/*
 * Copyright 2016-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
 */
package kotlin.coroutines

// DOKKA STUB
public interface CoroutineContext {
    public operator fun <E : Element> get(key: Key<E>): E?
    public fun <R> fold(initial: R, operation: (R, Element) -> R): R
    public operator fun plus(context: CoroutineContext): CoroutineContext = TODO()
    public fun minusKey(key: Key<*>): CoroutineContext
    public interface Key<E : Element>
    public interface Element : CoroutineContext {
        public val key: Key<*>

        public override operator fun <E : Element> get(key: Key<E>): E? =
            @Suppress("UNCHECKED_CAST")
            if (this.key == key) this as E else null

        public override fun <R> fold(initial: R, operation: (R, Element) -> R): R =
            operation(initial, this)

        public override fun minusKey(key: Key<*>): CoroutineContext =
            if (this.key == key) EmptyCoroutineContext else this
    }
}

public object EmptyCoroutineContext : CoroutineContext {
    private const val serialVersionUID: Long = 0
    private fun readResolve(): Any = EmptyCoroutineContext

    public override fun <E : CoroutineContext.Element> get(key: CoroutineContext.Key<E>): E? = null
    public override fun <R> fold(initial: R, operation: (R, CoroutineContext.Element) -> R): R = initial
    public override fun plus(context: CoroutineContext): CoroutineContext = context
    public override fun minusKey(key: CoroutineContext.Key<*>): CoroutineContext = this
    public override fun hashCode(): Int = 0
    public override fun toString(): String = "EmptyCoroutineContext"
}