From 0d54e01dda81d6e96f8f31a9113af2f4a75b2f89 Mon Sep 17 00:00:00 2001
From: Chris Masone <cmasone@atticlabs.io>
Date: Tue, 15 Dec 2015 17:05:48 -0800
Subject: [PATCH 1/3] Implement compoundSet.Filter()

Implementation is based on newTypedSet(), so hopefully has similar
performance characteristics.
---
 types/compound_set.go      | 12 +++++++++++-
 types/compound_set_test.go | 24 ++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/types/compound_set.go b/types/compound_set.go
index a961a0a099..ec8649bf55 100644
--- a/types/compound_set.go
+++ b/types/compound_set.go
@@ -66,7 +66,17 @@ func (cs compoundSet) Subtract(others ...Set) Set {
 }
 
 func (cs compoundSet) Filter(cb setFilterCallback) Set {
-	panic("not implemented")
+	seq := newEmptySequenceChunker(makeSetLeafChunkFn(cs.t, cs.cs), newSetMetaSequenceChunkFn(cs.t, cs.cs), newSetLeafBoundaryChecker(), newOrderedMetaSequenceBoundaryChecker)
+
+	// Could conceivably use IterAllP() here.
+	cs.IterAll(func(v Value) {
+		if cb(v) {
+			seq.Append(v)
+		}
+	})
+
+	s := seq.Done()
+	return internalValueFromType(s, s.Type()).(Set)
 }
 
 // TODO: seek should return false if it failed to find the value
diff --git a/types/compound_set_test.go b/types/compound_set_test.go
index d96220db05..a1ae2cdb8e 100644
--- a/types/compound_set_test.go
+++ b/types/compound_set_test.go
@@ -167,3 +167,27 @@ func TestCompoundSetIterAll(t *testing.T) {
 	doTest(getTestRefToNativeOrderSet())
 	doTest(getTestRefToValueOrderSet())
 }
+
+func TestCompoundSetFilter(t *testing.T) {
+	assert := assert.New(t)
+
+	doTest := func(ts testSet) {
+		set := ts.toCompoundSet(chunks.NewMemoryStore())
+		sort.Sort(ts)
+		pivot := ts.values[10]
+		actual := set.Filter(func(v Value) bool {
+			return ts.less(v, pivot)
+		})
+
+		idx := 0
+		actual.IterAll(func(v Value) {
+			assert.True(ts.values[idx].Equals(v), "%v != %v", v, ts.values[idx])
+			idx++
+		})
+	}
+
+	doTest(getTestNativeOrderSet())
+	doTest(getTestRefValueOrderSet())
+	doTest(getTestRefToNativeOrderSet())
+	doTest(getTestRefToValueOrderSet())
+}

From 8171014b200ddbfaf60757e025cba87d984e0b61 Mon Sep 17 00:00:00 2001
From: Chris Masone <cmasone@atticlabs.io>
Date: Tue, 15 Dec 2015 17:37:25 -0800
Subject: [PATCH 2/3] remove comment

---
 types/compound_set.go | 1 -
 1 file changed, 1 deletion(-)

diff --git a/types/compound_set.go b/types/compound_set.go
index ec8649bf55..6cf73f8e15 100644
--- a/types/compound_set.go
+++ b/types/compound_set.go
@@ -68,7 +68,6 @@ func (cs compoundSet) Subtract(others ...Set) Set {
 func (cs compoundSet) Filter(cb setFilterCallback) Set {
 	seq := newEmptySequenceChunker(makeSetLeafChunkFn(cs.t, cs.cs), newSetMetaSequenceChunkFn(cs.t, cs.cs), newSetLeafBoundaryChecker(), newOrderedMetaSequenceBoundaryChecker)
 
-	// Could conceivably use IterAllP() here.
 	cs.IterAll(func(v Value) {
 		if cb(v) {
 			seq.Append(v)

From 18c446e9344c255f122e2797f474e56c81a9e2e4 Mon Sep 17 00:00:00 2001
From: Chris Masone <cmasone@atticlabs.io>
Date: Tue, 15 Dec 2015 20:08:51 -0800
Subject: [PATCH 3/3] Add set-equivalence check to unit test

---
 types/compound_set_test.go | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/types/compound_set_test.go b/types/compound_set_test.go
index a1ae2cdb8e..9bab35e0bc 100644
--- a/types/compound_set_test.go
+++ b/types/compound_set_test.go
@@ -174,10 +174,12 @@ func TestCompoundSetFilter(t *testing.T) {
 	doTest := func(ts testSet) {
 		set := ts.toCompoundSet(chunks.NewMemoryStore())
 		sort.Sort(ts)
-		pivot := ts.values[10]
+		pivotPoint := 10
+		pivot := ts.values[pivotPoint]
 		actual := set.Filter(func(v Value) bool {
 			return ts.less(v, pivot)
 		})
+		assert.True(newTypedSet(set.cs, set.t, ts.values[:pivotPoint+1]...).Equals(actual))
 
 		idx := 0
 		actual.IterAll(func(v Value) {