Merge pull request #297 from seiflotfy/better-bitmap

optimise bitmaps

bitmapcontainer.go

@@ -113,7 +113,7 @@ type bitmapContainerShortIterator struct {
 
 func (bcsi *bitmapContainerShortIterator) next() uint16 {
 	j := bcsi.i
-	bcsi.i = bcsi.ptr.NextSetBit(bcsi.i + 1)
+	bcsi.i = bcsi.ptr.NextSetBit(uint(bcsi.i) + 1)
 	return uint16(j)
 }
 func (bcsi *bitmapContainerShortIterator) hasNext() bool {
@@ -126,7 +126,7 @@ func (bcsi *bitmapContainerShortIterator) peekNext() uint16 {
 
 func (bcsi *bitmapContainerShortIterator) advanceIfNeeded(minval uint16) {
 	if bcsi.hasNext() && bcsi.peekNext() < minval {
-		bcsi.i = bcsi.ptr.NextSetBit(int(minval))
+		bcsi.i = bcsi.ptr.NextSetBit(uint(minval))
 	}
 }
 
@@ -1007,20 +1007,23 @@ func (bc *bitmapContainer) fillArray(container []uint16) {
 	}
 }
 
-func (bc *bitmapContainer) NextSetBit(i int) int {
-	x := i / 64
-	if x >= len(bc.bitmap) {
+func (bc *bitmapContainer) NextSetBit(i uint) int {
+	var (
+		x      = i / 64
+		length = uint(len(bc.bitmap))
+	)
+	if x >= length {
 		return -1
 	}
 	w := bc.bitmap[x]
 	w = w >> uint(i%64)
 	if w != 0 {
-		return i + countTrailingZeros(w)
+		return int(i) + countTrailingZeros(w)
 	}
 	x++
-	for ; x < len(bc.bitmap); x++ {
+	for ; x < length; x++ {
 		if bc.bitmap[x] != 0 {
-			return (x * 64) + countTrailingZeros(bc.bitmap[x])
+			return int(x*64) + countTrailingZeros(bc.bitmap[x])
 		}
 	}
 	return -1

bitmapcontainer_test.go

@@ -1,9 +1,10 @@
 package roaring
 
 import (
-	"github.com/stretchr/testify/assert"
 	"math/rand"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
 // bitmapContainer's numberOfRuns() function should be correct against the runContainer equivalent
@@ -169,7 +170,7 @@ func TestBitmapNextSet(t *testing.T) {
 
 	m := 0
 
-	for n := 0; m < testSize; n, m = bc.NextSetBit(n+1), m+1 {
+	for n := 0; m < testSize; n, m = bc.NextSetBit(uint(n)+1), m+1 {
 		assert.Equal(t, m, n)
 	}
 

roaring_test.go

@@ -1744,7 +1744,7 @@ func validate(bc *bitmapContainer, ac *arrayContainer) bool {
 	// Checking that the two containers contain the same values
 	counter := 0
 
-	for i := bc.NextSetBit(0); i >= 0; i = bc.NextSetBit(i + 1) {
+	for i := bc.NextSetBit(0); i >= 0; i = bc.NextSetBit(uint(i) + 1) {
 		counter++
 		if !ac.contains(uint16(i)) {
 			log.Println("content differs")