no direct access to allot lookup table

allot_lookuptbl.go

@@ -3,11 +3,19 @@
 
 package bart
 
+// IdxToAllotment returns the precalculated bitset for idx.
+// Only used for fast bitset intersections instead of
+// range loops in table overlaps methods.
+//
+// Please read the ART paper ./doc/artlookup.pdf
+// to understand the allotment algorithm.
+func idxToAllot(idx uint) [8]uint64 {
+	return allotLookupTbl[idx]
+}
+
 // allotLookupTbl, as precalculated bitsets,
 // map the baseIndex to bitset with precomputed complete binary tree.
 //
-// Used for bitset intersections instead of range loops in overlaps tests.
-//
 //	  // 1 <= idx <= 511
 //		func allotRec(aTbl *bitset.BitSet, idx uint) {
 //			aTbl = aTbl.Set(idx)

overlaps.go

@@ -177,7 +177,7 @@ func (n *node[V]) overlapsChildrenIn(o *node[V]) bool {
 
 	for _, idx := range allIndices {
 		// get pre alloted bitset for idx
-		a8 := allotLookupTbl[idx]
+		a8 := idxToAllot(idx)
 		prefixRoutes.InPlaceUnion(bitset.BitSet(a8[:]))
 	}
 
@@ -241,7 +241,7 @@ func (n *node[V]) overlapsOneRouteIn(o *node[V]) bool {
 	// use bitset intersection with alloted stride table instead of range loops
 
 	// copy pre alloted bitset for idx
-	a8 := allotLookupTbl[idx]
+	a8 := idxToAllot(idx)
 	allotedPrefixRoutes := bitset.BitSet(a8[:])
 
 	// use bitset intersection instead of range loops
@@ -260,7 +260,7 @@ func (n *node[V]) overlapsPrefix(octet byte, pfxLen int) bool {
 	// use bitset intersection with alloted stride table instead of range loops
 
 	// copy pre alloted bitset for idx
-	a8 := allotLookupTbl[idx]
+	a8 := idxToAllot(idx)
 	allotedPrefixRoutes := bitset.BitSet(a8[:])
 
 	// use bitset intersection instead of range loops