From a0d98cfb30c48f121751885b93d0d1c0aae2011f Mon Sep 17 00:00:00 2001
From: Todd Gruben <tgruben@umbel.com>
Date: Thu, 15 Jun 2017 11:13:34 -0500
Subject: [PATCH] support for difference of run and bitmap

---
 roaring/roaring.go               | 55 ++++++++++++++++++++++++++------
 roaring/roaring_internal_test.go | 28 ++++++++++++++--
 2 files changed, 71 insertions(+), 12 deletions(-)

diff --git a/roaring/roaring.go b/roaring/roaring.go
index f5bda8cf6..354bda36e 100644
--- a/roaring/roaring.go
+++ b/roaring/roaring.go
@@ -2540,7 +2540,6 @@ func differenceRunArray(a, b *container) *container {
 
 // differenceRunBitmap computes the difference of an run from a bitmap.
 func differenceRunBitmap(a, b *container) *container {
-	// TODO
 	if a.n == 0 || b.n == 0 {
 		return a.clone()
 	}
@@ -2548,16 +2547,54 @@ func differenceRunBitmap(a, b *container) *container {
 	output := &container{runs: make([]interval32, 0, a.n)}
 	itr := newBufIterator(newBitmapIterator(b.bitmap))
 
-	for i := 0; ; {
-		vb, eof := itr.next()
-		if eof {
-			break
+	vb, eof := itr.next()
+	j := 0
+	vr := a.runs[j]
+	working := !eof
+	for working {
+		switch {
+		case vb < vr.start: //before
+		case vb > vr.last: //after
+			if vr.start <= vr.last {
+				output.n += output.runAppendInterval(vr)
+			}
+			j++
+			if j < len(a.runs) {
+				vr = a.runs[j]
+			} else {
+				working = false
+			}
+		case vb == vr.start: //begining of run
+			vr.start++
+		case vb == a.runs[j].last: //end of run
+			vr.last--
+			if vr.last >= vr.start {
+				output.n += output.runAppendInterval(vr)
+			}
+			j++
+			if j < len(a.runs) {
+				vr = a.runs[j]
+			} else {
+				working = false
+			}
+		case vb > vr.start: //inside run
+			output.n += output.runAppendInterval(interval32{start: vr.start, last: vb - 1})
+			vr.start = vb + 1
+
+		}
+		vb, eof = itr.next()
+		if eof {
+			working = false
 		}
-		fmt.Println(i, vb)
-
-		i++
 	}
-
+	if vr.start <= vr.last {
+		output.n += output.runAppendInterval(vr)
+	}
+	if output.n < ArrayMaxSize && len(output.runs) > output.n/2 {
+		output.runToArray()
+	} else if len(output.runs) > RunMaxSize {
+		output.runToBitmap()
+	}
 	return output
 }
 
diff --git a/roaring/roaring_internal_test.go b/roaring/roaring_internal_test.go
index 0c4bf8e0d..29b95f52d 100644
--- a/roaring/roaring_internal_test.go
+++ b/roaring/roaring_internal_test.go
@@ -1164,8 +1164,6 @@ func TestDifferenceRunArray(t *testing.T) {
 	}
 }
 
-/*
-
 func TestDifferenceRunBitmap(t *testing.T) {
 	a := &container{}
 	b := &container{bitmap: make([]uint64, bitmapN)}
@@ -1179,6 +1177,31 @@ func TestDifferenceRunBitmap(t *testing.T) {
 			bitmap: []uint64{0x0000FFFF000000F0},
 			exp:    []interval32{{start: 0, last: 3}, {start: 8, last: 31}, {start: 48, last: 63}},
 		},
+		{
+			runs:   []interval32{{start: 0, last: 63}},
+			bitmap: []uint64{0x8000000000000000},
+			exp:    []interval32{{start: 0, last: 62}},
+		},
+		{
+			runs:   []interval32{{start: 0, last: 63}},
+			bitmap: []uint64{0x0000000000000001},
+			exp:    []interval32{{start: 1, last: 63}},
+		},
+		{
+			runs:   []interval32{{start: 0, last: 63}},
+			bitmap: []uint64{0x0, 0x0000000000000001},
+			exp:    []interval32{{start: 0, last: 63}},
+		},
+		{
+			runs:   []interval32{{start: 0, last: 65}},
+			bitmap: []uint64{0x0, 0x0000000000000001},
+			exp:    []interval32{{start: 0, last: 63}, {start: 65, last: 65}},
+		},
+		{
+			runs:   []interval32{{start: 0, last: 65}},
+			bitmap: []uint64{0x0, 0x8000000000000000},
+			exp:    []interval32{{start: 0, last: 65}},
+		},
 	}
 	for i, test := range tests {
 		a.runs = test.runs
@@ -1193,7 +1216,6 @@ func TestDifferenceRunBitmap(t *testing.T) {
 		}
 	}
 }
-*/
 
 func TestDifferenceBitmapRun(t *testing.T) {
 	a := &container{bitmap: make([]uint64, bitmapN)}