migrate to Scala 3 new control syntax

Author: bjornregnell

src/main/scala/introprog/BlockGame.scala

@@ -85,11 +85,11 @@ abstract class BlockGame(
     * It draws only updated blocks aiming at the desired frame rate.
     * It calls each `onXXX` method if a corresponding event is detected.
     */
-  protected def gameLoop(stopWhen: => Boolean): Unit = while (!stopWhen) {
+  protected def gameLoop(stopWhen: => Boolean): Unit = while !stopWhen do {
     import PixelWindow.Event
     val t0 = System.currentTimeMillis
     pixelWindow.awaitEvent(MaxWaitForEventMillis.toLong)
-    while (pixelWindow.lastEventType != PixelWindow.Event.Undefined) {
+    while pixelWindow.lastEventType != PixelWindow.Event.Undefined do {
       pixelWindow.lastEventType match {
         case Event.KeyPressed    => onKeyDown(pixelWindow.lastKey)
         case Event.KeyReleased   => onKeyUp(pixelWindow.lastKey)
@@ -103,17 +103,17 @@ abstract class BlockGame(
     gameLoopAction()
     drawUpdatedBlocks()
     val elapsed = System.currentTimeMillis - t0
-    if ((gameLoopDelayMillis - elapsed) < MaxWaitForEventMillis) {
+    if (gameLoopDelayMillis - elapsed) < MaxWaitForEventMillis then {
       onFrameTimeOverrun(elapsed)
     }
     Thread.sleep((gameLoopDelayMillis - elapsed) max 0)
   }
 
   /** Draw updated blocks and carry out post-update actions if any. */
   private def drawUpdatedBlocks(): Unit = {
-    for (x <- blockBuffer.indices) {
-      for (y <- blockBuffer(x).indices) {
-        if (isBufferUpdated(x)(y)) {
+    for x <- blockBuffer.indices do {
+      for y <- blockBuffer(x).indices do {
+        if isBufferUpdated(x)(y) then {
           val pwx = x * blockSize
           val pwy = y * blockSize
           pixelWindow.fill(pwx, pwy, blockSize, blockSize, blockBuffer(x)(y))
@@ -129,24 +129,24 @@ abstract class BlockGame(
   def clearWindow(): Unit = {
     pixelWindow.clear()
     clearMessageArea()
-    for (x <- blockBuffer.indices) {
-      for (y <- blockBuffer(x).indices) {
+    for x <- blockBuffer.indices do {
+      for y <- blockBuffer(x).indices do {
           blockBuffer(x)(y) = background
       }
     }
   }
 
   /** Paint a block in color `c` at (`x`,`y`) in block coordinates. */
   def drawBlock(x: Int, y: Int, c: Color): Unit = {
-    if (blockBuffer(x)(y) != c) {
+    if blockBuffer(x)(y) != c then {
       blockBuffer(x)(y) = c
       isBufferUpdated(x)(y) = true
     }
   }
 
   /** Erase the block at (`x`,`y`) to `background` color. */
   def eraseBlock(x: Int, y: Int): Unit = {
-    if (blockBuffer(x)(y) != background) {
+    if blockBuffer(x)(y) != background then {
       blockBuffer(x)(y) = background
       isBufferUpdated(x)(y) = true
     }

src/main/scala/introprog/PixelWindow.scala

@@ -166,7 +166,7 @@ class PixelWindow(
       }
 
     case ke: java.awt.event.KeyEvent =>
-      if (ke.getKeyChar == java.awt.event.KeyEvent.CHAR_UNDEFINED || ke.getKeyChar < ' ')
+      if ke.getKeyChar == java.awt.event.KeyEvent.CHAR_UNDEFINED || ke.getKeyChar < ' ' then
         _lastKeyText = PixelWindow.keyTextLookup.getOrElse(ke.getKeyCode, java.awt.event.KeyEvent.getKeyText(ke.getKeyCode))
       else _lastKeyText = ke.getKeyChar.toString
 
