Some update.

include/Basic/Basic.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <llvm/ADT/StringRef.h>
+#include <llvm/ADT/StringExtras.h>
+
+namespace clice::proto {
+
+/// range in [-2^31, 2^31- 1]
+using integer = std::int32_t;
+
+/// range in [0, 2^31- 1]
+using uinteger = std::uint32_t;
+
+using string = std::string;
+
+using string_literal = llvm::StringLiteral;
+
+template <typename T>
+using array = std::vector<T>;
+
+using DocumentUri = std::string;
+
+// TODO: figure out URI.
+using URI = std::string;
+
+/// Beacuse C++ does support string enum, so define `enum_type` for
+/// tag when serialize/deserialize.
+template <typename T>
+struct enum_type {
+    T value;
+
+    using underlying_type = T;
+
+    constexpr enum_type(T value) : value(value) {}
+
+    friend bool operator== (const enum_type& lhs, const enum_type& rhs) = default;
+};
+
+}  // namespace clice::proto