from WidgetRedirector import WidgetRedirector

from 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()