Implement transfer function for interpreting nullptr, address_of (&) operator, comparison between pointers.

PiperOrigin-RevId: 453859336
diff --git a/nullability_verification/pointer_nullability_matchers.h b/nullability_verification/pointer_nullability_matchers.h
index ed30a23..7115678 100644
--- a/nullability_verification/pointer_nullability_matchers.h
+++ b/nullability_verification/pointer_nullability_matchers.h
@@ -11,11 +11,12 @@
 namespace tidy {
 namespace nullability {
 
-ast_matchers::internal::Matcher<Stmt> isPointerExpr();
+ast_matchers::internal::Matcher<Stmt> isPointerVariableReference();
+ast_matchers::internal::Matcher<Stmt> isNullPointerLiteral();
+ast_matchers::internal::Matcher<Stmt> isAddrOf();
 ast_matchers::internal::Matcher<Stmt> isPointerDereference();
-ast_matchers::internal::Matcher<Stmt> isNEQNullBinOp(llvm::StringRef BindID);
-ast_matchers::internal::Matcher<Stmt> isImplicitCastPtrToBool();
-
+ast_matchers::internal::Matcher<Stmt> isPointerCheckBinOp();
+ast_matchers::internal::Matcher<Stmt> isImplicitCastPointerToBool();
 }  // namespace nullability
 }  // namespace tidy
 }  // namespace clang