Properly handle REPL snippets with exceptions ...

so the REPL remain operational after exception in one of the snippets:
- separately return script class and script instance on evaluation (
  because in case of an exception the class is valid, while the instance
  is not).
- store both the class and the instance in the history
- handle this data accordingly

libraries/scripting/common/src/kotlin/script/experimental/api/scriptEvaluation.kt

@@ -69,7 +69,7 @@ val ScriptEvaluationConfigurationKeys.constructorArgs by PropertiesCollection.ke
  * For the first snippet in a REPL an empty list should be passed explicitly
  * An array of the previous snippets will be passed to the current snippet constructor
  */
-val ScriptEvaluationConfigurationKeys.previousSnippets by PropertiesCollection.key<List<Any>>(isTransient = true)
+val ScriptEvaluationConfigurationKeys.previousSnippets by PropertiesCollection.key<List<Any?>>(isTransient = true)
 
 @Deprecated("use scriptsInstancesSharing flag instead", level = DeprecationLevel.ERROR)
 val ScriptEvaluationConfigurationKeys.scriptsInstancesSharingMap by PropertiesCollection.key<MutableMap<KClass<*>, EvaluationResult>>(isTransient = true)
@@ -134,24 +134,28 @@ fun ScriptEvaluationConfiguration.refineBeforeEvaluation(
 /**
  * The script evaluation result value
  */
-sealed class ResultValue(val scriptInstance: Any? = null) {
+sealed class ResultValue(val scriptClass: KClass<*>? = null, val scriptInstance: Any? = null) {
 
     /**
      * The result value representing a script return value - the value of the last expression in the script
      * @param name assigned name of the result field - used e.g. in REPL
      * @param value actual result value
      * @param type name of the result type
+     * @param scriptClass the loaded class of the script
      * @param scriptInstance instance of the script class
      */
-    class Value(val name: String, val value: Any?, val type: String, scriptInstance: Any) : ResultValue(scriptInstance) {
+    class Value(val name: String, val value: Any?, val type: String, scriptClass: KClass<*>, scriptInstance: Any) :
+        ResultValue(scriptClass, scriptInstance) {
+
         override fun toString(): String = "$name: $type = $value"
     }
 
     /**
      * The result value representing unit result, e.g. when the script ends with a statement
+     * @param scriptClass the loaded class of the script
      * @param scriptInstance instance of the script class
      */
-    class Unit(scriptInstance: Any) : ResultValue(scriptInstance) {
+    class Unit(scriptClass: KClass<*>, scriptInstance: Any) : ResultValue(scriptClass, scriptInstance) {
         override fun toString(): String = "Unit"
     }
 
@@ -159,8 +163,9 @@ sealed class ResultValue(val scriptInstance: Any? = null) {
      * The result value representing an exception from script itself
      * @param error the actual exception thrown on script evaluation
      * @param wrappingException the wrapping exception e.g. InvocationTargetException, sometimes useful for calculating the relevant stacktrace
+     * @param scriptClass the loaded class of the script, if any
      */
-    class Error(val error: Throwable, val wrappingException: Throwable? = null) : ResultValue() {
+    class Error(val error: Throwable, val wrappingException: Throwable? = null, scriptClass: KClass<*>? = null) : ResultValue(scriptClass) {
         override fun toString(): String = error.toString()
     }
 

libraries/scripting/jsr223-test/test/kotlin/script/experimental/jsr223/test/KotlinJsr223ScriptEngineIT.kt

@@ -85,6 +85,23 @@ class KotlinJsr223ScriptEngineIT {
         Assert.assertEquals(5, res3)
     }
 
