1 files changed, 104 insertions, 0 deletions
diff --git a/Lib/idlelib/percolator.py b/Lib/idlelib/percolator.py
new file mode 100644
index 0000000000..d18daf0586
--- /dev/null
+++ b/Lib/idlelib/percolator.py
@@ -0,0 +1,104 @@
+from idlelib.delegator import Delegator
+from idlelib.redirector import WidgetRedirector
+
+
+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 _percolator(parent):  # htest #
+    import tkinter as tk
+
+    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)
+
+    box = tk.Toplevel(parent)
+    box.title("Test Percolator")
+    x, y = map(int, parent.geometry().split('+')[1:])
+    box.geometry("+%d+%d" % (x, y + 175))
+    text = tk.Text(box)
+    p = Percolator(text)
+    pin = p.insertfilter
+    pout = p.removefilter
+    t1 = Tracer("t1")
+    t2 = Tracer("t2")
+
+    def toggle1():
+        (pin if var1.get() else pout)(t1)
+    def toggle2():
+        (pin if var2.get() else pout)(t2)
+
+    text.pack()
+    var1 = tk.IntVar(parent)
+    cb1 = tk.Checkbutton(box, text="Tracer1", command=toggle1, variable=var1)
+    cb1.pack()
+    var2 = tk.IntVar(parent)
+    cb2 = tk.Checkbutton(box, text="Tracer2", command=toggle2, variable=var2)
+    cb2.pack()
+
+if __name__ == "__main__":
+    import unittest
+    unittest.main('idlelib.idle_test.test_percolator', verbosity=2,
+                  exit=False)
+
+    from idlelib.idle_test.htest import run
+    run(_percolator)