Evaluator: Support when expressions (EA-119639)

idea/idea-jvm/src/org/jetbrains/kotlin/idea/debugger/evaluate/classLoading/AndroidOClassLoadingAdapter.kt

@@ -24,8 +24,8 @@ import com.sun.jdi.*
 import org.jetbrains.kotlin.idea.debugger.isDexDebug
 
 class AndroidOClassLoadingAdapter : AbstractAndroidClassLoadingAdapter() {
-    override fun isApplicable(context: EvaluationContextImpl, hasAdditionalClasses: Boolean, hasLoops: Boolean): Boolean {
+    override fun isApplicable(context: EvaluationContextImpl, info: ClassLoadingAdapter.Companion.ClassInfoForEvaluator) = with(info) {
-        return (hasAdditionalClasses || hasLoops) && context.debugProcess.isDexDebug()
+        isCompilingEvaluatorPreferred && context.debugProcess.isDexDebug()
     }
 
     private fun resolveClassLoaderClass(context: EvaluationContextImpl): ClassType? {

idea/idea-jvm/src/org/jetbrains/kotlin/idea/debugger/evaluate/classLoading/ClassLoadingAdapter.kt

@@ -25,9 +25,7 @@ import com.sun.jdi.ClassLoaderReference
 import com.sun.jdi.Value
 import org.jetbrains.org.objectweb.asm.ClassReader
 import org.jetbrains.org.objectweb.asm.Label
-import org.jetbrains.org.objectweb.asm.tree.ClassNode
+import org.jetbrains.org.objectweb.asm.tree.*
-import org.jetbrains.org.objectweb.asm.tree.JumpInsnNode
-import org.jetbrains.org.objectweb.asm.tree.LabelNode
 import kotlin.math.min
 
 interface ClassLoadingAdapter {
@@ -40,15 +38,15 @@ interface ClassLoadingAdapter {
         )
 
         fun loadClasses(context: EvaluationContextImpl, classes: Collection<ClassToLoad>): ClassLoaderReference? {
-            val hasAdditionalClasses = classes.size > 1
+            val mainClass = classes.firstOrNull { it.isMainClass() } ?: return null
-            val hasLoops = classes.isNotEmpty() && doesContainLoops(classes.first { it.isMainClass() }.bytes)
+
+            var info = ClassInfoForEvaluator(containsAdditionalClasses = classes.size > 1)
+            if (!info.containsAdditionalClasses) {
+                info = analyzeClass(mainClass, info)
+            }
 
             for (adapter in ADAPTERS) {
-                if (adapter.isApplicable(
+                if (adapter.isApplicable(context, info)) {
-                        context,
-                        hasAdditionalClasses = hasAdditionalClasses,
-                        hasLoops = hasLoops
-                )) {
                     return adapter.loadClasses(context, classes)
                 }
             }
@@ -56,30 +54,44 @@ interface ClassLoadingAdapter {
             return null
         }
 
-        private fun doesContainLoops(clazz: ByteArray): Boolean {
+        data class ClassInfoForEvaluator(
-            val classNode = ClassNode().apply { ClassReader(clazz).accept(this, ClassReader.EXPAND_FRAMES) }
+            val containsLoops: Boolean = false,
+            val containsCodeUnsupportedInEval4J: Boolean = false,
+            val containsAdditionalClasses: Boolean = false
+        ) {
+            val isCompilingEvaluatorPreferred: Boolean
+                get() = containsLoops || containsCodeUnsupportedInEval4J || containsAdditionalClasses
+        }
+
+        private fun analyzeClass(classToLoad: ClassToLoad, info: ClassInfoForEvaluator): ClassInfoForEvaluator {
+            val classNode = ClassNode().apply { ClassReader(classToLoad.bytes).accept(this, ClassReader.EXPAND_FRAMES) }
             val methodToRun = classNode.methods.single()
 
