build(antlr): 引入第三方 ANTLR4 runtime/tool 并接入构建

third_party/antlr4-runtime-4.13.2/runtime/src/support/Casts.h

@@ -0,0 +1,34 @@
+/* Copyright (c) 2012-2021 The ANTLR Project. All rights reserved.
+ * Use of this file is governed by the BSD 3-clause license that
+ * can be found in the LICENSE.txt file in the project root.
+ */
+
+#pragma once
+
+#include <cassert>
+#include <memory>
+#include <type_traits>
+
+namespace antlrcpp {
+
+  template <typename To, typename From>
+  To downCast(From* from) {
+    static_assert(std::is_pointer_v<To>, "Target type not a pointer.");
+    static_assert(std::is_base_of_v<From, std::remove_pointer_t<To>>, "Target type not derived from source type.");
+  #if !defined(__GNUC__) || defined(__GXX_RTTI)
+    assert(from == nullptr || dynamic_cast<To>(from) != nullptr);
+  #endif
+    return static_cast<To>(from);
+  }
+
+  template <typename To, typename From>
+  To downCast(From& from) {
+    static_assert(std::is_lvalue_reference_v<To>, "Target type not a lvalue reference.");
+    static_assert(std::is_base_of_v<From, std::remove_reference_t<To>>, "Target type not derived from source type.");
+  #if !defined(__GNUC__) || defined(__GXX_RTTI)
+    assert(dynamic_cast<std::add_pointer_t<std::remove_reference_t<To>>>(std::addressof(from)) != nullptr);
+  #endif
+    return static_cast<To>(from);
+  }
+
+}