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      1 from idlelib.WidgetRedirector import WidgetRedirector
      2 from idlelib.Delegator import Delegator
      3 
      4 class Percolator:
      5 
      6     def __init__(self, text):
      7         # XXX would be nice to inherit from Delegator
      8         self.text = text
      9         self.redir = WidgetRedirector(text)
     10         self.top = self.bottom = Delegator(text)
     11         self.bottom.insert = self.redir.register("insert", self.insert)
     12         self.bottom.delete = self.redir.register("delete", self.delete)
     13         self.filters = []
     14 
     15     def close(self):
     16         while self.top is not self.bottom:
     17             self.removefilter(self.top)
     18         self.top = None
     19         self.bottom.setdelegate(None); self.bottom = None
     20         self.redir.close(); self.redir = None
     21         self.text = None
     22 
     23     def insert(self, index, chars, tags=None):
     24         # Could go away if inheriting from Delegator
     25         self.top.insert(index, chars, tags)
     26 
     27     def delete(self, index1, index2=None):
     28         # Could go away if inheriting from Delegator
     29         self.top.delete(index1, index2)
     30 
     31     def insertfilter(self, filter):
     32         # Perhaps rename to pushfilter()?
     33         assert isinstance(filter, Delegator)
     34         assert filter.delegate is None
     35         filter.setdelegate(self.top)
     36         self.top = filter
     37 
     38     def removefilter(self, filter):
     39         # XXX Perhaps should only support popfilter()?
     40         assert isinstance(filter, Delegator)
     41         assert filter.delegate is not None
     42         f = self.top
     43         if f is filter:
     44             self.top = filter.delegate
     45             filter.setdelegate(None)
     46         else:
     47             while f.delegate is not filter:
     48                 assert f is not self.bottom
     49                 f.resetcache()
     50                 f = f.delegate
     51             f.setdelegate(filter.delegate)
     52             filter.setdelegate(None)
     53 
     54 
     55 def main():
     56     class Tracer(Delegator):
     57         def __init__(self, name):
     58             self.name = name
     59             Delegator.__init__(self, None)
     60         def insert(self, *args):
     61             print self.name, ": insert", args
     62             self.delegate.insert(*args)
     63         def delete(self, *args):
     64             print self.name, ": delete", args
     65             self.delegate.delete(*args)
     66     root = Tk()
     67     root.wm_protocol("WM_DELETE_WINDOW", root.quit)
     68     text = Text()
     69     text.pack()
     70     text.focus_set()
     71     p = Percolator(text)
     72     t1 = Tracer("t1")
     73     t2 = Tracer("t2")
     74     p.insertfilter(t1)
     75     p.insertfilter(t2)
     76     root.mainloop()
     77     p.removefilter(t2)
     78     root.mainloop()
     79     p.insertfilter(t2)
     80     p.removefilter(t1)
     81     root.mainloop()
     82 
     83 if __name__ == "__main__":
     84     from Tkinter import *
     85     main()
     86