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bitmap.go
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bitmap.go
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// Package bitmap provides a []bool/bitmap implementation with standardized
// iteration. Bitmaps are the equivalent of []bool, with improved compression
// for runs of similar values, and faster operations on ranges and the like.
package bitmap
import (
"math"
"github.com/RoaringBitmap/roaring"
"github.com/anacrolix/missinggo/iter"
)
const MaxInt = -1
type BitIndex = int
type Interface interface {
Len() int
}
// Bitmaps store the existence of values in [0,math.MaxUint32] more
// efficiently than []bool. The empty value starts with no bits set.
type Bitmap struct {
RB *roaring.Bitmap
}
var ToEnd int = -1
// The number of set bits in the bitmap. Also known as cardinality.
func (me *Bitmap) Len() int {
if me.RB == nil {
return 0
}
return int(me.RB.GetCardinality())
}
func (me Bitmap) ToSortedSlice() (ret []int) {
if me.RB == nil {
return
}
for _, ui32 := range me.RB.ToArray() {
ret = append(ret, int(int32(ui32)))
}
return
}
func (me *Bitmap) lazyRB() *roaring.Bitmap {
if me.RB == nil {
me.RB = roaring.NewBitmap()
}
return me.RB
}
func (me Bitmap) Iter(cb iter.Callback) {
me.IterTyped(func(i int) bool {
return cb(i)
})
}
// Returns true if all values were traversed without early termination.
func (me Bitmap) IterTyped(f func(int) bool) bool {
if me.RB == nil {
return true
}
it := me.RB.Iterator()
for it.HasNext() {
if !f(int(it.Next())) {
return false
}
}
return true
}
func checkInt(i BitIndex) {
if i < math.MinInt32 || i > math.MaxInt32 {
panic("out of bounds")
}
}
func (me *Bitmap) Add(is ...BitIndex) {
rb := me.lazyRB()
for _, i := range is {
checkInt(i)
rb.AddInt(i)
}
}
func (me *Bitmap) AddRange(begin, end BitIndex) {
if begin >= end {
return
}
me.lazyRB().AddRange(uint64(begin), uint64(end))
}
func (me *Bitmap) Remove(i BitIndex) bool {
if me.RB == nil {
return false
}
return me.RB.CheckedRemove(uint32(i))
}
func (me *Bitmap) Union(other Bitmap) {
me.lazyRB().Or(other.lazyRB())
}
func (me *Bitmap) Contains(i int) bool {
if me.RB == nil {
return false
}
return me.RB.Contains(uint32(i))
}
func (me *Bitmap) Sub(other Bitmap) {
if other.RB == nil {
return
}
if me.RB == nil {
return
}
me.RB.AndNot(other.RB)
}
func (me *Bitmap) Clear() {
if me.RB == nil {
return
}
me.RB.Clear()
}
func (me Bitmap) Copy() (ret Bitmap) {
ret = me
if ret.RB != nil {
ret.RB = ret.RB.Clone()
}
return
}
func (me *Bitmap) FlipRange(begin, end BitIndex) {
me.lazyRB().FlipInt(begin, end)
}
func (me *Bitmap) Get(bit BitIndex) bool {
return me.RB != nil && me.RB.ContainsInt(bit)
}
func (me *Bitmap) Set(bit BitIndex, value bool) {
if value {
me.lazyRB().AddInt(bit)
} else {
if me.RB != nil {
me.RB.Remove(uint32(bit))
}
}
}
func (me *Bitmap) RemoveRange(begin, end BitIndex) *Bitmap {
if me.RB == nil {
return me
}
rangeEnd := uint64(end)
if end == ToEnd {
rangeEnd = 0x100000000
}
me.RB.RemoveRange(uint64(begin), rangeEnd)
return me
}
func (me Bitmap) IsEmpty() bool {
return me.RB == nil || me.RB.IsEmpty()
}