diff --git a/CMakeLists.txt b/CMakeLists.txt
index db8dc50..5be6ab5 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -15,7 +15,9 @@ include_directories(
 
 set(CMAKE_CXX_STANDARD 17)
 
-set(SOURCE_FILES)
+set(SOURCE_FILES
+  src/regular/RegularTree.cpp
+  )
 
 set(TEST_FILES)
 
diff --git a/include/regular/RegularTree.hpp b/include/regular/RegularTree.hpp
new file mode 100644
index 0000000..02dd856
--- /dev/null
+++ b/include/regular/RegularTree.hpp
@@ -0,0 +1,31 @@
+#pragma once
+#include <variant>
+#include <vector>
+#include <memory>
+#include <string>
+#include <string_view>
+
+namespace regular {
+class RegularTree {
+ public:
+  class Node {
+   public:
+    Node();
+
+    void Parse(const std::string&);
+    void Parse(const std::string_view);
+
+    enum class Type {
+      Addition, Concatenation
+    };
+    std::variant<std::vector<std::unique_ptr<Node>>, std::string> value;
+    Type type;
+   private:
+  };
+
+  RegularTree(const std::string&);
+
+ private:
+  Node node_;
+};
+}
diff --git a/src/main.cpp b/src/main.cpp
index a03be09..14eb3b0 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1,5 +1,7 @@
 #include <iostream>
+#include "regular/RegularTree.hpp"
 
 int main() {
-  std::cout << "hello world";
+  using namespace regular;
+  RegularTree reg_tree("(ab)*");
 }
diff --git a/src/regular/RegularTree.cpp b/src/regular/RegularTree.cpp
new file mode 100644
index 0000000..96128e8
--- /dev/null
+++ b/src/regular/RegularTree.cpp
@@ -0,0 +1,22 @@
+#include "regular/RegularTree.hpp"
+#include <iostream>
+
+namespace regular {
+RegularTree::Node::Node() {}
+
+void RegularTree::Node::Parse(const std::string& regular) {
+  Parse(std::string_view(regular.c_str(), regular.size()));
+}
+
+void RegularTree::Node::Parse(const std::string_view regular) {
+  const int n = regular.size();
+  for (int i = 0; i < n; ++i) {
+    std::cout << regular[i];
+  }
+  std::cout << std::endl;
+}
+
+RegularTree::RegularTree(const std::string& regular) {
+  node_.Parse(regular);
+}
+}