.

wcfs/internal/xbtree/rangeset.go

@@ -20,6 +20,10 @@
 package xbtree
 // set of [lo,hi) Key ranges.
 
+import (
+	"fmt"
+)
+
 // Range represents [lo,hi) Key range.
 type Range struct {
 	lo  Key
@@ -69,12 +73,19 @@ func (A *RangeSet) Difference(B *RangeSet) *RangeSet {
 
 // --------
 
+// Clone returns copy of the set.
+func (orig *RangeSet) Clone() *RangeSet {
+	klon := &RangeSet{}
+	klon.rangev = append(klon.rangev, orig.rangev...)
+	return klon
+}
+
 // XXX RangeSet.verify to check ranges are not overlapping and ↑
 
 
 func (r Range) String() string {
-        slo  := "-∞";  if rn.lo  > KeyMin { slo = fmt.Sprintf("%v", rn.lo) }
-        shi  := "∞";   if rn.hi_ < KeyMax { shi = fmt.Sprintf("%v", rn.hi_+1) }
+        slo  := "-∞";  if r.lo  > KeyMin { slo = fmt.Sprintf("%v", r.lo) }
+        shi  := "∞";   if r.hi_ < KeyMax { shi = fmt.Sprintf("%v", r.hi_+1) }
 	return fmt.Sprintf("[%s,%s)", slo, shi)
 }
 

wcfs/internal/xbtree/δbtail.go

@@ -172,7 +172,7 @@ func (orig *ΔBtail) clone() *ΔBtail {
 	klon.byRoot = make(map[zodb.Oid]*ΔTtail, len(orig.byRoot))
 	for root, origΔTtail := range orig.byRoot {
 		klonΔTtail := &ΔTtail{}
-		klonΔTtail.vδT = append(klonΔTtail.vδT, origΔTtail.vδT...)
+		klonΔTtail.vδT = append(nil, origΔTtail.vδT...)
 		klonΔTtail.KVAtTail = make(map[Key]Value, len(origΔTtail.KVAtTail))
 		for k, v := range origΔTtail.KVAtTail {
 			klonΔTtail.KVAtTail[k] = v