add generic sets package to utils

Author: Han Kang

sets/OWNERS

@@ -0,0 +1,10 @@
+# See the OWNERS docs at https://go.k8s.io/owners
+
+reviewers:
+  - logicalhan
+  - thockin
+  - lavalamp
+approvers:
+  - logicalhan
+  - thockin
+  - lavalamp

sets/set.go

@@ -0,0 +1,187 @@
+/*
+Copyright 2022 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package sets
+
+import "sort"
+
+type Ordered interface {
+	int | int8 | int16 | int32 | int64 | uint | uint8 | uint16 | uint32 | uint64 | uintptr | float32 | float64 | string
+}
+
+// Empty is public since it is used by some internal API objects for conversions between external
+// string arrays and internal sets, and conversion logic requires public types today.
+type Empty struct{}
+
+type Set[E Ordered] map[E]Empty
+
+// NewSet creates a new set.
+func NewSet[E Ordered](items ...E) Set[E] {
+	ss := Set[E]{}
+	ss.Insert(items...)
+	return ss
+}
+
+// NewSetFromMapKeys creates a Set[E] from a keys of a map[E](? extends interface{}).
+func NewSetFromMapKeys[E Ordered, 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.
+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.
+func (s Set[E]) Delete(items ...E) Set[E] {
+	for _, item := range items {
+		delete(s, item)
+	}
+	return s
+}
+
+// Has returns true if and only if item is contained in the set.
+func (s Set[E]) Has(item E) bool {
+	_, contained := s[item]
+	return contained
+}
+
+// HasAll returns true if and only if all items are contained in the set.
+func (s Set[E]) HasAll(items ...E) bool {
+	for _, item := range items {
+		if !s.Has(item) {
+			return false
+		}
+	}
+	return true
+}
+
+// HasAny returns true if any items are contained in the set.
+func (s Set[E]) HasAny(items ...E) bool {
+	for _, item := range items {
+		if s.Has(item) {
+			return true
+		}
+	}
+	return false
+}
+
+func (s Set[E]) Union(s2 Set[E]) Set[E] {
+	result := Set[E]{}
+	result.Insert(s.List()...)
+	result.Insert(s2.List()...)
+	return result
+}
+
+// Len returns the size of the set.
+func (s Set[E]) Len() int {
+	return len(s)
+}
+
+func (s Set[E]) Intersection(s2 Set[E]) Set[E] {
+	var walk, other Set[E]
+	result := Set[E]{}
+	if s.Len() < s2.Len() {
+		walk = s
+		other = s2
+	} else {
+		walk = s2
+		other = s
+	}
+	for key := range walk {
+		if other.Has(key) {
+			result.Insert(key)
+		}
+	}
+	return result
+}
+
+// IsSuperset returns true if and only if s1 is a superset of s2.
+func (s Set[E]) IsSuperset(s2 Set[E]) bool {
+	for item := range s2 {
+		if !s.Has(item) {
+			return false
+		}
+	}
+	return true
+}
+
+// Difference returns a set of objects that are not in s2
+// For example:
+// s1 = {a1, a2, a3}
+// s2 = {a1, a2, a4, a5}
+// s1.Difference(s2) = {a3}
+// s2.Difference(s1) = {a4, a5}
+func (s Set[E]) Difference(s2 Set[E]) Set[E] {
+	result := Set[E]{}
+	for key := range s {
+		if !s2.Has(key) {
+			result.Insert(key)
+		}
+	}
+	return result
+}
+
+// Equal returns true if and only if s1 is equal (as a set) to s2.
+// Two sets are equal if their membership is identical.
+// (In practice, this means same elements, order doesn't matter)
+func (s Set[E]) Equal(s2 Set[E]) bool {
+	return s.Len() == s.Len() && s.IsSuperset(s2)
+}
+
+type sortableSlice[E Ordered] []E
+
+func (s sortableSlice[E]) Len() int {
+	return len(s)
+}
+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] }
+
+// List returns the contents as a sorted int slice.
+func (s Set[E]) List() []E {
+	res := make(sortableSlice[E], 0, s.Len())
+	for key := range s {
+		res = append(res, key)
+	}
+	sort.Sort(res)
+	return res
+}
+
+// UnsortedList returns the slice with contents in random order.
+func (s Set[E]) UnsortedList() []E {
+	res := make(sortableSlice[E], 0, len(s))
+	for key := range s {
+		res = append(res, key)
+	}
+	return res
+}
+
+// PopAny returns a single element from the set.
+func (s Set[E]) PopAny() (E, bool) {
+	for key := range s {
+		s.Delete(key)
+		return key, true
+	}
+	var zeroValue E
+	return zeroValue, false
+}