.

wcfs/internal/xbtree/pptreesubset.go

@@ -147,7 +147,7 @@ func (A PPTreeSubSet) Union(B PPTreeSubSet) PPTreeSubSet {
 // In other words it adds B nodes to A.
 func (A PPTreeSubSet) UnionInplace(B PPTreeSubSet) {
 	if debugPPSet {
-		fmt.Printf("\n\nUnionInplace:\n")
+		fmt.Printf("\n\nUnion:\n")
 		fmt.Printf("  A: %s\n", A)
 		fmt.Printf("  B: %s\n", B)
 		defer fmt.Printf("->U: %s\n", A)
@@ -175,7 +175,7 @@ func (A PPTreeSubSet) Difference(B PPTreeSubSet) PPTreeSubSet {
 // In other words it removes B nodes from A while still maintaining A as PP-connected.
 func (A PPTreeSubSet) DifferenceInplace(B PPTreeSubSet) {
 	if debugPPSet {
-		fmt.Printf("\n\nDifferenceInplace:\n")
+		fmt.Printf("\n\nDifference:\n")
 		fmt.Printf("  A: %s\n", A)
 		fmt.Printf("  B: %s\n", B)
 		defer fmt.Printf("->D: %s\n", A)
@@ -192,7 +192,7 @@ func (A PPTreeSubSet) DifferenceInplace(B PPTreeSubSet) {
 
 func (A PPTreeSubSet) xUnionInplace(B PPTreeSubSet) {
 	if debugPPSet {
-		fmt.Printf("\n\n  xUnionInplace:\n")
+		fmt.Printf("\n\n  xUnion:\n")
 		fmt.Printf("    a: %s\n", A)
 		fmt.Printf("    b: %s\n", B)
 		defer fmt.Printf("  ->u: %s\n", A)
@@ -226,7 +226,7 @@ func (A PPTreeSubSet) xUnionInplace(B PPTreeSubSet) {
 
 func (A PPTreeSubSet) xDifferenceInplace(B PPTreeSubSet) {
 	if debugPPSet {
-		fmt.Printf("\n\n  xDifferenceInplace:\n")
+		fmt.Printf("\n\n  xDifference:\n")
 		fmt.Printf("    a: %s\n", A)
 		fmt.Printf("    b: %s\n", B)
 		defer fmt.Printf("  ->d: %s\n", A)

wcfs/internal/xbtree/rangeset.go

@@ -31,18 +31,25 @@ type Range struct {
 }
 
 // RangeSet is set of non-overlapping Key ranges.
+// XXX RangeSet is set of Keys with adjacent keys coaleced into Ranges.
+// XXX -> RangedSet ?
 type RangeSet struct {
 	// TODO rework to use BTree lo->hi_ instead if performance turns out to
 	// be not acceptable
 	rangev []Range // lo↑
 }
 
+// XXX Add/Del - just add/del key
+
+
 // Add adds Range r to the set of keys.		// XXX -> UnionInplace1 ?
+// XXX -> AddRange ?
 func (S *RangeSet) Add(r Range) {
 	panic("TODO")	// XXX
 }
 
 // Del removes Range r from the set of keys.	// XXX -> DifferenceInplace1 ?
+// XXX -> DelRange?
 func (S *RangeSet) Del(r Range) {
 	panic("TODO")	// XXX
 }
@@ -118,12 +125,12 @@ func (S *RangeSet) verify() {
 
 	hi_Prev := KeyMin
 	for i, r := range S.rangev {
-		if !(r.hi_ >= r.lo) {
-			badf("[%d]: hi_ < lo", i)
-		}
-		if !(r.lo >= hi_Prev) {
+		if !(hi_Prev <= r.lo) {
 			badf("[%d]: lo < hi_Prev", i)
 		}
+		if !(r.lo < r.hi_) {
+			badf("[%d]: lo >= hi_", i)
+		}
 		hi_Prev = r.hi_
 	}
 }

wcfs/internal/xbtree/rangeset_test.go

@@ -64,7 +64,9 @@ func TestRangeSet(t *testing.T) {
 				S(1,2),	// U
 				S()),	// D
 
-		// XXX
+		// XXX Add -> merge
+		// XXX Del -> split
+		// XXX several ranges -> Del(-oo, oo) -> ø
 	}
 
 	for _, tt := range testv {