| /* |
| * Copyright 2016-2017 JetBrains s.r.o. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package kotlinx.coroutines.experimental |
| |
| import kotlinx.coroutines.experimental.CoroutineStart.* |
| import kotlinx.coroutines.experimental.intrinsics.* |
| import kotlin.coroutines.experimental.* |
| |
| /** |
| * Defines start option for coroutines builders. |
| * It is used in `start` parameter of [launch], [async], and other coroutine builder functions. |
| * |
| * The summary of coroutine start options is: |
| * * [DEFAULT] -- immediately schedules coroutine for execution according to its context; |
| * * [LAZY] -- starts coroutine lazily, only when it is needed; |
| * * [ATOMIC] -- atomically (in a non-cancellable way) schedules coroutine for execution according to its context; |
| * * [UNDISPATCHED] -- immediately executes coroutine until its first suspension point _in the current thread_. |
| */ |
| public enum class CoroutineStart { |
| /** |
| * Default -- immediately schedules coroutine for execution according to its context. |
| * |
| * If the [CoroutineDispatcher] of the coroutine context returns `true` from [CoroutineDispatcher.isDispatchNeeded] |
| * function as most dispatchers do, then the coroutine code is dispatched for execution later, while the code that |
| * invoked the coroutine builder continues execution. |
| * |
| * Note, that [Unconfined] dispatcher always returns `false` from its [CoroutineDispatcher.isDispatchNeeded] |
| * function, so starting coroutine with [Unconfined] dispatcher by [DEFAULT] is the same as using [UNDISPATCHED]. |
| * |
| * If coroutine [Job] is cancelled before it even had a chance to start executing, then it will not start its |
| * execution at all, but complete with an exception. |
| * |
| * Cancellability of coroutine at suspension points depends on the particular implementation details of |
| * suspending functions. Use [suspendCancellableCoroutine] to implement cancellable suspending functions. |
| */ |
| DEFAULT, |
| |
| /** |
| * Starts coroutine lazily, only when it is needed. |
| * |
| * See the documentation for the corresponding coroutine builders for details |
| * (like [launch] and [async]). |
| * |
| * If coroutine [Job] is cancelled before it even had a chance to start executing, then it will not start its |
| * execution at all, but complete with an exception. |
| */ |
| LAZY, |
| |
| /** |
| * Atomically (in non-cancellable way) schedules coroutine for execution according to its context. |
| * This is similar to [DEFAULT], but the coroutine cannot be cancelled before it starts executing. |
| * |
| * Cancellability of coroutine at suspension points depends on the particular implementation details of |
| * suspending functions as in [DEFAULT]. |
| */ |
| ATOMIC, |
| |
| /** |
| * Immediately executes coroutine until its first suspension point _in the current thread_ as if it the |
| * coroutine was started using [Unconfined] dispatcher. However, when coroutine is resumed from suspension |
| * it is dispatched according to the [CoroutineDispatcher] in its context. |
| * |
| * This is similar to [ATOMIC] in the sense that coroutine starts executing even if it was already cancelled, |
| * but the difference is that it start executing in the same thread. |
| * |
| * Cancellability of coroutine at suspension points depends on the particular implementation details of |
| * suspending functions as in [DEFAULT]. |
| */ |
| UNDISPATCHED; |
| |
| /** |
| * Starts the corresponding block as a coroutine with this coroutine start strategy. |
| * |
| * * [DEFAULT] uses [startCoroutineCancellable]. |
| * * [ATOMIC] uses [startCoroutine]. |
| * * [UNDISPATCHED] uses [startCoroutineUndispatched]. |
| * * [LAZY] does nothing. |
| */ |
| public operator fun <T> invoke(block: suspend () -> T, completion: Continuation<T>) = |
| when (this) { |
| CoroutineStart.DEFAULT -> block.startCoroutineCancellable(completion) |
| CoroutineStart.ATOMIC -> block.startCoroutine(completion) |
| CoroutineStart.UNDISPATCHED -> block.startCoroutineUndispatched(completion) |
| CoroutineStart.LAZY -> Unit // will start lazily |
| } |
| |
| /** |
| * Starts the corresponding block with receiver as a coroutine with this coroutine start strategy. |
| * |
| * * [DEFAULT] uses [startCoroutineCancellable]. |
| * * [ATOMIC] uses [startCoroutine]. |
| * * [UNDISPATCHED] uses [startCoroutineUndispatched]. |
| * * [LAZY] does nothing. |
| */ |
| public operator fun <R, T> invoke(block: suspend R.() -> T, receiver: R, completion: Continuation<T>) = |
| when (this) { |
| CoroutineStart.DEFAULT -> block.startCoroutineCancellable(receiver, completion) |
| CoroutineStart.ATOMIC -> block.startCoroutine(receiver, completion) |
| CoroutineStart.UNDISPATCHED -> block.startCoroutineUndispatched(receiver, completion) |
| CoroutineStart.LAZY -> Unit // will start lazily |
| } |
| |
| /** |
| * Returns `true` when [LAZY]. |
| */ |
| public val isLazy: Boolean get() = this === LAZY |
| } |