Add pylint to depot_tools.

third_party/logilab/astng/bases.py

+# -*- coding: utf-8 -*-
+# copyright 2003-2011 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
+# copyright 2003-2010 Sylvain Thenault, all rights reserved.
+# contact mailto:thenault@gmail.com
+#
+# This file is part of logilab-astng.
+#
+# logilab-astng is free software: you can redistribute it and/or modify it
+# under the terms of the GNU Lesser General Public License as published by the
+# Free Software Foundation, either version 2.1 of the License, or (at your
+# option) any later version.
+#
+# logilab-astng 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 Lesser General Public License
+# for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License along
+# with logilab-astng. If not, see <http://www.gnu.org/licenses/>.
+"""This module contains base classes and functions for the nodes and some
+inference utils.
+"""
+
+__docformat__ = "restructuredtext en"
+
+from contextlib import contextmanager
+
+from logilab.common.compat import builtins
+
+from logilab.astng import BUILTINS_MODULE
+from logilab.astng.exceptions import InferenceError, ASTNGError, \
+                                       NotFoundError, UnresolvableName
+from logilab.astng.as_string import as_string
+
+BUILTINS_NAME = builtins.__name__
+
+class Proxy(object):
+    """a simple proxy object"""
+    _proxied = None
+
+    def __init__(self, proxied=None):
+        if proxied is not None:
+            self._proxied = proxied
+
+    def __getattr__(self, name):
+        if name == '_proxied':
+            return getattr(self.__class__, '_proxied')
+        if name in self.__dict__:
+            return self.__dict__[name]
+        return getattr(self._proxied, name)
+
+    def infer(self, context=None):
+        yield self
+
+
+# Inference ##################################################################
+
+class InferenceContext(object):
+    __slots__ = ('path', 'lookupname', 'callcontext', 'boundnode')
+
+    def __init__(self, path=None):
+        if path is None:
+            self.path = set()
+        else:
+            self.path = path
+        self.lookupname = None
+        self.callcontext = None
+        self.boundnode = None
+
+    def push(self, node):
+        name = self.lookupname
+        if (node, name) in self.path:
+            raise StopIteration()
+        self.path.add( (node, name) )
+
+    def clone(self):
+        # XXX copy lookupname/callcontext ?
+        clone = InferenceContext(self.path)
+        clone.callcontext = self.callcontext
+        clone.boundnode = self.boundnode
+        return clone
+
+    @contextmanager
+    def restore_path(self):
+        path = set(self.path)
+        yield
+        self.path = path
+
+def copy_context(context):
+    if context is not None:
+        return context.clone()
+    else:
+        return InferenceContext()
+
+
+def _infer_stmts(stmts, context, frame=None):
+    """return an iterator on statements inferred by each statement in <stmts>
+    """
+    stmt = None
+    infered = False
+    if context is not None:
+        name = context.lookupname
+        context = context.clone()
+    else:
+        name = None
+        context = InferenceContext()
+    for stmt in stmts:
+        if stmt is YES:
+            yield stmt
+            infered = True
+            continue
+        context.lookupname = stmt._infer_name(frame, name)
+        try:
+            for infered in stmt.infer(context):
+                yield infered
+                infered = True
+        except UnresolvableName:
+            continue
+        except InferenceError:
+            yield YES
+            infered = True
+    if not infered:
+        raise InferenceError(str(stmt))
+
+
+# special inference objects (e.g. may be returned as nodes by .infer()) #######
+
+class _Yes(object):
+    """a yes object"""
+    def __repr__(self):
+        return 'YES'
+    def __getattribute__(self, name):
+        if name.startswith('__') and name.endswith('__'):
+            # to avoid inspection pb
+            return super(_Yes, self).__getattribute__(name)
+        return self
+    def __call__(self, *args, **kwargs):
+        return self
+
+
+YES = _Yes()
+
+
+class Instance(Proxy):
+    """a special node representing a class instance"""
+    def getattr(self, name, context=None, lookupclass=True):
+        try:
+            values = self._proxied.instance_attr(name, context)
+        except NotFoundError:
+            if name == '__class__':
+                return [self._proxied]
+            if lookupclass:
+                # class attributes not available through the instance
+                # unless they are explicitly defined
+                if name in ('__name__', '__bases__', '__mro__', '__subclasses__'):
+                    return self._proxied.local_attr(name)
+                return self._proxied.getattr(name, context)
+            raise NotFoundError(name)
+        # since we've no context information, return matching class members as
+        # well
+        if lookupclass:
+            try:
+                return values + self._proxied.getattr(name, context)
+            except NotFoundError:
+                pass
+        return values
+
+    def igetattr(self, name, context=None):
+        """inferred getattr"""
+        try:
+            # XXX frame should be self._proxied, or not ?
