path: root/rebuilder.py

# copyright 2003-2013 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of astroid.
#
# astroid 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.
#
# astroid 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 astroid. If not, see <http://www.gnu.org/licenses/>.
"""this module contains utilities for rebuilding a _ast tree in
order to get a single Astroid representation
"""

import sys
from warnings import warn
from _ast import (Expr as Discard, Str,
    # binary operators
    Add, Div, FloorDiv,  Mod, Mult, Pow, Sub, BitAnd, BitOr, BitXor,
    LShift, RShift,
    # logical operators
    And, Or,
    # unary operators
    UAdd, USub, Not, Invert,
    # comparison operators
    Eq, Gt, GtE, In, Is, IsNot, Lt, LtE, NotEq, NotIn,
    )

from astroid import nodes as new


_BIN_OP_CLASSES = {Add: '+',
                   BitAnd: '&',
                   BitOr: '|',
                   BitXor: '^',
                   Div: '/',
                   FloorDiv: '//',
                   Mod: '%',
                   Mult: '*',
                   Pow: '**',
                   Sub: '-',
                   LShift: '<<',
                   RShift: '>>'}

_BOOL_OP_CLASSES = {And: 'and',
                    Or: 'or'}

_UNARY_OP_CLASSES = {UAdd: '+',
                     USub: '-',
                     Not: 'not',
                     Invert: '~'}

_CMP_OP_CLASSES = {Eq: '==',
                   Gt: '>',
                   GtE: '>=',
                   In: 'in',
                   Is: 'is',
                   IsNot: 'is not',
                   Lt: '<',
                   LtE: '<=',
                   NotEq: '!=',
                   NotIn: 'not in'}

CONST_NAME_TRANSFORMS = {'None':  None,
                         'True':  True,
                         'False': False}

REDIRECT = {'arguments': 'Arguments',
            'Attribute': 'Getattr',
            'comprehension': 'Comprehension',
            'Call': 'CallFunc',
            'ClassDef': 'Class',
            "ListCompFor": 'Comprehension',
            "GenExprFor": 'Comprehension',
            'excepthandler': 'ExceptHandler',
            'Expr': 'Discard',
            'FunctionDef': 'Function',
            'GeneratorExp': 'GenExpr',
            'ImportFrom': 'From',
            'keyword': 'Keyword',
            'Repr': 'Backquote',
            }

def _init_set_doc(node, newnode):
    newnode.doc = None
    try:
        if isinstance(node.body[0], Discard) and isinstance(node.body[0].value, Str):
            newnode.tolineno = node.body[0].lineno
            newnode.doc = node.body[0].value.s
            node.body = node.body[1:]

    except IndexError:
        pass # ast built from scratch

def _lineno_parent(oldnode, newnode, parent):
    newnode.parent = parent
    if hasattr(oldnode, 'lineno'):
        newnode.lineno = oldnode.lineno
    if hasattr(oldnode, 'col_offset'):
        newnode.col_offset = oldnode.col_offset

def _set_infos(oldnode, newnode, parent):
    newnode.parent = parent
    if hasattr(oldnode, 'lineno'):
        newnode.lineno = oldnode.lineno
    if hasattr(oldnode, 'col_offset'):
        newnode.col_offset = oldnode.col_offset
    newnode.set_line_info(newnode.last_child()) # set_line_info accepts None




class TreeRebuilder(object):
    """Rebuilds the _ast tree to become an Astroid tree"""

    def __init__(self, manager):
        self._manager = manager
        self.asscontext = None
        self._metaclass = ['']
        self._global_names = []
        self._from_nodes = []
        self._delayed_assattr = []
        self._visit_meths = {}

    def _transform(self, node):
        try:
            transforms = self._manager.transforms[type(node)]
        except KeyError:
            return node # no transform registered for this class of node
        orig_node = node # copy the reference
        for transform_func, predicate in transforms:
            if predicate is None or predicate(node):
                ret = transform_func(node)
                # if the transformation function returns something, it's
                # expected to be a replacement for the node
                if ret is not None:
                    if node is not orig_node:
                        # node has already be modified by some previous
                        # transformation, warn about it
                        warn('node %s substitued multiple times' % node)
                    node = ret
        return node

