astef/bitmask

Arbitrary size bitmask (aka bitset) with efficient Slice method

bitmask

Arbitrary size bitmask (aka bitset) with efficient Slice method.

.Slice doesn't create copies of the underlying buffer, just like Go slices

bm := bitmask.New(4)        // [4]{0000}
bm.Set(3)                   // [4]{0001}
bm.Slice(2, 4).ToggleAll()  // [4]{0010}
bm.Slice(1, 3).ToggleAll()  // [4]{0100}
bm.Slice(0, 2).ToggleAll()  // [4]{1000}
bm.ClearAll()               // [4]{0000}

It's safe to copy overlapping bitmasks, which were created by slicing the original one

base := bitmask.New(10)
base.Set(0)
base.Set(9)                 // [10]{1000000001}

src := base.Slice(0, 8)     // [8]{10000000}
dst := base.Slice(2, 10)    // [8]{00000001}

bitmask.Copy(dst, src)

fmt.Println(base)

[10]{1010000000}

Iteration

bm := bitmask.New(5)
bm.Set(0)
bm.Set(3)

it := bm.Iterator()
for {
    ok, value, index := it.Next()
    if !ok {
        break
    }

    // use the value
    fmt.Printf("%v) %v\n", index, value)
}

0) true
1) false
2) false
3) true
4) false

.String() is O(1), it starts stripping after 512 bits

bm := bitmask.New(513)
bm.Slice(255, 321).SetAll()
fmt.Println(bm)

[513]{0000000000000000000000000000000000000000000000000000000000000000 0000000000000000000000000000000000000000000000000000000000000000 0000000000000000000000000000000000000000000000000000000000000000 0000000000000000000000000000000000000000000000000000000000000001 <more 64 bits> 1000000000000000000000000000000000000000000000000000000000000000 0000000000000000000000000000000000000000000000000000000000000000 0000000000000000000000000000000000000000000000000000000000000000 0}