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Implement ObservableValue<T>.asFlow() (#1789)
* Implement ObservableValue<T>.asFlow() Fixes #1695
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7 files changed

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‎ui/kotlinx-coroutines-javafx/api/kotlinx-coroutines-javafx.api

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public final class kotlinx/coroutines/javafx/JavaFxConvertKt {
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public static final fun asFlow (Ljavafx/beans/value/ObservableValue;)Lkotlinx/coroutines/flow/Flow;
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}
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public abstract class kotlinx/coroutines/javafx/JavaFxDispatcher : kotlinx/coroutines/MainCoroutineDispatcher, kotlinx/coroutines/Delay {
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public fun delay (JLkotlin/coroutines/Continuation;)Ljava/lang/Object;
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public fun dispatch (Lkotlin/coroutines/CoroutineContext;Ljava/lang/Runnable;)V

‎ui/kotlinx-coroutines-javafx/src/JavaFxConvert.kt

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/*
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* Copyright 2016-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
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*/
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package kotlinx.coroutines.javafx
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import javafx.beans.value.ChangeListener
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import javafx.beans.value.ObservableValue
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import kotlinx.coroutines.*
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import kotlinx.coroutines.channels.awaitClose
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import kotlinx.coroutines.flow.*
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/**
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* Creates an instance of a cold [Flow] that subscribes to the given [ObservableValue] and emits
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* its values as they change. The resulting flow is conflated, meaning that if several values arrive in quick
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* succession, only the last one will be emitted.
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* Since this implementation uses [ObservableValue.addListener], even if this [ObservableValue]
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* supports lazy evaluation, eager computation will be enforced while the flow is being collected.
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* All the calls to JavaFX API are performed in [Dispatchers.JavaFx].
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* This flow emits at least the initial value.
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*
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* ### Operator fusion
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*
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* Adjacent applications of [flowOn], [buffer], [conflate], and [produceIn] to the result of `asFlow` are fused.
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* [conflate] has no effect, as this flow is already conflated; one can use [buffer] to change that instead.
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*/
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@ExperimentalCoroutinesApi
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public fun <T> ObservableValue<T>.asFlow(): Flow<T> = callbackFlow<T> {
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val listener = ChangeListener<T> { _, _, newValue ->
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try {
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offer(newValue)
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} catch (e: CancellationException) {
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// In case the event fires after the channel is closed
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}
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}
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addListener(listener)
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send(value)
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awaitClose {
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removeListener(listener)
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}
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}.flowOn(Dispatchers.JavaFx).conflate()

‎ui/kotlinx-coroutines-javafx/src/JavaFxDispatcher.kt

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}
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}
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/** @return [true] if initialized successfully, and [false] if no display is detected */
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/** @return true if initialized successfully, and false if no display is detected */
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internal fun initPlatform(): Boolean = PlatformInitializer.success
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// Lazily try to initialize JavaFx platform just once

‎ui/kotlinx-coroutines-javafx/test/JavaFxTest.kt renamed to ‎ui/kotlinx-coroutines-javafx/test/JavaFxDispatcherTest.kt

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@@ -8,7 +8,7 @@ import javafx.application.*
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import kotlinx.coroutines.*
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import org.junit.*
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class JavaFxTest : TestBase() {
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class JavaFxDispatcherTest : TestBase() {
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@Before
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fun setup() {
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ignoreLostThreads("JavaFX Application Thread", "Thread-", "QuantumRenderer-", "InvokeLaterDispatcher")

‎ui/kotlinx-coroutines-javafx/test/JavaFxObservableAsFlowTest.kt

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package kotlinx.coroutines.javafx
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import javafx.beans.property.SimpleIntegerProperty
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import kotlinx.coroutines.TestBase
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import kotlinx.coroutines.*
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import kotlinx.coroutines.flow.*
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import org.junit.Before
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import org.junit.Test
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import kotlin.test.*
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class JavaFxObservableAsFlowTest : TestBase() {
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@Before
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fun setup() {
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ignoreLostThreads("JavaFX Application Thread", "Thread-", "QuantumRenderer-", "InvokeLaterDispatcher")
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}
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@Test
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fun testFlowOrder() = runTest {
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if (!initPlatform()) {
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println("Skipping JavaFxTest in headless environment")
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return@runTest // ignore test in headless environments
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}
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val integerProperty = SimpleIntegerProperty(0)
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val n = 1000
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val flow = integerProperty.asFlow().takeWhile { j -> j != n }
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newSingleThreadContext("setter").use { pool ->
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launch(pool) {
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for (i in 1..n) {
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launch(Dispatchers.JavaFx) {
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integerProperty.set(i)
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}
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}
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}
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var i = -1
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flow.collect { j ->
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assertTrue(i < (j as Int), "Elements are neither repeated nor shuffled")
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i = j
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}
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}
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}
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@Test
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fun testConflation() = runTest {
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if (!initPlatform()) {
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println("Skipping JavaFxTest in headless environment")
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return@runTest // ignore test in headless environments
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}
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withContext(Dispatchers.JavaFx) {
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val END_MARKER = -1
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val integerProperty = SimpleIntegerProperty(0)
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val flow = integerProperty.asFlow().takeWhile { j -> j != END_MARKER }
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launch {
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yield() // to subscribe to [integerProperty]
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yield() // send 0
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integerProperty.set(1)
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expect(3)
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yield() // send 1
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expect(5)
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integerProperty.set(2)
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for (i in (-100..-2)) {
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integerProperty.set(i) // should be skipped due to conflation
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}
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integerProperty.set(3)
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expect(6)
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yield() // send 2 and 3
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integerProperty.set(-1)
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}
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expect(1)
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flow.collect { i ->
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when (i) {
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0 -> expect(2)
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1 -> expect(4)
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2 -> expect(7)
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3 -> expect(8)
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else -> fail("i is $i")
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}
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}
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finish(9)
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}
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}
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}

