1 files changed, 75 insertions, 0 deletions
diff --git a/core/src/main/kotlin/ca/allanwang/kau/utils/CoroutineUtils.kt b/core/src/main/kotlin/ca/allanwang/kau/utils/CoroutineUtils.kt
new file mode 100644
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+++ b/core/src/main/kotlin/ca/allanwang/kau/utils/CoroutineUtils.kt
@@ -0,0 +1,75 @@
+/*
+ * 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 kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.CoroutineStart
+import kotlinx.coroutines.android.asCoroutineDispatcher
+import kotlinx.coroutines.async
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+import kotlin.coroutines.CoroutineContext
+import kotlin.coroutines.EmptyCoroutineContext
+
+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.
+ * 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.
+ */
+internal 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)