X-Git-Url: https://git.arvados.org/lightning.git/blobdiff_plain/365adc74eb21f1654611cb309738ffb07c1ca357..cf6bba16548ea76aef580fce9fdd04abebcd7d3f:/mask.go

diff --git a/mask.go b/mask.go
index 7d614fa4aa..42232e04f5 100644
--- a/mask.go
+++ b/mask.go
@@ -27,6 +27,9 @@ type mask struct {
 }
 
 func (m *mask) Add(seqname string, start, end int) {
+	if m.frozen {
+		panic("bug: (*mask)Add() called after Freeze()")
+	}
 	if m.intervals == nil {
 		m.intervals = map[string][]interval{}
 	}
@@ -48,6 +51,17 @@ func (m *mask) Check(seqname string, start, end int) bool {
 	return m.itrees[seqname].check(0, interval{start, end})
 }
 
+func (m *mask) Len() int {
+	if !m.frozen {
+		return 0
+	}
+	n := 0
+	for _, intervals := range m.intervals {
+		n += len(intervals)
+	}
+	return n
+}
+
 func (m *mask) freeze(in []interval) intervalTree {
 	if len(in) == 0 {
 		return nil
@@ -60,10 +74,10 @@ func (m *mask) freeze(in []interval) intervalTree {
 		itreesize = itreesize * 2
 	}
 	itree := make(intervalTree, itreesize)
-	itree.importSlice(0, in)
-	for i := len(in); i < itreesize; i++ {
+	for i := 0; i < itreesize; i++ {
 		itree[i].maxend = -1
 	}
+	itree.importSlice(0, in)
 	return itree
 }