访问未导出的函数“ not.string”

Question

I want to convert a big.Int to simple base32. Not the standard base32 stuff like the RFC 4648 implemented by base32 nor zBase32 nor Crockford I want just simple normal 5-bits per character 0-9A-V character set.

I am aware of the base32 package and it does not do what I want - it builds the result in a standard base 32 number with padding and stuff I don't want. Certainly I could use it and tear off the trailing "=" characters and hack what remains but that just seems like a brutal solution.

There is a big.SetString(string, base) that can parse a base32 number in string form but there is no reverse - which is what I am really looking for, a big.GetString(base) like the Java BigInteger.toString(int base).

There is, however, a nat.string which does exactly what I want. How can I gain access to it?

Is there a way I could manually extend big to implement big.GetString(base) which trivially calls nat.string with the correct charset?

Is there a way I can reach into the unexported big.nat which big uses and call nat.string?

Is there something else I can do?

P.S. I'd also be interested in using nat.trailingZeroBits - I had to write my own because I didn't realise this was already done.

Answer 1

You can't access unexported functions at all. You'd need to re-write at least some portion of nat.go in order to achieve that functionality. Some of those functions look very useful, so it may be worth sending a feature request to the golang-nuts group asking for some of them to be exported in a future release.

You can however use strconv.FormatInt() to do what you require.

given a big.Int b you can do:

strconv.FormatInt(b.Int64(), 32)

Full example:

package main

import (
    "fmt"
    "math/big"
    "strconv"
)

func main() {
    i := 3286583923486565782 // Some random integer
    b := big.NewInt(int64(i))
    fmt.Println(strconv.FormatInt(b.Int64(), 32))
}

Produces:

2r72al99uq9cm

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