core/src/main/java/dev/kske/undoredo/core/ChangeManager.java

@@ -1,11 +1,15 @@
 package dev.kske.undoredo.core;
 
-import java.util.List;
+import java.util.*;
 
 /**
  * A change manager keeps track of subsequent changes and allows un- and redoing them. A specific
  * change can be marked using {@link #mark()} to keep track of a saved state in the application that
  * uses the manager.
+ * <p>
+ * If you intend to listen to the state of a change manager, consider writing a wrapper
+ * implementation for an existing change manager that adds the necessary hooks. If you use JavaFX,
+ * take a look at the {@code dev.kske.undoredo.javafx} module.
  *
  * @param <C> the change type to store in this change manager
  * @author Maximilian K&auml;fer
@@ -22,6 +26,12 @@ public interface ChangeManager<C extends Change> {
 	 */
 	void addChange(C change);
 
+	/**
+	 * @return the change that was applied last
+	 * @since 0.0.1
+	 */
+	Optional<C> getLastChange();
+
 	/**
 	 * Undoes the current change.
 	 *

core/src/main/java/dev/kske/undoredo/core/UnlimitedChangeManager.java

@@ -22,6 +22,11 @@ public final class UnlimitedChangeManager<C extends Change> implements ChangeMan
 		++index;
 	}
 
+	@Override
+	public Optional<C> getLastChange() {
+		return index < 0 ? Optional.empty() : Optional.of(changes.get(index));
+	}
+
 	@Override
 	public boolean undo() {
 		if (isUndoAvailable()) {

core/src/test/java/dev/kske/undoredo/core/ChangeManagerTest.java

@@ -27,20 +27,33 @@ class ChangeManagerTest {
 	 * @since 0.0.1
 	 */
 	@Test
-	@Order(1)
+	@Order(10)
 	void testAddChange() {
 		assertSame(0, wrapper.value);
 		manager.addChange(change);
 		assertSame(1, wrapper.value);
 	}
 
+	/**
+	 * Tests retrieving the last change.
+	 *
+	 * @since 0.0.1
+	 */
+	@Test
+	@Order(20)
+	void testLastChange() {
+		assertTrue(manager.getLastChange().isEmpty());
+		manager.addChange(change);
+		assertEquals(change, manager.getLastChange().get());
+	}
+
 	/**
 	 * Tests the consistency of the change list.
 	 *
 	 * @since 0.0.1
 	 */
 	@Test
-	@Order(2)
+	@Order(30)
 	void testGetChanges() {
 		assertTrue(manager.getChanges().isEmpty());
 		manager.addChange(change);
@@ -54,7 +67,7 @@ class ChangeManagerTest {
 	 * @since 0.0.1
 	 */
 	@Test
-	@Order(2)
+	@Order(40)
 	void testUndo() {
 		assertFalse(manager.isUndoAvailable());
 		assertFalse(manager.undo());
@@ -63,6 +76,7 @@ class ChangeManagerTest {
 		assertTrue(manager.undo());
 		assertFalse(manager.isUndoAvailable());
 		assertFalse(manager.undo());
+		assertTrue(manager.getLastChange().isEmpty());
 	}
 
 	/**
@@ -71,7 +85,7 @@ class ChangeManagerTest {
 	 * @since 0.0.1
 	 */
 	@Test
-	@Order(4)
+	@Order(50)
 	void testRedo() {
 		assertFalse(manager.isRedoAvailable());
 		assertFalse(manager.redo());
@@ -83,6 +97,7 @@ class ChangeManagerTest {
 		assertTrue(manager.redo());
 		assertFalse(manager.isRedoAvailable());
 		assertFalse(manager.redo());
+		assertEquals(change, manager.getLastChange().get());
 	}
 
 	/**
@@ -91,7 +106,7 @@ class ChangeManagerTest {
 	 * @since 0.0.1
 	 */
 	@Test
-	@Order(5)
+	@Order(60)
 	void testMark() {
 		assertTrue(manager.isAtMarkedIndex());
 		manager.addChange(change);

javafx/.classpath

@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<classpath>
+	<classpathentry kind="src" output="target/classes" path="src/main/java">
+		<attributes>
+			<attribute name="optional" value="true"/>
+			<attribute name="maven.pomderived" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="src" output="target/test-classes" path="src/test/java">
+		<attributes>
+			<attribute name="optional" value="true"/>
+			<attribute name="maven.pomderived" value="true"/>
+			<attribute name="test" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-11">
+		<attributes>
+			<attribute name="maven.pomderived" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="con" path="org.eclipse.m2e.MAVEN2_CLASSPATH_CONTAINER">
+		<attributes>
+			<attribute name="maven.pomderived" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="output" path="target/classes"/>
+</classpath>

