|
| 1 | +/* |
| 2 | +Copyright 2022 The Kubernetes Authors. |
| 3 | +
|
| 4 | +Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | +you may not use this file except in compliance with the License. |
| 6 | +You may obtain a copy of the License at |
| 7 | +
|
| 8 | + http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | +
|
| 10 | +Unless required by applicable law or agreed to in writing, software |
| 11 | +distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | +See the License for the specific language governing permissions and |
| 14 | +limitations under the License. |
| 15 | +*/ |
| 16 | + |
| 17 | +package sets |
| 18 | + |
| 19 | +import ( |
| 20 | + "sort" |
| 21 | +) |
| 22 | + |
| 23 | +// Set is a set of the same type elements, implemented via map[comparable]struct{} for minimal memory consumption. |
| 24 | +type Set[T comparable] map[T]Empty |
| 25 | + |
| 26 | +// cast transforms specified set to generic Set[T]. |
| 27 | +func cast[T comparable](s map[T]Empty) Set[T] { return s } |
| 28 | + |
| 29 | +// New creates a Set from a list of values. |
| 30 | +// NOTE: type param must be explicitly instantiated if given items are empty. |
| 31 | +func New[T comparable](items ...T) Set[T] { |
| 32 | + ss := make(Set[T], len(items)) |
| 33 | + ss.Insert(items...) |
| 34 | + return ss |
| 35 | +} |
| 36 | + |
| 37 | +// KeySet creates a Set from a keys of a map[comparable](? extends interface{}). |
| 38 | +// If the value passed in is not actually a map, this will panic. |
| 39 | +func KeySet[T comparable, V any](theMap map[T]V) Set[T] { |
| 40 | + ret := Set[T]{} |
| 41 | + for keyValue := range theMap { |
| 42 | + ret.Insert(keyValue) |
| 43 | + } |
| 44 | + return ret |
| 45 | +} |
| 46 | + |
| 47 | +// Insert adds items to the set. |
| 48 | +func (s Set[T]) Insert(items ...T) Set[T] { |
| 49 | + for _, item := range items { |
| 50 | + s[item] = Empty{} |
| 51 | + } |
| 52 | + return s |
| 53 | +} |
| 54 | + |
| 55 | +func Insert[T comparable](set Set[T], items ...T) Set[T] { |
| 56 | + return set.Insert(items...) |
| 57 | +} |
| 58 | + |
| 59 | +// Delete removes all items from the set. |
| 60 | +func (s Set[T]) Delete(items ...T) Set[T] { |
| 61 | + for _, item := range items { |
| 62 | + delete(s, item) |
| 63 | + } |
| 64 | + return s |
| 65 | +} |
| 66 | + |
| 67 | +// Clear empties the set. |
| 68 | +// It is preferable to replace the set with a newly constructed set, |
| 69 | +// but not all callers can do that (when there are other references to the map). |
| 70 | +// In some cases the set *won't* be fully cleared, e.g. a Set[float32] containing NaN |
| 71 | +// can't be cleared because NaN can't be removed. |
| 72 | +// For sets containing items of a type that is reflexive for ==, |
| 73 | +// this is optimized to a single call to runtime.mapclear(). |
| 74 | +func (s Set[T]) Clear() Set[T] { |
| 75 | + for key := range s { |
| 76 | + delete(s, key) |
| 77 | + } |
| 78 | + return s |
| 79 | +} |
| 80 | + |
| 81 | +// Has returns true if and only if item is contained in the set. |
| 82 | +func (s Set[T]) Has(item T) bool { |
| 83 | + _, contained := s[item] |
| 84 | + return contained |
| 85 | +} |
| 86 | + |
| 87 | +// HasAll returns true if and only if all items are contained in the set. |
| 88 | +func (s Set[T]) HasAll(items ...T) bool { |
| 89 | + for _, item := range items { |
| 90 | + if !s.Has(item) { |
| 91 | + return false |
| 92 | + } |
| 93 | + } |
| 94 | + return true |
| 95 | +} |
| 96 | + |
| 97 | +// HasAny returns true if any items are contained in the set. |
| 98 | +func (s Set[T]) HasAny(items ...T) bool { |
| 99 | + for _, item := range items { |
| 100 | + if s.Has(item) { |
| 101 | + return true |
| 102 | + } |
| 103 | + } |
| 104 | + return false |
| 105 | +} |
| 106 | + |
| 107 | +// Clone returns a new set which is a copy of the current set. |
| 108 | +func (s Set[T]) Clone() Set[T] { |
| 109 | + result := make(Set[T], len(s)) |
| 110 | + for key := range s { |
| 111 | + result.Insert(key) |
| 112 | + } |
| 113 | + return result |
| 114 | +} |
| 115 | + |
| 116 | +// Difference returns a set of objects that are not in s2. |
| 117 | +// For example: |
| 118 | +// s1 = {a1, a2, a3} |
| 119 | +// s2 = {a1, a2, a4, a5} |
| 120 | +// s1.Difference(s2) = {a3} |
