unionArrayRun implementation

roaring/roaring.go

@@ -1860,8 +1860,31 @@ func unionArrayArray(a, b *container) *container {
 	return output
 }
 
+// unionArrayRun optimistically assumes that the result will be a run container,
+// and converts to a bitmap or array container afterwards if necessary.
 func unionArrayRun(a, b *container) *container {
-	return nil
+	output := &container{}
+	na, nb := len(a.array), len(b.runs)
+	var vb interval32
+	var va uint32
+	for i, j := 0, 0; i < na || j < nb; {
+		if i < na {
+			va = a.array[i]
+		}
+		if j < nb {
+			vb = b.runs[j]
+		}
+		if i < na && (j >= nb || va < vb.start) {
+			output.runAppendInterval(interval32{start: va, last: va})
+			i++
+		} else {
+			output.runAppendInterval(vb)
+			j++
+		}
+	}
+	return output
+}
+
 func (c *container) runAppendInterval(v interval32) {
 	if len(c.runs) == 0 {
 		c.runs = append(c.runs, v)
@@ -1880,9 +1903,8 @@ func unionRunRun(a, b *container) *container {
 	output := &container{
 		runs: make([]interval32, 0, na+nb),
 	}
-	i, j := 0, 0
 	var va, vb interval32
-	for i < na || j < nb {
+	for i, j := 0, 0; i < na || j < nb; {
 		if i < na {
 			va = a.runs[i]
 		}

roaring/roaring_internal_test.go

@@ -584,3 +584,43 @@ func TestUnionRunRun(t *testing.T) {
 		}
 	}
 }
+
+func TestUnionArrayRun(t *testing.T) {
+	a := &container{}
+	b := &container{}
+	tests := []struct {
+		array []uint32
+		runs  []interval32
+		exp   []interval32
+	}{
+		{
+			array: []uint32{1, 4, 5, 7, 10, 11, 12},
+			runs:  []interval32{{start: 5, last: 10}},
+			exp:   []interval32{{start: 1, last: 1}, {start: 4, last: 12}},
+		},
+		{
+			array: []uint32{},
+			runs:  []interval32{{start: 5, last: 10}},
+			exp:   []interval32{{start: 5, last: 10}},
+		},
+		{
+			array: []uint32{1, 4, 5, 7, 10, 11, 12},
+			runs:  []interval32{},
+			exp:   []interval32{{start: 1, last: 1}, {start: 4, last: 5}, {start: 7, last: 7}, {start: 10, last: 12}},
+		},
+		{
+			array: []uint32{0, 1, 4, 5, 7, 10, 11, 12},
+			runs:  []interval32{{start: 0, last: 5}, {start: 7, last: 7}},
+			exp:   []interval32{{start: 0, last: 5}, {start: 7, last: 7}, {start: 10, last: 12}},
+		},
+	}
+
+	for i, test := range tests {
+		a.array = test.array
+		b.runs = test.runs
+		ret := unionArrayRun(a, b)
+		if !reflect.DeepEqual(ret.runs, test.exp) {
+			t.Fatalf("test #%v expected %v, but got %v", i, test.exp, ret.array)
+		}
+	}
+}