Debugger: get topmost element at offset as contextElement

idea/idea-analysis/src/org/jetbrains/kotlin/idea/caches/resolve/CodeFragmentAnalyzer.kt

@@ -70,8 +70,13 @@ public class CodeFragmentAnalyzer(
                    is JetDeclarationWithBody -> this.getBodyExpression()
                    is JetBlockExpression -> this.getStatements().lastOrNull()
                    else -> {
-                       this.siblings(forward = false, withItself = false).firstIsInstanceOrNull<JetExpression>()
-                       ?: this.parents.firstIsInstanceOrNull<JetExpression>()
+                       val previousSibling = this.siblings(forward = false, withItself = false).firstIsInstanceOrNull<JetExpression>()
+                       if (previousSibling != null) return previousSibling
+                       for (parent in this.parents) {
+                           if (parent is JetWhenEntry || parent is JetIfExpression || parent is JetBlockExpression) return this
+                           if (parent is JetExpression) return parent
+                       }
+                       null
                    }
                } ?: this
     }

idea/src/org/jetbrains/kotlin/idea/codeInsight/CodeInsightUtils.java

@@ -284,4 +284,25 @@ public class CodeInsightUtils {
 
         return element;
     }
+
+    @Nullable
+    public static <T> T getTopmostElementAtOffset(@NotNull PsiElement element, int offset, @NotNull Class<T> klass) {
+        T lastElementOfType = null;
+        if (klass.isInstance(element)) {
+            lastElementOfType = (T) element;
+        }
+        do {
+            PsiElement parent = element.getParent();
+            if (parent == null || (parent.getTextOffset() < offset) || parent instanceof JetBlockExpression) {
+                break;
+            }
+            if (klass.isInstance(parent)) {
+                lastElementOfType = (T) parent;
+            }
+            element = parent;
+        }
+        while(true);
+
+        return lastElementOfType;
+    }
 }

idea/src/org/jetbrains/kotlin/idea/debugger/evaluate/KotlinCodeFragmentFactory.kt

@@ -37,14 +37,17 @@ import com.sun.jdi.PrimitiveValue
 import com.sun.jdi.Value
 import org.jetbrains.kotlin.asJava.KotlinLightClass
 import org.jetbrains.kotlin.idea.JetFileType
+import org.jetbrains.kotlin.idea.codeInsight.CodeInsightUtils
 import org.jetbrains.kotlin.idea.core.refactoring.j2kText
 import org.jetbrains.kotlin.idea.debugger.KotlinEditorTextProvider
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.getElementTextWithContext
 import org.jetbrains.kotlin.types.JetType
+import org.jetbrains.kotlin.utils.addToStdlib.check
 import java.util.HashMap
 import java.util.concurrent.atomic.AtomicReference
+import kotlin.reflect.jvm.java
 
 class KotlinCodeFragmentFactory: CodeFragmentFactory() {
     private val LOG = Logger.getInstance(this.javaClass)
@@ -143,14 +146,21 @@ class KotlinCodeFragmentFactory: CodeFragmentFactory() {
             val containingFile = elementAt.containingFile
             if (containingFile !is JetFile) return null
 
-            val expressionAtOffset = PsiTreeUtil.findElementOfClassAtOffset(containingFile, elementAt.textOffset, javaClass<JetExpression>(), false)
-            if (expressionAtOffset != null && KotlinEditorTextProvider.isAcceptedAsCodeFragmentContext(elementAt)) {
-                return expressionAtOffset
+            var result = PsiTreeUtil.findElementOfClassAtOffset(containingFile, elementAt.textOffset, javaClass<JetExpression>(), false)
+            if (result.check()) {
+                return CodeInsightUtils.getTopmostElementAtOffset(result!!, result.textOffset, JetExpression::class.java)
             }
 
-            return KotlinEditorTextProvider.findExpressionInner(elementAt, true) ?: containingFile
+            result = KotlinEditorTextProvider.findExpressionInner(elementAt, true)
+            if (result.check()) {
+                return result
+            }
+
+            return containingFile
         }
 
+        private fun JetElement?.check(): Boolean = this != null && this.check { KotlinEditorTextProvider.isAcceptedAsCodeFragmentContext(it) } != null
+
         //internal for tests
         fun createCodeFragmentForLabeledObjects(project: Project, markupMap: Map<*, ValueMarkup>): Pair<String, Map<String, Value>> {
             val sb = StringBuilder()

idea/testData/checker/codeFragments/smartCasts.kt

@@ -1,6 +1,6 @@
 fun foo() {
     val a: Int? = 1
     if (a != null) {
-        <caret> a
+        <caret>a
     }
 }