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@cuixin
Created Nov 8, 2018
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dummy bitset in golang
package main
import (
"encoding/binary"
"encoding/json"
"errors"
"fmt"
"strings"
"log"
)
type BitSet struct {
data []uint64
size uint
}
func New(s uint) *BitSet {
return &BitSet{
data: make([]uint64, s/64+1),
size: s/64 + 1,
}
}
func (b *BitSet) Get(i uint) bool {
v := b.data[i/64]
return v>>((i%64)-1)&1 == 1
}
func (b *BitSet) Set(i uint) bool {
if b.Get(i) {
return false
} else {
v := b.data[i/64]
offset := (i % 64) - 1
v |= 1 << offset
b.data[i/64] = v
return true
}
}
func (b BitSet) String() string {
header := fmt.Sprintf("Size [%d] Data", b.size)
strBuf := make([]string, b.size)
for i := 0; i < int(b.size); i++ {
strBuf[i] = fmt.Sprintf("%b", b.data[i])
}
return fmt.Sprintf("%s %s", header, strings.Join(strBuf, ","))
}
func (b BitSet) MarshalJSON() ([]byte, error) {
r := make([]byte, b.size*8)
for i, v := range b.data {
binary.BigEndian.PutUint64(r[i*8:], v)
}
return json.Marshal(r)
}
func (b *BitSet) UnmarshalJSON(data []byte) error {
if b == nil {
return errors.New("json.*BitSet: UnmarshalJSON on nil pointer")
}
src := make([]byte, len(data))
err := json.Unmarshal(data, &src)
if err != nil {
return err
}
bSize := len(src) / 8
if bSize > 0 && (len(src)%8) > 0 {
return errors.New("json.*BitSet: UnmarshalJSON on size illegal")
}
b.size = uint(bSize)
b.data = make([]uint64, bSize)
for i := 0; i < bSize; i++ {
b.data[i] = binary.BigEndian.Uint64(src[i*8:])
}
return nil
}
func TestBitSet() {
bs := New(65)
set := []uint{1, 2, 3, 4, 65}
for _, v := range set {
if bs.Set(v) == false {
log.Fatal("Set Cannot be false %v", v)
}
if bs.Set(v) {
log.Fatal("Set Cannot be true %v", v)
}
if !bs.Get(v) {
log.Fatal("Get Cannot be false %v", v)
}
}
}
func TestMarshal(bs *BitSet) ([]byte, error) {
return json.Marshal(bs)
}
func TestUnmarshal(data []byte) (*BitSet, error) {
bs := BitSet{}
err := json.Unmarshal(data, &bs)
return &bs, err
}
func main() {
TestBitSet()
bs := New(65)
set := []uint{1, 2, 3, 4, 65}
for _, v := range set {
bs.Set(v)
}
b, err := TestMarshal(bs)
if err != nil {
log.Fatal("Marshal BitSet error [%v]", err)
}
bs2, err := TestUnmarshal(b)
if err != nil {
log.Fatal("Unmarshal BitSet error [%v]", err)
}
fmt.Println(bs, bs2)
}
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