Extract out WrappedRecord as a convenience base class; NFC.

Author: rjmccall

clang/utils/TableGen/ASTTableGen.h

@@ -42,41 +42,50 @@
 namespace clang {
 namespace tblgen {
 
-/// An (optional) reference to a TableGen node representing a class
-/// in one of Clang's AST hierarchies.
-class ASTNode {
+class WrappedRecord {
   llvm::Record *Record;
+
+protected:
+  WrappedRecord(llvm::Record *record = nullptr) : Record(record) {}
+
+  llvm::Record *get() const {
+    assert(Record && "accessing null record");
+    return Record;
+  }
+
 public:
-  ASTNode(llvm::Record *record = nullptr) : Record(record) {}
+  llvm::Record *getRecord() const { return Record; }
 
   explicit operator bool() const { return Record != nullptr; }
 
-  llvm::Record *getRecord() const { return Record; }
-  llvm::StringRef getName() const {
-    assert(Record && "getting name of null record");
-    return Record->getName();
-  }
   llvm::ArrayRef<llvm::SMLoc> getLoc() const {
-    assert(Record && "getting location of null record");
-    return Record->getLoc();
+    return get()->getLoc();
+  }
+
+  /// Does the node inherit from the given TableGen class?
+  bool isSubClassOf(llvm::StringRef className) const {
+    return get()->isSubClassOf(className);
+  }
+};
+
+/// An (optional) reference to a TableGen node representing a class
+/// in one of Clang's AST hierarchies.
+class ASTNode : public WrappedRecord {
+public:
+  ASTNode(llvm::Record *record = nullptr) : WrappedRecord(record) {}
+
+  llvm::StringRef getName() const {
+    return get()->getName();
   }
 
   /// Return the node for the base, if there is one.
   ASTNode getBase() const {
-    assert(Record && "getting base of null record");
-    return Record->getValueAsOptionalDef(BaseFieldName);
+    return get()->getValueAsOptionalDef(BaseFieldName);
   }
 
   /// Is the corresponding class abstract?
   bool isAbstract() const {
-    assert(Record && "querying null record");
-    return Record->getValueAsBit(AbstractFieldName);
-  }
-
-  /// Does the node inherit from the given TableGen class?
-  bool isSubClassOf(llvm::StringRef className) const {
-    assert(Record && "querying null record");
-    return Record->isSubClassOf(className);
+    return get()->getValueAsBit(AbstractFieldName);
   }
 
   friend bool operator<(ASTNode lhs, ASTNode rhs) {