diff --git a/src/data_format/bound_symbol_list.cpp b/src/data_format/bound_symbol_list.cpp
index 8bfb2ed..0be4a12 100644
--- a/src/data_format/bound_symbol_list.cpp
+++ b/src/data_format/bound_symbol_list.cpp
@@ -6,8 +6,8 @@ namespace di::data_format {
 
 constexpr int BOUND_SYMBOL_LIST_FORMAT_VERSION = 1;
 
-BoundSymbolList::BoundSymbolList(std::string_view path) {
-    std::ifstream ifs(path.data());
+void BoundSymbolList::read(const std::filesystem::path& path) {
+    std::ifstream ifs(path);
     if (!ifs) {
         throw std::runtime_error("Failed to open data path.");
     }
@@ -17,6 +17,7 @@ BoundSymbolList::BoundSymbolList(std::string_view path) {
         throw std::runtime_error("Unsupported data version.");
     }
 
+    m_entities.clear();
     for (const auto& entity : data["data"]) {
         m_entities.emplace(
             BoundSymbol{entity["symbol"], entity["rva"], entity["is_function"]}
@@ -24,15 +25,7 @@ BoundSymbolList::BoundSymbolList(std::string_view path) {
     }
 }
 
-void BoundSymbolList::record(
-    std::string_view symbol,
-    uint64_t         rva,
-    bool             is_function
-) {
-    m_entities.emplace(BoundSymbol{std::string(symbol), rva, is_function});
-}
-
-void BoundSymbolList::write_to(const std::string& path) const {
+void BoundSymbolList::write(const std::filesystem::path& path) const {
     std::ofstream ofs(path);
     if (!ofs) {
         throw std::runtime_error("Failed to open file!");
@@ -52,4 +45,12 @@ void BoundSymbolList::write_to(const std::string& path) const {
     ofs << data.dump(4);
 }
 
+void BoundSymbolList::record(
+    std::string_view symbol,
+    uint64_t         rva,
+    bool             is_function
+) {
+    m_entities.emplace(BoundSymbol{std::string(symbol), rva, is_function});
+}
+
 } // namespace di::data_format
diff --git a/src/data_format/bound_symbol_list.h b/src/data_format/bound_symbol_list.h
index c616764..c51f3e5 100644
--- a/src/data_format/bound_symbol_list.h
+++ b/src/data_format/bound_symbol_list.h
@@ -1,18 +1,18 @@
 #pragma once
 
+#include "data_format/io_base.h"
 #include "data_format/type/bound_symbol.h"
 
 namespace di::data_format {
 
-class BoundSymbolList {
+class BoundSymbolList : public IOBase {
 public:
     using for_each_callback_t = std::function<void(BoundSymbol const&)>;
 
-    explicit BoundSymbolList() = default;
-    explicit BoundSymbolList(std::string_view path);
+    void read(const std::filesystem::path& path) override;
+    void write(const std::filesystem::path& path) const override;
 
     void record(std::string_view symbol, uint64_t rva, bool is_function);
-    void write_to(const std::string& path) const;
 