+    @Test
+    fun testEvalWithException() {
+        val engine = ScriptEngineManager().getEngineByExtension("kts")!!
+        try {
+            engine.eval("throw Exception(\"!!\")")
+            Assert.fail("Expecting exception to propagate")
+        } catch (e: ScriptException) {
+            Assert.assertEquals("!!", e.cause?.message)
+        }
+        // engine should remain operational
+        val res1 = engine.eval("val x = 3")
+        Assert.assertNull(res1)
+        val res2 = engine.eval("x + 4")
+        Assert.assertEquals(7, res2)
+    }
+
+
     @Test
     fun testEngineRepeatWithReset() {
         val code = "open class A {}\n" +

libraries/scripting/jvm-host-test/test/kotlin/script/experimental/jvmhost/test/ReplTest.kt

@@ -80,9 +80,11 @@ class ReplTest : TestCase() {
             simpleScriptompilationConfiguration,
             simpleScriptEvaluationConfiguration,
             sequenceOf(
-                "throw RuntimeException(\"abc\")"
+                "throw RuntimeException(\"abc\")",
+                "val x = 3",
+                "x + 1"
             ),
-            sequenceOf(RuntimeException("abc"))
+            sequenceOf(RuntimeException("abc"), null, 4)
         )
     }
 
@@ -107,11 +109,12 @@ class ReplTest : TestCase() {
                     }
                 }
                 .onSuccess {
-                    it.returnValue.scriptInstance?.let { snippetInstance ->
-                        currentEvalConfig = ScriptEvaluationConfiguration(currentEvalConfig) {
-                            previousSnippets.append(snippetInstance)
+                    val snippetClass = it.returnValue.scriptClass
+                    currentEvalConfig = ScriptEvaluationConfiguration(currentEvalConfig) {
+                        previousSnippets.append(it.returnValue.scriptInstance)
+                        if (snippetClass != null) {
                             jvm {
-                                baseClassLoader(snippetInstance::class.java.classLoader)
+                                baseClassLoader(snippetClass.java.classLoader)
                             }
                         }
                     }

libraries/scripting/jvm-host/src/kotlin/script/experimental/jvmhost/jsr223/KotlinJsr223ScriptEngineImpl.kt

@@ -7,7 +7,6 @@ package kotlin.script.experimental.jvmhost.jsr223
 
 import org.jetbrains.kotlin.cli.common.repl.*
 import java.util.concurrent.locks.ReentrantReadWriteLock
-import javax.script.Bindings
 import javax.script.ScriptContext
 import javax.script.ScriptEngineFactory
 import kotlin.script.experimental.api.ScriptCompilationConfiguration
@@ -71,7 +70,7 @@ class KotlinJsr223ScriptEngineImpl(
         get() = null
 
     override val backwardInstancesHistory: Sequence<Any>
-        get() = getCurrentState(getContext()).asState(JvmReplEvaluatorState::class.java).history.asReversed().asSequence().map { it.item }
+        get() = getCurrentState(getContext()).asState(JvmReplEvaluatorState::class.java).history.asReversed().asSequence().map { it.item.second }.filterNotNull()
 
     override val baseClassLoader: ClassLoader
         get() = evaluationConfiguration[ScriptEvaluationConfiguration.jvm.baseClassLoader]!!

libraries/scripting/jvm-host/src/kotlin/script/experimental/jvmhost/repl/legacyReplEvaluation.kt

@@ -9,6 +9,7 @@ import kotlinx.coroutines.runBlocking
 import org.jetbrains.kotlin.cli.common.repl.*
 import java.util.concurrent.locks.ReentrantReadWriteLock
 import kotlin.concurrent.write
+import kotlin.reflect.KClass
 import kotlin.script.experimental.api.*
 import kotlin.script.experimental.jvm.BasicJvmScriptEvaluator
 import kotlin.script.experimental.jvm.baseClassLoader
@@ -37,15 +38,15 @@ class JvmReplEvaluator(
         val compiledScript = (compileResult.data as? KJvmCompiledScript<*>)
             ?: return ReplEvalResult.Error.CompileTime("Unable to access compiled script: ${compileResult.data}")
 
