made JetFile implements JetElement

compiler/frontend/src/org/jetbrains/jet/lang/psi/JetElementImpl.java

@@ -55,13 +55,7 @@ public class JetElementImpl extends ASTWrapperPsiElement implements JetElement {
 
     @Override
     public <D> void acceptChildren(@NotNull JetTreeVisitor<D> visitor, D data) {
-        PsiElement child = getFirstChild();
-        while (child != null) {
-            if (child instanceof JetElement) {
-                ((JetElement) child).accept(visitor, data);
-            }
-            child = child.getNextSibling();
-        }
+        JetPsiUtil.visitChildren(this, visitor, data);
     }
 
     @Override

compiler/frontend/src/org/jetbrains/jet/lang/psi/JetFile.java

@@ -34,7 +34,7 @@ import org.jetbrains.jet.plugin.JetLanguage;
 
 import java.util.List;
 
-public class JetFile extends PsiFileBase implements JetDeclarationContainer {
+public class JetFile extends PsiFileBase implements JetDeclarationContainer, JetElement {
     public JetFile(FileViewProvider viewProvider) {
         super(viewProvider, JetLanguage.INSTANCE);
     }
@@ -111,10 +111,25 @@ public class JetFile extends PsiFileBase implements JetDeclarationContainer {
     @Override
     public void accept(@NotNull PsiElementVisitor visitor) {
         if (visitor instanceof JetVisitorVoid) {
-            ((JetVisitorVoid) visitor).visitJetFile(this);
+            accept((JetVisitorVoid) visitor);
         }
         else {
             visitor.visitFile(this);
         }
     }
+
+    @Override
+    public <D> void acceptChildren(@NotNull JetTreeVisitor<D> visitor, D data) {
+        JetPsiUtil.visitChildren(this, visitor, data);
+    }
+
+    @Override
+    public void accept(@NotNull JetVisitorVoid visitor) {
+        visitor.visitJetFile(this);
+    }
+
+    @Override
+    public <R, D> R accept(@NotNull JetVisitor<R, D> visitor, D data) {
+        return visitor.visitJetFile(this, data);
+    }
 }

compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java

@@ -51,6 +51,16 @@ public class JetPsiUtil {
     private JetPsiUtil() {
     }
 
+    public static <D> void visitChildren(@NotNull JetElement element, @NotNull JetTreeVisitor<D> visitor, D data) {
+        PsiElement child = element.getFirstChild();
+        while (child != null) {
+            if (child instanceof JetElement) {
+                ((JetElement) child).accept(visitor, data);
+            }
+            child = child.getNextSibling();
+        }
+    }
+
     @Nullable
     public static JetExpression deparenthesizeWithNoTypeResolution(@NotNull JetExpression expression) {
         return deparenthesizeWithResolutionStrategy(expression, null);