| 121 | +// s2.Difference(s1) = {a4, a5} |
| 122 | +func (s1 Set[T]) Difference(s2 Set[T]) Set[T] { |
| 123 | + result := New[T]() |
| 124 | + for key := range s1 { |
| 125 | + if !s2.Has(key) { |
| 126 | + result.Insert(key) |
| 127 | + } |
| 128 | + } |
| 129 | + return result |
| 130 | +} |
| 131 | + |
| 132 | +// SymmetricDifference returns a set of elements which are in either of the sets, but not in their intersection. |
| 133 | +// For example: |
| 134 | +// s1 = {a1, a2, a3} |
| 135 | +// s2 = {a1, a2, a4, a5} |
| 136 | +// s1.SymmetricDifference(s2) = {a3, a4, a5} |
| 137 | +// s2.SymmetricDifference(s1) = {a3, a4, a5} |
| 138 | +func (s1 Set[T]) SymmetricDifference(s2 Set[T]) Set[T] { |
| 139 | + return s1.Difference(s2).Union(s2.Difference(s1)) |
| 140 | +} |
| 141 | + |
| 142 | +// Union returns a new set which includes items in either s1 or s2. |
| 143 | +// For example: |
| 144 | +// s1 = {a1, a2} |
| 145 | +// s2 = {a3, a4} |
| 146 | +// s1.Union(s2) = {a1, a2, a3, a4} |
| 147 | +// s2.Union(s1) = {a1, a2, a3, a4} |
| 148 | +func (s1 Set[T]) Union(s2 Set[T]) Set[T] { |
| 149 | + result := s1.Clone() |
| 150 | + for key := range s2 { |
| 151 | + result.Insert(key) |
| 152 | + } |
| 153 | + return result |
| 154 | +} |
| 155 | + |
| 156 | +// Intersection returns a new set which includes the item in BOTH s1 and s2 |
| 157 | +// For example: |
| 158 | +// s1 = {a1, a2} |
| 159 | +// s2 = {a2, a3} |
| 160 | +// s1.Intersection(s2) = {a2} |
| 161 | +func (s1 Set[T]) Intersection(s2 Set[T]) Set[T] { |
| 162 | + var walk, other Set[T] |
| 163 | + result := New[T]() |
| 164 | + if s1.Len() < s2.Len() { |
| 165 | + walk = s1 |
| 166 | + other = s2 |
| 167 | + } else { |
| 168 | + walk = s2 |
| 169 | + other = s1 |
| 170 | + } |
| 171 | + for key := range walk { |
| 172 | + if other.Has(key) { |
| 173 | + result.Insert(key) |
| 174 | + } |
| 175 | + } |
| 176 | + return result |
| 177 | +} |
| 178 | + |
| 179 | +// IsSuperset returns true if and only if s1 is a superset of s2. |
| 180 | +func (s1 Set[T]) IsSuperset(s2 Set[T]) bool { |
| 181 | + for item := range s2 { |
| 182 | + if !s1.Has(item) { |
| 183 | + return false |
| 184 | + } |
| 185 | + } |
| 186 | + return true |
| 187 | +} |
| 188 | + |
| 189 | +// Equal returns true if and only if s1 is equal (as a set) to s2. |
| 190 | +// Two sets are equal if their membership is identical. |
| 191 | +// (In practice, this means same elements, order doesn't matter) |
| 192 | +func (s1 Set[T]) Equal(s2 Set[T]) bool { |
| 193 | + return len(s1) == len(s2) && s1.IsSuperset(s2) |
| 194 | +} |
| 195 | + |
| 196 | +type sortableSliceOfGeneric[T ordered] []T |
| 197 | + |
| 198 | +func (g sortableSliceOfGeneric[T]) Len() int { return len(g) } |
| 199 | +func (g sortableSliceOfGeneric[T]) Less(i, j int) bool { return less[T](g[i], g[j]) } |
| 200 | +func (g sortableSliceOfGeneric[T]) Swap(i, j int) { g[i], g[j] = g[j], g[i] } |
| 201 | + |
| 202 | +// List returns the contents as a sorted T slice. |
| 203 | +// |
| 204 | +// This is a separate function and not a method because not all types supported |
| 205 | +// by Generic are ordered and only those can be sorted. |
| 206 | +func List[T ordered](s Set[T]) []T { |
| 207 | + res := make(sortableSliceOfGeneric[T], 0, len(s)) |
| 208 | + for key := range s { |
| 209 | + res = append(res, key) |
| 210 | + } |
| 211 | + sort.Sort(res) |
| 212 | + return res |
| 213 | +} |
| 214 | + |
| 215 | +// UnsortedList returns the slice with contents in random order. |
| 216 | +func (s Set[T]) UnsortedList() []T { |
| 217 | + res := make([]T, 0, len(s)) |
| 218 | + for key := range s { |
| 219 | + res = append(res, key) |
| 220 | + } |
| 221 | + return res |
| 222 | +} |
| 223 | + |
| 224 | +// PopAny returns a single element from the set. |
| 225 | +func (s Set[T]) PopAny() (T, bool) { |
| 226 | + for key := range s { |
| 227 | + s.Delete(key) |
| 228 | + return key, true |
| 229 | + } |
| 230 | + var zeroValue T |
| 231 | + return zeroValue, false |
| 232 | +} |
| 233 | + |
| 234 | +// Len returns the size of the set. |
| 235 | +func (s Set[T]) Len() int { |
| 236 | + return len(s) |
| 237 | +} |
| 238 | + |
| 239 | +func less[T ordered](lhs, rhs T) bool { |
| 240 | + return lhs < rhs |
| 241 | +} |
0 commit comments