-            val labelsVisited = hashSetOf<Label>()
+            val visitedLabels = hashSetOf<Label>()
-            var currentInsn = methodToRun.instructions.first
+
-            while (currentInsn != null) {
+            tailrec fun analyzeInsn(insn: AbstractInsnNode, info: ClassInfoForEvaluator): ClassInfoForEvaluator {
-                if (currentInsn is LabelNode) {
+                when (insn) {
-                    labelsVisited += currentInsn.label
+                    is LabelNode -> visitedLabels += insn.label
-                }
+                    is JumpInsnNode -> {
-                else if (currentInsn is JumpInsnNode) {
+                        if (insn.label.label in visitedLabels) {
-                    if (currentInsn.label.label in labelsVisited) {
+                            return info.copy(containsLoops = true)
-                        return true
+                        }
+                    }
+                    is TableSwitchInsnNode, is LookupSwitchInsnNode -> {
+                        return info.copy(containsCodeUnsupportedInEval4J = true)
                     }
                 }
 
-                currentInsn = currentInsn.next
+                val nextInsn = insn.next ?: return info
+                return analyzeInsn(nextInsn, info)
             }
 
-            return false
+            val firstInsn = methodToRun.instructions?.first ?: return info
+            return analyzeInsn(firstInsn, info)
         }
     }
 
-    fun isApplicable(context: EvaluationContextImpl, hasAdditionalClasses: Boolean, hasLoops: Boolean): Boolean
+    fun isApplicable(context: EvaluationContextImpl, info: ClassInfoForEvaluator): Boolean
 
     fun loadClasses(context: EvaluationContextImpl, classes: Collection<ClassToLoad>): ClassLoaderReference
 

idea/idea-jvm/src/org/jetbrains/kotlin/idea/debugger/evaluate/classLoading/OrdinaryClassLoadingAdapter.kt

@@ -37,8 +37,8 @@ class OrdinaryClassLoadingAdapter : ClassLoadingAdapter {
         private val LAMBDA_SUPERCLASSES = listOf(ClassBytes("kotlin.jvm.internal.Lambda"))
     }
 
-    override fun isApplicable(context: EvaluationContextImpl, hasAdditionalClasses: Boolean, hasLoops: Boolean): Boolean {
+    override fun isApplicable(context: EvaluationContextImpl, info: ClassLoadingAdapter.Companion.ClassInfoForEvaluator) = with(info) {
-        return (hasAdditionalClasses || hasLoops) && context.classLoader != null && !context.debugProcess.isDexDebug()
+        isCompilingEvaluatorPreferred && context.classLoader != null && !context.debugProcess.isDexDebug()
     }
 
     override fun loadClasses(context: EvaluationContextImpl, classes: Collection<ClassToLoad>): ClassLoaderReference {

idea/testData/debugger/tinyApp/src/evaluate/singleBreakpoint/whenEvaluation.kt

@@ -0,0 +1,10 @@
+package whenEvaluation
+
+fun main(args: Array<String>) {
+    val a = "x"
+    //Breakpoint!
+    args.size
+}
+
+// EXPRESSION: when (a) { "a" -> "A"; "b" -> "B"; else -> "C" }
+// RESULT: "C": Ljava/lang/String;

idea/testData/debugger/tinyApp/src/evaluate/singleBreakpoint/whenEvaluation.out

@@ -0,0 +1,8 @@
+LineBreakpoint created at whenEvaluation.kt:6
+Run Java
+Connected to the target VM
+whenEvaluation.kt:6
+Compile bytecode for when (a) { "a" -> "A"; "b" -> "B"; else -> "C" }
+Disconnected from the target VM
+
+Process finished with exit code 0

idea/tests/org/jetbrains/kotlin/idea/debugger/evaluate/KotlinEvaluateExpressionTestGenerated.java

@@ -331,6 +331,11 @@ public class KotlinEvaluateExpressionTestGenerated extends AbstractKotlinEvaluat
             runTest("idea/testData/debugger/tinyApp/src/evaluate/singleBreakpoint/vars.kt");
         }
 
+        @TestMetadata("whenEvaluation.kt")
+        public void testWhenEvaluation() throws Exception {
+            runTest("idea/testData/debugger/tinyApp/src/evaluate/singleBreakpoint/whenEvaluation.kt");
+        }
+
         @TestMetadata(".kt.kt")
         public void test_kt() throws Exception {
             runTest("idea/testData/debugger/tinyApp/src/evaluate/singleBreakpoint/.kt.kt");