allow for named blocks

[aem]

Kotlin supports named blocks in cases where you want to return early or return from an inner block without returning a function, the syntax is as so:

fun printNFromList(list: List<*>, count: Int) {
  list.mapIndexed a@{ item, index ->
    if (index > count) return@a
    println(item)
  }
}
printNFromList(listOf(1, 2, 3), 2)

obviously that's contrived because return@map would suffice as well, but our code sometimes requires operations like .map { .map { } } which means return@method doesn't work, named blocks are required.

[shyiko]

Hi @aem. Did you mean prevLeaf?.node?.elementType == KtTokens.AT? (compilation failed)

[aem]

whoops. yes. this is what i get for using vim 😞

[shyiko]

@aem no worries! :) Thank you for the PR! 🙇‍♂️

[aem]

@shyiko always, never a fan of people opening issues on my projects without trying to do something about it, figured i'd be a good OSS citizen myself :)

[shyiko]

@aem we might have a problem here.

I was about to release a new version of ktlint but decided to check what Intellij formatter does when asked to reformat a block of code containing lambda expression with a label and, alas, a space is inserted between @ and {.

fun foo() {
    ints.forEach lit@{
        if (it == 0) return@lit
        print(it)
    }
}

becomes

fun foo() {
    ints.forEach lit@ {
        if (it == 0) return@lit
        print(it)
    }
}

(example taken from https://kotlinlang.org/docs/reference/returns.html)
In other words, previous behavior was in line with IDEA's built-in formatter (which pretty much reflects official code style).

[aem]

interesting. looks like you're correct and we've been doing this differently in our codebase. i'm happy to update our styleguide to add the space before the brace if you want to back this change out

[shyiko]

@aem 🤝 yeah, I think it's better this way (staying as much IDEA-code-style-compatible as possible). Sorry about all the confusion.

[aem]

no worries, should've checked docs/intellij's formatting first