Initial hotkey infra

- Duplicate keyhandler into hotkeyhandler
- Define some view to handle hot keys, like AppView and MenuBarView
- Catalog app binds some menus to hot keys
- Bind all normal keys a-z with alt
- Relates #823
- Relates #826

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

@@ -229,12 +229,24 @@ public class TerminalUI {
 
 	private void handleKeyEvent(KeyEvent event) {
 		log.trace("handleKeyEvent {}", event);
-		if (rootView != null && rootView.hasFocus()) {
-			KeyHandler handler = rootView.getKeyHandler();
+
+		if (rootView != null) {
+			// if hotkeys consume, we're done
+			KeyHandler handler = rootView.getHotKeyHandler();
 			if (handler != null) {
 				KeyHandlerResult result = handler.handle(KeyHandler.argsOf(event));
-				if (result.focus() != null) {
-					setFocus(result.focus());
+				if (result.consumed()) {
+					return;
+				}
+			}
+			// continue with one having focus
+			if (rootView.hasFocus()) {
+				handler = rootView.getKeyHandler();
+				if (handler != null) {
+					KeyHandlerResult result = handler.handle(KeyHandler.argsOf(event));
+					if (result.focus() != null) {
+						setFocus(result.focus());
+					}
 				}
 			}
 		}

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

@@ -55,6 +55,7 @@ public abstract class AbstractView extends AbstractControl implements View {
 	private int layer;
 	private EventLoop eventLoop;
 	private Map<Integer, KeyBindingValue> keyBindings = new HashMap<>();
+	private Map<Integer, KeyBindingValue> hotKeyBindings = new HashMap<>();
 	private Map<Integer, MouseBindingValue> mouseBindings = new HashMap<>();
 
 	public AbstractView() {
@@ -180,6 +181,25 @@ public abstract class AbstractView extends AbstractControl implements View {
 		return handler;
 	}
 
+	@Override
+	public KeyHandler getHotKeyHandler() {
+		log.trace("getHotKeyHandler() {}", this);
+		KeyHandler handler = args -> {
+			KeyEvent event = args.event();
+			boolean consumed = false;
+			Integer key = event.key();
+			if (key != null) {
+				KeyBindingValue keyBindingValue = getHotKeyBindings().get(key);
+				if (keyBindingValue != null) {
+					consumed = dispatchRunCommand(event, keyBindingValue);
+				}
+
+			}
+			return KeyHandler.resultOf(event, consumed, null);
+		};
+		return handler;
+	}
+
 	/**
 	 * Sets a callback function which is invoked after a {@link View} has been
 	 * drawn.
@@ -236,6 +256,24 @@ public abstract class AbstractView extends AbstractControl implements View {
 		});
 	}
 
+	protected void registerHotKeyBinding(Integer keyType, String keyCommand) {
+		registerHotKeyBinding(keyType, keyCommand, null, null);
+	}
+
+	protected void registerHotKeyBinding(Integer keyType, KeyBindingConsumer keyConsumer) {
+		registerHotKeyBinding(keyType, null, keyConsumer, null);
+	}
+
+	protected void registerHotKeyBinding(Integer keyType, Runnable keyRunnable) {
+		registerHotKeyBinding(keyType, null, null, keyRunnable);
+	}
+
+	private void registerHotKeyBinding(Integer keyType, String keyCommand, KeyBindingConsumer keyConsumer, Runnable keyRunnable) {
+		hotKeyBindings.compute(keyType, (key, old) -> {
+			return KeyBindingValue.of(old, keyCommand, keyConsumer, keyRunnable);
+		});
+	}
+
 	record KeyBindingValue(String keyCommand, KeyBindingConsumer keyConsumer, Runnable keyRunnable) {
 		static KeyBindingValue of(KeyBindingValue old, String keyCommand, KeyBindingConsumer keyConsumer,
 				Runnable keyRunnable) {
@@ -257,6 +295,15 @@ public abstract class AbstractView extends AbstractControl implements View {
 		return keyBindings;
 	}
 
+	/**
+	 * Get hotkey bindings.
+	 *
+	 * @return hotkey bindings
+	 */
+	protected Map<Integer, KeyBindingValue> getHotKeyBindings() {
+		return hotKeyBindings;
+	}
+
 	record MouseBindingValue(String mouseCommand, MouseBindingConsumer mouseConsumer, Runnable mouseRunnable,
 			Predicate<MouseEvent> mousePredicate) {
 		static MouseBindingValue of(MouseBindingValue old, String mouseCommand, MouseBindingConsumer mouseConsumer,

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

@@ -133,6 +133,11 @@ public class AppView extends BoxView {
 		return otherHandler.thenIfNotConsumed(handler);
 	}
 
+	@Override
+	public KeyHandler getHotKeyHandler() {
+		return menu != null ? menu.getHotKeyHandler() : super.getHotKeyHandler();
+	}
+
 	@Override
 	public boolean hasFocus() {
 		if (grid != null) {

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

@@ -35,8 +35,8 @@ import org.springframework.shell.component.view.geom.Dimension;
 import org.springframework.shell.component.view.geom.Rectangle;
 import org.springframework.shell.component.view.screen.Screen;
 import org.springframework.shell.component.view.screen.Screen.Writer;
-import org.springframework.shell.style.ThemeResolver;
 import org.springframework.shell.component.view.screen.ScreenItem;
+import org.springframework.shell.style.ThemeResolver;
 
