Regexp.SubexpNames in Go
SubexpNames returns the names of the parenthesized subexpressions in this Regexp. The name for the first sub-expression is names[1], so that if m is a match slice, the name for m[i] is SubexpNames()[i]. Since the Regexp as a whole cannot be named, names[0] is always the empty string. The slice should not be modified.
package main
import (
"fmt"
"regexp"
)
func main() {
re := regexp.MustCompile(`(?P<first>[a-zA-Z]+) (?P<last>[a-zA-Z]+)`)
fmt.Println(re.MatchString("Alan Turing"))
fmt.Printf("%q\n", re.SubexpNames())
reversed := fmt.Sprintf("${%s} ${%s}", re.SubexpNames()[2], re.SubexpNames()[1])
fmt.Println(reversed)
fmt.Println(re.ReplaceAllString("Alan Turing", reversed))
}