    def visit_module(self, node, modname, package):
        """visit a Module node by returning a fresh instance of it"""
        newnode = new.Module(modname, None)
        newnode.package = package
        _lineno_parent(node, newnode, parent=None)
        _init_set_doc(node, newnode)
        newnode.body = [self.visit(child, newnode) for child in node.body]
        newnode.set_line_info(newnode.last_child())
        return self._transform(newnode)

    def visit(self, node, parent):
        cls = node.__class__
        if cls in self._visit_meths:
            visit_method = self._visit_meths[cls]
        else:
            cls_name = cls.__name__
            visit_name = 'visit_' + REDIRECT.get(cls_name, cls_name).lower()
            visit_method = getattr(self, visit_name)
            self._visit_meths[cls] = visit_method
        return self._transform(visit_method(node, parent))

    def _save_assignment(self, node, name=None):
        """save assignement situation since node.parent is not available yet"""
        if self._global_names and node.name in self._global_names[-1]:
            node.root().set_local(node.name, node)
        else:
            node.parent.set_local(node.name, node)


    def visit_arguments(self, node, parent):
        """visit a Arguments node by returning a fresh instance of it"""
        newnode = new.Arguments()
        _lineno_parent(node, newnode, parent)
        self.asscontext = "Ass"
        newnode.args = [self.visit(child, newnode) for child in node.args]
        self.asscontext = None
        newnode.defaults = [self.visit(child, newnode) for child in node.defaults]
        newnode.kwonlyargs = []
        newnode.kw_defaults = []
        newnode.vararg = node.vararg
        newnode.kwarg = node.kwarg
        # save argument names in locals:
        if node.vararg:
            newnode.parent.set_local(newnode.vararg, newnode)
        if node.kwarg:
            newnode.parent.set_local(newnode.kwarg, newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_assattr(self, node, parent):
        """visit a AssAttr node by returning a fresh instance of it"""
        assc, self.asscontext = self.asscontext, None
        newnode = new.AssAttr()
        _lineno_parent(node, newnode, parent)
        newnode.expr = self.visit(node.expr, newnode)
        self.asscontext = assc
        self._delayed_assattr.append(newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_assert(self, node, parent):
        """visit a Assert node by returning a fresh instance of it"""
        newnode = new.Assert()
        _lineno_parent(node, newnode, parent)
        newnode.test = self.visit(node.test, newnode)
        if node.msg is not None:
            newnode.fail = self.visit(node.msg, newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_assign(self, node, parent):
        """visit a Assign node by returning a fresh instance of it"""
        newnode = new.Assign()
        _lineno_parent(node, newnode, parent)
        self.asscontext = "Ass"
        newnode.targets = [self.visit(child, newnode) for child in node.targets]
        self.asscontext = None
        newnode.value = self.visit(node.value, newnode)
        # set some function or metaclass infos  XXX explain ?
        klass = newnode.parent.frame()
        if (isinstance(klass, new.Class)
            and isinstance(newnode.value, new.CallFunc)
            and isinstance(newnode.value.func, new.Name)):
            func_name = newnode.value.func.name
            for ass_node in newnode.targets:
                try:
                    meth = klass[ass_node.name]
                    if isinstance(meth, new.Function):
                        if func_name in ('classmethod', 'staticmethod'):
                            meth.type = func_name
                        elif func_name == 'classproperty': # see lgc.decorators
                            meth.type = 'classmethod'
                        meth.extra_decorators.append(newnode.value)
                except (AttributeError, KeyError):
                    continue
        elif getattr(newnode.targets[0], 'name', None) == '__metaclass__':
            # XXX check more...
            self._metaclass[-1] = 'type' # XXX get the actual metaclass
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_assname(self, node, parent, node_name=None):
        '''visit a node and return a AssName node'''
        newnode = new.AssName()
        _set_infos(node, newnode, parent)
        newnode.name = node_name
        self._save_assignment(newnode)
        return newnode

