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// Copyright (C) 2022 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package containers
import (
"io"
"git.lukeshu.com/go/lowmemjson"
"golang.org/x/exp/constraints"
"git.lukeshu.com/btrfs-progs-ng/lib/maps"
)
// Set[T] is an unordered set of T.
//
// Despite Set[T] being unordered, T is required to be an ordered type
// in order that a Set[T] have a deterministic JSON representation.
type Set[T constraints.Ordered] map[T]struct{}
var (
_ lowmemjson.Encodable = Set[int]{}
_ lowmemjson.Decodable = (*Set[int])(nil)
)
func (o Set[T]) EncodeJSON(w io.Writer) error {
return lowmemjson.Encode(w, maps.SortedKeys(o))
}
func (o *Set[T]) DecodeJSON(r io.RuneScanner) error {
c, _, _ := r.ReadRune()
if c == 'n' {
_, _, _ = r.ReadRune() // u
_, _, _ = r.ReadRune() // l
_, _, _ = r.ReadRune() // l
*o = nil
return nil
}
_ = r.UnreadRune()
*o = Set[T]{}
return lowmemjson.DecodeArray(r, func(r io.RuneScanner) error {
var val T
if err := lowmemjson.Decode(r, &val); err != nil {
return err
}
(*o)[val] = struct{}{}
return nil
})
}
func NewSet[T constraints.Ordered](values ...T) Set[T] {
ret := make(Set[T], len(values))
for _, value := range values {
ret.Insert(value)
}
return ret
}
func (o Set[T]) Insert(v T) {
o[v] = struct{}{}
}
func (o Set[T]) InsertFrom(p Set[T]) {
for v := range p {
o[v] = struct{}{}
}
}
func (o Set[T]) Delete(v T) {
if o == nil {
return
}
delete(o, v)
}
func (o Set[T]) DeleteFrom(p Set[T]) {
if o == nil {
return
}
for v := range p {
delete(o, v)
}
}
func (o Set[T]) TakeOne() T {
for v := range o {
return v
}
var zero T
return zero
}
func (o Set[T]) Has(v T) bool {
_, has := o[v]
return has
}
func (small Set[T]) HasAny(big Set[T]) bool {
if len(big) < len(small) {
small, big = big, small
}
for v := range small {
if _, ok := big[v]; ok {
return true
}
}
return false
}
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