forget the past.

forget the past.

1 files changed, 108 insertions, 0 deletions

diff --git a/visitor.py b/visitor.py
new file mode 100644
index 0000000..2fa42eb
--- /dev/null
+++ b/visitor.py
@@ -0,0 +1,108 @@
+# This program is free software; you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free Software
+# Foundation; either version 2 of the License, or (at your option) any later
+# version.
+#
+# This program 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program; if not, write to the Free Software Foundation, Inc.,
+# 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+""" Copyright (c) 2002-2003 LOGILAB S.A. (Paris, FRANCE).
+ http://www.logilab.fr/ -- mailto:contact@logilab.fr
+ 
+a generic visitor abstract implementation
+"""
+
+__revision__ = "$Id: visitor.py,v 1.14 2006-02-18 03:17:16 ludal Exp $"
+
+def no_filter(_):
+    return 1
+
+
+# Iterators ###################################################################
+class FilteredIterator:
+
+    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:
+
+    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 begining 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)
+
+