Hi friends! <In this code>, I ended up using `var` , but I was wondering if there was a way of getti...

# codereview

[Paulo Cereda]

Hi friends! In this code, I ended up using var , but I was wondering if there was a way of getting rid of them (just as a personal challenge). Of course, my life would be easier if BreakIterator could implement Iterable, but no luck. 😉 Here's the code added for convenience:

fun toGraphemes(str: String) = buildList {
    val boundary = BreakIterator.getCharacterInstance()
    boundary.setText(str)
    var start = boundary.first()
    var end = boundary.next()
    while (end != BreakIterator.DONE) {
        add(str.substring(start, end))
        start = end
        end = boundary.next()
    }
}

Any suggestion is welcome! Thank you! 🦆

[Klitos Kyriacou]

Not an answer, but Iterator doesn't implement Iterable, so why should BreakIterator?

[Paulo Cereda]

Sorry, I didn't mean it should actually implement Iterable, it was more as a joke. 🙂 I will clarify in the original post, sorry!

[ephemient]

anything can be used in a for loop if there is an operator fun iterator(): Iterator<?>, for example

operator fun BreakIterator.iterator(): Iterator<IntRange> = iterator {
    var start = first()
    while (true) {
        val end = next()
        if (end == BreakIterator.DONE) {
            break
        }
        yield(start until end)
        start = end
    }
}

val text = "Hello, world!"
val breakIterator = BreakIterator.getWordInstance()
breakIterator.setText(text)
for (range in breakIterator) {
    println(text.substring(range))
}

prints

Hello
,
 
world
!

[Paulo Cereda]

@ephemient This is brilliant, thank you so much! I've so much to learn!

[ephemient]

this isn't meant to be an obscure feature of Kotlin either; kotlin-stdlib contains a

operator fun <T> Iterator<T>.iterator(): Iterator<T> = this

so while Iterator doesn't implement Iterable, you can write

for (i in iterator)