Make component more functionnal

include/ftxui/component/checkbox.hpp

@@ -1,10 +1,13 @@
 #ifndef FTXUI_COMPONENT_CHECKBOX_HPP
 #define FTXUI_COMPONENT_CHECKBOX_HPP
 
-#include <string>
+#include <functional>  // for function
+#include <string>      // for wstring, allocator
 
-#include "ftxui/component/component.hpp"
-#include "ftxui/screen/box.hpp"
+#include "ftxui/component/component.hpp"       // for Component
+#include "ftxui/component/component_base.hpp"  // for ComponentBase
+#include "ftxui/dom/elements.hpp"  // for Element, Decorator, inverted, nothing
+#include "ftxui/screen/box.hpp"    // for Box
 
 namespace ftxui {
 struct Event;
@@ -12,14 +15,14 @@ struct Event;
 /// @brief A Checkbox. It can be checked or unchecked.Display an element on a
 /// ftxui::Screen.
 /// @ingroup dom
-class CheckBox : public Component {
+class CheckboxBase : public ComponentBase {
  public:
-  // Constructor.
-  CheckBox() = default;
-  ~CheckBox() override = default;
+  // Access this interface from a Component
+  static CheckboxBase* From(Component component);
 
-  bool state = false;  // The current state. true=checked, false:unchecked.
-  std::wstring label = L"label";  // The CheckBox label.
+  // Constructor.
+  CheckboxBase(const std::wstring* label, bool* state);
+  ~CheckboxBase() override = default;
 
 #if defined(_WIN32)
   std::wstring checked = L"[X] ";    /// Prefix for  a "checked" state.
@@ -32,7 +35,7 @@ class CheckBox : public Component {
   Decorator focused_style = inverted;   /// Decorator used when focused.
   Decorator unfocused_style = nothing;  /// Decorator used when unfocused.
 
-  /// Called when the user change the state of the CheckBox.
+  /// Called when the user change the state of the CheckboxBase.
   std::function<void()> on_change = []() {};
 
   // Component implementation.
@@ -42,6 +45,8 @@ class CheckBox : public Component {
  private:
   bool OnMouseEvent(Event event);
 
+  const std::wstring* const label_;
+  bool* const state_;
   int cursor_position = 0;
   Box box_;
 };