+            get_attr = self.getattr(name, context, lookupclass=False)
+            return _infer_stmts(self._wrap_attr(get_attr, context), context,
+                                frame=self)
+        except NotFoundError:
+            try:
+                # fallback to class'igetattr since it has some logic to handle
+                # descriptors
+                return self._wrap_attr(self._proxied.igetattr(name, context),
+                                       context)
+            except NotFoundError:
+                raise InferenceError(name)
+
+    def _wrap_attr(self, attrs, context=None):
+        """wrap bound methods of attrs in a InstanceMethod proxies"""
+        for attr in attrs:
+            if isinstance(attr, UnboundMethod):
+                if BUILTINS_NAME + '.property' in attr.decoratornames():
+                    for infered in attr.infer_call_result(self, context):
+                        yield infered
+                else:
+                    yield BoundMethod(attr, self)
+            else:
+                yield attr
+
+    def infer_call_result(self, caller, context=None):
+        """infer what a class instance is returning when called"""
+        infered = False
+        for node in self._proxied.igetattr('__call__', context):
+            for res in node.infer_call_result(caller, context):
+                infered = True
+                yield res
+        if not infered:
+            raise InferenceError()
+
+    def __repr__(self):
+        return '<Instance of %s.%s at 0x%s>' % (self._proxied.root().name,
+                                                self._proxied.name,
+                                                id(self))
+    def __str__(self):
+        return 'Instance of %s.%s' % (self._proxied.root().name,
+                                      self._proxied.name)
+
+    def callable(self):
+        try:
+            self._proxied.getattr('__call__')
+            return True
+        except NotFoundError:
+            return False
+
+    def pytype(self):
+        return self._proxied.qname()
+
+    def display_type(self):
+        return 'Instance of'
+
+
+class UnboundMethod(Proxy):
+    """a special node representing a method not bound to an instance"""
+    def __repr__(self):
+        frame = self._proxied.parent.frame()
+        return '<%s %s of %s at 0x%s' % (self.__class__.__name__,
+                                         self._proxied.name,
+                                         frame.qname(), id(self))
+
+    def is_bound(self):
+        return False
+
+    def getattr(self, name, context=None):
+        if name == 'im_func':
+            return [self._proxied]
+        return super(UnboundMethod, self).getattr(name, context)
+
+    def igetattr(self, name, context=None):
+        if name == 'im_func':
+            return iter((self._proxied,))
+        return super(UnboundMethod, self).igetattr(name, context)
+
+    def infer_call_result(self, caller, context):
+        # If we're unbound method __new__ of builtin object, the result is an
+        # instance of the class given as first argument.
+        if (self._proxied.name == '__new__' and
+                self._proxied.parent.frame().qname() == '%s.object' % BUILTINS_MODULE):
+            return (x is YES and x or Instance(x) for x in caller.args[0].infer())
+        return self._proxied.infer_call_result(caller, context)
+
+
+class BoundMethod(UnboundMethod):
+    """a special node representing a method bound to an instance"""
+    def __init__(self,  proxy, bound):
+        UnboundMethod.__init__(self, proxy)
+        self.bound = bound
+
+    def is_bound(self):
+        return True
+
+    def infer_call_result(self, caller, context):
+        context = context.clone()
+        context.boundnode = self.bound
+        return self._proxied.infer_call_result(caller, context)
+
+
+class Generator(Instance):
+    """a special node representing a generator"""
+    def callable(self):
+        return True
+
+    def pytype(self):
+        return '%s.generator' % BUILTINS_MODULE
+
+    def display_type(self):
+        return 'Generator'
+
+    def __repr__(self):
+        return '<Generator(%s) l.%s at 0x%s>' % (self._proxied.name, self.lineno, id(self))
+
+    def __str__(self):
+        return 'Generator(%s)' % (self._proxied.name)
+
+
+# decorators ##################################################################
+
+def path_wrapper(func):
+    """return the given infer function wrapped to handle the path"""
+    def wrapped(node, context=None, _func=func, **kwargs):
+        """wrapper function handling context"""
+        if context is None:
+            context = InferenceContext()
+        context.push(node)
+        yielded = set()
+        for res in _func(node, context, **kwargs):
+            # unproxy only true instance, not const, tuple, dict...
+            if res.__class__ is Instance:
+                ares = res._proxied
+            else:
+                ares = res
+            if not ares in yielded:
+                yield res
+                yielded.add(ares)
+    return wrapped
+
+def yes_if_nothing_infered(func):
+    def wrapper(*args, **kwargs):
+        infered = False
+        for node in func(*args, **kwargs):
+            infered = True
+            yield node
+        if not infered:
+            yield YES
+    return wrapper
+
+def raise_if_nothing_infered(func):
+    def wrapper(*args, **kwargs):
+        infered = False
+        for node in func(*args, **kwargs):
+            infered = True
+            yield node
+        if not infered:
+            raise InferenceError()
+    return wrapper
+
+
+# Node  ######################################################################
+
+class NodeNG(object):
+    """Base Class for all ASTNG node classes.
