.

wcfs/internal/xbtree/rangeset.go

@@ -235,8 +235,31 @@ func (S *RangeSet) DelRange(r Range) {
 }
 
 // HasRange returns whether all keys from Range r belong to the set.
-func (S *RangeSet) HasRange(r Range) bool {
-	panic("TODO")
+func (S *RangeSet) HasRange(r Range) (yes bool) {
+	if traceRangeSet {
+		fmt.Printf("\n\nHasRange:\n")
+		fmt.Printf("  S: %s\n", S)
+		fmt.Printf("  r: %s\n", r)
+		defer func() {
+			fmt.Printf("->·: %v\n", yes)
+		}()
+	}
+
+	S.verify()
+
+	// find first ilo: r.lo < [ilo].hi
+	l := len(S.rangev)
+	ilo := sort.Search(l, func(i int) bool {
+		 return r.lo <= S.rangev[i].hi_
+	})
+	debugfRSet("\tilo: %d\n", ilo)
+
+	if ilo == l { // not found
+		return false
+	}
+
+	// all keys from r are in S if r ∈ [ilo]
+	return r.hi_ <= S.rangev[ilo].hi_
 }