Rename filter funcs and clean up docs

attribute/set.go

@@ -263,7 +263,7 @@ func NewSetWithSortableFiltered(kvs []KeyValue, tmp *Sortable, filter Filter) (S
 
 	*tmp = nil
 
-	uniq := filterBack(kvs, func() func(kv KeyValue) bool {
+	uniq := filteredToFront(kvs, func() func(kv KeyValue) bool {
 		firstCall := true
 		var prev Key
 		return func(kv KeyValue) bool {
@@ -283,7 +283,7 @@ func NewSetWithSortableFiltered(kvs []KeyValue, tmp *Sortable, filter Filter) (S
 	if filter != nil {
 		// Unique prior to filtering so the returned dropped attributes will
 		// not also include the deduplicated attributes.
-		k := filterFront(kvs, filter)
+		k := filteredToBack(kvs, filter)
 		if k == len(kvs) {
 			return Set{equivalent: computeDistinct(kvs[:k])}, nil
 		}
@@ -293,10 +293,11 @@ func NewSetWithSortableFiltered(kvs []KeyValue, tmp *Sortable, filter Filter) (S
 	return Set{equivalent: computeDistinct(kvs)}, nil
 }
 
-// filterFront filters the slice in-place using f. All kept KeyValues are moved
-// to the front of slice (in order), and all dropped KeyValues are moved the
-// end. The index for the first dropped KeyValue is returned.
-func filterFront(slice []KeyValue, f Filter) int {
+// filteredToBack filters slice in-place using f. All KeyValues that need to be
+// removed are moved to the end. All KeyValues that need to be kept are moved
+// (in-order) to the front. The index for the first KeyValue to be removed is
+// returned.
+func filteredToBack(slice []KeyValue, f Filter) int {
 	n := len(slice)
 	if n == 0 {
 		return 0
@@ -312,10 +313,11 @@ func filterFront(slice []KeyValue, f Filter) int {
 	return j + 1
 }
 
-// filterBack filters the slice in-place using f. All kept KeyValues are moved
-// to the end of slice (in order), and all dropped KeyValues are moved the
-// front. The index for the first kept KeyValue is returned.
-func filterBack(slice []KeyValue, f Filter) int {
+// filteredToFront filters slice in-place using f. All KeyValues that need to
+// be removed are moved to the front. All KeyValues that need to be kept are
+// moved (in-order) to the back. The index for the first KeyValue to be kept is
+// returned.
+func filteredToFront(slice []KeyValue, f Filter) int {
 	n := len(slice)
 	if n == 0 {
 		return 0
@@ -365,7 +367,7 @@ func (l *Set) Filter(re Filter) (Set, []KeyValue) {
 	end := len(slice) - 1
 	slice[start], slice[end] = slice[end], slice[start]
 
-	div := filterFront(slice[start:end], re) + start
+	div := filteredToBack(slice[start:end], re) + start
 	return Set{equivalent: computeDistinct(slice[:div])}, slice[div:]
 }
 

attribute/set_internal_test.go

@@ -72,22 +72,22 @@ func TestFilters(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
-			t.Run("filterFront", func(t *testing.T) {
+			t.Run("filteredToBack", func(t *testing.T) {
 				in := make([]KeyValue, len(test.in))
 				copy(in, test.in)
 
-				k := filterFront(in, test.fltr)
+				k := filteredToBack(in, test.fltr)
 				require.Equal(t, len(test.kept), k, "partition index")
 
 				assert.Equal(t, test.kept, in[:k], "kept")
 				assert.ElementsMatch(t, test.drop, in[k:], "dropped")
 			})
 
-			t.Run("filterBack", func(t *testing.T) {
+			t.Run("filteredToFront", func(t *testing.T) {
 				in := make([]KeyValue, len(test.in))
 				copy(in, test.in)
 
-				k := filterBack(in, test.fltr)
+				k := filteredToFront(in, test.fltr)
 				require.Equal(t, len(test.drop), k, "partition index")
 
 				assert.ElementsMatch(t, test.drop, in[:k], "dropped")