Anyone has any idea how to write an external for s...

# javascript

[Tomasz Krakowiak]

Anyone has any idea how to write an external for such declaration (WebIDL):

enum DOMParserSupportedType {
  "text/html",
  "text/xml",
  "application/xml",
  "application/xhtml+xml",
  "image/svg+xml"
};

😅

[Big Chungus]

How is that declared on js side?

[Marc Knaup]

I think it’s just a string.

So the legit way would be something like this:

external interface DOMParserSupportedType

object DOMParserSupportedTypeStatic {

    inline val text_html get() = "text/html".unsafeCast<DOMParserSupportedType>()
    inline val text_xml get() = "text/xml".unsafeCast<DOMParserSupportedType>()
    inline val application_xml get() = "application/xml".unsafeCast<DOMParserSupportedType>()
    inline val application_xhtml_xml get() = "application/xhtml+xml".unsafeCast<DOMParserSupportedType>()
    inline val image_svg_xml get() = "image/svg+xml".unsafeCast<DOMParserSupportedType>()
}

And nicer usage but quite unsafe:

external interface DOMParserSupportedType {

    @Suppress(
        "INLINE_EXTERNAL_DECLARATION",
        "NAME_CONTAINS_ILLEGAL_CHARS",
        "NESTED_CLASS_IN_EXTERNAL_INTERFACE",
        "ObjectPropertyName",
        "WRONG_BODY_OF_EXTERNAL_DECLARATION",
    )
    companion object {

        inline val `text/html` get() = "text/html".unsafeCast<DOMParserSupportedType>()
        inline val `text/xml` get() = "text/xml".unsafeCast<DOMParserSupportedType>()
        inline val `application/xml` get() = "application/xml".unsafeCast<DOMParserSupportedType>()
        inline val `application/xhtml+xml` get() = "application/xhtml+xml".unsafeCast<DOMParserSupportedType>()
        inline val `image/svg+xml` get() = "image/svg+xml".unsafeCast<DOMParserSupportedType>()
    }
}

[Big Chungus]

If it's just a string, why make it external?

typealias DOMParserSupportedType = String

inline val DOMParserSupportedType.text_html: DOMParserSupportedType get() = "text/html"
// others

[Marc Knaup]

Because typealias drops type safety

[Marc Knaup]

val x: DOMParserSupportedType = "foo"

[Big Chungus]

In what way? String is a String

[Marc Knaup]

It’s an enum. It’s just represented as a string.

[Tomasz Krakowiak]

@Marc Knaup That's probably fine, since js enums are just strings.

[Big Chungus]

Ah, you're right

[Big Chungus]

Looks like the best approach is this:

external interface DOMParserSupportedType {
  companion object
}
inline val DOMParserSupportedType.Companion.text_html get() = "text/html".unsafeCast<DOMParserSupportedType>()
// others

[Tomasz Krakowiak]

TS declarations can be found in - https://github.com/microsoft/TypeScript/blob/master/src/lib/dom.generated.d.ts
Specification can be found - https://html.spec.whatwg.org/multipage/dynamic-markup-insertion.html
I'm actually not writing this code by hand. I'm working on WebIDL -> Kotlin compiler

[Marc Knaup]

@Big Chungus a companion object within an external interface is not legit. At least not in IR.

[Marc Knaup]

@Tomasz Krakowiak you can use Dukat to automatically create external definitions from TypeScript definitions. See what it comes up with 🙂

[Big Chungus]

Then this "might" (emphasis on might) work

external interface DOMParserSupportedType
inline val DOMParserSupportedType.Companion.text_html get() = "text/html".unsafeCast<DOMParserSupportedType>()
// others

[Marc Knaup]

@Big Chungus no, because there is no Companion.

[Marc Knaup]

Okay, Dukat doesn’t work. Kotlin’s stdlib already has DOMParser definitions and simply uses dynamic for DOMParserSupportedType 😮

[Tomasz Krakowiak]

Ok. Thanks everyone : ) I'll try Dukat. I think it supports WebIDL as well : ) (with at least one exception I support ; p)

[Marc Knaup]

image.png

[turansky]

https://pl.kotl.in/Xn953tRm-

[turansky]

And following works in IR with suppresses
https://pl.kotl.in/mCQRt3SfR

[turansky]

Screen Shot 2020-11-27 at 9.59.59 AM.png

[turansky]

If you need external interface companions - you can vote here

[Tomasz Krakowiak]

Tried to go with something like - https://pl.kotl.in/d6LfPhnBD
But I got some duplicated declarations. (NOTE: I am also looking for server-side support of reasonable portion of web APIs)