.

wcfs/internal/xbtree.py

@@ -129,6 +129,53 @@ def topoEncode(treeStruct):
     1/0
 
 
+# iterAllStructPermutation iterates though all structures for BTrees with
+# specified keys and btree depth up-to maxdepth. Eatch tree node is split by
+# up-to maxsplit points.
+def iterAllStructPermutations(keys, maxdepth, maxsplit):
+    assert isinstance(maxdepth, int); assert maxdepth >= 0
+    assert isinstance(maxsplit, int); assert maxsplit >= 0
+    ks = set(keys)
+    for k in keys:
+        assert isinstance(k, int)
+        assert k in ks  # no duplicates
+        del keys[k]
+    keyv = list(keys)
+    keyv.sort()
+
+    # initial [lo, hi) covering keys with +-1
+    klo = -inf
+    khi = +inf
+    if len(keyv) > 0:
+        klo = keyv[0]  - 1
+        khi = keyv[-1] + 1 + 1   # hi is ")", not "]"
+
+
+    _keyvSliceBy(keyv, klo, khi)
+
+
+
+def _iterAllStructPermutations(keyv, maxdepth, maxsplit):
+    for nsplit in range(0, maxsplit):
+
+
+# _keyvSliceBy returns [] of keys from keyv : k ∈ [klo, khi)
+def _keyvSliceBy(keyv, klo, khi):
+    assert klo <= khi
+    assert _keyvSorted(keyv)
+    return list([k for k in keyv if (klo <= k < khi)])
+
+# iterSplitBy iterates through all nsplit splitting of [lo, hi) range.
+# hi > lo
+# XXX nsplit > ...
+def iterSplitBy(lo, hi, nsplit): # -> [] of [lo, s1, s2, ..., sn, hi)
+    if nsplit == 0:
+        yield [lo, hi]
+        return
+
+    # XXX
+
+
 # ---- misc ----
 
 # _indent returns text with each line of it indented with prefix.

wcfs/internal/xbtree_test.py

@@ -55,6 +55,8 @@ def test_topologyOf():
     assert btree.TopoEncodingOf(t) == \
         (4,), (2,),(), (),(),(6,10), B(1),B(3),(),(),(), (),B(7),B(11), B(5)
 
+        # T4 T2-T T-T-T6,10 B1-B3-T-T-T T-B7-B11 B5
+
     """
     assert xbtree.TopologyOf(t) == ( (4,),
                                      ((2,),      ()),