‎ui/kotlinx-coroutines-javafx/test/JavaFxStressTest.kt

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package kotlinx.coroutines.javafx
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import javafx.beans.property.SimpleIntegerProperty
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import kotlinx.coroutines.*
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import kotlinx.coroutines.flow.first
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import org.junit.*
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class JavaFxStressTest : TestBase() {
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@Before
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fun setup() {
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ignoreLostThreads("JavaFX Application Thread", "Thread-", "QuantumRenderer-", "InvokeLaterDispatcher")
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}
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@get:Rule
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val pool = ExecutorRule(1)
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@Test
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fun testCancellationRace() = runTest {
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if (!initPlatform()) {
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println("Skipping JavaFxTest in headless environment")
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return@runTest // ignore test in headless environments
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}
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val integerProperty = SimpleIntegerProperty(0)
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val flow = integerProperty.asFlow()
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var i = 1
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val n = 1000 * stressTestMultiplier
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repeat (n) {
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launch(pool) {
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flow.first()
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}
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withContext(Dispatchers.JavaFx) {
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integerProperty.set(i)
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}
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i += 1
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}
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}
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}

‎ui/kotlinx-coroutines-javafx/test/examples/FxAsFlow.kt

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package examples
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import javafx.application.Application
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import javafx.scene.Scene
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import javafx.scene.control.*
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import javafx.scene.layout.GridPane
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import javafx.stage.Stage
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import javafx.beans.property.SimpleStringProperty
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import javafx.event.EventHandler
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import kotlinx.coroutines.*
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import kotlinx.coroutines.flow.*
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import kotlinx.coroutines.javafx.*
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import kotlin.coroutines.CoroutineContext
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fun main(args: Array<String>) {
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Application.launch(FxAsFlowApp::class.java, *args)
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}
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/**
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* Adapted from
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* https://github.com/ReactiveX/RxJavaFX/blob/a78ca7d15f7d82d201df8fafb6eba732ec17e327/src/test/java/io/reactivex/rxjavafx/RxJavaFXTest.java
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*/
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class FxAsFlowApp: Application(), CoroutineScope {
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private var job = Job()
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override val coroutineContext: CoroutineContext
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get() = JavaFx + job
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private val incrementButton = Button("Increment")
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private val incrementLabel = Label("")
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private val textInput = TextField()
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private val flippedTextLabel = Label()
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private val spinner = Spinner<Int>()
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private val spinnerChangesLabel = Label()
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public override fun start( primaryStage: Stage) {
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val gridPane = GridPane()
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gridPane.apply {
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hgap = 10.0
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vgap = 10.0
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add(incrementButton, 0, 0)
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add(incrementLabel, 1, 0)
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add(textInput, 0, 1)
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add(flippedTextLabel, 1, 1)
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add(spinner, 0, 2)
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add(spinnerChangesLabel, 1, 2)
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}
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val scene = Scene(gridPane)
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primaryStage.apply {
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width = 275.0
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setScene(scene)
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show()
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}
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}
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public override fun stop() {
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super.stop()
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job.cancel()
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job = Job()
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}
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init {
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// Initializing the "Increment" button
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val stringProperty = SimpleStringProperty()
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var i = 0
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incrementButton.onAction = EventHandler {
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i += 1
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stringProperty.set(i.toString())
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}
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launch {
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stringProperty.asFlow().collect {
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if (it != null) {
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stringProperty.set(it)
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}
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}
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}
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incrementLabel.textProperty().bind(stringProperty)
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// Initializing the reversed text field
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val stringProperty2 = SimpleStringProperty()
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launch {
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textInput.textProperty().asFlow().collect {
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if (it != null) {
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stringProperty2.set(it.reversed())
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}
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}
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}
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flippedTextLabel.textProperty().bind(stringProperty2)
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// Initializing the spinner
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spinner.valueFactory = SpinnerValueFactory.IntegerSpinnerValueFactory(0, 100)
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spinner.isEditable = true
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val stringProperty3 = SimpleStringProperty()
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launch {
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spinner.valueProperty().asFlow().collect {
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if (it != null) {
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stringProperty3.set("NEW: $it")
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}
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}
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}
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spinnerChangesLabel.textProperty().bind(stringProperty3)
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}
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}

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