refactor: cancel the namespace Rust.

- all sub-functions are put into respective position.

src/yycc/primitive.hpp

@@ -0,0 +1,27 @@
+#pragma once
+#include <cstdint>
+#include <cstddef>
+#include <string_view>
+
+namespace yycc::primitive {
+
+	// `bool` is keyword so should not declare it anymore.
+	// `char` is keyword so should not declare it anymore.
+
+	using i8 = std::int8_t;
+	using i16 = std::int16_t;
+	using i32 = std::int32_t;
+	using i64 = std::int64_t;
+	using u8 = std::uint8_t;
+	using u16 = std::uint16_t;
+	using u32 = std::uint32_t;
+	using u64 = std::uint64_t;
+
+	using isize = std::ptrdiff_t;
+	using usize = std::size_t;
+
+	using f32 = float;
+	using f64 = double;
+
+	using str = std::u8string_view;
+}