Kotlin property delegate utils

1_property.kt

import kotlin.properties.ReadOnlyProperty
import kotlin.properties.ReadWriteProperty
import kotlin.reflect.KProperty

private typealias GetValue<This, R> = (thisRef: This, property: KProperty<*>) -> R
private typealias SetValue<This, R> = (thisRef: This, property: KProperty<*>, value: R) -> Unit

inline fun <This, R> property(
    crossinline getValue: GetValue<This, R>
) =
    object : ReadOnlyProperty<This, R> {
        override fun getValue(thisRef: This, property: KProperty<*>) = getValue(thisRef, property)
    }

inline fun <This, R> property(
    crossinline getValue: GetValue<This, R>,
    crossinline setValue: SetValue<This, R>
) =
    object : ReadWriteProperty<This, R> {
        override fun getValue(thisRef: This, property: KProperty<*>) = getValue(thisRef, property)
        override fun setValue(thisRef: This, property: KProperty<*>, value: R) = setValue(thisRef, property, value)
    }

2_propertyDelegate.kt

import kotlin.reflect.KProperty
import kotlin.SinceKotlin

private typealias ProvideDelegate<This, Delegate> = (thisRef: This, property: KProperty<*>) -> Delegate

@SinceKotlin("1.1") // provideDelegate
interface PropertyDelegateProvider<This, Delegate : Any> {
    operator fun provideDelegate(thisRef: This, property: KProperty<*>): Delegate
}

@SinceKotlin("1.1") // provideDelegate
inline fun <This, Delegate : Any> propertyDelegate(
    crossinline provideDelegate: ProvideDelegate<This, Delegate>
) =
    object : PropertyDelegateProvider<This, Delegate> {
        override fun provideDelegate(thisRef: This, property: KProperty<*>) = provideDelegate(thisRef, property)
    }

3_sample.kt

import kotlin.properties.Delegates
import kotlin.properties.ReadWriteProperty

// top-level

val sampleGet: String by property { thisRef, property -> "" }
var sampleSet: String by property({ thisRef, property -> "" }, { thisRef, property, value -> })

val sampleProvideGet by propertyDelegate<Nothing?, Lazy<String>> { thisRef, property -> lazy { "" } }
var sampleProvideSet by propertyDelegate<Nothing?, ReadWriteProperty<Nothing?, String>> { thisRef, property -> Delegates.notNull() }

class InsideClass {
    
    val sampleGet: String by property { thisRef, property -> "" }
    var sampleSet: String by property({ thisRef, property -> "" }, { thisRef, property, value -> })

    val sampleProvideGet by propertyDelegate<InsideClass, Lazy<String>> { thisRef, property -> lazy { "" } }
    var sampleProvideSet by propertyDelegate<InsideClass, ReadWriteProperty<InsideClass, String>> { thisRef, property -> Delegates.notNull() }
}