Align set with k/k apimachinery

This aligns the features of generic Set with the version in
apimachinery. The main change is that sets can be instantiated with
any comparable type, not only ordered types; as a result, SortedList()
can no longer be implemented as a method, and is replaced by the
List() function to match apimachinery.

Signed-off-by: Stephen Kitt <[email protected]>

Author: skitt

set/set.go

@@ -24,34 +24,36 @@ import (
 // string arrays and internal sets, and conversion logic requires public types today.
 type Empty struct{}
 
-// Set is a set of the same type elements, implemented via map[ordered]struct{} for minimal memory consumption.
-type Set[E ordered] map[E]Empty
+// Set is a set of the same type elements, implemented via map[comparable]struct{} for minimal memory consumption.
+type Set[E comparable] map[E]Empty
 
 // New creates a new set.
-func New[E ordered](items ...E) Set[E] {
-	ss := Set[E]{}
+// NOTE: type param must be explicitly instantiated if given items are empty.
+func New[E comparable](items ...E) Set[E] {
+	ss := make(Set[E], len(items))
 	ss.Insert(items...)
 	return ss
 }
 
 // KeySet creates a Set[E] from a keys of a map[E](? extends interface{}).
-func KeySet[E ordered, A any](theMap map[E]A) Set[E] {
+// If the value passed in is not actually a map, this will panic.
+func KeySet[E comparable, A any](theMap map[E]A) Set[E] {
 	ret := Set[E]{}
 	for key := range theMap {
 		ret.Insert(key)
 	}
 	return ret
 }
 
-// Insert adds items to the set.
+// Insert adds the given items to the set.
 func (s Set[E]) Insert(items ...E) Set[E] {
 	for _, item := range items {
 		s[item] = Empty{}
 	}
 	return s
 }
 
-// Delete removes all items from the set.
+// Delete removes the given items from the set.
 func (s Set[E]) Delete(items ...E) Set[E] {
 	for _, item := range items {
 		delete(s, item)
@@ -85,16 +87,17 @@ func (s Set[E]) HasAny(items ...E) bool {
 	return false
 }
 
-// Union returns a new set which includes items in either s1 or s2.
+// Union returns a new set which includes items in either s or s2.
 // For example:
-// s1 = {a1, a2}
+// s = {a1, a2}
 // s2 = {a3, a4}
-// s1.Union(s2) = {a1, a2, a3, a4}
-// s2.Union(s1) = {a1, a2, a3, a4}
+// s.Union(s2) = {a1, a2, a3, a4}
+// s2.Union(s) = {a1, a2, a3, a4}
 func (s Set[E]) Union(s2 Set[E]) Set[E] {
-	result := Set[E]{}
-	result.Insert(s.UnsortedList()...)
-	result.Insert(s2.UnsortedList()...)
+	result := s.Clone()
+	for k2 := range s2 {
+		result.Insert(k2)
+	}
 	return result
 }
 
@@ -103,11 +106,11 @@ func (s Set[E]) Len() int {
 	return len(s)
 }
 
-// Intersection returns a new set which includes the item in BOTH s1 and s2
+// Intersection returns a new set which includes the item in BOTH s and s2
 // For example:
-// s1 = {a1, a2}
+// s = {a1, a2}
 // s2 = {a2, a3}
-// s1.Intersection(s2) = {a2}
+// s.Intersection(s2) = {a2}
 func (s Set[E]) Intersection(s2 Set[E]) Set[E] {
 	var walk, other Set[E]
 	result := Set[E]{}
@@ -126,7 +129,7 @@ func (s Set[E]) Intersection(s2 Set[E]) Set[E] {
 	return result
 }
 
-// IsSuperset returns true if and only if s1 is a superset of s2.
+// IsSuperset returns true if and only if s is a superset of s2.
 func (s Set[E]) IsSuperset(s2 Set[E]) bool {
 	for item := range s2 {
 		if !s.Has(item) {
@@ -138,10 +141,10 @@ func (s Set[E]) IsSuperset(s2 Set[E]) bool {
 
 // Difference returns a set of objects that are not in s2
 // For example:
-// s1 = {a1, a2, a3}
+// s = {a1, a2, a3}
 // s2 = {a1, a2, a4, a5}
-// s1.Difference(s2) = {a3}
-// s2.Difference(s1) = {a4, a5}
+// s.Difference(s2) = {a3}
+// s2.Difference(s) = {a4, a5}
 func (s Set[E]) Difference(s2 Set[E]) Set[E] {
 	result := Set[E]{}
 	for key := range s {
@@ -152,7 +155,7 @@ func (s Set[E]) Difference(s2 Set[E]) Set[E] {
 	return result
 }
 
-// Equal returns true if and only if s1 is equal (as a set) to s2.
+// Equal returns true if and only if s is equal (as a set) to s2.
 // Two sets are equal if their membership is identical.
 func (s Set[E]) Equal(s2 Set[E]) bool {
 	return s.Len() == s2.Len() && s.IsSuperset(s2)
@@ -166,9 +169,12 @@ func (s sortableSlice[E]) Len() int {
 func (s sortableSlice[E]) Less(i, j int) bool { return s[i] < s[j] }
 func (s sortableSlice[E]) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
 