    def visit_augassign(self, node, parent):
        """visit a AugAssign node by returning a fresh instance of it"""
        newnode = new.AugAssign()
        _lineno_parent(node, newnode, parent)
        newnode.op = _BIN_OP_CLASSES[node.op.__class__] + "="
        self.asscontext = "Ass"
        newnode.target = self.visit(node.target, newnode)
        self.asscontext = None
        newnode.value = self.visit(node.value, newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_backquote(self, node, parent):
        """visit a Backquote node by returning a fresh instance of it"""
        newnode = new.Backquote()
        _lineno_parent(node, newnode, parent)
        newnode.value = self.visit(node.value, newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_binop(self, node, parent):
        """visit a BinOp node by returning a fresh instance of it"""
        newnode = new.BinOp()
        _lineno_parent(node, newnode, parent)
        newnode.left = self.visit(node.left, newnode)
        newnode.right = self.visit(node.right, newnode)
        newnode.op = _BIN_OP_CLASSES[node.op.__class__]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_boolop(self, node, parent):
        """visit a BoolOp node by returning a fresh instance of it"""
        newnode = new.BoolOp()
        _lineno_parent(node, newnode, parent)
        newnode.values = [self.visit(child, newnode) for child in node.values]
        newnode.op = _BOOL_OP_CLASSES[node.op.__class__]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_break(self, node, parent):
        """visit a Break node by returning a fresh instance of it"""
        newnode = new.Break()
        _set_infos(node, newnode, parent)
        return newnode

    def visit_callfunc(self, node, parent):
        """visit a CallFunc node by returning a fresh instance of it"""
        newnode = new.CallFunc()
        _lineno_parent(node, newnode, parent)
        newnode.func = self.visit(node.func, newnode)
        newnode.args = [self.visit(child, newnode) for child in node.args]
        if node.starargs is not None:
            newnode.starargs = self.visit(node.starargs, newnode)
        if node.kwargs is not None:
            newnode.kwargs = self.visit(node.kwargs, newnode)
        newnode.args.extend(self.visit(child, newnode) for child in node.keywords)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_class(self, node, parent):
        """visit a Class node to become astroid"""
        self._metaclass.append(self._metaclass[-1])
        newnode = new.Class(node.name, None)
        _lineno_parent(node, newnode, parent)
        _init_set_doc(node, newnode)
        newnode.bases = [self.visit(child, newnode) for child in node.bases]
        newnode.body = [self.visit(child, newnode) for child in node.body]
        if 'decorator_list' in node._fields and node.decorator_list:# py >= 2.6
            newnode.decorators = self.visit_decorators(node, newnode)
        newnode.set_line_info(newnode.last_child())
        metaclass = self._metaclass.pop()
        if not newnode.bases:
            # no base classes, detect new / style old style according to
            # current scope
            newnode._newstyle = metaclass == 'type'
        newnode.parent.frame().set_local(newnode.name, newnode)
        return newnode

    def visit_const(self, node, parent):
        """visit a Const node by returning a fresh instance of it"""
        newnode = new.Const(node.value)
        _set_infos(node, newnode, parent)
        return newnode

    def visit_continue(self, node, parent):
        """visit a Continue node by returning a fresh instance of it"""
        newnode = new.Continue()
        _set_infos(node, newnode, parent)
        return newnode

