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Enhance SuspendLazy

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Him188 2019-12-18 10:35:23 +08:00
parent 0c6e09361d
commit e90be8b93d
1 changed files with 9 additions and 15 deletions
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24
mirai-core/src/commonMain/kotlin/net.mamoe.mirai/utils/SuspendLazy.kt
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@ -2,16 +2,18 @@
package net.mamoe.mirai.utils
import kotlinx.coroutines.CompletableDeferred
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Deferred
import kotlinx.coroutines.async
import net.mamoe.mirai.contact.QQ
import kotlin.coroutines.CoroutineContext
import kotlin.coroutines.EmptyCoroutineContext
/**
* 创建一个在当前 [CoroutineScope] 下执行的 [SuspendLazy]
* 创建一个在当前 [CoroutineScope] 下执行初始化的 [SuspendLazy]
*/
fun <R> CoroutineScope.SuspendLazy(initializer: suspend () -> R): Lazy<Deferred<R>> = SuspendLazy(this, initializer)
fun <R> CoroutineScope.SuspendLazy(context: CoroutineContext = EmptyCoroutineContext, initializer: suspend () -> R): Lazy<Deferred<R>> =
SuspendLazy(this, context, initializer)
/**
* 挂起初始化的 [lazy], 是属性不能 `suspend` 的替代品.
@ -27,20 +29,12 @@ fun <R> CoroutineScope.SuspendLazy(initializer: suspend () -> R): Lazy<Deferred<
* @sample QQ.profile
*/
@PublishedApi
internal class SuspendLazy<R>(scope: CoroutineScope, initializer: suspend () -> R) : Lazy<Deferred<R>> {
private val valueUpdater: Deferred<R> by lazy { scope.async { initializer() } }
internal class SuspendLazy<R>(scope: CoroutineScope, coroutineContext: CoroutineContext = EmptyCoroutineContext, initializer: suspend () -> R) :
Lazy<Deferred<R>> {
private val valueUpdater: Deferred<R> by lazy { scope.async(context = coroutineContext) { initializer() } }
@Suppress("EXPERIMENTAL_API_USAGE")
override val value: Deferred<R>
get() = if (isInitialized()) {
CompletableDeferred(valueUpdater.getCompleted())
} else {
CompletableDeferred<R>().apply {
valueUpdater.invokeOnCompletion {
this.complete(valueUpdater.getCompleted())
}
}
}
get() = valueUpdater
override fun isInitialized(): Boolean = valueUpdater.isCompleted
}