     constexpr void for_each(const for_each_callback_t& callback) const {
         for (const auto& entity : m_entities) callback(entity);
diff --git a/src/data_format/human_readable_symbol_list.cpp b/src/data_format/human_readable_symbol_list.cpp
deleted file mode 100644
index 36d53f9..0000000
--- a/src/data_format/human_readable_symbol_list.cpp
+++ /dev/null
@@ -1,20 +0,0 @@
-#include "data_format/human_readable_symbol_list.h"
-
-namespace di::data_format {
-
-void HumanReadableSymbolList::record(std::string_view symbol, uint64_t rva) {
-    m_symbol_rva_map.try_emplace(std::string(symbol), rva);
-}
-
-void HumanReadableSymbolList::write_to(std::string_view path) const {
-    std::ofstream ofs(path.data());
-    if (!ofs) {
-        throw std::runtime_error("Failed to open save file.");
-    }
-
-    for (const auto& [symbol, rva] : m_symbol_rva_map) {
-        ofs << std::format("[{:#x}] {}\n", rva, symbol);
-    }
-}
-
-} // namespace di::data_format
diff --git a/src/data_format/human_readable_symbol_list.h b/src/data_format/human_readable_symbol_list.h
deleted file mode 100644
index 6318d07..0000000
--- a/src/data_format/human_readable_symbol_list.h
+++ /dev/null
@@ -1,14 +0,0 @@
-#pragma once
-
-namespace di::data_format {
-
-class HumanReadableSymbolList {
-public:
-    void record(std::string_view symbol, uint64_t rva);
-    void write_to(std::string_view path) const;
-
-protected:
-    std::unordered_map<std::string, uint64_t> m_symbol_rva_map;
-};
-
-} // namespace di::data_format
diff --git a/src/data_format/io_base.h b/src/data_format/io_base.h
new file mode 100644
index 0000000..6bcb283
--- /dev/null
+++ b/src/data_format/io_base.h
@@ -0,0 +1,13 @@
+#pragma once
+
+namespace di::data_format {
+
+class IOBase {
+public:
+    virtual ~IOBase() = default;
+
+    virtual void read(const std::filesystem::path& path)        = 0;
+    virtual void write(const std::filesystem::path& path) const = 0;
+};
+
+} // namespace di::data_format
diff --git a/src/data_format/raw_text.cpp b/src/data_format/raw_text.cpp
index 98a6611..6547a32 100644
--- a/src/data_format/raw_text.cpp
+++ b/src/data_format/raw_text.cpp
@@ -2,13 +2,16 @@
 
 namespace di::data_format {
 
-void RawText::record(std::string_view content) {
-    m_data += content;
-    m_data += '\n';
+void RawText::read(const std::filesystem::path& path) {
+    std::ifstream ifs(path);
+
+    auto size = std::filesystem::file_size(path);
+    m_data.reserve(size);
+    m_data.assign(std::istreambuf_iterator<char>(ifs), {});
 }
 
-void RawText::write_to(std::string_view path) const {
-    std::ofstream ofs(path.data());
+void RawText::write(const std::filesystem::path& path) const {
+    std::ofstream ofs(path);
     if (!ofs) {
         throw std::runtime_error("Failed to open save file.");
     }
@@ -16,4 +19,9 @@ void RawText::write_to(std::string_view path) const {
     ofs << m_data;
 }
 
+void RawText::record(std::string_view content) {
+    m_data += content;
+    m_data += '\n';
+}
+
 } // namespace di::data_format
diff --git a/src/data_format/raw_text.h b/src/data_format/raw_text.h
index 11b6a0a..654a4e1 100644
--- a/src/data_format/raw_text.h
+++ b/src/data_format/raw_text.h
@@ -1,11 +1,15 @@
 #pragma once
 
+#include "data_format/io_base.h"
+
 namespace di::data_format {
 
-class RawText {
+class RawText : public IOBase {
 public:
+    void read(const std::filesystem::path& path) override;
+    void write(const std::filesystem::path& path) const override;
+
     void record(std::string_view line);
-    void write_to(std::string_view path) const;
 
 private:
     std::string m_data;
diff --git a/src/data_format/raw_type_data.cpp b/src/data_format/raw_type_data.cpp
index e179729..b3d9b2e 100644
--- a/src/data_format/raw_type_data.cpp
+++ b/src/data_format/raw_type_data.cpp
@@ -12,11 +12,13 @@ using namespace llvm::pdb;
 
 namespace di::data_format {
 
-RawTypeData::RawTypeData(std::string_view path)
-: m_storaged_TPI(m_allocator),
-  m_storaged_IPI(m_allocator) {
+void RawTypeData::read(const std::filesystem::path& path) {
     std::unique_ptr<IPDBSession> pdb_session;
-    if (llvm::pdb::loadDataForPDB(PDB_ReaderType::Native, path, pdb_session)) {
+    if (llvm::pdb::loadDataForPDB(
+            PDB_ReaderType::Native,
+            path.string(),
+            pdb_session
+        )) {
         throw std::runtime_error("Failed to load PDB.");
     }
 
diff --git a/src/data_format/raw_type_data.h b/src/data_format/raw_type_data.h
index 57fadec..09238d0 100644
--- a/src/data_format/raw_type_data.h
+++ b/src/data_format/raw_type_data.h
@@ -1,17 +1,24 @@
 #pragma once
 