    def visit_compare(self, node, parent):
        """visit a Compare node by returning a fresh instance of it"""
        newnode = new.Compare()
        _lineno_parent(node, newnode, parent)
        newnode.left = self.visit(node.left, newnode)
        newnode.ops = [(_CMP_OP_CLASSES[op.__class__], self.visit(expr, newnode))
                    for (op, expr) in zip(node.ops, node.comparators)]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_comprehension(self, node, parent):
        """visit a Comprehension node by returning a fresh instance of it"""
        newnode = new.Comprehension()
        _lineno_parent(node, newnode, parent)
        self.asscontext = "Ass"
        newnode.target = self.visit(node.target, newnode)
        self.asscontext = None
        newnode.iter = self.visit(node.iter, newnode)
        newnode.ifs = [self.visit(child, newnode) for child in node.ifs]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_decorators(self, node, parent):
        """visit a Decorators node by returning a fresh instance of it"""
        # /!\ node is actually a _ast.Function node while
        # parent is a astroid.nodes.Function node
        newnode = new.Decorators()
        _lineno_parent(node, newnode, parent)
        if 'decorators' in node._fields: # py < 2.6, i.e. 2.5
            decorators = node.decorators
        else:
            decorators= node.decorator_list
        newnode.nodes = [self.visit(child, newnode) for child in decorators]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_delete(self, node, parent):
        """visit a Delete node by returning a fresh instance of it"""
        newnode = new.Delete()
        _lineno_parent(node, newnode, parent)
        self.asscontext = "Del"
        newnode.targets = [self.visit(child, newnode) for child in node.targets]
        self.asscontext = None
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_dict(self, node, parent):
        """visit a Dict node by returning a fresh instance of it"""
        newnode = new.Dict()
        _lineno_parent(node, newnode, parent)
        newnode.items = [(self.visit(key, newnode), self.visit(value, newnode))
                          for key, value in zip(node.keys, node.values)]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_dictcomp(self, node, parent):
        """visit a DictComp node by returning a fresh instance of it"""
        newnode = new.DictComp()
        _lineno_parent(node, newnode, parent)
        newnode.key = self.visit(node.key, newnode)
        newnode.value = self.visit(node.value, newnode)
        newnode.generators = [self.visit(child, newnode)
                              for child in node.generators]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_discard(self, node, parent):
        """visit a Discard node by returning a fresh instance of it"""
        newnode = new.Discard()
        _lineno_parent(node, newnode, parent)
        newnode.value = self.visit(node.value, newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_ellipsis(self, node, parent):
        """visit an Ellipsis node by returning a fresh instance of it"""
        newnode = new.Ellipsis()
        _set_infos(node, newnode, parent)
        return newnode

    def visit_emptynode(self, node, parent):
        """visit an EmptyNode node by returning a fresh instance of it"""
        newnode = new.EmptyNode()
        _set_infos(node, newnode, parent)
        return newnode

    def visit_excepthandler(self, node, parent):
        """visit an ExceptHandler node by returning a fresh instance of it"""
        newnode = new.ExceptHandler()
        _lineno_parent(node, newnode, parent)
        if node.type is not None:
            newnode.type = self.visit(node.type, newnode)
        if node.name is not None:
            # /!\ node.name can be a tuple
            self.asscontext = "Ass"
            newnode.name = self.visit(node.name, newnode)
            self.asscontext = None
        newnode.body = [self.visit(child, newnode) for child in node.body]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_exec(self, node, parent):
        """visit an Exec node by returning a fresh instance of it"""
        newnode = new.Exec()
        _lineno_parent(node, newnode, parent)
        newnode.expr = self.visit(node.body, newnode)
        if node.globals is not None:
            newnode.globals = self.visit(node.globals, newnode)
        if node.locals is not None:
            newnode.locals = self.visit(node.locals, newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_extslice(self, node, parent):
        """visit an ExtSlice node by returning a fresh instance of it"""
        newnode = new.ExtSlice()
        _lineno_parent(node, newnode, parent)
        newnode.dims = [self.visit(dim, newnode) for dim in node.dims]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_for(self, node, parent):
        """visit a For node by returning a fresh instance of it"""
        newnode = new.For()
        _lineno_parent(node, newnode, parent)
        self.asscontext = "Ass"
        newnode.target = self.visit(node.target, newnode)
        self.asscontext = None
        newnode.iter = self.visit(node.iter, newnode)
        newnode.body = [self.visit(child, newnode) for child in node.body]
        newnode.orelse = [self.visit(child, newnode) for child in node.orelse]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_from(self, node, parent):
        """visit a From node by returning a fresh instance of it"""
        names = [(alias.name, alias.asname) for alias in node.names]
        newnode = new.From(node.module or '', names, node.level or None)
        _set_infos(node, newnode, parent)
        # store From names to add them to locals after building
        self._from_nodes.append(newnode)
        return newnode

