda: update consumption analysis variable
+        """
+        # do not check for not used locals here
+        self._to_consume.pop()
+
+    def visit_function(self, node):
+        """visit function: update consumption analysis variable and check locals
+        """
+        globs = node.root().globals
+        for name, stmt in node.items():
+            if globs.has_key(name) and not isinstance(stmt, astng.Global):
+                line = globs[name][0].lineno
+                self.add_message('W0621', args=(name, line), node=stmt)
+            elif self._is_builtin(name):
+                self.add_message('W0622', args=name, node=stmt)
+        self._to_consume.append((copy(node.locals), {}, 'function'))
+        self._vars.append({})
+        
+    def leave_function(self, node):
+        """leave function: check function's locals are consumed
+        """
+        not_consumed = self._to_consume.pop()[0]
+        self._vars.pop(0)
+        is_method = node.is_method()
+        klass = node.parent.frame()
+        # don't check arguments of abstract methods or within an interface
+        if is_method and (klass.type == 'interface' or node.is_abstract()):
+            return
+        if is_error(node):
+            return
+        authorized_rgx = self.config.dummy_variables_rgx
+        for name, stmts in not_consumed.items():
+            # ignore some special names specified by user configuration
+            if authorized_rgx.match(name):
+                continue
+            # ignore names imported by the global statement
+            # FIXME: should only ignore them if it's assigned latter
+            stmt = stmts[0]
+            if isinstance(stmt, astng.Global):
+                continue
+            # care about functions with unknown argument (builtins)
+            if node.argnames is not None and name in node.argnames:
+                # don't warn if the first argument of a method is not used
+                if is_method and node.argnames and name == node.argnames[0]:
+                    continue
+                # don't check callback arguments
+                if node.name.startswith('cb_') or \
+                       node.name.endswith('_cb'):
+                    continue
+                self.add_message('W0613', args=name, node=node)
+            else:
+                self.add_message('W0612', args=name, node=stmt)
+
+    def visit_global(self, node):
+        """check names imported exists in the global scope"""
+        frame = node.frame()
+        if isinstance(frame, astng.Module):
+            self.add_message('W0604', node=node)
+            return        
+        module = frame.root()
+        default_message = True
+        for name in node.names:
+            try:
+                assign_nodes = module.getattr(name)
+            except astng.NotFoundError:
+                # unassigned global, skip
+                assign_nodes = []
+            for anode in assign_nodes:
+                if anode.frame() is frame:
+                    # same scope level assigment
+                    break
+            else:
+                # global but no assigment
+                self.add_message('W0602', args=name, node=node)
+                default_message = False
+            if not assign_nodes:
+                continue
+            for anode in assign_nodes:
+                if anode.frame() is module:
+                    # module level assigment
+                    break
+            else:
+                # global undefined at the module scope
+                self.add_message('W0601', args=name, node=node)
+                default_message = False
+        if default_message:
+            self.add_message('W0603', node=node) 
+
+    def _loopvar_name(self, node, name):
+        # filter variables according to node's scope
+        astmts = [stmt for stmt in node.lookup(name)[1]
+                  if hasattr(stmt, 'ass_type') and
+                  not stmt.statement().parent_of(node)]
+        # filter variables according their respective scope
+        if not astmts or astmts[0].statement().parent_of(node):
+            _astmts = []
+        else:
+            _astmts = astmts[:1]
+        for i, stmt in enumerate(astmts[1:]):
+            if astmts[i].statement().parent_of(stmt):
+                continue
+            _astmts.append(stmt)
+        astmts = _astmts
+        if len(astmts) == 1:
+            ass = astmts[0].ass_type()
+            if isinstance(ass, (astng.For, astng.ListCompFor, astng.GenExpr)) \
+                   and not ass.statement() is node.statement():
+                self.add_message('W0631', args=name, node=node)
+    
+    def visit_name(self, node):
+        """check that a name is defined if the current scope and doesn't
+        redefine a built-in
+        """
+        name = node.name
+        stmt = node.statement()
+        frame = stmt.frame()
+        # if the name node is used as a function default argument's value, then
+        # start from the parent frame of the function instead of the function
+        # frame
+        if is_func_default(node) or is_ancestor_name(frame, node):
+            start_index = len(self._to_consume) - 2
+        else:
+            start_index = len(self._to_consume) - 1
+        # iterates through parent scopes, from the inner to the outer
+        for i in range(start_index, -1, -1):
+            to_consume, consumed, scope_type = self._to_consume[i]
+            # if the current scope is a class scope but it's not the inner
+            # scope, ignore it. This prevents to access this scope instead of
+            # the globals one in function members when there are some common
+            # names
+            if scope_type == 'class' and i != start_index:
+                continue
+            # the name has already been consumed, only check it's not a loop
