generate all combinations of sets of interface{} sets

gistfile1.go

package main

import "fmt"

type Set []interface{}

func Combinations(s []Set) Set {
	lens := make([]int, len(s))
	length := 1
	for i, v := range s {
		lens[i] = len(v)
		length = length * lens[i]
	}

	pad := 1
	res := make([][]int, len(s))
	for i := len(s) - 1; i >= 0; i-- {
		setLength := lens[i]
		row := make([]int, length)
		index := 0
		for k := 0; k < (length / setLength / pad); k++ {
			for i := 0; i < setLength; i++ {
				for p := 0; p < pad; p++ {
					row[index] = i
					index++
				}
			}
		}
		res[i] = row
		pad = pad * setLength
	}

	r := Set{}
	for i := 0; i < length; i++ {
		q := make([]interface{}, len(s))
		for j := 0; j < len(s); j++ {
			q[j] = s[j][res[j][i]]
		}
		r = append(r, q)
	}

	return r
}

func main() {
	s1 := Set{"a", "b", "c"}
	s2 := Set{1, 2, 3}
	s3 := Set{"A", "B"}

	sx := []Set{s1, s2, s3}

	r := Combinations(sx)

	fmt.Println(r)
}