kotlinx-coroutines-core/common/src/flow/internal/NullSurrogate.kt

/*
 * Copyright 2016-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
 */

package kotlinx.coroutines.flow.internal

import kotlinx.coroutines.internal.*
import kotlin.jvm.*
import kotlin.native.concurrent.*

/**
 * This value is used a a surrogate `null` value when needed.
 * It should never leak to the outside world.
 * Its usage typically are paired with [Symbol.unbox] usages.
 */
@JvmField
@SharedImmutable
internal val NULL = Symbol("NULL")

/**
 * Symbol to indicate that the value is not yet initialized.
 * It should never leak to the outside world.
 */
@JvmField
@SharedImmutable
internal val UNINITIALIZED = Symbol("UNINITIALIZED")

/*
 * Symbol used to indicate that the flow is complete.
 * It should never leak to the outside world.
 */
@JvmField
@SharedImmutable
internal val DONE = Symbol("DONE")