diff --git a/gen/org/intellij/grammar/psi/BnfTypes.java b/gen/org/intellij/grammar/psi/BnfTypes.java
index 2d342808..b03de77c 100644
--- a/gen/org/intellij/grammar/psi/BnfTypes.java
+++ b/gen/org/intellij/grammar/psi/BnfTypes.java
@@ -81,9 +81,6 @@ else if (type == BNF_ATTR_PATTERN) {
       else if (type == BNF_CHOICE) {
         return new BnfChoiceImpl(node);
       }
-      else if (type == BNF_EXPRESSION) {
-        return new BnfExpressionImpl(node);
-      }
       else if (type == BNF_EXTERNAL_EXPRESSION) {
         return new BnfExternalExpressionImpl(node);
       }
diff --git a/gen/org/intellij/grammar/psi/impl/BnfExpressionImpl.java b/gen/org/intellij/grammar/psi/impl/BnfExpressionImpl.java
index 6e4f18c6..e60155c2 100644
--- a/gen/org/intellij/grammar/psi/impl/BnfExpressionImpl.java
+++ b/gen/org/intellij/grammar/psi/impl/BnfExpressionImpl.java
@@ -24,7 +24,7 @@
 import static org.intellij.grammar.psi.BnfTypes.*;
 import org.intellij.grammar.psi.*;
 
-public class BnfExpressionImpl extends BnfCompositeElementImpl implements BnfExpression {
+public abstract class BnfExpressionImpl extends BnfCompositeElementImpl implements BnfExpression {
 
   public BnfExpressionImpl(ASTNode node) {
     super(node);
diff --git a/gen/org/intellij/jflex/psi/JFlexTypes.java b/gen/org/intellij/jflex/psi/JFlexTypes.java
index d83ac19b..5907e422 100644
--- a/gen/org/intellij/jflex/psi/JFlexTypes.java
+++ b/gen/org/intellij/jflex/psi/JFlexTypes.java
@@ -156,9 +156,6 @@ else if (type == FLEX_CLASS_EXPRESSION) {
       else if (type == FLEX_DECLARATIONS_SECTION) {
         return new JFlexDeclarationsSectionImpl(node);
       }
-      else if (type == FLEX_EXPRESSION) {
-        return new JFlexExpressionImpl(node);
-      }
       else if (type == FLEX_JAVA_CODE) {
         return new JFlexJavaCodeImpl(node);
       }
diff --git a/gen/org/intellij/jflex/psi/impl/JFlexExpressionImpl.java b/gen/org/intellij/jflex/psi/impl/JFlexExpressionImpl.java
index 16edfb8c..1d982034 100644
--- a/gen/org/intellij/jflex/psi/impl/JFlexExpressionImpl.java
+++ b/gen/org/intellij/jflex/psi/impl/JFlexExpressionImpl.java
@@ -24,7 +24,7 @@
 import static org.intellij.jflex.psi.JFlexTypes.*;
 import org.intellij.jflex.psi.*;
 
-public class JFlexExpressionImpl extends JFlexCompositeElementImpl implements JFlexExpression {
+public abstract class JFlexExpressionImpl extends JFlexCompositeElementImpl implements JFlexExpression {
 
   public JFlexExpressionImpl(ASTNode node) {
     super(node);
diff --git a/testData/generator/BnfGrammar.PSI.expected.java b/testData/generator/BnfGrammar.PSI.expected.java
index cf2a0283..2212b2e1 100644
--- a/testData/generator/BnfGrammar.PSI.expected.java
+++ b/testData/generator/BnfGrammar.PSI.expected.java
@@ -68,9 +68,6 @@ else if (type == BNF_ATTR_PATTERN) {
       else if (type == BNF_CHOICE) {
         return new BnfChoiceImpl(node);
       }
-      else if (type == BNF_EXPRESSION) {
-        return new BnfExpressionImpl(node);
-      }
       else if (type == BNF_EXTERNAL_EXPRESSION) {
         return new BnfExternalExpressionImpl(node);
       }
@@ -592,7 +589,7 @@ public List<BnfExpression> getExpressionList() {
 import static org.intellij.grammar.psi.BnfTypes.*;
 import org.intellij.grammar.psi.*;
 
-public class BnfExpressionImpl extends BnfCompositeElementImpl implements BnfExpression {
+public abstract class BnfExpressionImpl extends BnfCompositeElementImpl implements BnfExpression {
 
   public BnfExpressionImpl(ASTNode node) {
     super(node);
diff --git a/testData/generator/Fixes.PSI.expected.java b/testData/generator/Fixes.PSI.expected.java
index 01468f9a..f22ecb9c 100644
--- a/testData/generator/Fixes.PSI.expected.java
+++ b/testData/generator/Fixes.PSI.expected.java
@@ -365,7 +365,7 @@ public Zome getZome() {
 import com.intellij.extapi.psi.ASTWrapperPsiElement;
 import generated.psi.*;
 
-public class ExprImpl extends ASTWrapperPsiElement implements Expr {
+public abstract class ExprImpl extends ASTWrapperPsiElement implements Expr {
 
   public ExprImpl(ASTNode node) {
     super(node);
@@ -459,7 +459,7 @@ public void accept(@NotNull PsiElementVisitor visitor) {
 import static generated.GeneratedTypes.*;
 import generated.psi.*;
 