+#include "data_format/io_base.h"
+
 #include <llvm/DebugInfo/CodeView/MergingTypeTableBuilder.h>
 
 namespace di::data_format {
 
-class RawTypeData {
+class RawTypeData : public IOBase {
 public:
     using for_each_callback_t =
         std::function<void(codeview::TypeIndex, codeview::CVType)>;
 
     enum TypedStream { TPI, IPI };
 
-    explicit RawTypeData(std::string_view path);
+    RawTypeData() : m_storaged_IPI(m_allocator), m_storaged_TPI(m_allocator) {}
+
+    void read(const std::filesystem::path& path) override;
+    void write(const std::filesystem::path& path) const override {
+        throw std::runtime_error("Unsupported operation.");
+    }
 
     template <TypedStream Stream>
     void for_each(const for_each_callback_t& callback) /*const*/ {
@@ -26,8 +33,8 @@ public:
 private:
     BumpPtrAllocator m_allocator;
 
-    codeview::MergingTypeTableBuilder m_storaged_TPI;
     codeview::MergingTypeTableBuilder m_storaged_IPI;
+    codeview::MergingTypeTableBuilder m_storaged_TPI;
 };
 
 } // namespace di::data_format
diff --git a/src/data_format/type/decl_type.h b/src/data_format/type/decl_type.h
index b9dc1b6..ba20251 100644
--- a/src/data_format/type/decl_type.h
+++ b/src/data_format/type/decl_type.h
@@ -64,6 +64,35 @@ public:
 
     constexpr Enum data() const { return m_data; }
 
+    constexpr std::string string() const {
+        using namespace util::string;
+
+        // clang-format off
+
+        switch (m_data) {
+    #define HSTR(x)                                                                \
+        case x:                                                                    \
+            return #x;
+        HSTR(Function);
+        HSTR(CXXDeductionGuide);
+        HSTR(CXXMethod);
+        HSTR(CXXConstructor);
+        HSTR(CXXConversion);
+        HSTR(CXXDestructor);
+        HSTR(Var);
+        HSTR(Decomposition);
+        HSTR(ImplicitParam);
+        HSTR(OMPCapturedExpr);
+        HSTR(ParamVar);
+        HSTR(VarTemplateSpecialization);
+    #undef HSTR
+        default:
+            throw std::runtime_error("Unexpected decl type.");
+        }
+
+        // clang-format on
+    }
+
     constexpr bool operator==(const DeclType& other) const {
         return m_data == other.m_data;
     }
diff --git a/src/data_format/typed_symbol_list.cpp b/src/data_format/typed_symbol_list.cpp
index 0d3880d..550a193 100644
--- a/src/data_format/typed_symbol_list.cpp
+++ b/src/data_format/typed_symbol_list.cpp
@@ -2,33 +2,40 @@
 
 namespace di::data_format {
 
-TypedSymbolList::TypedSymbolList(const std::vector<std::string>& paths) {
-    for (const auto& path : paths) {
-        std::ifstream ifs(path.data());
-        if (!ifs) {
-            throw std::runtime_error("Failed to open symlist file.");
+void TypedSymbolList::read(const std::filesystem::path& path) {
+    std::ifstream ifs(path);
+    if (!ifs) {
+        throw std::runtime_error("Failed to open symlist file.");
+    }
+
+    std::string line;
+    while (std::getline(ifs, line)) {
+        if (line.empty()) continue;
+
+        auto sep_pos = line.find(", ");
+        if (sep_pos == std::string::npos) {
+            throw std::runtime_error(
+                "Symbol data is not included declType, please re-generate "
+                "symlist file with -record-decl-name."
+            );
         }
 
-        std::string line;
-        while (std::getline(ifs, line)) {
-            if (line.empty()) continue;
+        auto decl_type_s = line.substr(0, sep_pos);
+        auto symbol      = line.substr(sep_pos + 2);
 
-            auto separator_pos = line.find(", ");
-            if (separator_pos == std::string::npos) {
-                throw std::runtime_error(
-                    "Symbol data is not included declType, please re-generate "
-                    "symlist file with -record-decl-name."
-                );
-            }
-
-            auto declType_s = line.substr(0, separator_pos);
-            auto symbol     = line.substr(separator_pos + 2);
-
-            m_data.emplace(symbol, DeclType(declType_s));
-        }
-
-        std::println("Read {} symbols from dumped symlist.", m_data.size());
+        m_data.emplace(symbol, DeclType(decl_type_s));
     }
 }
 
