From 50dab75c829666441a7c3c02157275c26b7fa733 Mon Sep 17 00:00:00 2001
From: Todd Gruben <tgruben@umbel.com>
Date: Fri, 15 Sep 2017 21:57:23 -0500
Subject: [PATCH] optimize unionArrayBitmap

---
 roaring/roaring.go               | 31 ++++++-------------------------
 roaring/roaring_internal_test.go | 16 ++++++++++------
 2 files changed, 16 insertions(+), 31 deletions(-)

diff --git a/roaring/roaring.go b/roaring/roaring.go
index 0ee541514..151ab7f2c 100644
--- a/roaring/roaring.go
+++ b/roaring/roaring.go
@@ -2378,33 +2378,14 @@ func (c *container) bitmapZeroRange(i, j uint64) {
 }
 
 func unionArrayBitmap(a, b *container) *container {
-	output := &container{container_type: ContainerArray}
-	itr := newBufBitmapIterator(newBitmapIterator(b.bitmap))
-	for i := 0; ; {
-		vb, eof := itr.next()
-		if i >= len(a.array) && eof {
-			break
-		} else if i >= len(a.array) {
-			output.add(vb)
-			continue
-		} else if eof {
-			output.add(a.array[i])
-			i++
-			continue
-		}
-
-		va := a.array[i]
-		if va < vb {
-			output.add(va)
-			i++
-			itr.unread()
-		} else if va > vb {
-			output.add(vb)
-		} else {
-			output.add(va)
-			i++
+	output := b.clone()
+	for _, v := range a.array {
+		if !output.bitmapContains(v) {
+			output.bitmap[v/64] |= (1 << uint64(v%64))
+			output.n++
 		}
 	}
+
 	return output
 }
 
diff --git a/roaring/roaring_internal_test.go b/roaring/roaring_internal_test.go
index d33a4d513..e711fecc8 100644
--- a/roaring/roaring_internal_test.go
+++ b/roaring/roaring_internal_test.go
@@ -647,7 +647,6 @@ func TestIntersectBitmapRunArray(t *testing.T) {
 func TestUnionMixed(t *testing.T) {
 	a := &container{}
 	b := &container{}
-	c := &container{}
 
 	a.runs = []interval16{{start: 5, last: 10}}
 	a.container_type = ContainerRun
@@ -669,24 +668,30 @@ func TestUnionMixed(t *testing.T) {
 	if !reflect.DeepEqual(res.runs, []interval16{{start: 5, last: 10}}) {
 		t.Fatalf("test #3 expected %v, but got %v", []interval16{{start: 5, last: 10}}, res.runs)
 	}
-	c.bitmap = []uint64{0x3}
+
+	c := &container{bitmap: make([]uint64, bitmapN)}
+	c.bitmap[0] = uint64(0x3)
 	c.n = 2
 	c.container_type = ContainerBitmap
 
+	expected := make([]uint64, bitmapN)
+	expected[0] = uint64(2019)
+
 	res = union(c, a)
-	if !reflect.DeepEqual(res.bitmap, []uint64{2019}) {
+	if !reflect.DeepEqual(res.bitmap, expected) {
 		t.Fatalf("test #4 expected %v, but got %v", []uint64{2019}, res.bitmap)
 	}
 	res = union(a, c)
-	if !reflect.DeepEqual(res.bitmap, []uint64{2019}) {
+	if !reflect.DeepEqual(res.bitmap, expected) {
 		t.Fatalf("test #5 expected %v, but got %v", []uint64{2019}, res.bitmap)
 	}
-
 	res = union(b, c)
+	res.bitmapToArray() //just added so test setup was easier
 	if !reflect.DeepEqual(res.array, []uint16{0, 1, 4, 5, 7, 10, 11, 12}) {
 		t.Fatalf("test #6 expected %v, but got %v", []uint16{0, 1, 4, 5, 7, 10, 11, 12}, res.array)
 	}
 	res = union(c, b)
+	res.bitmapToArray() //just added so test setup was easier
 	if !reflect.DeepEqual(res.array, []uint16{0, 1, 4, 5, 7, 10, 11, 12}) {
 		t.Fatalf("test #6 expected %v, but got %v", []uint16{0, 1, 4, 5, 7, 10, 11, 12}, res.array)
 	}
@@ -793,7 +798,6 @@ func TestDifferenceMixed(t *testing.T) {
 	}
 
 	res = difference(c, b)
-	fmt.Println(res)
 	if !reflect.DeepEqual(res.array, []uint16{5}) {
 		t.Fatalf("test #7 expected %v, but got %v", []uint16{5}, res.array)
 	}