@@ -203,7 +203,7 @@ class PixelWindow(
     */
   def awaitEvent(timeoutInMillis: Long = 1): Unit = {
     val e = eventQueue.poll(timeoutInMillis, java.util.concurrent.TimeUnit.MILLISECONDS)
-    if (e != null) handleEvent(e) else _lastEventType = Event.Undefined
+    if e != null then handleEvent(e) else _lastEventType = Event.Undefined
   }
 
   /** Draw a line from (`x1`, `y1`) to (`x2`, `y2`) using `color` and `lineWidth`. */

src/main/scala/introprog/Swing.scala

@@ -31,7 +31,7 @@ object Swing {
 
   /** Test if the current operating system name includes `partOfName`. */
   def isOS(partOfName: String): Boolean =
-    if (partOfName.toLowerCase.startsWith("win") && isInProc("windows", "wsl", "microsoft")) true //WSL
+    if partOfName.toLowerCase.startsWith("win") && isInProc("windows", "wsl", "microsoft") then true //WSL
     else scala.sys.props("os.name").toLowerCase.contains(partOfName.toLowerCase)
 
   /** Check whether `/proc/version` on this filesystem contains any of the strings in `parts`. 
@@ -45,16 +45,16 @@ object Swing {
   private var isInit = false
 
   /** Init the Swing GUI toolkit and set platform-specific look and feel.*/
-  def init(): Unit = if (!isInit) {
+  def init(): Unit = if !isInit then {
     setPlatformSpecificLookAndFeel()
     isInit = true
   }
 
   private def setPlatformSpecificLookAndFeel(): Unit = {
     import javax.swing.UIManager.setLookAndFeel
-    if (isOS("win")) findLookAndFeel("win").foreach(setLookAndFeel)
-    else if (isOS("linux")) findLookAndFeel("gtk").foreach(setLookAndFeel)
-    else if (isOS("mac")) findLookAndFeel("apple").foreach(setLookAndFeel)
+    if isOS("win") then findLookAndFeel("win").foreach(setLookAndFeel)
+    else if isOS("linux") then findLookAndFeel("gtk").foreach(setLookAndFeel)
+    else if isOS("mac") then findLookAndFeel("apple").foreach(setLookAndFeel)
     else javax.swing.UIManager.setLookAndFeel(
       javax.swing.UIManager.getSystemLookAndFeelClassName()
     )

src/main/scala/introprog/examples/TestBlockGame.scala

@@ -55,7 +55,7 @@ object TestBlockGame {
       def rndPos: (Int, Int) = (nextInt(dim._1), nextInt(dim._2))
       def rndColor = new java.awt.Color(nextInt(256), nextInt(256), nextInt(256))
       print(".")
-      if (isDrawingRandomBlocks) {
+      if isDrawingRandomBlocks then {
         drawBlock(rndPos._1, rndPos._2, rndColor)
       }
     }

src/main/scala/introprog/examples/TestIO.scala

@@ -17,7 +17,7 @@ object TestIO {
     val highscores2 = IO.loadObject[Map[Person, Int]]("highscores.ser")
 
     val isSameContents = highscores2 == highscores
-    val testResult = if (isSameContents) "SUCCESS :)" else "FAILURE :("
+    val testResult = if isSameContents then "SUCCESS :)" else "FAILURE :("
     assert(isSameContents, s"$highscores != $highscores2")
     println(s"$highscores == $highscores2\n$testResult")
 

src/main/scala/introprog/examples/TestPixelWindow.scala

@@ -34,10 +34,10 @@ object TestPixelWindow {
     square(150,200, 50)
     w.line(0,0,w.width,w.height)
 
-    while (w.lastEventType != Event.WindowClosed) {
+    while w.lastEventType != Event.WindowClosed do {
       w.awaitEvent(10)  // wait for next event for max 10 milliseconds
 
-      if (w.lastEventType != Event.Undefined) {
+      if w.lastEventType != Event.Undefined then {
         println(s"lastEventType: ${w.lastEventType} => ${Event.show(w.lastEventType)}")
       }