-public class SomeExprImpl extends ExprImpl implements SomeExpr {
+public abstract class SomeExprImpl extends ExprImpl implements SomeExpr {
 
   public SomeExprImpl(ASTNode node) {
     super(node);
diff --git a/testData/generator/FlexGrammar.PSI.expected.java b/testData/generator/FlexGrammar.PSI.expected.java
index f060b5c6..c212bfa3 100644
--- a/testData/generator/FlexGrammar.PSI.expected.java
+++ b/testData/generator/FlexGrammar.PSI.expected.java
@@ -143,9 +143,6 @@ else if (type == FLEX_CLASS_EXPRESSION) {
       else if (type == FLEX_DECLARATIONS_SECTION) {
         return new JFlexDeclarationsSectionImpl(node);
       }
-      else if (type == FLEX_EXPRESSION) {
-        return new JFlexExpressionImpl(node);
-      }
       else if (type == FLEX_JAVA_CODE) {
         return new JFlexJavaCodeImpl(node);
       }
@@ -785,7 +782,7 @@ public List<JFlexStateDeclaration> getStateDeclarationList() {
 import static org.intellij.jflex.psi.JFlexTypes.*;
 import org.intellij.jflex.psi.*;
 
-public class JFlexExpressionImpl extends JFlexCompositeElementImpl implements JFlexExpression {
+public abstract class JFlexExpressionImpl extends JFlexCompositeElementImpl implements JFlexExpression {
 
   public JFlexExpressionImpl(ASTNode node) {
     super(node);
diff --git a/testData/generator/PsiGen.PSI.expected.java b/testData/generator/PsiGen.PSI.expected.java
index 33bbd438..e381c857 100644
--- a/testData/generator/PsiGen.PSI.expected.java
+++ b/testData/generator/PsiGen.PSI.expected.java
@@ -110,15 +110,9 @@ else if (type == ROOT_C) {
       else if (type == ROOT_D) {
         return new XRootDImpl(node);
       }
-      else if (type == SOME_EXPR) {
-        return new XSomeExprImpl(node);
-      }
       else if (type == SPECIAL_REF) {
         return new XSpecialRefImpl(node);
       }
-      else if (type == STATEMENT) {
-        return new XStatementImpl(node);
-      }
       throw new AssertionError("Unknown element type: " + type);
     }
   }
@@ -1348,7 +1342,7 @@ public List<XGrammarElement> getGrammarElementList() {
 import static generated.GeneratedTypes.*;
 import generated.psi.*;
 
-public class XSomeExprImpl extends XExprImpl implements XSomeExpr {
+public abstract class XSomeExprImpl extends XExprImpl implements XSomeExpr {
 
   public XSomeExprImpl(ASTNode node) {
     super(node);
@@ -1413,7 +1407,7 @@ public XRefExpr getRefExpr() {
 import com.intellij.extapi.psi.ASTWrapperPsiElement;
 import generated.psi.*;
 
-public class XStatementImpl extends ASTWrapperPsiElement implements XStatement {
+public abstract class XStatementImpl extends ASTWrapperPsiElement implements XStatement {
 
   public XStatementImpl(ASTNode node) {
     super(node);
diff --git a/testData/generator/Self.PSI.expected.java b/testData/generator/Self.PSI.expected.java
index 4c84dec6..819c5240 100644
--- a/testData/generator/Self.PSI.expected.java
+++ b/testData/generator/Self.PSI.expected.java
@@ -64,9 +64,6 @@ else if (type == BNF_ATTR_VALUE) {
       else if (type == BNF_CHOICE) {
         return new BnfChoiceImpl(node);
       }
-      else if (type == BNF_EXPRESSION) {
-        return new BnfExpressionImpl(node);
-      }
       else if (type == BNF_LITERAL_EXPRESSION) {
         return new BnfLiteralExpressionImpl(node);
       }
@@ -500,7 +497,7 @@ public List<BnfExpression> getExpressionList() {
 import static org.intellij.grammar.psi.BnfTypes.*;
 import org.intellij.grammar.psi.*;
 
-public class BnfExpressionImpl extends BnfCompositeElementImpl implements BnfExpression {
+public abstract class BnfExpressionImpl extends BnfCompositeElementImpl implements BnfExpression {
 
   public BnfExpressionImpl(ASTNode node) {
     super(node);
diff --git a/testData/generator/Stub.PSI.expected.java b/testData/generator/Stub.PSI.expected.java
index 035afafa..cbe554ec 100644
--- a/testData/generator/Stub.PSI.expected.java
+++ b/testData/generator/Stub.PSI.expected.java
@@ -44,9 +44,6 @@ else if (type == INTERFACE_TYPE) {
       else if (type == STRUCT_TYPE) {
         return new StructTypeImpl(node);
       }
-      else if (type == TYPE) {
-        return new TypeImpl(node);
-      }
       throw new AssertionError("Unknown element type: " + type);
     }
   }
@@ -558,7 +555,7 @@ public void accept(@NotNull PsiElementVisitor visitor) {
 import com.intellij.psi.stubs.IStubElementType;
 import com.intellij.psi.tree.IElementType;
 
-public class TypeImpl extends GenericBase<TypeStub> implements Type {
+public abstract class TypeImpl extends GenericBase<TypeStub> implements Type {
 
   public TypeImpl(TypeStub p0, IStubElementType p1) {
     super(p0, p1);