Feature: Selection

Add support for selection content in the dom.

include/ftxui/dom/selection.hpp

@@ -0,0 +1,50 @@
+// Copyright 2024 Arthur Sonzogni. All rights reserved.
+// Use of this source code is governed by the MIT license that can be found in
+// the LICENSE file.
+
+#ifndef FTXUI_DOM_SELECTION_HPP
+#define FTXUI_DOM_SELECTION_HPP
+
+#include <functional>
+
+#include <sstream>
+#include "ftxui/screen/box.hpp"    // for Box
+#include "ftxui/screen/pixel.hpp"  // for Pixel
+
+namespace ftxui {
+
+/// @brief Represent a selection in the terminal.
+class Selection {
+ public:
+  Selection();  // Empty selection.
+  Selection(int start_x, int start_y, int end_x, int end_y);
+
+  const Box& GetBox() const;
+
+  Selection SaturateHorizontal(Box box);
+  Selection SaturateVertical(Box box);
+  bool IsEmpty() const { return empty_; }
+
+  void AddPart(const std::string& part, int y, int left, int right);
+  std::string GetParts() { return parts_.str(); }
+
+ private:
+  Selection(int start_x, int start_y, int end_x, int end_y, Selection* parent);
+
+  Selection* const parent_ = this;
+  const bool empty_ = true;
+  const int start_x_ = 0;
+  const int start_y_ = 0;
+  const int end_x_ = 0;
+  const int end_y_ = 0;
+  const Box box_ = {};
+  std::stringstream parts_;
+
+  // The position of the last inserted part.
+  int x_ = 0;
+  int y_ = 0;
+};
+
+}  // namespace ftxui
+
+#endif /* end of include guard: FTXUI_DOM_SELECTION_HPP */