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108 lines
3.3 KiB
Python
108 lines
3.3 KiB
Python
# copyright 2003-2011 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
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# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
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#
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# This file is part of logilab-common.
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#
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# logilab-common is free software: you can redistribute it and/or modify it under
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# the terms of the GNU Lesser General Public License as published by the Free
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# Software Foundation, either version 2.1 of the License, or (at your option) any
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# later version.
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#
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# logilab-common is distributed in the hope that it will be useful, but WITHOUT
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# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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# FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
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# details.
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#
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# You should have received a copy of the GNU Lesser General Public License along
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# with logilab-common. If not, see <http://www.gnu.org/licenses/>.
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"""A generic visitor abstract implementation.
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"""
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__docformat__ = "restructuredtext en"
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def no_filter(_):
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return 1
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# Iterators ###################################################################
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class FilteredIterator(object):
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def __init__(self, node, list_func, filter_func=None):
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self._next = [(node, 0)]
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if filter_func is None:
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filter_func = no_filter
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self._list = list_func(node, filter_func)
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def next(self):
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try:
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return self._list.pop(0)
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except :
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return None
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# Base Visitor ################################################################
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class Visitor(object):
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def __init__(self, iterator_class, filter_func=None):
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self._iter_class = iterator_class
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self.filter = filter_func
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def visit(self, node, *args, **kargs):
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"""
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launch the visit on a given node
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call 'open_visit' before the beginning of the visit, with extra args
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given
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when all nodes have been visited, call the 'close_visit' method
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"""
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self.open_visit(node, *args, **kargs)
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return self.close_visit(self._visit(node))
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def _visit(self, node):
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iterator = self._get_iterator(node)
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n = iterator.next()
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while n:
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result = n.accept(self)
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n = iterator.next()
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return result
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def _get_iterator(self, node):
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return self._iter_class(node, self.filter)
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def open_visit(self, *args, **kargs):
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"""
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method called at the beginning of the visit
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"""
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pass
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def close_visit(self, result):
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"""
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method called at the end of the visit
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"""
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return result
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# standard visited mixin ######################################################
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class VisitedMixIn(object):
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"""
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Visited interface allow node visitors to use the node
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"""
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def get_visit_name(self):
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"""
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return the visit name for the mixed class. When calling 'accept', the
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method <'visit_' + name returned by this method> will be called on the
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visitor
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"""
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try:
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return self.TYPE.replace('-', '_')
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except:
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return self.__class__.__name__.lower()
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def accept(self, visitor, *args, **kwargs):
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func = getattr(visitor, 'visit_%s' % self.get_visit_name())
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return func(self, *args, **kwargs)
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def leave(self, visitor, *args, **kwargs):
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func = getattr(visitor, 'leave_%s' % self.get_visit_name())
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return func(self, *args, **kwargs)
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