This is based on Implementing Fractional Indexing by David Greenspan .
Fractional indexing is a technique to create an ordering that can be used for Realtime Editing of Ordered Sequences.
This implementation includes variable-length integers, and the prepend/append optimization described in David's article.
This should be byte-for-byte compatible with https://github.com/rocicorp/fractional-indexing.
package main
import (
"fmt"
"roci.dev/fracdex"
)
func main() {
first, _ := fracdex.KeyBetween("", "") // a0
fmt.Println(first)
// Insert after 1st
second, _ := fracdex.KeyBetween(first, "") // "a1"
fmt.Println(second)
// Insert after 2nd
third, _ := fracdex.KeyBetween(second, "") // "a2"
fmt.Println(third)
// Insert before 1st
zeroth, _ := fracdex.KeyBetween("", first) // "Zz"
fmt.Println(zeroth)
// Insert in between 2nd and 3rd
secondAndHalf, _ := fracdex.KeyBetween(second, third) // "a1V"
fmt.Println(secondAndHalf)
}