from idlelib.WidgetRedirector import WidgetRedirector
from idlelib.Delegator import Delegator

class Percolator:

def __init__(self, text):
# XXX would be nice to inherit from Delegator
self.text = text
self.redir = WidgetRedirector(text)
self.top = self.bottom = Delegator(text)
self.bottom.insert = self.redir.register("insert", self.insert)
self.bottom.delete = self.redir.register("delete", self.delete)
self.filters = []

def close(self):
while self.top is not self.bottom:
self.removefilter(self.top)
self.top = None
self.bottom.setdelegate(None); self.bottom = None
self.redir.close(); self.redir = None
self.text = None

def insert(self, index, chars, tags=None):
# Could go away if inheriting from Delegator
self.top.insert(index, chars, tags)

def delete(self, index1, index2=None):
# Could go away if inheriting from Delegator
self.top.delete(index1, index2)

def insertfilter(self, filter):
# Perhaps rename to pushfilter()?
assert isinstance(filter, Delegator)
assert filter.delegate is None
filter.setdelegate(self.top)
self.top = filter

def removefilter(self, filter):
# XXX Perhaps should only support popfilter()?
assert isinstance(filter, Delegator)
assert filter.delegate is not None
f = self.top
if f is filter:
self.top = filter.delegate
filter.setdelegate(None)
else:
while f.delegate is not filter:
assert f is not self.bottom
f.resetcache()
f = f.delegate
f.setdelegate(filter.delegate)
filter.setdelegate(None)


def main():
class Tracer(Delegator):
def __init__(self, name):
self.name = name
Delegator.__init__(self, None)
def insert(self, *args):
print self.name, ": insert", args
self.delegate.insert(*args)
def delete(self, *args):
print self.name, ": delete", args
self.delegate.delete(*args)
root = Tk()
root.wm_protocol("WM_DELETE_WINDOW", root.quit)
text = Text()
text.pack()
text.focus_set()
p = Percolator(text)
t1 = Tracer("t1")
t2 = Tracer("t2")
p.insertfilter(t1)
p.insertfilter(t2)
root.mainloop()
p.removefilter(t2)
root.mainloop()
p.insertfilter(t2)
p.removefilter(t1)
root.mainloop()

if __name__ == "__main__":
from Tkinter import *
main()