Simple dependency providers primitives.

MutableProviderImpl.kt

package provider

internal class MutableProviderImpl<T>(
    scope: ProviderScope? = null,
    private val factory: InstanceFactory<T>? = null,
) : ReadWriteProvider<T> {

    init {
        require(scope is ProviderScopeImpl)
        scope.listeners.add { value = null }
    }

    private var value: T? = null

    override fun set(value: T) {
        this.value = value
    }

    override fun get(): T {
        if (value == null) {
            value = factory?.invoke()
        }
        return requireNotNull(value)
    }
}

ProviderFactory.kt

@file:Suppress("FunctionName")

package provider

public fun <T : Any> LateInitProvider(): ReadWriteProvider<T> = MutableProviderImpl()

public fun <T> MutableProvider(): ReadWriteProvider<T?> = MutableProviderImpl()

public fun <T> MutableProvider(
    factory: InstanceFactory<T>,
): ReadWriteProvider<T> = MutableProviderImpl(factory = factory)

public fun <T> SingleProvider(
    factory: InstanceFactory<T>,
): ReadOnlyProvider<T> = MutableProviderImpl(factory = factory)

public fun <T> ScopedProvider(
    scope: ProviderScope,
    factory: InstanceFactory<T>,
): ReadOnlyProvider<T> = MutableProviderImpl(scope = scope, factory = factory)

public fun <T> TransientProvider(
    factory: InstanceFactory<T>,
): ReadOnlyProvider<T> = TransientProviderImpl(factory = factory)

ProviderScope.kt

package provider

public sealed interface ProviderScope {
    public fun clear()
}

public fun ProviderScope(): ProviderScope = ProviderScopeImpl()

ProviderScopeImpl.kt

package provider

internal class ProviderScopeImpl internal constructor(
    var listeners: MutableSet<OnClearListener> = mutableSetOf(),
) : ProviderScope {

    override fun clear() {
        listeners.forEach { it.invoke() }
    }
}

ReadOnlyProvider.kt

package provider

import kotlin.reflect.KProperty

public sealed interface ReadOnlyProvider<T> {
    public fun get(): T
}

/**
 * Permits property delegation of `val`s using `by` for [ReadOnlyProvider].
 */
@Suppress("NOTHING_TO_INLINE")
public inline operator fun <T> ReadOnlyProvider<T>.getValue(thisObj: Any?, property: KProperty<*>): T = get()

ReadWriteProvider.kt

package provider

public sealed interface ReadWriteProvider<T> : ReadOnlyProvider<T>, WriteOnlyProvider<T>

TransientProviderImpl.kt

package provider

internal class TransientProviderImpl<T>(
    private val factory: InstanceFactory<T>,
) : ReadOnlyProvider<T> {

    override fun get(): T = factory.invoke()
}

Typealiases.kt

package provider

internal typealias OnClearListener = () -> Unit

internal typealias InstanceFactory<T> = () -> T

WriteOnlyProvider.kt

package provider

import kotlin.reflect.KProperty

public interface WriteOnlyProvider<T> {
    public fun set(value: T)
}

/**
 * Permits property delegation of `var`s using `by` for [WriteOnlyProvider].
 */
@Suppress("NOTHING_TO_INLINE")
public inline operator fun <T> WriteOnlyProvider<T>.setValue(thisObj: Any?, property: KProperty<*>, value: T) {
    set(value)
}