Split worksheet implementation

Author: Duhemm

language-server/src/dotty/tools/languageserver/DottyLanguageServer.scala

@@ -29,6 +29,7 @@ import Interactive.Include
 import config.Printers.interactiv
 
 import languageserver.config.ProjectConfig
+import languageserver.worksheet.Worksheet
 
 import lsp4j.services._
 

language-server/src/dotty/tools/languageserver/Worksheet.scala

@@ -0,0 +1,29 @@
+package dotty.tools.languageserver.worksheet
+
+import org.eclipse.lsp4j.jsonrpc.CancelChecker
+
+import java.util.concurrent.CancellationException
+
+/**
+ * Regularly check whether execution has been cancelled, kill REPL if it is.
+ */
+private class CancellationThread(private[this] var cancelChecker: CancelChecker,
+                                 evaluator: Evaluator) extends Thread {
+  private final val checkCancelledDelayMs = 50
+
+  override def run(): Unit = {
+    try {
+      while (evaluator.isAlive() && !Thread.interrupted()) {
+        cancelChecker.checkCanceled()
+        Thread.sleep(checkCancelledDelayMs)
+      }
+    } catch {
+      case _: CancellationException => evaluator.exit()
+      case _: InterruptedException => evaluator.exit()
+    }
+  }
+
+  def setCancelChecker(cancelChecker: CancelChecker): Unit = {
+    this.cancelChecker = cancelChecker
+  }
+}