.

wcfs/internal/xbtree.py

@@ -21,7 +21,7 @@
 """Package xbtree provides utilities for inspecting/manipulating internal
 structure of integer-keyed BTrees.
 
-It is primarily used to verify ΔBTail in wcfs.
+It is primarily used to help verify ΔBTail in wcfs.
 
 - `Tree` represents a tree node.
 - `Bucket` represents a bucket node.
@@ -91,7 +91,7 @@ in left-to-right order.
 Visualization
 -------------
 
-The following visualization utilities are provided to help understanding BTrees
+The following visualization utilities are provided to help understand BTrees
 better:
 
 - `topoview` displays BTree structure given its topology-encoded representation.
@@ -158,7 +158,6 @@ class Tree(object):
         return s
     __repr__ = __str__
 
-
     # copy returns a deep copy of the tree.
     # if onlyKeys=Y buckets in returned tree will contain only keys not values.
     def copy(t, onlyKeys=False):
@@ -285,7 +284,7 @@ def Restructure(ztree, newStructure):
 
     zcheck(ztree) # verify ztree before our tweaks
 
-    # dict with all k->v from ztree
+    # {} with all k->v from ztree
     kv = dict(ztree)
 
     # walk original and new structures level by level.
@@ -333,7 +332,6 @@ def Restructure(ztree, newStructure):
                 assert abs(v) < 1E3
                 return v
             def d2(x,y):
-                #return abs(fin(x)-fin(y))
                 return (fin(x)-fin(y))**2
             return d2(a.range.klo, b.range.klo) + \
                    d2(a.range.khi, b.range.khi)
@@ -349,8 +347,8 @@ def Restructure(ztree, newStructure):
         # find the assignments.
         # TODO try to avoid scipy dependency; we could also probably make
         # assignments more efficiently taking into account that Av and Bv are
-        # key↑ and the property of D function so that if B2 > B1 (all keys in
-        # B2 > all keys in B1) and A < B1.hi, then D(B2, A) > D(B1, A).
+        # key↑ and the property of D function is so that if B2 > B1 (all keys
+        # in B2 > all keys in B1) and A < B1.hi, then D(B2, A) > D(B1, A).
         jv, iv = scipy.optimize.linear_sum_assignment(C)
         for (j,i) in zip(jv, iv):
             RNv[j].node.Z = RZv[i].node
@@ -381,7 +379,7 @@ def Restructure(ztree, newStructure):
     zrlevelv = list(__zwalkBFS(ztree))   # [] of _NodeInRange
     rlevelv  = list( __walkBFS(tnew))    # [] of _NodeInRange
 
-    # associate every non-bucket node in tnew to a znode
+    # associate every non-bucket node in tnew to a znode,
     # extract bucket nodes.
     zrbucketv = [] # of _NodeInRange
     rbucketv  = [] # of _NodeInRange
@@ -818,7 +816,10 @@ def TopoEncode(tree, vencode=lambda v: '%d' % v):
                         assert ',' not in vtxt
                         assert '-' not in vtxt
                         vtxtv.append(vtxt)
-                        vencoded[vtxt] = v
+                        if vtxt in vencoded:
+                            assert vencoded[vtxt] == v
+                        else:
+                            vencoded[vtxt] = v
                     tnode += ','.join(['%d:%s' % (k,vtxt)
                                     for (k,vtxt) in zip(node.keyv, vtxtv)])
             else:
@@ -843,7 +844,7 @@ class TopoDecodeError(Exception):
     pass
 def TopoDecode(text, vdecode=int):
     levelv = text.split('/')  # T3/T-T/B1:a-T5/B-B7,8,9  -> T3 T-T B1:a-T5 B-B7,8,9
-    # XXX forbid mixing buckets-with-value with buckets-without-value?
+    # NOTE we don't forbid mixing buckets-with-value with buckets-without-value
 
     # build nodes from bottom-up
     currentv = [] # of nodes on current level (that we are building)