Support Kotlin higher-order functions/lambdas

NativeScript supports marshalling Java bytecode generated by Kotlin. But Kotlin has a way to specify that a function takes another function in a much better way than Java.

Like this:

fun myfun(callback: (arg: String) -> Void)

It compiles to something like

public final void myfun(@org.jetbrains.annotations.NotNull final kotlin.jvm.functions.Function1<? super String, Void> callback)

where Function1 is a class containing an invoke method. Depending on how many args the function takes, it'll be called Function2, Function3 and so on.

Interacting with myfun from JavaScript would be done this way:

myfun(new kotlin.jvm.functions.Function1({ invoke: () => console.log("invoked") }))

It would be so cool if NativeScript supported Kotlin-functions out of the box, so the callback wouldn't need to be wrapped in FunctionX and myfun could be run via myfun(() => console.log("invoked")). This would make it easier to align with an Objective-C library, where blocks are supported.

To support Kotlin, my app.gradle currently looks like this:

buildscript {
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.3.3'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.2.30"
    }
}

dependencies {
  compile fileTree(dir: "libs", include: ["*.jar"])
  compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:1.2.30"
}

android {  
  defaultConfig {  
    generatedDensities = []
    applicationId = "org.nativescript.test"  
  }  
  aaptOptions {  
    additionalParameters "--no-version-vectors"  
  }  
} 

未指定仓库文件或测试。首先追踪 NativeScript Android 的 Java 字节码封送，以及 kotlin.jvm.functions.Function1、Function2 和更高元数如何表示；将其与现有的 JavaScript 回调包装路径进行比较。完成标准是 Kotlin 函数参数可以直接接收 JavaScript 回调，而无需手动构造 FunctionX 实例。