    def visit_function(self, node, parent):
        """visit an Function node to become astroid"""
        self._global_names.append({})
        newnode = new.Function(node.name, None)
        _lineno_parent(node, newnode, parent)
        _init_set_doc(node, newnode)
        newnode.args = self.visit(node.args, newnode)
        newnode.body = [self.visit(child, newnode) for child in node.body]
        if 'decorators' in node._fields: # py < 2.6
            attr = 'decorators'
        else:
            attr = 'decorator_list'
        decorators = getattr(node, attr)
        if decorators:
            newnode.decorators = self.visit_decorators(node, newnode)
        newnode.set_line_info(newnode.last_child())
        self._global_names.pop()
        frame = newnode.parent.frame()
        if isinstance(frame, new.Class):
            if newnode.name == '__new__':
                newnode.type = 'classmethod'
            else:
                newnode.type = 'method'
        if newnode.decorators is not None:
            for decorator_expr in newnode.decorators.nodes:
                if isinstance(decorator_expr, new.Name):
                    if decorator_expr.name in ('classmethod', 'staticmethod'):
                        newnode.type = decorator_expr.name
                    elif decorator_expr.name == 'classproperty':
                        newnode.type = 'classmethod'
        frame.set_local(newnode.name, newnode)
        return newnode

    def visit_genexpr(self, node, parent):
        """visit a GenExpr node by returning a fresh instance of it"""
        newnode = new.GenExpr()
        _lineno_parent(node, newnode, parent)
        newnode.elt = self.visit(node.elt, newnode)
        newnode.generators = [self.visit(child, newnode) for child in node.generators]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_getattr(self, node, parent):
        """visit a Getattr node by returning a fresh instance of it"""
        if self.asscontext == "Del":
            # FIXME : maybe we should reintroduce and visit_delattr ?
            # for instance, deactivating asscontext
            newnode = new.DelAttr()
        elif self.asscontext == "Ass":
            # FIXME : maybe we should call visit_assattr ?
            newnode = new.AssAttr()
            self._delayed_assattr.append(newnode)
        else:
            newnode = new.Getattr()
        _lineno_parent(node, newnode, parent)
        asscontext, self.asscontext = self.asscontext, None
        newnode.expr = self.visit(node.value, newnode)
        self.asscontext = asscontext
        newnode.attrname = node.attr
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_global(self, node, parent):
        """visit an Global node to become astroid"""
        newnode = new.Global(node.names)
        _set_infos(node, newnode, parent)
        if self._global_names: # global at the module level, no effect
            for name in node.names:
                self._global_names[-1].setdefault(name, []).append(newnode)
        return newnode

    def visit_if(self, node, parent):
        """visit a If node by returning a fresh instance of it"""
        newnode = new.If()
        _lineno_parent(node, newnode, parent)
        newnode.test = self.visit(node.test, newnode)
        newnode.body = [self.visit(child, newnode) for child in node.body]
        newnode.orelse = [self.visit(child, newnode) for child in node.orelse]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_ifexp(self, node, parent):
        """visit a IfExp node by returning a fresh instance of it"""
        newnode = new.IfExp()
        _lineno_parent(node, newnode, parent)
        newnode.test = self.visit(node.test, newnode)
        newnode.body = self.visit(node.body, newnode)
        newnode.orelse = self.visit(node.orelse, newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_import(self, node, parent):
        """visit a Import node by returning a fresh instance of it"""
        newnode = new.Import()
        _set_infos(node, newnode, parent)
        newnode.names = [(alias.name, alias.asname) for alias in node.names]
        # save import names in parent's locals:
        for (name, asname) in newnode.names:
            name = asname or name
            newnode.parent.set_local(name.split('.')[0], newnode)
        return newnode

