/
bit.go
183 lines (146 loc) · 2.87 KB
/
bit.go
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package bitset
import (
"math/bits"
)
func bucketFor(i uint64) int {
return int(i / 64)
}
func indexFor(i uint64) uint64 {
return 1 << (i % 64)
}
func New(i int) Bitset64 {
var b Bitset64
b.buckets = make([]uint64, i)
return b
}
func WithBucketsFor(i uint64) Bitset64 {
return New(bucketFor(i))
}
func FromRaw(parts ...uint64) Bitset64 {
var b Bitset64
b.buckets = parts
return b
}
func ToRawParts(b Bitset64) []uint64 {
ret := make([]uint64, len(b.buckets))
copy(ret, b.buckets)
return ret
}
type Bitset64 struct {
buckets []uint64
}
func IsEmpty(b Bitset64) bool {
for i := range b.buckets {
if b.buckets[i] != 0 {
return false
}
}
return true
}
func Copy(b Bitset64) Bitset64 {
var n Bitset64
n.buckets = make([]uint64, len(b.buckets))
copy(n.buckets, b.buckets)
return n
}
func (b *Bitset64) resize(bucket int) {
if bucket < len(b.buckets) {
return
}
buckets := make([]uint64, bucket+1)
copy(buckets, b.buckets)
b.buckets = buckets
}
func (b *Bitset64) Set(i uint64) {
bucket := bucketFor(i)
bit := indexFor(i)
b.resize(bucket)
b.buckets[bucket] |= bit
}
func (b Bitset64) Unset(i uint64) {
bucket := bucketFor(i)
if bucket >= len(b.buckets) {
return
}
b.buckets[bucket] &= ^indexFor(i)
}
func (b Bitset64) IsSet(i uint64) bool {
bucket := bucketFor(i)
if bucket >= len(b.buckets) {
return false
}
bit := indexFor(i)
return bit == (bit & b.buckets[bucket])
}
func (b Bitset64) Complement() Bitset64 {
n := Copy(b)
for i, bits := range n.buckets {
n.buckets[i] = ^bits
}
return n
}
func (b Bitset64) Intersect(n Bitset64) Bitset64 {
buckets := min(len(b.buckets), len(n.buckets))
r := Bitset64{}
r.buckets = make([]uint64, buckets)
for i := range r.buckets {
r.buckets[i] = b.buckets[i] & n.buckets[i]
}
return r
}
func (b Bitset64) Union(n Bitset64) Bitset64 {
if len(n.buckets) > len(b.buckets) {
b, n = n, b
}
ret := Copy(b)
for i, bits := range n.buckets {
ret.buckets[i] |= bits
}
return ret
}
func (b Bitset64) Difference(n Bitset64) Bitset64 {
buckets := make([]uint64, max(len(b.buckets), len(n.buckets)))
copy(buckets, n.buckets)
n.buckets = buckets
return b.Intersect(n.Complement())
}
func (b Bitset64) Eq(n Bitset64) bool {
hi, lo := b.buckets, n.buckets
if len(lo) > len(hi) {
hi, lo = lo, hi
}
if len(lo) < len(hi) {
for _, bucket := range hi[len(lo):] {
if bucket != 0 {
return false
}
}
}
for i := range lo {
if lo[i] != hi[i] {
return false
}
}
return true
}
func (b Bitset64) Len() int {
var count int
for _, bucket := range b.buckets {
for ; bucket != 0; bucket &= bucket - 1 {
count++
}
}
return count
}
func (b Bitset64) Elems() []uint64 {
var elems []uint64
for k, bucket := range b.buckets {
k := uint64(k)
for bucket != 0 {
tz := uint64(bits.TrailingZeros64(bucket))
elems = append(elems, k*64+tz)
bucket ^= (1 << tz)
}
}
return elems
}