Introduce CatchEvent (#104)

src/ftxui/component/catch_event.cpp

@@ -0,0 +1,57 @@
+#include <functional>  // for function
+#include <memory>  // for __shared_ptr_access, __shared_ptr_access<>::element_type, shared_ptr
+#include <utility>  // for move
+
+#include "ftxui/component/component.hpp"  // for Component, Make, CatchEvent
+#include "ftxui/component/component_base.hpp"  // for ComponentBase
+#include "ftxui/component/event.hpp"           // for Event
+
+namespace ftxui {
+
+/// @brief A component executing a provided function for catching events.
+/// @ingroup component.
+class CatchEventBase : public ComponentBase {
+ public:
+  // Constructor.
+  CatchEventBase(std::function<bool(Event)> on_event)
+      : on_event_(std::move(on_event)) {}
+  ~CatchEventBase() override = default;
+
+  // Component implementation.
+  bool OnEvent(Event event) override {
+    if (on_event_(event))
+      return true;
+    else
+      return ComponentBase::OnEvent(event);
+  }
+
+ protected:
+  std::function<bool(Event)> on_event_;
+};
+
+/// @brief Return a component, using |on_event| to catch events. This function
+/// must returns true when the event has been handled, false otherwise.
+/// @param on_event The function drawing the interface.
+/// @ingroup component
+///
+/// ### Example
+///
+/// ```cpp
+/// auto screen = ScreenInteractive::TerminalOutput();
+/// auto renderer = Renderer([] {
+///   return text(L"My interface");
+/// });
+/// screen.Loop(renderer);
+/// ```
+Component CatchEvent(Component child,
+                     std::function<bool(Event event)> on_event) {
+  auto out = Make<CatchEventBase>(std::move(on_event));
+  out->Add(std::move(child));
+  return out;
+}
+
+}  // namespace ftxui
+
+// Copyright 2021 Arthur Sonzogni. All rights reserved.
+// Use of this source code is governed by the MIT license that can be found in
+// the LICENSE file.

src/ftxui/screen/string.cpp

@@ -1,7 +1,8 @@
 #include "ftxui/screen/string.hpp"
 
-#include <codecvt>
-#include <locale>
+#include <codecvt>  // for codecvt_utf8_utf16
+#include <locale>   // for wstring_convert
+#include <utility>  // for move
 
 namespace ftxui {
 #ifdef _MSC_VER