Bloom Filter

bf.go

package main

import "fmt"

type bloomFilter struct {
	bits          uint
	hashFunctions []hashFunction
}

type hashFunction struct {
	descriptor int
}

func (b *bloomFilter) add(val int) {
	for _, v := range b.hashFunctions {
		b.bits |= 1 << v.calc(val)
	}
}

func (b *bloomFilter) contains(val int) bool {
	for _, v := range b.hashFunctions {
		if b.bits&1<<v.calc(val) == 0 {
			return false
		}
	}
	return true
}

func (h *hashFunction) calc(val int) int {
	return val % h.descriptor
}

func main() {
	h1 := hashFunction{descriptor: 5}
	h2 := hashFunction{descriptor: 7}
	h3 := hashFunction{descriptor: 23}
	b := bloomFilter{
		bits:          0,
		hashFunctions: []hashFunction{h1, h2, h3},
	}

	b.add(3)
	b.add(10)
	b.add(25)
	fmt.Printf("%b\n", b.bits)
	fmt.Println(b.contains(3))
}