+
+    It represents a node of the new abstract syntax tree.
+    """
+    is_statement = False
+    optional_assign = False # True  for For (and for Comprehension if py <3.0)
+    is_function = False # True for Function nodes
+    # attributes below are set by the builder module or by raw factories
+    lineno = None
+    fromlineno = None
+    tolineno = None
+    col_offset = None
+    # parent node in the tree
+    parent = None
+    # attributes containing child node(s) redefined in most concrete classes:
+    _astng_fields = ()
+
+    def _repr_name(self):
+        """return self.name or self.attrname or '' for nice representation"""
+        return getattr(self, 'name', getattr(self, 'attrname', ''))
+
+    def __str__(self):
+        return '%s(%s)' % (self.__class__.__name__, self._repr_name())
+
+    def __repr__(self):
+        return '<%s(%s) l.%s [%s] at Ox%x>' % (self.__class__.__name__,
+                                           self._repr_name(),
+                                           self.fromlineno,
+                                           self.root().name,
+                                           id(self))
+
+
+    def accept(self, visitor):
+        klass = self.__class__.__name__
+        func = getattr(visitor, "visit_" + self.__class__.__name__.lower())
+        return func(self)
+
+    def get_children(self):
+        for field in self._astng_fields:
+            attr = getattr(self, field)
+            if attr is None:
+                continue
+            if isinstance(attr, (list, tuple)):
+                for elt in attr:
+                    yield elt
+            else:
+                yield attr
+
+    def last_child(self):
+        """an optimized version of list(get_children())[-1]"""
+        for field in self._astng_fields[::-1]:
+            attr = getattr(self, field)
+            if not attr: # None or empty listy / tuple
+                continue
+            if isinstance(attr, (list, tuple)):
+                return attr[-1]
+            else:
+                return attr
+        return None
+
+    def parent_of(self, node):
+        """return true if i'm a parent of the given node"""
+        parent = node.parent
+        while parent is not None:
+            if self is parent:
+                return True
+            parent = parent.parent
+        return False
+
+    def statement(self):
+        """return the first parent node marked as statement node"""
+        if self.is_statement:
+            return self
+        return self.parent.statement()
+
+    def frame(self):
+        """return the first parent frame node (i.e. Module, Function or Class)
+        """
+        return self.parent.frame()
+
+    def scope(self):
+        """return the first node defining a new scope (i.e. Module, Function,
+        Class, Lambda but also GenExpr)
+        """
+        return self.parent.scope()
+
+    def root(self):
+        """return the root node of the tree, (i.e. a Module)"""
+        if self.parent:
+            return self.parent.root()
+        return self
+
+    def child_sequence(self, child):
+        """search for the right sequence where the child lies in"""
+        for field in self._astng_fields:
+            node_or_sequence = getattr(self, field)
+            if node_or_sequence is child:
+                return [node_or_sequence]
+            # /!\ compiler.ast Nodes have an __iter__ walking over child nodes
+            if isinstance(node_or_sequence, (tuple, list)) and child in node_or_sequence:
+                return node_or_sequence
+        else:
+            msg = 'Could not found %s in %s\'s children'
+            raise ASTNGError(msg % (repr(child), repr(self)))
+
+    def locate_child(self, child):
+        """return a 2-uple (child attribute name, sequence or node)"""
+        for field in self._astng_fields:
+            node_or_sequence = getattr(self, field)
+            # /!\ compiler.ast Nodes have an __iter__ walking over child nodes
+            if child is node_or_sequence:
+                return field, child
+            if isinstance(node_or_sequence, (tuple, list)) and child in node_or_sequence:
+                return field, node_or_sequence
+        msg = 'Could not found %s in %s\'s children'
+        raise ASTNGError(msg % (repr(child), repr(self)))
+    # FIXME : should we merge child_sequence and locate_child ? locate_child
+    # is only used in are_exclusive, child_sequence one time in pylint.
+
+    def next_sibling(self):
+        """return the next sibling statement"""
+        return self.parent.next_sibling()
+
+    def previous_sibling(self):
+        """return the previous sibling statement"""
+        return self.parent.previous_sibling()
+
+    def nearest(self, nodes):
+        """return the node which is the nearest before this one in the
+        given list of nodes
+        """
+        myroot = self.root()
+        mylineno = self.fromlineno
+        nearest = None, 0
+        for node in nodes:
+            assert node.root() is myroot, \
+                   'nodes %s and %s are not from the same module' % (self, node)
+            lineno = node.fromlineno
+            if node.fromlineno > mylineno:
+                break
+            if lineno > nearest[1]:
+                nearest = node, lineno
+        # FIXME: raise an exception if nearest is None ?