javafx/.project

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>undo-redo-javafx</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.eclipse.jdt.core.javabuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+		<buildCommand>
+			<name>org.eclipse.m2e.core.maven2Builder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.eclipse.jdt.core.javanature</nature>
+		<nature>org.eclipse.m2e.core.maven2Nature</nature>
+	</natures>
+</projectDescription>

javafx/pom.xml

@@ -0,0 +1,28 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+
+	<artifactId>javafx</artifactId>
+	<name>Undo-Redo JavaFX Integration</name>
+
+	<parent>
+		<groupId>dev.kske</groupId>
+		<artifactId>undo-redo</artifactId>
+		<version>0.0.1-SNAPSHOT</version>
+	</parent>
+
+	<dependencies>
+		<dependency>
+			<groupId>dev.kske</groupId>
+			<artifactId>undo-redo-core</artifactId>
+			<version>0.0.1-SNAPSHOT</version>
+		</dependency>
+		<dependency>
+			<groupId>org.openjfx</groupId>
+			<artifactId>javafx-base</artifactId>
+			<version>11</version>
+		</dependency>
+	</dependencies>
+
+</project>

javafx/src/main/java/dev/kske/undoredo/javafx/ChangeManagerWrapper.java

@@ -0,0 +1,134 @@
+package dev.kske.undoredo.javafx;
+
+import java.util.List;
+
+import javafx.beans.property.*;
+
+import dev.kske.undoredo.core.*;
+
+/**
+ * Wraps an ordinary change manager into an observable change manager, providing the required
+ * properties for concrete implementations.
+ * <p>
+ * The properties have the same name as their corresponding {@code -property()} methods and can be
+ * accessed reflectively from JavaFX, e.g. through
+ * {@link javafx.beans.binding.Bindings#select(Object, String...)}. Alternatively, the property
+ * names are available as constants.
+ *
+ * @param <C> the change type to store in this change manager
+ * @param <M> the type of change manager to wrap
+ * @author Kai S. K. Engelbart
+ * @since 0.0.1
+ */
+public class ChangeManagerWrapper<C extends Change, M extends ChangeManager<C>>
+	implements ObservableChangeManager<C> {
+
+	public static final String	LAST_CHANGE		= "lastChange";
+	public static final String	AT_MARKED_INDEX	= "atMarkedIndex";
+	public static final String	UNDO_AVAILABLE	= "undoAvailable";
+	public static final String	REDO_AVAILABLE	= "redoAvailable";
+
+	protected ReadOnlyObjectWrapper<C>	lastChange		=
+		new ReadOnlyObjectWrapper<>(this, LAST_CHANGE);
+	protected ReadOnlyBooleanWrapper	atMarkedIndex	=
+		new ReadOnlyBooleanWrapper(this, AT_MARKED_INDEX);
+	protected ReadOnlyBooleanWrapper	undoAvailable	=
+		new ReadOnlyBooleanWrapper(this, UNDO_AVAILABLE);
+	protected ReadOnlyBooleanWrapper	redoAvailable	=
+		new ReadOnlyBooleanWrapper(this, REDO_AVAILABLE);
+
+	protected final M manager;
+
+	/**
+	 * Initializes a change manager wrapper.
+	 *
+	 * @param manager the change manager to wrap
+	 * @since 0.0.1
+	 */
+	public ChangeManagerWrapper(M manager) {
+		this.manager = manager;
+	}
+
+	@Override
+	public void addChange(C change) {
+		manager.addChange(change);
+		updateProperties();
+	}
+
+	@Override
+	public boolean undo() {
+		if (manager.undo()) {
+			updateProperties();
+			return true;
+		}
+		return false;
+	}
+
+	@Override
+	public boolean redo() {
+		if (manager.redo()) {
+			updateProperties();
+			return true;
+		}
+		return false;
+	}
+
+	@Override
+	public void mark() {
+		manager.mark();
+		setAtMarkedIndex(manager.isAtMarkedIndex());
+	}
+
+	/**
+	 * Sets the values of all properties to those present in the wrapped change manager.
+	 *
+	 * @since 0.0.1
+	 */
+	private void updateProperties() {
+		setLastChange(manager.getLastChange().orElse(null));
+		setAtMarkedIndex(manager.isAtMarkedIndex());
+		setUndoAvailable(manager.isUndoAvailable());
+		setRedoAvailable(manager.isRedoAvailable());
+	}
+
+	@Override
+	public final ReadOnlyObjectProperty<C> lastChangeProperty() {
+		return lastChange.getReadOnlyProperty();
+	}
+
+	protected final void setLastChange(C lastChange) {
+		this.lastChange.set(lastChange);
+	}
+
+	@Override
+	public final ReadOnlyBooleanProperty atMarkedIndexProperty() {
+		return atMarkedIndex.getReadOnlyProperty();
+	}
+
+	protected final void setAtMarkedIndex(boolean atMarkedIndex) {
+		this.atMarkedIndex.set(atMarkedIndex);
+	}
+
+	@Override
+	public final ReadOnlyBooleanProperty undoAvailableProperty() {
+		return undoAvailable.getReadOnlyProperty();
+	}
+
+	protected final void setUndoAvailable(boolean undoAvailable) {
+		this.undoAvailable.set(undoAvailable);
+	}
+
+	@Override
+	public final ReadOnlyBooleanProperty redoAvailableProperty() {
+		return redoAvailable.getReadOnlyProperty();
+	}
+
+	protected final void setRedoAvailable(boolean redoAvailable) {
+		this.redoAvailable.set(redoAvailable);
+	}
+
+	@Override
+	public List<C> getChanges() {
+		return manager.getChanges();
+	}
+}