-// SortedList returns the contents as a sorted slice.
-func (s Set[E]) SortedList() []E {
-	res := make(sortableSlice[E], 0, s.Len())
+// List returns the contents as a sorted T slice.
+//
+// This is a separate function and not a method because not all types supported
+// by Generic are ordered and only those can be sorted.
+func List[E ordered](s Set[E]) []E {
+	res := make(sortableSlice[E], 0, len(s))
 	for key := range s {
 		res = append(res, key)
 	}
@@ -206,10 +212,10 @@ func (s Set[T]) Clone() Set[T] {
 
 // SymmetricDifference returns a set of elements which are in either of the sets, but not in their intersection.
 // For example:
-// s1 = {a1, a2, a3}
+// s = {a1, a2, a3}
 // s2 = {a1, a2, a4, a5}
-// s1.SymmetricDifference(s2) = {a3, a4, a5}
-// s2.SymmetricDifference(s1) = {a3, a4, a5}
+// s.SymmetricDifference(s2) = {a3, a4, a5}
+// s2.SymmetricDifference(s) = {a3, a4, a5}
 func (s Set[T]) SymmetricDifference(s2 Set[T]) Set[T] {
 	return s.Difference(s2).Union(s2.Difference(s))
 }

set/set_test.go

@@ -100,8 +100,9 @@ func TestNewStringSetWithMultipleStrings(t *testing.T) {
 
 func TestStringSetSortedList(t *testing.T) {
 	s := New[string]("z", "y", "x", "a")
-	if !reflect.DeepEqual(s.SortedList(), []string{"a", "x", "y", "z"}) {
-		t.Errorf("SortedList gave unexpected result: %#v", s.SortedList())
+	l := List(s)
+	if !reflect.DeepEqual(l, []string{"a", "x", "y", "z"}) {
+		t.Errorf("List gave unexpected result: %#v", l)
 	}
 }
 
@@ -122,13 +123,13 @@ func TestStringSetDifference(t *testing.T) {
 		t.Errorf("Expected len=1: %d", len(c))
 	}
 	if !c.Has("3") {
-		t.Errorf("Unexpected contents: %#v", c.SortedList())
+		t.Errorf("Unexpected contents: %#v", List(c))
 	}
 	if len(d) != 2 {
 		t.Errorf("Expected len=2: %d", len(d))
 	}
 	if !d.Has("4") || !d.Has("5") {
-		t.Errorf("Unexpected contents: %#v", d.SortedList())
+		t.Errorf("Unexpected contents: %#v", List(d))
 	}
 }
 
@@ -239,7 +240,7 @@ func TestStringUnion(t *testing.T) {
 		}
 
 		if !union.Equal(test.expected) {
-			t.Errorf("Expected union.Equal(expected) but not true.  union:%v expected:%v", union.SortedList(), test.expected.SortedList())
+			t.Errorf("Expected union.Equal(expected) but not true.  union:%v expected:%v", List(union), List(test.expected))
 		}
 	}
 }
@@ -284,7 +285,7 @@ func TestStringIntersection(t *testing.T) {
 		}
 
 		if !intersection.Equal(test.expected) {
-			t.Errorf("Expected intersection.Equal(expected) but not true.  intersection:%v expected:%v", intersection.SortedList(), test.expected.SortedList())
+			t.Errorf("Expected intersection.Equal(expected) but not true.  intersection:%v expected:%v", List(intersection), List(test.expected))
 		}
 	}
 }
@@ -295,11 +296,11 @@ func TestKeySet(t *testing.T) {
 		"goodbye": "and goodnight",
 	}
 	expected := []string{"goodbye", "hallo"}
-	gotList := KeySet(m).SortedList() // List() returns a sorted list
+	gotList := List(KeySet(m)) // List() returns a sorted list
 	if len(gotList) != len(m) {
 		t.Fatalf("got %v elements, wanted %v", len(gotList), len(m))
 	}
-	for i, entry := range KeySet(m).SortedList() {
+	for i, entry := range gotList {
 		if entry != expected[i] {
 			t.Errorf("got %v, expected %v", entry, expected[i])
 		}
@@ -312,10 +313,10 @@ func TestSetSymmetricDifference(t *testing.T) {
 	c := a.SymmetricDifference(b)
 	d := b.SymmetricDifference(a)
 	if !c.Equal(New("3", "4", "5")) {
-		t.Errorf("Unexpected contents: %#v", c.SortedList())
+		t.Errorf("Unexpected contents: %#v", List(c))
 	}
 	if !d.Equal(New("3", "4", "5")) {
-		t.Errorf("Unexpected contents: %#v", d.SortedList())
+		t.Errorf("Unexpected contents: %#v", List(d))
 	}
 }