# copyright 2003-2011 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of logilab-common.
#
# logilab-common 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-common 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-common. If not, see <http://www.gnu.org/licenses/>.
"""A generic visitor abstract implementation.
"""
from typing import Any, Callable, Optional, Union
from logilab.common.types import Node, HTMLWriter, TextWriter
__docformat__ = "restructuredtext en"
[docs]def no_filter(_: Node) -> int:
return 1
# Iterators ###################################################################
[docs]class FilteredIterator:
def __init__(self, node: Node, list_func: Callable, filter_func: Optional[Any] = None) -> None:
self._next = [(node, 0)]
if filter_func is None:
filter_func = no_filter
self._list = list_func(node, filter_func)
def __next__(self) -> Optional[Node]:
try:
return self._list.pop(0)
except Exception:
return None
next = __next__
# Base Visitor ################################################################
[docs]class Visitor:
def __init__(self, iterator_class, filter_func=None):
self._iter_class = iterator_class
self.filter = filter_func
[docs] def visit(self, node, *args, **kargs):
"""
launch the visit on a given node
call 'open_visit' before the beginning of the visit, with extra args
given
when all nodes have been visited, call the 'close_visit' method
"""
self.open_visit(node, *args, **kargs)
return self.close_visit(self._visit(node))
def _visit(self, node):
iterator = self._get_iterator(node)
n = next(iterator)
while n:
result = n.accept(self)
n = next(iterator)
return result
def _get_iterator(self, node):
return self._iter_class(node, self.filter)
[docs] def open_visit(self, *args, **kargs):
"""
method called at the beginning of the visit
"""
[docs] def close_visit(self, result):
"""
method called at the end of the visit
"""
return result
# standard visited mixin ######################################################
[docs]class VisitedMixIn:
"""
Visited interface allow node visitors to use the node
"""
[docs] def get_visit_name(self) -> str:
"""
return the visit name for the mixed class. When calling 'accept', the
method <'visit_' + name returned by this method> will be called on the
visitor
"""
try:
# mypy: "VisitedMixIn" has no attribute "TYPE"
# dynamic attribute
return self.TYPE.replace("-", "_") # type: ignore
except Exception:
return self.__class__.__name__.lower()
[docs] def accept(
self, visitor: Union[HTMLWriter, TextWriter], *args: Any, **kwargs: Any
) -> Optional[Any]:
func = getattr(visitor, f"visit_{self.get_visit_name()}")
return func(self, *args, **kwargs)
[docs] def leave(self, visitor, *args, **kwargs):
func = getattr(visitor, f"leave_{self.get_visit_name()}")
return func(self, *args, **kwargs)