+void TypedSymbolList::write(const std::filesystem::path& path) const {
+    std::ofstream ofs;
+    for (const auto& [symbol, decl_type] : m_data) {
+        ofs << symbol << ", " << decl_type.string() << "\n";
+    }
+}
+
+void TypedSymbolList::record(std::string_view symbol, DeclType type) {
+    m_data.emplace(symbol, type);
+}
+
 } // namespace di::data_format
diff --git a/src/data_format/typed_symbol_list.h b/src/data_format/typed_symbol_list.h
index dba24ae..34c9b62 100644
--- a/src/data_format/typed_symbol_list.h
+++ b/src/data_format/typed_symbol_list.h
@@ -1,16 +1,22 @@
 #pragma once
 
+#include "data_format/io_base.h"
+
+#include "data_format/type/decl_type.h"
 #include "data_format/type/typed_symbol.h"
 
 namespace di::data_format {
 
-class TypedSymbolList {
+class TypedSymbolList : public IOBase {
 public:
     using for_each_callback_t = std::function<void(TypedSymbol const&)>;
 
-    explicit TypedSymbolList(const std::string& path)
-    : TypedSymbolList(std::vector<std::string>{path}) {};
-    explicit TypedSymbolList(const std::vector<std::string>& paths);
+    // this method in this class supports multiple calls (reading multiple
+    // files)
+    void read(const std::filesystem::path& path) override;
+    void write(const std::filesystem::path& path) const override;
+
+    void record(std::string_view name, DeclType type);
 
     constexpr void for_each(const for_each_callback_t& callback) const {
         for (const auto& entity : m_data) callback(entity);
diff --git a/src/object_file/COFF.cpp b/src/object_file/COFF.cpp
index 309edee..52810bc 100644
--- a/src/object_file/COFF.cpp
+++ b/src/object_file/COFF.cpp
@@ -2,10 +2,10 @@
 
 namespace di::object_file {
 
-COFF::COFF(std::string_view path) {
+COFF::COFF(const std::filesystem::path& path) {
     using namespace object;
 
-    auto obj_or_err = ObjectFile::createObjectFile(path);
+    auto obj_or_err = ObjectFile::createObjectFile(path.string());
     if (!obj_or_err) {
         throw std::runtime_error("Failed to create object file.");
     }
diff --git a/src/object_file/COFF.h b/src/object_file/COFF.h
index f5fbc44..35429f6 100644
--- a/src/object_file/COFF.h
+++ b/src/object_file/COFF.h
@@ -6,7 +6,7 @@ namespace di::object_file {
 
 class COFF {
 public:
-    explicit COFF(std::string_view path);
+    explicit COFF(const std::filesystem::path& path);
 
     codeview::PDB70DebugInfo get_debug_info() const;
 
diff --git a/src/object_file/PDB.cpp b/src/object_file/PDB.cpp
index c4b3e9e..c285d1f 100644
--- a/src/object_file/PDB.cpp
+++ b/src/object_file/PDB.cpp
@@ -24,11 +24,11 @@ PDB::PDB() : m_builder(m_allocator) {
     }
 }
 
-void PDB::write(std::string_view path) {
+void PDB::write(const std::filesystem::path& path) {
     build();
 
-    auto guid = m_builder.getInfoBuilder().getGuid();
-    if (m_builder.commit(path, &guid)) {
+    codeview::GUID out_guid;
+    if (m_builder.commit(path.string(), &out_guid)) {
         throw std::runtime_error("Failed to create pdb!");
     }
 }
diff --git a/src/object_file/PDB.h b/src/object_file/PDB.h
index c2cc5ba..e565221 100644
--- a/src/object_file/PDB.h
+++ b/src/object_file/PDB.h
@@ -30,7 +30,7 @@ public:
         m_owning_raw_type_data = std::move(raw_type_data);
     }
 
