Iterate over a []rune | string passed in generics

Question

I am working with generics with this constrained rule:

type LineParser[T []rune | string] struct {
}

And I have this generic method of that struct:

func (it *LineParser[T]) Parser(line T)

Inside of that method I want to iterate the line but I am getting this error:

invalid operation: cannot slice line (variable of type T constrained by []rune|string): T has no core type

any suggestions?

Answer 1

Convert the line value to a []rune value before iterating. This way, every instance of the method will iterate over the same type.

type LineParser[T []rune | string] struct {}

func (it *LineParser[T]) Parser(line T) {
    for _, r := range []rune(line) {
        // do something with the next rune
        _ = r
    }
}