    def visit_index(self, node, parent):
        """visit a Index node by returning a fresh instance of it"""
        newnode = new.Index()
        _lineno_parent(node, newnode, parent)
        newnode.value = self.visit(node.value, newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_keyword(self, node, parent):
        """visit a Keyword node by returning a fresh instance of it"""
        newnode = new.Keyword()
        _lineno_parent(node, newnode, parent)
        newnode.arg = node.arg
        newnode.value = self.visit(node.value, newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_lambda(self, node, parent):
        """visit a Lambda node by returning a fresh instance of it"""
        newnode = new.Lambda()
        _lineno_parent(node, newnode, parent)
        newnode.args = self.visit(node.args, newnode)
        newnode.body = self.visit(node.body, newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_list(self, node, parent):
        """visit a List node by returning a fresh instance of it"""
        newnode = new.List()
        _lineno_parent(node, newnode, parent)
        newnode.elts = [self.visit(child, newnode) for child in node.elts]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_listcomp(self, node, parent):
        """visit a ListComp node by returning a fresh instance of it"""
        newnode = new.ListComp()
        _lineno_parent(node, newnode, parent)
        newnode.elt = self.visit(node.elt, newnode)
        newnode.generators = [self.visit(child, newnode)
                              for child in node.generators]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_name(self, node, parent):
        """visit a Name node by returning a fresh instance of it"""
        # True and False can be assigned to something in py2x, so we have to
        # check first the asscontext
        if self.asscontext == "Del":
            newnode = new.DelName()
        elif self.asscontext is not None: # Ass
            assert self.asscontext == "Ass"
            newnode = new.AssName()
        elif node.id in CONST_NAME_TRANSFORMS:
            newnode = new.Const(CONST_NAME_TRANSFORMS[node.id])
            _set_infos(node, newnode, parent)
            return newnode
        else:
            newnode = new.Name()
        _lineno_parent(node, newnode, parent)
        newnode.name = node.id
        # XXX REMOVE me :
        if self.asscontext in ('Del', 'Ass'): # 'Aug' ??
            self._save_assignment(newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_bytes(self, node, parent):
        """visit a Bytes node by returning a fresh instance of Const"""
        newnode = new.Const(node.s)
        _set_infos(node, newnode, parent)
        return newnode

    def visit_num(self, node, parent):
        """visit a Num node by returning a fresh instance of Const"""
        newnode = new.Const(node.n)
        _set_infos(node, newnode, parent)
        return newnode

    def visit_pass(self, node, parent):
        """visit a Pass node by returning a fresh instance of it"""
        newnode = new.Pass()
        _set_infos(node, newnode, parent)
        return newnode

    def visit_str(self, node, parent):
        """visit a Str node by returning a fresh instance of Const"""
        newnode = new.Const(node.s)
        _set_infos(node, newnode, parent)
        return newnode