-    void write(std::string_view path);
+    void write(const std::filesystem::path& path);
 
 private:
     void build();
diff --git a/src/pch.h b/src/pch.h
index bc4a97f..9e53107 100644
--- a/src/pch.h
+++ b/src/pch.h
@@ -6,6 +6,7 @@ using namespace llvm;
 
 // Standard Libraries
 
+#include <filesystem>
 #include <fstream>
 #include <print>
 
diff --git a/src/tools/askrva/main.cpp b/src/tools/askrva/main.cpp
index 8ef1265..046fc87 100644
--- a/src/tools/askrva/main.cpp
+++ b/src/tools/askrva/main.cpp
@@ -1,7 +1,4 @@
-#include "util/string.h"
-
 #include "data_format/bound_symbol_list.h"
-#include "data_format/human_readable_symbol_list.h"
 #include "data_format/raw_text.h"
 #include "data_format/typed_symbol_list.h"
 
@@ -11,15 +8,12 @@
 #include <pl/SymbolProvider.h>
 #endif
 
-enum class OutputFormat { Text, MakePDB };
-
 using namespace di;
 
 [[nodiscard]] auto load_args(int argc, char* argv[]) {
     argparse::ArgumentParser program("askrva");
 
     struct {
-        OutputFormat             m_output_format;
         std::vector<std::string> m_input_paths;
         std::string              m_output_path;
 
@@ -54,25 +48,6 @@ using namespace di;
 
     program.parse_args(argc, argv);
 
-    args.m_output_format = [&output_format, &args]() -> OutputFormat {
-        using namespace util::string;
-
-        switch (H(output_format)) {
-        case H("text"):
-            return OutputFormat::Text;
-        case H("makepdb"):
-            return OutputFormat::MakePDB;
-        case H("auto"):
-        default: {
-            if (args.m_output_path.ends_with(".json")) {
-                return OutputFormat::MakePDB;
-            } else {
-                return OutputFormat::Text;
-            }
-        }
-        }
-    }();
-
     if (program.is_used("--output-failed")) {
         args.m_output_failed_path = program.get<std::string>("--output-failed");
     }
@@ -83,11 +58,10 @@ using namespace di;
 int main(int argc, char* argv[]) try {
 
     auto args    = load_args(argc, argv);
-    auto symlist = data_format::TypedSymbolList(args.m_input_paths);
+    auto symlist = data_format::TypedSymbolList();
 
-    data_format::BoundSymbolList         bound_symbol_list;
-    data_format::HumanReadableSymbolList human_readable_symbol_list;
-    data_format::RawText                 raw_text;
+    data_format::BoundSymbolList bound_symbol_list;
+    data_format::RawText         raw_text;
 
     symlist.for_each([&](const TypedSymbol& symbol) {
         auto& sym = symbol.m_name;
@@ -110,9 +84,9 @@ int main(int argc, char* argv[]) try {
         }
     });
 
-    bound_symbol_list.write_to(args.m_output_path);
+    bound_symbol_list.write(args.m_output_path);
     if (args.m_output_failed_path) {
-        raw_text.write_to(*args.m_output_failed_path);
+        raw_text.write(*args.m_output_failed_path);
     }
 
     std::println("Everything is OK.");
diff --git a/src/tools/makepdb/main.cpp b/src/tools/makepdb/main.cpp
index 5b79c40..1303beb 100644
--- a/src/tools/makepdb/main.cpp
+++ b/src/tools/makepdb/main.cpp
@@ -55,13 +55,13 @@ int main(int argc, char* argv[]) try {
     auto server_program =
         std::make_unique<object_file::COFF>(args.server_program_path);
 
-    auto symbol_data =
-        std::make_unique<data_format::BoundSymbolList>(args.symbol_data_path);
+    auto symbol_data = std::make_unique<data_format::BoundSymbolList>();
+    symbol_data->read(args.symbol_data_path);
 
     std::unique_ptr<data_format::RawTypeData> raw_type_data;
     if (args.typeinfo_pdb_path) {
-        raw_type_data =
-            std::make_unique<data_format::RawTypeData>(*args.typeinfo_pdb_path);
+        raw_type_data = std::make_unique<data_format::RawTypeData>();
+        raw_type_data->read(*args.typeinfo_pdb_path);
     }
 
     object_file::PDB pdb;