bitsets: cleanup

Signed-off-by: Vicent Marti <vmg@strn.cat>

go/vt/vtgate/semantics/bitset/bitset.go

@@ -118,20 +118,19 @@ func (bs Bitset) Set(offset int) Bitset {
  return toBitset(words)
 }
 
-func (bs Bitset) Single() (offset int) {
- var found bool
+func (bs Bitset) SingleBit() int {
+ offset := -1
  for i := 0; i < len(bs); i++ {
  t := bs[i]
  if t == 0 {
  continue
  }
- if found || bits.OnesCount8(t) != 1 {
+ if offset >= 0 || bits.OnesCount8(t) != 1 {
  return -1
  }
  offset = i*bitsetWidth + bits.TrailingZeros8(t)
- found = true
  }
- return
+ return offset
 }
 
 func (bs Bitset) IsContainedBy(b2 Bitset) bool {
@@ -168,8 +167,12 @@ func (bs Bitset) ForEach(yield func(int)) {
 }
 
 func Build(bits ...int) Bitset {
- var max int
- for _, b := range bits {
+ if len(bits) == 0 {
+ return ""
+ }
+
+ max := bits[0]
+ for _, b := range bits[1:] {
  if b > max {
  max = b
  }

go/vt/vtgate/semantics/bitset/bitset_test.go

@@ -1,7 +1,6 @@
 package bitset
 
 import (
- "encoding/binary"
  "testing"
 
  "github.com/stretchr/testify/require"
@@ -11,10 +10,8 @@ func TestSingletons(t *testing.T) {
  for i := 0; i < 40; i++ {
  bs := Single(i)
 
- t.Logf("%d: %#v", i, []byte(bs))
-
  require.Equal(t, 1, bs.Popcount())
- require.Equal(t, i, bs.Single())
+ require.Equal(t, i, bs.SingleBit())
 
  var called bool
  bs.ForEach(func(offset int) {
@@ -25,11 +22,3 @@ func TestSingletons(t *testing.T) {
  require.True(t, called)
  }
 }
-
-func Test1(t *testing.T) {
- var bytes []byte
- for i := 8; i < 16; i++ {
- bytes = binary.BigEndian.AppendUint16(bytes, 1<<i)
- }
- t.Logf("%#v", string(bytes))
-}

go/vt/vtgate/semantics/tabletset.go

@@ -62,7 +62,7 @@ func (ts TableSet) IsEmpty() bool {
 
 // TableOffset returns the offset in the Tables array from TableSet
 func (ts TableSet) TableOffset() int {
- return bitset.Bitset(ts).Single()
+ return bitset.Bitset(ts).SingleBit()
 }
 
 // ForEachTable calls the given callback with the indices for all tables in this TableSet