    def visit_print(self, node, parent):
        """visit a Print node by returning a fresh instance of it"""
        newnode = new.Print()
        _lineno_parent(node, newnode, parent)
        newnode.nl = node.nl
        if node.dest is not None:
            newnode.dest = self.visit(node.dest, newnode)
        newnode.values = [self.visit(child, newnode) for child in node.values]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_raise(self, node, parent):
        """visit a Raise node by returning a fresh instance of it"""
        newnode = new.Raise()
        _lineno_parent(node, newnode, parent)
        if node.type is not None:
            newnode.exc = self.visit(node.type, newnode)
        if node.inst is not None:
            newnode.inst = self.visit(node.inst, newnode)
        if node.tback is not None:
            newnode.tback = self.visit(node.tback, newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_return(self, node, parent):
        """visit a Return node by returning a fresh instance of it"""
        newnode = new.Return()
        _lineno_parent(node, newnode, parent)
        if node.value is not None:
            newnode.value = self.visit(node.value, newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_set(self, node, parent):
        """visit a Set node by returning a fresh instance of it"""
        newnode = new.Set()
        _lineno_parent(node, newnode, parent)
        newnode.elts = [self.visit(child, newnode) for child in node.elts]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_setcomp(self, node, parent):
        """visit a SetComp node by returning a fresh instance of it"""
        newnode = new.SetComp()
        _lineno_parent(node, newnode, parent)
        newnode.elt = self.visit(node.elt, newnode)
        newnode.generators = [self.visit(child, newnode)
                              for child in node.generators]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_slice(self, node, parent):
        """visit a Slice node by returning a fresh instance of it"""
        newnode = new.Slice()
        _lineno_parent(node, newnode, parent)
        if node.lower is not None:
            newnode.lower = self.visit(node.lower, newnode)
        if node.upper is not None:
            newnode.upper = self.visit(node.upper, newnode)
        if node.step is not None:
            newnode.step = self.visit(node.step, newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_subscript(self, node, parent):
        """visit a Subscript node by returning a fresh instance of it"""
        newnode = new.Subscript()
        _lineno_parent(node, newnode, parent)
        subcontext, self.asscontext = self.asscontext, None
        newnode.value = self.visit(node.value, newnode)
        newnode.slice = self.visit(node.slice, newnode)
        self.asscontext = subcontext
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_tryexcept(self, node, parent):
        """visit a TryExcept node by returning a fresh instance of it"""
        newnode = new.TryExcept()
        _lineno_parent(node, newnode, parent)
        newnode.body = [self.visit(child, newnode) for child in node.body]
        newnode.handlers = [self.visit(child, newnode) for child in node.handlers]
        newnode.orelse = [self.visit(child, newnode) for child in node.orelse]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_tryfinally(self, node, parent):
        """visit a TryFinally node by returning a fresh instance of it"""
        newnode = new.TryFinally()
        _lineno_parent(node, newnode, parent)
        newnode.body = [self.visit(child, newnode) for child in node.body]
        newnode.finalbody = [self.visit(n, newnode) for n in node.finalbody]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_tuple(self, node, parent):
        """visit a Tuple node by returning a fresh instance of it"""
        newnode = new.Tuple()
        _lineno_parent(node, newnode, parent)
        newnode.elts = [self.visit(child, newnode) for child in node.elts]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_unaryop(self, node, parent):
        """visit a UnaryOp node by returning a fresh instance of it"""
        newnode = new.UnaryOp()
        _lineno_parent(node, newnode, parent)
        newnode.operand = self.visit(node.operand, newnode)
        newnode.op = _UNARY_OP_CLASSES[node.op.__class__]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_while(self, node, parent):
        """visit a While node by returning a fresh instance of it"""
        newnode = new.While()
        _lineno_parent(node, newnode, parent)
        newnode.test = self.visit(node.test, newnode)
        newnode.body = [self.visit(child, newnode) for child in node.body]
        newnode.orelse = [self.visit(child, newnode) for child in node.orelse]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_with(self, node, parent):
        newnode = new.With()
        _lineno_parent(node, newnode, parent)
        expr = self.visit(node.context_expr, newnode)
        self.asscontext = "Ass"
        if node.optional_vars is not None:
            vars = self.visit(node.optional_vars, newnode)
        else:
            vars = None
        self.asscontext = None
        newnode.items = [(expr, vars)]
        newnode.body = [self.visit(child, newnode) for child in node.body]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_yield(self, node, parent):
        """visit a Yield node by returning a fresh instance of it"""
        newnode = new.Yield()
        _lineno_parent(node, newnode, parent)
        if node.value is not None:
            newnode.value = self.visit(node.value, newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode


class TreeRebuilder3k(TreeRebuilder):
    """extend and overwrite TreeRebuilder for python3k"""

