refactor: rename encoding/stlcvt to encoding/stl

src/yycc/encoding/stl.hpp

@@ -0,0 +1,43 @@
+#pragma once
+#include <string>
+#include <string_view>
+#include <expected>
+
+namespace yycc::encoding::stl {
+
+    /// @brief Possible convertion error occurs in this module.
+    struct ConvError {};
+
+    /// @brief The result type of this module.
+    template<typename T>
+    using ConvResult = std::expected<T, ConvError>;
+
+    /**
+     * @brief UTF8 -> UTF16
+     * @param src
+     * @return
+     */
+    ConvResult<std::u16string> to_utf16(const std::u8string_view& src);
+
+    /**
+     * @brief UTF16 -> UTF8
+     * @param src
+     * @return
+     */
+    ConvResult<std::u8string> to_utf8(const std::u16string_view& src);
+
+    /**
+     * @brief UTF8 -> UTF32
+     * @param src
+     * @return
+     */
+    ConvResult<std::u32string> to_utf32(const std::u8string_view& src);
+
+    /**
+     * @brief UTF32 -> UTF8
+     * @param src
+     * @return
+     */
+    ConvResult<std::u8string> to_utf8(const std::u32string_view& src);
+
+}