Non-fullscreen view

- ViewComponent can take view and drive it as non-fullscreen
- ViewDoneEvent which InputView now uses
- ComponentUiCommands is a sample where we add ideas for
  views in flow components
- Allow View to set eventloop
- Relates #850

spring-shell-core/src/main/java/org/springframework/shell/component/ViewComponent.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.shell.component;
+
+import org.jline.terminal.Terminal;
+
+import org.springframework.messaging.Message;
+import org.springframework.shell.component.view.TerminalUI;
+import org.springframework.shell.component.view.control.View;
+import org.springframework.shell.component.view.control.ViewDoneEvent;
+import org.springframework.shell.component.view.event.EventLoop;
+import org.springframework.shell.component.view.message.ShellMessageBuilder;
+import org.springframework.util.Assert;
+
+/**
+ * Handles view execution in a non-fullscreen setup.
+ *
+ * @author Janne Valkealahti
+ */
+public class ViewComponent {
+
+	private final Terminal terminal;
+	private final View view;
+	private EventLoop eventLoop;
+
+	public ViewComponent(Terminal terminal, View view) {
+		Assert.notNull(terminal, "terminal must be set");
+		Assert.notNull(view, "view must be set");
+		this.terminal = terminal;
+		this.view = view;
+	}
+
+	/**
+	 * Run a view execution loop.
+	 */
+	public void run() {
+		TerminalUI ui = new TerminalUI(terminal);
+		eventLoop = ui.getEventLoop();
+		eventLoop.onDestroy(eventLoop.viewEvents(ViewDoneEvent.class, view)
+			.subscribe(event -> {
+					exit();
+				}
+			));
+		view.setEventLoop(eventLoop);
+		ui.setRoot(view, false);
+		ui.run();
+	}
+
+	/**
+	 * Request exit from an execution loop.
+	 */
+	public void exit() {
+		if (eventLoop == null) {
+			return;
+		}
+		Message<String> msg = ShellMessageBuilder.withPayload("int")
+			.setEventType(EventLoop.Type.SYSTEM)
+			.setPriority(0)
+			.build();
+		eventLoop.dispatch(msg);
+	}
+
+}

spring-shell-core/src/main/java/org/springframework/shell/component/view/control/InputView.java

@@ -23,6 +23,7 @@ import org.springframework.shell.component.view.event.KeyEvent.Key;
 import org.springframework.shell.component.view.event.KeyHandler;
 import org.springframework.shell.component.view.geom.Position;
 import org.springframework.shell.component.view.geom.Rectangle;
+import org.springframework.shell.component.view.message.ShellMessageBuilder;
 import org.springframework.shell.component.view.screen.Screen;
 
 /**
@@ -41,6 +42,7 @@ public class InputView extends BoxView {
 		registerKeyBinding(Key.CursorRight, event -> right());
 		registerKeyBinding(Key.Delete, () -> delete());
 		registerKeyBinding(Key.Backspace, () -> backspace());
+		registerKeyBinding(Key.Enter, () -> done());
 	}
 
 	@Override
@@ -117,4 +119,9 @@ public class InputView extends BoxView {
 	private void right() {
 		moveCursor(1);
 	}
+
+	private void done() {
+		dispatch(ShellMessageBuilder.ofView(this, ViewDoneEvent.of(this)));
+	}
+
 }

spring-shell-core/src/main/java/org/springframework/shell/component/view/control/View.java

@@ -16,6 +16,7 @@
 package org.springframework.shell.component.view.control;
 
 import org.springframework.lang.Nullable;
+import org.springframework.shell.component.view.event.EventLoop;
 import org.springframework.shell.component.view.event.KeyHandler;
 import org.springframework.shell.component.view.event.MouseHandler;
 
@@ -79,4 +80,11 @@ public interface View extends Control {
 	@Nullable
 	KeyHandler getHotKeyHandler();
 
+	/**
+	 * Sets an {@link EventLoop}.
+	 *
+	 * @param eventLoop the event loop
+	 */
+	void setEventLoop(@Nullable EventLoop eventLoop);
+
 }

spring-shell-core/src/main/java/org/springframework/shell/component/view/control/ViewDoneEvent.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2023 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.shell.component.view.control;
+
+/**
+ * Spesialisation of a {@link ViewEvent} indicating that a {@link View} is done.
+ *
+ * @author Janne Valkealahti
+ */
+public interface ViewDoneEvent extends ViewEvent {
+
+	/**
+	 * Create a generic event with empty view args.
+	 *
+	 * @param view the view
+	 * @return a generic view done event
+	 */
+	static ViewDoneEvent of(View view) {
+		return new GenericViewDoneEvent(view, ViewEventArgs.EMPTY);
+	}
+
+	record GenericViewDoneEvent(View view, ViewEventArgs args) implements ViewDoneEvent {
+	}
+
+}