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/*
* Copyright 2019 Allan Wang
*
* 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 ca.allanwang.kau.utils
import android.content.Context
import android.os.Handler
import android.os.Looper
import ca.allanwang.kau.internal.KauBaseActivity
import kotlin.coroutines.CoroutineContext
import kotlin.coroutines.EmptyCoroutineContext
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.CoroutineStart
import kotlinx.coroutines.android.asCoroutineDispatcher
import kotlinx.coroutines.async
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContext
object ContextHelper : CoroutineScope {
val looper = Looper.getMainLooper()
val handler = Handler(looper)
/**
* Creating dispatcher from main handler to avoid IO
* See https://github.com/Kotlin/kotlinx.coroutines/issues/878
*/
val dispatcher = handler.asCoroutineDispatcher("kau-main")
override val coroutineContext: CoroutineContext get() = dispatcher
}
/**
* Most context items implement [CoroutineScope] by default (through [KauBaseActivity]).
* We will add a fallback just in case.
* It is expected that the scope returned always has the Android main dispatcher as part of the context.
*/
inline val Context.ctxCoroutine: CoroutineScope
get() = this as? CoroutineScope ?: ContextHelper
/**
* Calls [launch] with an explicit dispatcher for Android's main thread
*/
fun CoroutineScope.launchMain(
context: CoroutineContext = EmptyCoroutineContext,
start: CoroutineStart = CoroutineStart.DEFAULT,
block: suspend CoroutineScope.() -> Unit
) = launch(ContextHelper.dispatcher + context, start, block)
/**
* Calls [async] with an explicit dispatcher for Android's main thread
*/
fun CoroutineScope.asyncMain(
context: CoroutineContext = EmptyCoroutineContext,
start: CoroutineStart = CoroutineStart.DEFAULT,
block: suspend CoroutineScope.() -> Unit
) = async(ContextHelper.dispatcher + context, start, block)
/**
* Calls [withContext] with an explicit dispatcher for Android's main thread
*/
suspend fun <T> withMainContext(block: suspend CoroutineScope.() -> T) =
withContext(ContextHelper.dispatcher, block)
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