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/Unicode.h

@@ -0,0 +1,28 @@
+/* Copyright (c) 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 "antlr4-common.h"
+
+namespace antlrcpp {
+
+  class ANTLR4CPP_PUBLIC Unicode final {
+  public:
+    static constexpr char32_t REPLACEMENT_CHARACTER = 0xfffd;
+
+    static constexpr bool isValid(char32_t codePoint) {
+      return codePoint < 0xd800 || (codePoint > 0xdfff && codePoint <= 0x10ffff);
+    }
+
+  private:
+    Unicode() = delete;
+    Unicode(const Unicode&) = delete;
+    Unicode(Unicode&&) = delete;
+    Unicode& operator=(const Unicode&) = delete;
+    Unicode& operator=(Unicode&&) = delete;
+  };
+
+}