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include/ftxui/dom/node.hpp

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+// Copyright 2020 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_NODE_HPP
+#define FTXUI_DOM_NODE_HPP
+
+#include <memory>  // for shared_ptr
+#include <vector>  // for vector
+
+#include "ftxui/dom/requirement.hpp"  // for Requirement
+#include "ftxui/screen/box.hpp"       // for Box
+#include "ftxui/screen/screen.hpp"
+
+namespace ftxui {
+
+class Node;
+class Screen;
+
+using Element = std::shared_ptr<Node>;
+using Elements = std::vector<Element>;
+
+class Node {
+ public:
+  Node();
+  Node(Elements children);
+  Node(const Node&) = delete;
+  Node(const Node&&) = delete;
+  Node& operator=(const Node&) = delete;
+  Node& operator=(const Node&&) = delete;
+
+  virtual ~Node();
+
+  // Step 1: Compute layout requirement. Tell parent what dimensions this
+  //         element wants to be.
+  //         Propagated from Children to Parents.
+  virtual void ComputeRequirement();
+  Requirement requirement() { return requirement_; }
+
+  // Step 2: Assign this element its final dimensions.
+  //         Propagated from Parents to Children.
+  virtual void SetBox(Box box);
+
+  // Step 3: Draw this element.
+  virtual void Render(Screen& screen);
+
+  // Layout may not resolve within a single iteration for some elements. This
+  // allows them to request additionnal iterations. This signal must be
+  // forwarded to children at least once.
+  struct Status {
+    int iteration = 0;
+    bool need_iteration = false;
+  };
+  virtual void Check(Status* status);
+
+ protected:
+  Elements children_;
+  Requirement requirement_;
+  Box box_;
+};
+
+void Render(Screen& screen, const Element& element);
+void Render(Screen& screen, Node* node);
+
+}  // namespace ftxui
+
+#endif  // FTXUI_DOM_NODE_HPP