# Source code for logilab.common.visitor

    # 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"

    def no_filter(_: Node) -> int:
        return 1

    # Iterators ###################################################################
    class FilteredIterator(object):
        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 ################################################################
    class Visitor(object):
        def __init__(self, iterator_class, filter_func=None):
            self._iter_class = iterator_class
            self.filter = filter_func

        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)

        def open_visit(self, *args, **kargs):
            """
            method called at the beginning of the visit
            """

        def close_visit(self, result):
            """
            method called at the end of the visit
            """
            return result

    # standard visited mixin ######################################################
    class VisitedMixIn(object):
        """
        Visited interface allow node visitors to use the node
        """

        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()

        def accept(
            self, visitor: Union[HTMLWriter, TextWriter], *args: Any, **kwargs: Any
        ) -> Optional[Any]:
            func = getattr(visitor, "visit_%s" % self.get_visit_name())
            return func(self, *args, **kwargs)

        def leave(self, visitor, *args, **kwargs):
            func = getattr(visitor, "leave_%s" % self.get_visit_name())
            return func(self, *args, **kwargs)