-        val lastSnippetInstance = history.peek()?.item
-        val historyBeforeSnippet = history.previousItems(compileResult.lineId)
+        val lastSnippetClass = history.peek()?.item?.first
+        val historyBeforeSnippet = history.previousItems(compileResult.lineId).map { it.second }.toList()
         val currentConfiguration = ScriptEvaluationConfiguration(baseScriptEvaluationConfiguration) {
-            if (historyBeforeSnippet.any()) {
-                previousSnippets.put(historyBeforeSnippet.toList())
+            if (historyBeforeSnippet.isNotEmpty()) {
+                previousSnippets.put(historyBeforeSnippet)
             }
-            if (lastSnippetInstance != null) {
+            if (lastSnippetClass != null) {
                 jvm {
-                    baseClassLoader(lastSnippetInstance::class.java.classLoader)
+                    baseClassLoader(lastSnippetClass.java.classLoader)
                 }
             }
             if (scriptArgs != null) {
@@ -59,17 +60,18 @@ class JvmReplEvaluator(
             is ResultWithDiagnostics.Success -> {
                 when (val retVal = res.value.returnValue) {
                     is ResultValue.Error -> {
+                        history.replaceOrPush(compileResult.lineId, retVal.scriptClass to null)
                         ReplEvalResult.Error.Runtime(
                             retVal.error.message ?: "unknown error",
                             (retVal.error as? Exception) ?: (retVal.wrappingException as? Exception)
                         )
                     }
                     is ResultValue.Value -> {
-                        history.replaceOrPush(compileResult.lineId, retVal.scriptInstance!!)
+                        history.replaceOrPush(compileResult.lineId, retVal.scriptClass to retVal.scriptInstance)
                         ReplEvalResult.ValueResult(retVal.name, retVal.value, retVal.type)
                     }
                     is ResultValue.Unit -> {
-                        history.replaceOrPush(compileResult.lineId, retVal.scriptInstance!!)
+                        history.replaceOrPush(compileResult.lineId, retVal.scriptClass to retVal.scriptInstance)
                         ReplEvalResult.UnitResult()
                     }
                     else -> throw IllegalStateException("Unexpected snippet result value $retVal")
@@ -87,8 +89,8 @@ class JvmReplEvaluator(
 open class JvmReplEvaluatorState(
     scriptEvaluationConfiguration: ScriptEvaluationConfiguration,
     override val lock: ReentrantReadWriteLock = ReentrantReadWriteLock()
-) : IReplStageState<Any> {
-    override val history: IReplStageHistory<Any> = ReplStageHistoryWithReplace(lock)
+) : IReplStageState<Pair<KClass<*>?, Any?>> {
+    override val history: IReplStageHistory<Pair<KClass<*>?, Any?>> = ReplStageHistoryWithReplace(lock)
 
     override val currentGeneration: Int get() = (history as BasicReplStageHistory<*>).currentGeneration.get()
 }

libraries/scripting/jvm/src/kotlin/script/experimental/jvm/BasicJvmScriptEvaluator.kt

@@ -41,11 +41,11 @@ open class BasicJvmScriptEvaluator : ScriptEvaluator {
 
                         compiledScript.resultField?.let { (resultFieldName, resultType) ->
                             val resultField = scriptClass.java.getDeclaredField(resultFieldName).apply { isAccessible = true }
-                            ResultValue.Value(resultFieldName, resultField.get(instance), resultType.typeName, instance)
-                        } ?: ResultValue.Unit(instance)
+                            ResultValue.Value(resultFieldName, resultField.get(instance), resultType.typeName, scriptClass, instance)
+                        } ?: ResultValue.Unit(scriptClass, instance)
 
                     } catch (e: InvocationTargetException) {
-                        ResultValue.Error(e.targetException ?: e, e)
+                        ResultValue.Error(e.targetException ?: e, e, scriptClass)
                     }
 
                     EvaluationResult(resultValue, refinedEvalConfiguration).let {