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# 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.
"""
__docformat__ = "restructuredtext en"
def no_filter(_):
return 1
# Iterators ###################################################################
class FilteredIterator(object):
def __init__(self, node, list_func, filter_func=None):
self._next = [(node, 0)]
if filter_func is None:
filter_func = no_filter
self._list = list_func(node, filter_func)
def next(self):
try:
return self._list.pop(0)
except :
return None
# 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 = iterator.next()
while n:
result = n.accept(self)
n = iterator.next()
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
"""
pass
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):
"""
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:
return self.TYPE.replace('-', '_')
except:
return self.__class__.__name__.lower()
def accept(self, visitor, *args, **kwargs):
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)
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