Support view commands in view

- Setup facilities in view system to register commands
  with a Runnable to get dispatched into an event loop.
- As first commands, setup ListView with lineDown and
  lineUp.
- Expose needed functions into View itself.
- Relates #867

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

@@ -17,6 +17,7 @@
 
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Set;
 import java.util.function.BiFunction;
 import java.util.function.Predicate;
 
@@ -55,6 +56,7 @@ public abstract class AbstractView extends AbstractControl implements View {
 	private int layer;
 	private EventLoop eventLoop;
 	private ViewService viewService;
+	private final Map<String, Runnable> commands = new HashMap<>();
 	private Map<Integer, KeyBindingValue> keyBindings = new HashMap<>();
 	private Map<Integer, KeyBindingValue> hotKeyBindings = new HashMap<>();
 	private Map<Integer, MouseBindingValue> mouseBindings = new HashMap<>();
@@ -173,7 +175,7 @@ public KeyHandler getKeyHandler() {
 			if (key != null) {
 				KeyBindingValue keyBindingValue = getKeyBindings().get(key);
 				if (keyBindingValue != null) {
-					consumed = dispatchRunCommand(event, keyBindingValue);
+					consumed = dispatchKeyRunCommand(event, keyBindingValue);
 				}
 
 			}
@@ -192,7 +194,7 @@ public KeyHandler getHotKeyHandler() {
 			if (key != null) {
 				KeyBindingValue keyBindingValue = getHotKeyBindings().get(key);
 				if (keyBindingValue != null) {
-					consumed = dispatchRunCommand(event, keyBindingValue);
+					consumed = dispatchKeyRunCommand(event, keyBindingValue);
 				}
 
 			}
@@ -257,6 +259,15 @@ protected ViewService getViewService() {
 		return viewService;
 	}
 
+	protected void registerViewCommand(String command, Runnable runnable) {
+		commands.put(command, runnable);
+	}
+
+	@Override
+	public Set<String> getViewCommands() {
+		return commands.keySet();
+	}
+
 	protected void registerKeyBinding(Integer keyType, String keyCommand) {
 		registerKeyBinding(keyType, keyCommand, null, null);
 	}
@@ -395,20 +406,43 @@ protected boolean dispatchRunnable(Runnable runnable) {
 		return true;
 	}
 
-	protected boolean dispatchRunCommand(KeyEvent event, KeyBindingValue command) {
+	@Override
+	public boolean runViewCommand(String command) {
+		if (eventLoop == null) {
+			return false;
+		}
+		if (command != null) {
+			Runnable runnable = commands.get(command);
+			if (runnable != null) {
+				Message<Runnable> message = ShellMessageBuilder
+					.withPayload(runnable)
+					.setEventType(EventLoop.Type.TASK)
+					.build();
+				dispatch(message);
+				return true;
+			}
+		}
+		return false;
+	}
+
+	protected boolean dispatchKeyRunCommand(KeyEvent event, KeyBindingValue keyBindingValue) {
 		if (eventLoop == null) {
 			return false;
 		}
-		Runnable runnable = command.keyRunnable();
-		if (runnable != null) {
+		String keyCommand = keyBindingValue.keyCommand();
+		if (runViewCommand(keyCommand)) {
+			return true;
+		}
+		Runnable keyRunnable = keyBindingValue.keyRunnable();
+		if (keyRunnable != null) {
 			Message<Runnable> message = ShellMessageBuilder
-				.withPayload(runnable)
+				.withPayload(keyRunnable)
 				.setEventType(EventLoop.Type.TASK)
 				.build();
 			dispatch(message);
 			return true;
 		}
-		KeyBindingConsumer keyConsumer = command.keyConsumer();
+		KeyBindingConsumer keyConsumer = keyBindingValue.keyConsumer();
 		if (keyConsumer != null) {
 			Message<KeyBindingConsumerArgs> message = ShellMessageBuilder
 				.withPayload(new KeyBindingConsumerArgs(keyConsumer, event))
@@ -420,20 +454,24 @@ protected boolean dispatchRunCommand(KeyEvent event, KeyBindingValue command) {
 		return false;
 	}
 
-	protected boolean dispatchMouseRunCommand(MouseEvent event, MouseBindingValue command) {
+	protected boolean dispatchMouseRunCommand(MouseEvent event, MouseBindingValue mouseBindingValue) {
 		if (eventLoop == null) {
 			return false;
 		}
-		Runnable runnable = command.mouseRunnable();
-		if (runnable != null) {
+		String mouseCommand = mouseBindingValue.mouseCommand();
+		if (runViewCommand(mouseCommand)) {
+			return true;
+		}
+		Runnable mouseRunnable = mouseBindingValue.mouseRunnable();
+		if (mouseRunnable != null) {
 			Message<Runnable> message = ShellMessageBuilder
-				.withPayload(runnable)
+				.withPayload(mouseRunnable)
 				.setEventType(EventLoop.Type.TASK)
 				.build();
 			dispatch(message);
 			return true;
 		}
-		MouseBindingConsumer mouseConsumer = command.mouseConsumer();
+		MouseBindingConsumer mouseConsumer = mouseBindingValue.mouseConsumer();
 		if (mouseConsumer != null) {
 			Message<MouseBindingConsumerArgs> message = ShellMessageBuilder
 				.withPayload(new MouseBindingConsumerArgs(mouseConsumer, event))