    def visit_arg(self, node, parent):
        """visit a arg node by returning a fresh AssName instance"""
        # the <arg> node is coming from py>=3.0, but we use AssName in py2.x
        # XXX or we should instead introduce a Arg node in astroid ?
        return self.visit_assname(node, parent, node.arg)

    def visit_arguments(self, node, parent):
        newnode = super(TreeRebuilder3k, self).visit_arguments(node, parent)
        self.asscontext = "Ass"
        newnode.kwonlyargs = [self.visit(child, newnode) for child in node.kwonlyargs]
        self.asscontext = None
        newnode.kw_defaults = [self.visit(child, newnode) if child else None for child in node.kw_defaults]
        return newnode

    def visit_excepthandler(self, node, parent):
        """visit an ExceptHandler node by returning a fresh instance of it"""
        newnode = new.ExceptHandler()
        _lineno_parent(node, newnode, parent)
        if node.type is not None:
            newnode.type = self.visit(node.type, newnode)
        if node.name is not None:
            newnode.name = self.visit_assname(node, newnode, node.name)
        newnode.body = [self.visit(child, newnode) for child in node.body]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_nonlocal(self, node, parent):
        """visit a Nonlocal node and return a new instance of it"""
        newnode = new.Nonlocal(node.names)
        _set_infos(node, newnode, parent)
        return newnode

    def visit_raise(self, node, parent):
        """visit a Raise node by returning a fresh instance of it"""
        newnode = new.Raise()
        _lineno_parent(node, newnode, parent)
        # no traceback; anyway it is not used in Pylint
        if node.exc is not None:
            newnode.exc = self.visit(node.exc, newnode)
        if node.cause is not None:
            newnode.cause = self.visit(node.cause, newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_starred(self, node, parent):
        """visit a Starred node and return a new instance of it"""
        newnode = new.Starred()
        _lineno_parent(node, newnode, parent)
        newnode.value = self.visit(node.value, newnode)
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_try(self, node, parent):
        # python 3.3 introduce a new Try node replacing TryFinally/TryExcept nodes
        if node.finalbody:
            newnode = new.TryFinally()
            _lineno_parent(node, newnode, parent)
            newnode.finalbody = [self.visit(n, newnode) for n in node.finalbody]
            if node.handlers:
                excnode = new.TryExcept()
                _lineno_parent(node, excnode, newnode)
                excnode.body = [self.visit(child, excnode) for child in node.body]
                excnode.handlers = [self.visit(child, excnode) for child in node.handlers]
                excnode.orelse = [self.visit(child, excnode) for child in node.orelse]
                excnode.set_line_info(excnode.last_child())
                newnode.body = [excnode]
            else:
                newnode.body = [self.visit(child, newnode) for child in node.body]
        elif node.handlers:
            newnode = new.TryExcept()
            _lineno_parent(node, newnode, parent)
            newnode.body = [self.visit(child, newnode) for child in node.body]
            newnode.handlers = [self.visit(child, newnode) for child in node.handlers]
            newnode.orelse = [self.visit(child, newnode) for child in node.orelse]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_with(self, node, parent):
        if 'items' not in node._fields:
            # python < 3.3
            return super(TreeRebuilder3k, self).visit_with(node, parent)

        newnode = new.With()
        _lineno_parent(node, newnode, parent)
        def visit_child(child):
            expr = self.visit(child.context_expr, newnode)
            self.asscontext = 'Ass'
            if child.optional_vars:
                var = self.visit(child.optional_vars, newnode)
            else:
                var = None
            self.asscontext = None
            return expr, var
        newnode.items = [visit_child(child)
                         for child in node.items]
        newnode.body = [self.visit(child, newnode) for child in node.body]
        newnode.set_line_info(newnode.last_child())
        return newnode

    def visit_yieldfrom(self, node, parent):
        return self.visit_yield(node, parent)

if sys.version_info >= (3, 0):
    TreeRebuilder = TreeRebuilder3k