javafx/src/main/java/dev/kske/undoredo/javafx/ObservableChangeManager.java

@@ -0,0 +1,47 @@
+package dev.kske.undoredo.javafx;
+
+import java.util.Optional;
+
+import javafx.beans.property.*;
+
+import dev.kske.undoredo.core.*;
+
+/**
+ * A change manager that exposes its state through JavaFX properties, thereby allowing a direct
+ * integration of Undo-Redo with JavaFX listeners and property bindings.
+ *
+ * @param <C> the change type to store in this change manager
+ * @author Kai S. K. Engelbart
+ * @since 0.0.1
+ * @see ChangeManagerWrapper
+ */
+public interface ObservableChangeManager<C extends Change> extends ChangeManager<C> {
+
+	ReadOnlyObjectProperty<C> lastChangeProperty();
+
+	@Override
+	default Optional<C> getLastChange() {
+		return Optional.of(lastChangeProperty().get());
+	}
+
+	ReadOnlyBooleanProperty atMarkedIndexProperty();
+
+	@Override
+	default boolean isAtMarkedIndex() {
+		return atMarkedIndexProperty().get();
+	}
+
+	ReadOnlyBooleanProperty undoAvailableProperty();
+
+	@Override
+	default boolean isUndoAvailable() {
+		return undoAvailableProperty().get();
+	}
+
+	ReadOnlyBooleanProperty redoAvailableProperty();
+
+	@Override
+	default boolean isRedoAvailable() {
+		return redoAvailableProperty().get();
+	}
+}

javafx/src/main/java/dev/kske/undoredo/javafx/package-info.java

@@ -0,0 +1,7 @@
+/**
+ * Contains JavaFX-based wrapper API for integrating Undo-Redo with JavaFX.
+ *
+ * @author Kai S. K. Engelbart
+ * @since 0.0.1
+ */
+package dev.kske.undoredo.javafx;

javafx/src/main/java/module-info.java

@@ -0,0 +1,15 @@
+/**
+ * Contains JavaFX-based wrapper API for integrating Undo-Redo with JavaFX.
+ *
+ * @author Kai S. K. Engelbart
+ * @since 0.0.1
+ */
+module dev.kske.undoredo.javafx {
+
+	exports dev.kske.undoredo.javafx;
+
+	opens dev.kske.undoredo.javafx to javafx.base;
+
+	requires transitive dev.kske.undoredo.core;
+	requires transitive javafx.base;
+}

pom.xml

@@ -14,6 +14,7 @@
 	
 	<modules>
 		<module>core</module>
+		<module>javafx</module>
 	</modules>
 
 	<licenses>
@@ -47,6 +48,16 @@
 			</roles>
 			<timezone>Europe/Berlin</timezone>
 		</developer>
+		<developer>
+			<name>Leon Hofmeister</name>
+			<email>leon@kske.dev</email>
+			<url>https://git.kske.dev/delvh</url>
+			<roles>
+				<role>architect</role>
+				<role>developer</role>
+			</roles>
+			<timezone>Europe/Berlin</timezone>
+		</developer>
 	</developers>
 
 	<scm>