Add compress regular tree

include/regular/RegularTree.hpp

@@ -28,6 +28,7 @@ class RegularTree {
     Modifier modifier = Modifier::None;
    private:
     void ParseCurrentType(const std::string_view);
+    void Compression();
     void Print(int nesting_level) const;
   };
 

src/regular/RegularTree.cpp

@@ -9,6 +9,7 @@ RegularTree::Node::Node(Type type) : type(type) {}
 void RegularTree::Node::Parse(const std::string& regular) {
   type = Type::Addition;
   ParseCurrentType(std::string_view(regular.c_str(), regular.size()));
+  Compression();
 }
 
 void RegularTree::Node::Print() const {
@@ -135,6 +136,16 @@ void RegularTree::Node::ParseCurrentType(const std::string_view regular) {
   }
 }
 
+void RegularTree::Node::Compression() {
+  for (auto& i: children) {
+    i->Compression();
+  }
+  if (children.size() == 1 && modifier == Modifier::None) {
+    auto tmp = std::move(*children[0]);
+    *this = std::move(tmp);
+  }
+}
+
 void RegularTree::Node::Print(int nesting_level) const {
   auto PrintNesingLevel = [](int nesting_level) {
     for (int i = 0; i < nesting_level; ++i) {