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

@@ -38,6 +38,12 @@
 /**
  * {@code ListView} is a {@link View} showing items in a vertical list.
  *
+ * <p>Supported view commands:
+ * <ul>
+ * <li>{@link ViewCommand#LINE_UP} - Move active line upwards.
+ * <li>{@link ViewCommand#LINE_DOWN} - Move active line downwards.
+ * </ul>
+ *
  * @author Janne Valkealahti
  */
 public class ListView<T> extends BoxView {
@@ -94,13 +100,16 @@ public ListView(@Nullable List<T> items, ItemStyle itemStyle) {
 
 	@Override
 	protected void initInternal() {
-		registerKeyBinding(Key.CursorUp, () -> up());
-		registerKeyBinding(Key.CursorDown, () -> down());
+		registerViewCommand(ViewCommand.LINE_UP, () -> up());
+		registerViewCommand(ViewCommand.LINE_DOWN, () -> down());
+
+		registerKeyBinding(Key.CursorUp, ViewCommand.LINE_UP);
+		registerKeyBinding(Key.CursorDown, ViewCommand.LINE_DOWN);
 		registerKeyBinding(Key.Enter, () -> enter());
 		registerKeyBinding(Key.Space, () -> space());
 
-		registerMouseBinding(MouseEvent.Type.Wheel | MouseEvent.Button.WheelUp, () -> up());
-		registerMouseBinding(MouseEvent.Type.Wheel | MouseEvent.Button.WheelDown, () -> down());
+		registerMouseBinding(MouseEvent.Type.Wheel | MouseEvent.Button.WheelUp, ViewCommand.LINE_UP);
+		registerMouseBinding(MouseEvent.Type.Wheel | MouseEvent.Button.WheelDown, ViewCommand.LINE_DOWN);
 		registerMouseBinding(MouseEvent.Type.Released | MouseEvent.Button.Button1, event -> click(event));
 	}
 

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

@@ -15,6 +15,8 @@
  */
 package org.springframework.shell.component.view.control;
 
+import java.util.Set;
+
 import org.springframework.lang.Nullable;
 import org.springframework.shell.component.view.event.EventLoop;
 import org.springframework.shell.component.view.event.KeyHandler;
@@ -87,4 +89,20 @@ public interface View extends Control {
 	 */
 	void setEventLoop(@Nullable EventLoop eventLoop);
 
+	/**
+	 * Get supported commands.
+	 *
+	 * @return supported commands
+	 * @see ViewCommand
+	 */
+	Set<String> getViewCommands();
+
+	/**
+	 * Run command.
+	 *
+	 * @param command the command to run
+	 * @return true if command was succesfully dispatched
+	 * @see ViewCommand
+	 */
+	boolean runViewCommand(String command);
 }

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

@@ -26,25 +26,17 @@
 public final class ViewCommand {
 
 	/**
-	 * Move line up. Generic use in something where selection needs to be moved up.
+	 * Move line up.
+	 *
+	 * For example where selection needs to be moved up.
 	 */
 	public static String LINE_UP = "LineUp";
 
 	/**
-	 * Move line down. Generic use in something where selection needs to be moved
-	 * down.
+	 * Move line down.
+	 *
+	 * For example where selection needs to be moved down.
 	 */
 	public static String LINE_DOWN = "LineDown";
 
-	/**
-	 * Open selected item. In a some sort of view where something can be selected
-	 * and that active selected should be opened.
-	 */
-	public static String OPEN_SELECTED_ITEM = "OpenSelectedItem";
-
-	public static String SELECT = "Select";
-	public static String LEFT = "Left";
-	public static String RIGHT = "Right";
-	public static String SELECTION_CHANGED = "SelectionChanged";
-
 }

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

@@ -18,6 +18,7 @@
 import java.time.Duration;
 import java.util.Arrays;
 
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Flux;
@@ -474,4 +475,46 @@ public void draw(Screen screen) {
 
 	}
 
+	@Nested
+	class ViewCommands {
+
+		@BeforeEach
+		void setup() {
+			view = new ListView<>();
+			configure(view);
+			view.setRect(0, 0, 80, 24);
+			view.setItems(Arrays.asList("item1", "item2"));
+		}
+
+		@Test
+		void supports() {
+			assertThat(view.getViewCommands()).contains(ViewCommand.LINE_DOWN, ViewCommand.LINE_UP);
+		}
+
+		@Test
+		void lineDown() {
+			StepVerifier verifier = StepVerifier.create(eventLoop.events())
+				.expectNextCount(1)
+				.thenCancel()
+				.verifyLater();
+			view.runViewCommand(ViewCommand.LINE_DOWN);
+			verifier.verify(Duration.ofSeconds(1));
+			assertThat(getIntField(view, START_FIELD)).isEqualTo(0);
+			assertThat(getIntField(view, POSITION_FIELD)).isEqualTo(1);
+		}
+
+		@Test
+		void lineUp() {
+			StepVerifier verifier = StepVerifier.create(eventLoop.events())
+				.expectNextCount(1)
+				.thenCancel()
+				.verifyLater();
+			view.runViewCommand(ViewCommand.LINE_UP);
+			verifier.verify(Duration.ofSeconds(1));
+			assertThat(getIntField(view, START_FIELD)).isEqualTo(0);
+			assertThat(getIntField(view, POSITION_FIELD)).isEqualTo(1);
+		}
+
+	}
+
 }