+        return nearest[0]
+
+    def set_line_info(self, lastchild):
+        if self.lineno is None:
+            self.fromlineno = self._fixed_source_line()
+        else:
+            self.fromlineno = self.lineno
+        if lastchild is None:
+            self.tolineno = self.fromlineno
+        else:
+            self.tolineno = lastchild.tolineno
+        return
+        # TODO / FIXME:
+        assert self.fromlineno is not None, self
+        assert self.tolineno is not None, self
+
+    def _fixed_source_line(self):
+        """return the line number where the given node appears
+
+        we need this method since not all nodes have the lineno attribute
+        correctly set...
+        """
+        line = self.lineno
+        _node = self
+        try:
+            while line is None:
+                _node = _node.get_children().next()
+                line = _node.lineno
+        except StopIteration:
+            _node = self.parent
+            while _node and line is None:
+                line = _node.lineno
+                _node = _node.parent
+        return line
+
+    def block_range(self, lineno):
+        """handle block line numbers range for non block opening statements
+        """
+        return lineno, self.tolineno
+
+    def set_local(self, name, stmt):
+        """delegate to a scoped parent handling a locals dictionary"""
+        self.parent.set_local(name, stmt)
+
+    def nodes_of_class(self, klass, skip_klass=None):
+        """return an iterator on nodes which are instance of the given class(es)
+
+        klass may be a class object or a tuple of class objects
+        """
+        if isinstance(self, klass):
+            yield self
+        for child_node in self.get_children():
+            if skip_klass is not None and isinstance(child_node, skip_klass):
+                continue
+            for matching in child_node.nodes_of_class(klass, skip_klass):
+                yield matching
+
+    def _infer_name(self, frame, name):
+        # overridden for From, Import, Global, TryExcept and Arguments
+        return None
+
+    def infer(self, context=None):
+        """we don't know how to resolve a statement by default"""
+        # this method is overridden by most concrete classes
+        raise InferenceError(self.__class__.__name__)
+
+    def infered(self):
+        '''return list of infered values for a more simple inference usage'''
+        return list(self.infer())
+
+    def instanciate_class(self):
+        """instanciate a node if it is a Class node, else return self"""
+        return self
+
+    def has_base(self, node):
+        return False
+
+    def callable(self):
+        return False
+
+    def eq(self, value):
+        return False
+
+    def as_string(self):
+        return as_string(self)
+
+    def repr_tree(self, ids=False):
+        """print a nice astng tree representation.
+
+        :param ids: if true, we also print the ids (usefull for debugging)"""
+        result = []
+        _repr_tree(self, result, ids=ids)
+        return "\n".join(result)
+
+
+class Statement(NodeNG):
+    """Statement node adding a few attributes"""
+    is_statement = True
+
+    def next_sibling(self):
+        """return the next sibling statement"""
+        stmts = self.parent.child_sequence(self)
+        index = stmts.index(self)
+        try:
+            return stmts[index +1]
+        except IndexError:
+            pass
+
+    def previous_sibling(self):
+        """return the previous sibling statement"""
+        stmts = self.parent.child_sequence(self)
+        index = stmts.index(self)
+        if index >= 1:
+            return stmts[index -1]
+
+INDENT = "    "
+
+def _repr_tree(node, result, indent='', _done=None, ids=False):
+    """built a tree representation of a node as a list of lines"""
+    if _done is None:
+        _done = set()
+    if not hasattr(node, '_astng_fields'): # not a astng node
+        return
+    if node in _done:
+        result.append( indent + 'loop in tree: %s' % node )
+        return
+    _done.add(node)
+    node_str = str(node)
+    if ids:
+        node_str += '  . \t%x' % id(node)
+    result.append( indent + node_str )
+    indent += INDENT
+    for field in node._astng_fields:
+        value = getattr(node, field)
+        if isinstance(value, (list, tuple) ):
+            result.append(  indent + field + " = [" )
+            for child in value:
+                if isinstance(child, (list, tuple) ):
+                    # special case for Dict # FIXME
+                    _repr_tree(child[0], result, indent, _done, ids)
+                    _repr_tree(child[1], result, indent, _done, ids)
+                    result.append(indent + ',')
+                else:
+                    _repr_tree(child, result, indent, _done, ids)
+            result.append(  indent + "]" )
+        else:
+            result.append(  indent + field + " = " )
+            _repr_tree(value, result, indent, _done, ids)
+
+