J2K: got rid from Converter.convertElement + fixed local classes conversion

#KT-5202 Fixed

j2k/src/org/jetbrains/jet/j2k/Converter.kt

@@ -218,7 +218,7 @@ public class Converter private(val project: Project, val settings: ConverterSett
         else -> throw IllegalArgumentException("Unknown member: $member")
     }
 
-    private fun convertClass(psiClass: PsiClass): Class {
+    fun convertClass(psiClass: PsiClass): Class {
         val annotations = convertAnnotations(psiClass)
         var modifiers = convertModifiers(psiClass)
         val typeParameters = convertTypeParameterList(psiClass.getTypeParameterList())
@@ -258,11 +258,12 @@ public class Converter private(val project: Project, val settings: ConverterSett
         val modifiers = convertModifiers(field)
         val name = field.declarationIdentifier()
         val converted = if (field is PsiEnumConstant) {
+            val argumentList = field.getArgumentList()
             EnumConstant(name,
                          annotations,
                          modifiers,
                          typeConverter.convertType(field.getType(), Nullability.NotNull),
-                         convertElement(field.getArgumentList()))
+                         ExpressionList(convertExpressions(argumentList?.getExpressions())).assignPrototype(argumentList))
         }
         else {
             val isVal = isVal(field)
@@ -418,13 +419,16 @@ public class Converter private(val project: Project, val settings: ConverterSett
         return expressionVisitor.result.assignPrototype(expression)
     }
 
-    //TODO: drop this method - it has unclear semantics
-    fun convertElement(element: PsiElement?): Element {
-        if (element == null) return Element.Empty
-
-        val elementVisitor = ElementVisitor(this)
-        element.accept(elementVisitor)
-        return elementVisitor.result.assignPrototype(element)
+    fun convertLocalVariable(variable: PsiLocalVariable): LocalVariable {
+        val isVal = variable.hasModifierProperty(PsiModifier.FINAL) ||
+                variable.getInitializer() == null/* we do not know actually and prefer val until we have better analysis*/ ||
+                !variable.hasWriteAccesses(variable.getContainingMethod())
+        return LocalVariable(variable.declarationIdentifier(),
+                               convertAnnotations(variable),
+                               convertModifiers(variable),
+                               variableTypeToDeclare(variable, settings.specifyLocalVariableTypeByDefault, isVal),
+                               convertExpression(variable.getInitializer(), variable.getType()),
+                               isVal).assignPrototype(variable)
     }
 
     fun convertCodeReferenceElement(element: PsiJavaCodeReferenceElement, hasExternalQualifier: Boolean, typeArgsConverted: List<Element>? = null): ReferenceElement {

j2k/src/org/jetbrains/jet/j2k/ast/TypeParameters.kt

@@ -61,8 +61,9 @@ class TypeParameterList(val parameters: List<TypeParameter>) : Element() {
     }
 }
 
-fun Converter.convertTypeParameter(psiTypeParameter: PsiTypeParameter): TypeParameter {
-    return convertElement(psiTypeParameter) as TypeParameter
+private fun Converter.convertTypeParameter(typeParameter: PsiTypeParameter): TypeParameter {
+    return TypeParameter(typeParameter.declarationIdentifier(),
+                           typeParameter.getExtendsListTypes().map { typeConverter.convertType(it) }).assignPrototype(typeParameter)
 }
 
 fun Converter.convertTypeParameterList(typeParameterList: PsiTypeParameterList?): TypeParameterList {

