Can you regexp.Split a string with regexp not containing word in golang?

I write a function which takes a string list of numbers, list items separator reg and range separator reg like:

func ParseList(list string, ls, rs *regexp.Regexp) (...) {
  ...
  for _, item := range ls.Split(list, -1) {
    for _, rng := range rs.Split(item, -1) {
      range_start, _ := strconv.ParseInt(rng[0])
      range_end := range_start
      if len(rng) > 1 {
        range_end, _ = strconv.ParseInt(rng[1])
      }
      ... save or analyse range
    }
  }
  ...
}

Input string could be, but not limited to:
1,3,5-10,15-20
1;3;5-10;15-20
1 3 5 to 10 15 to 20

So for first example regexps are easy, but third gives a problem, because list separator is " " and range separator also has " ".

UPDATE:

So i followed Trung Duong's suggestion and switched from "splitter" to "extractor" regexp like this:

func ParseList(list string, ex, rs *regexp.Regexp) (...) {
  ...
  for _, item := range ex.FindAllString(list, -1) {
    for _, rng := range rs.Split(item, -1) {
      range_start, _ := strconv.ParseInt(rng[0])
      range_end := range_start
      if len(rng) > 1 {
        range_end, _ = strconv.ParseInt(rng[1])
      }
      ... save or analyse range
    }
  }
  ...
}

So now i can use (\d+-\d+)|(\d+) or (\d+ to \d+)|(\d+) to extract ranges, and then split them.

You could use this pattern: (\d+\s+to\s+\d+)|(\d+)

See regex demo here.

Here is the algorithm You need.
We can simply do this with the help of iterations.

package main

import (
    "fmt"
    "strconv"
    "strings"
)

func main() {
    inputString := "1 2 7 to 10 15 16 to 20"

    // Split the string by space to get individual elements
    elements := strings.Split(inputString, " ")

    // Initialize a slice to store the output
    output := []string{}

    // Iterate through the elements
    i := 0
    for i < len(elements) {
        // If the element contains "to", it means it's a range
        if strings.Contains(elements[i], "to") {
            // Get the start and end of the range
            rangeEnds := strings.Split(elements[i], "to")
            start, _ := strconv.Atoi(rangeEnds[0])
            end, _ := strconv.Atoi(rangeEnds[1])
            // Add the range to the output
            output = append(output, fmt.Sprintf("%d to %d", start, end))
            i++
        } else {
            // If the element is not a range, simply add it to the output
            output = append(output, elements[i])
            i++
        }
    }

    // Print the output
    for _, element := range output {
        fmt.Println(element)
    }
}

OUTPUT:

1
2
7 to 10
15
16 to 20