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// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package sets implements sets of any type.
package sets
// A Set is a set of elements of some type.
type Set[Elem comparable] struct {
m map[Elem]struct{}
}
// Make makes a new set.
func Make[Elem comparable]() Set[Elem] {
return Set[Elem]{m: make(map[Elem]struct{})}
}
// Add adds an element to a set.
func (s Set[Elem]) Add(v Elem) {
s.m[v] = struct{}{}
}
// Delete removes an element from a set. If the element is not present
// in the set, this does nothing.
func (s Set[Elem]) Delete(v Elem) {
delete(s.m, v)
}
// Contains reports whether v is in the set.
func (s Set[Elem]) Contains(v Elem) bool {
_, ok := s.m[v]
return ok
}
// Len returns the number of elements in the set.
func (s Set[Elem]) Len() int {
return len(s.m)
}
// Values returns the values in the set.
// The values will be in an indeterminate order.
func (s Set[Elem]) Values() []Elem {
r := make([]Elem, 0, len(s.m))
for v := range s.m {
r = append(r, v)
}
return r
}
// Equal reports whether two sets contain the same elements.
func Equal[Elem comparable](s1, s2 Set[Elem]) bool {
if len(s1.m) != len(s2.m) {
return false
}
for v1 := range s1.m {
if !s2.Contains(v1) {
return false
}
}
return true
}
// Copy returns a copy of s.
func (s Set[Elem]) Copy() Set[Elem] {
r := Set[Elem]{m: make(map[Elem]struct{}, len(s.m))}
for v := range s.m {
r.m[v] = struct{}{}
}
return r
}
// AddSet adds all the elements of s2 to s.
func (s Set[Elem]) AddSet(s2 Set[Elem]) {
for v := range s2.m {
s.m[v] = struct{}{}
}
}
// SubSet removes all elements in s2 from s.
// Values in s2 that are not in s are ignored.
func (s Set[Elem]) SubSet(s2 Set[Elem]) {
for v := range s2.m {
delete(s.m, v)
}
}
// Intersect removes all elements from s that are not present in s2.
// Values in s2 that are not in s are ignored.
func (s Set[Elem]) Intersect(s2 Set[Elem]) {
for v := range s.m {
if !s2.Contains(v) {
delete(s.m, v)
}
}
}
// Iterate calls f on every element in the set.
func (s Set[Elem]) Iterate(f func(Elem)) {
for v := range s.m {
f(v)
}
}
// Filter deletes any elements from s for which f returns false.
func (s Set[Elem]) Filter(f func(Elem) bool) {
for v := range s.m {
if !f(v) {
delete(s.m, v)
}
}
}