Introduce WithRestoredIO (#307)

This function allow running a callback with the terminal hooks
temporarily uninstalled.

Co-authored-by: ArthurSonzogni <sonzogniarthur@gmail.com>

examples/component/CMakeLists.txt

@@ -31,3 +31,4 @@ example(slider_rgb)
 example(tab_horizontal)
 example(tab_vertical)
 example(toggle)
+example(with_restored_io)

examples/component/with_restored_io.cpp

@@ -0,0 +1,55 @@
+#include "ftxui/component/component.hpp"           // for Menu
+#include "ftxui/component/screen_interactive.hpp"  // for ScreenInteractive
+
+int main() {
+  using namespace ftxui;
+
+  auto screen = ScreenInteractive::Fullscreen();
+
+  // When pressing this button, "screen.WithRestoredIO" will execute the
+  // temporarily uninstall the terminal hook and execute the provided callback
+  // function. This allow running the application in a non-interactive mode.
+  auto btn_run = Button("Execute with restored IO", screen.WithRestoredIO([] {
+        std::system("bash");
+    std::cout << "This is a child program using stdin/stdout." << std::endl;
+    for (int i = 0; i < 10; ++i) {
+      std::cout << "Please enter 10 strings (" << i << "/10)" << std::flush;
+      std::string input;
+      std::getline(std::cin, input);
+    }
+        std::system("bash");
+  }));
+
+  auto btn_quit = Button("Quit", screen.ExitLoopClosure());
+
+  auto layout = Container::Horizontal({
+      btn_run,
+      btn_quit,
+  });
+
+  auto renderer = Renderer(layout, [&] {
+    auto explanation = paragraph(
+        "After clicking this button, the ScreenInteractive will be "
+        "suspended and access to stdin/stdout will temporarilly be "
+        "restore for running a function.");
+    auto element = vbox({
+        explanation | borderEmpty,
+        hbox({
+            btn_run->Render(),
+            filler(),
+            btn_quit->Render(),
+        }),
+    });
+
+    element = element | borderEmpty | border | size(WIDTH, LESS_THAN, 80) |
+              size(HEIGHT, LESS_THAN, 20) | center;
+    return element;
+  });
+
+  screen.Loop(renderer);
+  return EXIT_SUCCESS;
+}
+
+// Copyright 2022 Arthur Sonzogni. All rights reserved.
+// Use of this source code is governed by the MIT license that can be found in
+// the LICENSE file.