.

wcfs/internal/xbtree.py

@@ -52,7 +52,7 @@ The following example illustrates topology encoding represented by string
         || |7|8|9|      B-B7,8,9    represents empty Bucket() and Bucket(7,8,9)
 
 
-Topology encoding specification follows:
+Topology encoding specification:
 
 A Tree is encoded by depth-order traversal, delimiting layers with "/".
 Inside a layer Tree and Bucket nodes are signalled as
@@ -71,8 +71,8 @@ represented as
 
     "T-T1,3-B4,5"   ; layer with Tree([]), Tree([1,3]) and Bucket([4,5])
 
-XXX layer -> layer
-
+A layer consists of nodes that are followed by node-node links from upper layer
+in left-to-right order.
 """
 
 from __future__ import print_function, absolute_import
@@ -181,6 +181,14 @@ def StructureOf(node):
 # See top-level docstring for what topology is.
 def TopoEncode(tree):
     assert isinstance(tree, Tree)
+    topo = 'zzz'    # XXX
+
+    if 1:   # debug
+        t2 = TopoDecode(topo)
+        if t2 != tree:
+            panic("BUG: TopoEncode: D(E(·)) != identity\n·      = %s\n D(E(·) = %s" % (tree, t2))
+
+    return topo
 
 
 # TopoDecode decodes topology-encoded text into Tree structure.

wcfs/internal/xbtree_test.py

@@ -75,9 +75,23 @@ def test_structureOf():
 
 
 def test_topoEncoding():
-    1/0
+    T = xbtree.Tree
+    B = xbtree.Bucket
+    def X(tree):
+        topo = xbtree.TopoEncode(tree)
+        t2   = xbtree.TopoDecode(topo)
+        assert t2 == tree
+        return topo
+
+    assert X(T([], B()))            == 'T/B'
+    assert X(T([], B(1)))           == 'T/B1'
+    assert X(T([], B(1,3)))         == 'T/B1,3'
+    assert X(T([], T([], B())))     == 'T/T/B'
+
+    #assert X(T(
+
 
-def test_AllStructs():
+def test_allStructs():
     T = xbtree.Tree
     B = xbtree.Bucket
     def X(keys, maxdepth, maxsplit):