+            # variable used outside the loop
+            if consumed.has_key(name):
+                self._loopvar_name(node, name)
+                break
+            # mark the name as consumed if it's defined in this scope
+            # (ie no KeyError is raise by "to_consume[name]"
+            try:
+                consumed[name] = to_consume[name]
+                # checks for use before assigment
+                # FIXME: the last condition should just check attribute access
+                # is protected by a try: except NameError: (similar to #9219)
+                defnode = assign_parent(to_consume[name][0])
+                if defnode is not None:
+                    defstmt = defnode.statement()
+                    defframe = defstmt.frame()
+                    maybee0601 = True
+                    if not frame is defframe:
+                        maybee0601 = False
+                    elif defframe.parent is None:
+                        # we are at the module level, check the name is not
+                        # defined in builtins
+                        if builtin_lookup(name)[1]:
+                            maybee0601 = False
+                    else:
+                        # we are in a local scope, check the name is not
+                        # defined in global or builtin scope
+                        if defframe.root().lookup(name)[1]:
+                            maybee0601 = False
+                    if (maybee0601
+                        and stmt.source_line() <= defstmt.source_line()
+                        and not is_defined_before(node)
+                        and not are_exclusive(stmt, defstmt)):
+                        self.add_message('E0601', args=name, node=node)
+                del to_consume[name]
+                # check it's not a loop variable used outside the loop
+                self._loopvar_name(node, name)
+                break
+            except KeyError:
+                continue
+        else:
+            # we have not found the name, if it isn't a builtin, that's an
+            # undefined name !
+            if not self._is_builtin(name):
+                self.add_message('E0602', args=name, node=node)
+                
+    def visit_import(self, node):
+        """check modules attribute accesses"""
+        for name, _ in node.names:
+            name_parts = name.split('.')
+            try:
+                module = node.infer(name_parts[0], asname=False).next()
+            except astng.ResolveError:
+                continue
+            self._check_module_attrs(node, module, name_parts[1:])
+                                    
+    def visit_from(self, node):
+        """check modules attribute accesses"""
+        name_parts = node.modname.split('.')
+        try:
+            module = node.root().import_module(name_parts[0])
+        except KeyboardInterrupt:
+            raise
+        except:
+            return
+        module = self._check_module_attrs(node, module, name_parts[1:])
+        if not module:
+            return
+        for name, _ in node.names:
+            if name == '*':
+                continue
+            self._check_module_attrs(node, module, name.split('.'))
+
+##     def leave_getattr(self, node):
+##         """check modules attribute accesses
+        
+##         this function is a "leave_" because when parsing 'a.b.c'
+##         we want to check the innermost expression first.
+##         """
+##         if isinstance(node.expr, astng.Name):
+##             try:
+##                 module = node.expr.infer().next()
+##             except astng.InferenceError:
+##                 return
+##             if not isinstance(module, astng.Module):
+##                 # Not a module, don't check
+##                 return
+##         elif self._checking_mod_attr is not None:
+##             module = self._checking_mod_attr
+##         else:
+##             return
+##         self._checking_mod_attr = self._check_module_attrs(node, module,
+##                                                            [node.attrname])
+
+##     def leave_default(self, node):
+##         """by default, reset the _checking_mod_attr attribute"""
+##         self._checking_mod_attr = None
+        
+    def _check_module_attrs(self, node, module, module_names):
+        """check that module_names (list of string) are accessible through the
+        given module
+        if the latest access name corresponds to a module, return it
+        """
+        assert isinstance(module, astng.Module), module
+        while module_names:
+            name = module_names.pop(0)
+            if name == '__dict__':
+                module = None
+                break
+            try:
+                module = module.getattr(name)[0].infer().next()
+            except astng.NotFoundError:
+                self.add_message('E0611', args=(name, module.name), node=node)
+                return None
+            except astng.InferenceError:
+                return None
+        if module_names:
+            # FIXME: other message if name is not the latest part of
+            # module_names ?
+            modname = module and module.name or '__dict__'
+            self.add_message('E0611', node=node,
+                             args=('.'.join(module_names), modname))
+            return None
+        if isinstance(module, astng.Module):
+            return module
+        return None
+    
+    def _is_builtin(self, name):
+        """return True if the name is defined in the native builtin or
+        in the user specific builtins
+        """
+        return is_builtin(name) or name in self.config.additional_builtins
+    
+
+def register(linter):
+    """required method to auto register this checker"""
+    linter.register_checker(VariablesChecker(linter))