j2k/src/org/jetbrains/jet/j2k/visitors/ElementVisitor.kt

@@ -1,57 +0,0 @@
-/*
- * Copyright 2010-2013 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.jetbrains.jet.j2k.visitors
-
-import com.intellij.psi.*
-import org.jetbrains.jet.j2k.*
-import org.jetbrains.jet.j2k.ast.*
-
-class ElementVisitor(private val converter: Converter) : JavaElementVisitor() {
-    private val typeConverter = converter.typeConverter
-
-    public var result: Element = Element.Empty
-        protected set
-
-    override fun visitLocalVariable(variable: PsiLocalVariable) {
-        val isVal = variable.hasModifierProperty(PsiModifier.FINAL) ||
-                variable.getInitializer() == null/* we do not know actually and prefer val until we have better analysis*/ ||
-                !variable.hasWriteAccesses(variable.getContainingMethod())
-        result = LocalVariable(variable.declarationIdentifier(),
-                               converter.convertAnnotations(variable),
-                               converter.convertModifiers(variable),
-                               converter.variableTypeToDeclare(variable, converter.settings.specifyLocalVariableTypeByDefault, isVal),
-                               converter.convertExpression(variable.getInitializer(), variable.getType()),
-                               isVal)
-    }
-
-    override fun visitExpressionList(list: PsiExpressionList) {
-        result = ExpressionList(converter.convertExpressions(list.getExpressions()))
-    }
-
-    override fun visitTypeElement(`type`: PsiTypeElement) {
-        result = TypeElement(typeConverter.convertType(`type`.getType()))
-    }
-
-    override fun visitTypeParameter(classParameter: PsiTypeParameter) {
-        result = TypeParameter(classParameter.declarationIdentifier(),
-                               classParameter.getExtendsListTypes().map { typeConverter.convertType(it) })
-    }
-
-    override fun visitParameterList(list: PsiParameterList) {
-        result = converter.convertParameterList(list)
-    }
-}

j2k/src/org/jetbrains/jet/j2k/visitors/ExpressionVisitor.kt

@@ -122,10 +122,6 @@ open class ExpressionVisitor(private val converter: Converter) : JavaElementVisi
                              expression.isInSingleLine())
     }
 
-    override fun visitExpressionList(list: PsiExpressionList) {
-        result = ExpressionList(converter.convertExpressions(list.getExpressions()))
-    }
-
     override fun visitInstanceOfExpression(expression: PsiInstanceOfExpression) {
         val checkType = expression.getCheckType()
         result = IsOperator(converter.convertExpression(expression.getOperand()),

j2k/src/org/jetbrains/jet/j2k/visitors/StatementVisitor.kt

@@ -73,7 +73,13 @@ open class StatementVisitor(public val converter: Converter) : JavaElementVisito
     }
 
     override fun visitDeclarationStatement(statement: PsiDeclarationStatement) {
-        result = DeclarationStatement(statement.getDeclaredElements().map { converter.convertElement(it) })
+        result = DeclarationStatement(statement.getDeclaredElements().map {
+            when (it) {
+                is PsiLocalVariable -> converter.convertLocalVariable(it)
+                is PsiClass -> converter.convertClass(it)
+                else -> Element.Empty //what else can be here?
+            }
+        })
     }
 
     override fun visitDoWhileStatement(statement: PsiDoWhileStatement) {

j2k/tests/test/org/jetbrains/jet/j2k/test/JavaToKotlinConverterTestGenerated.java

@@ -2364,6 +2364,11 @@ public class JavaToKotlinConverterTestGenerated extends AbstractJavaToKotlinConv
             doTest("j2k/tests/testData/ast/nullability/MethodReturnsNullInAnonymousClass.java");
         }
         
+        @TestMetadata("MethodReturnsNullInLocalClass.java")
+        public void testMethodReturnsNullInLocalClass() throws Exception {
+            doTest("j2k/tests/testData/ast/nullability/MethodReturnsNullInLocalClass.java");
+        }
+        
         @TestMetadata("MethodReturnsTernaryNull.java")
         public void testMethodReturnsTernaryNull() throws Exception {
             doTest("j2k/tests/testData/ast/nullability/MethodReturnsTernaryNull.java");

j2k/tests/testData/ast/nullability/MethodReturnsNullInLocalClass.java

@@ -1,9 +1,8 @@
-//file
 class C {
     String foo() {
         class Local {
             String foo() { return null; }
-        };
+        }
         new Local().foo();
         return "";
     }

j2k/tests/testData/ast/nullability/MethodReturnsNullInLocalClass.kt

@@ -0,0 +1,11 @@
+class C {
+    fun foo(): String {
+        class Local {
+            fun foo(): String? {
+                return null
+            }
+        }
+        Local().foo()
+        return ""
+    }
+}