 /**
  * {@link MenuBarView} shows {@link MenuBarItem items} horizontally and is
@@ -187,6 +187,17 @@ public class MenuBarView extends BoxView {
 		return x;
 	}
 
+	private int itemIndex(MenuBarItem item) {
+		int index = 0;
+		for (MenuBarItem i : items) {
+			if (i == item) {
+				return index;
+			}
+			index++;
+		}
+		return -1;
+	}
+
 	private void select(MouseEvent event) {
 		int x = event.x();
 		int y = event.y();
@@ -256,6 +267,23 @@ public class MenuBarView extends BoxView {
 	public void setItems(List<MenuBarItem> items) {
 		this.items.clear();
 		this.items.addAll(items);
+		registerHotKeys();
+	}
+
+	private void selectItem(MenuBarItem item) {
+		int index = itemIndex(item);
+		if (index > -1) {
+			setSelected(index);
+			checkMenuView();
+		}
+	}
+
+	private void registerHotKeys() {
+		getItems().stream()
+			.filter(item -> item.getHotKey() != null)
+			.forEach(item -> {
+				registerHotKeyBinding(item.getHotKey(), () -> selectItem(item));
+			});
 	}
 
 	/**
@@ -265,6 +293,7 @@ public class MenuBarView extends BoxView {
 
 		private String title;
 		private List<MenuItem> items;
+		private Integer hotKey;
 
 		public MenuBarItem(String title) {
 			this(title, null);
@@ -286,6 +315,15 @@ public class MenuBarView extends BoxView {
 		public List<MenuItem> getItems() {
 			return items;
 		}
+
+		public Integer getHotKey() {
+			return hotKey;
+		}
+
+		public MenuBarItem setHotKey(Integer hotKey) {
+			this.hotKey = hotKey;
+			return this;
+		}
 	}
 
 }

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

@@ -60,13 +60,23 @@ public interface View extends Control {
 	MouseHandler getMouseHandler();
 
 	/**
-	 * Gets a {@link View} mouse {@link KeyHandler}. Can be {@code null} which
+	 * Gets a {@link View} key {@link KeyHandler}. Can be {@code null} which
 	 * indicates view will not handle any key events.
 	 *
-	 * @return a view mouse handler
+	 * @return a view key handler
 	 * @see KeyHandler
 	 */
 	@Nullable
 	KeyHandler getKeyHandler();
 
+	/**
+	 * Gets a {@link View} hotkey {@link KeyHandler}. Can be {@code null} which
+	 * indicates view will not handle any key events.
+	 *
+	 * @return a view hotkey handler
+	 * @see KeyHandler
+	 */
+	@Nullable
+	KeyHandler getHotKeyHandler();
+
 }

spring-shell-core/src/main/java/org/springframework/shell/component/view/event/KeyBinder.java

@@ -45,6 +45,10 @@ public class KeyBinder {
 			keyMap.bind(KeyEvent.Key.Char, Character.toString(i));
 		}
 
+		for (char i = KeyEvent.Key.a; i <= KeyEvent.Key.z; i++) {
+			keyMap.bind(i | KeyEvent.KeyMask.AltMask, alt(i));
+		}
+
 		keyMap.bind(KeyEvent.Key.q | KeyEvent.KeyMask.CtrlMask, ctrl('q'));
 
 		keyMap.bind(KeyEvent.Key.Mouse, key(terminal, Capability.key_mouse));

spring-shell-core/src/test/java/org/springframework/shell/component/view/control/MenuBarViewTests.java

@@ -44,6 +44,18 @@ class MenuBarViewTests extends AbstractViewTests {
 			assertThat(view.getItems()).hasSize(1);
 		}
 
+		@Test
+		void hotkeys() {
+			MenuBarItem item;
+
+			item = MenuBarItem.of("title");
+			assertThat(item.getHotKey()).isNull();
+			item.setHotKey(Key.f);
+			assertThat(item.getHotKey()).isEqualTo(Key.f);
+
+			item = MenuBarItem.of("title").setHotKey(Key.f);
+			assertThat(item.getHotKey()).isEqualTo(Key.f);
+		}
 	}
 
 	@Nested

spring-shell-samples/spring-shell-sample-catalog/src/main/java/org/springframework/shell/samples/catalog/Catalog.java

@@ -46,6 +46,7 @@ import org.springframework.shell.component.view.control.cell.ListCell;
 import org.springframework.shell.component.view.event.EventLoop;
 import org.springframework.shell.component.view.event.KeyEvent;
 import org.springframework.shell.component.view.event.KeyEvent.Key;
+import org.springframework.shell.component.view.event.KeyEvent.KeyMask;
 import org.springframework.shell.component.view.geom.Rectangle;
 import org.springframework.shell.component.view.message.ShellMessageBuilder;
 import org.springframework.shell.component.view.screen.Screen;
@@ -281,11 +282,13 @@ public class Catalog {
 			.toArray(MenuItem[]::new);
 		MenuBarView menuBar = MenuBarView.of(
 			MenuBarItem.of("File",
-				MenuItem.of("Quit", MenuItemCheckStyle.NOCHECK, quitAction)),
+					MenuItem.of("Quit", MenuItemCheckStyle.NOCHECK, quitAction))
+				.setHotKey(Key.f | KeyMask.AltMask),
 			MenuBarItem.of("Theme",
-				themeItems),
+					themeItems)
+				.setHotKey(Key.t | KeyMask.AltMask),
 			MenuBarItem.of("Help",
-				MenuItem.of("About"))
+					MenuItem.of("About"))
 		);
 
 		menuBar.setThemeResolver(themeResolver);