Add nextToUndo, nextToRedo properties to UndoManager.

FXMisc · Apr 27, 2017 · f32c6cb · f32c6cb
1 parent 6f9b5ad
commit f32c6cb
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Showing 7 changed files with 79 additions and 35 deletions.
diff --git a/undofx-demos/src/main/java/org/fxmisc/undo/demo/CircleProperties.java b/undofx-demos/src/main/java/org/fxmisc/undo/demo/CircleProperties.java
@@ -6,7 +6,6 @@
 import java.util.Optional;
 
 import javafx.application.Application;
-import javafx.beans.binding.Bindings;
 import javafx.geometry.Pos;
 import javafx.scene.Node;
 import javafx.scene.Scene;
@@ -194,8 +193,8 @@ public boolean equals(Object other) {
                     c -> c.redo(), // function to undo a change
                     (c1, c2) -> c1.mergeWith(c2)); // function to merge two changes
 
-        undoBtn.disableProperty().bind(Bindings.not(undoManager.undoAvailableProperty()));
-        redoBtn.disableProperty().bind(Bindings.not(undoManager.redoAvailableProperty()));
+        undoBtn.disableProperty().bind(undoManager.undoAvailableProperty().map(x -> !x));
+        redoBtn.disableProperty().bind(undoManager.redoAvailableProperty().map(x -> !x));
         undoBtn.setOnAction(evt -> undoManager.undo());
         redoBtn.setOnAction(evt -> undoManager.redo());
         saveBtn.disableProperty().bind(undoManager.atMarkedPositionProperty());

diff --git a/undofx/src/main/java/org/fxmisc/undo/UndoManager.java b/undofx/src/main/java/org/fxmisc/undo/UndoManager.java
@@ -2,6 +2,8 @@
 
 import javafx.beans.value.ObservableBooleanValue;
 
+import org.reactfx.value.Val;
+
 public interface UndoManager {
 
     /**
@@ -43,13 +45,13 @@ interface UndoPosition {
     /**
      * Indicates whether there is a change that can be undone.
      */
-    ObservableBooleanValue undoAvailableProperty();
+    Val<Boolean> undoAvailableProperty();
     boolean isUndoAvailable();
 
     /**
      * Indicates whether there is a change that can be redone.
      */
-    ObservableBooleanValue redoAvailableProperty();
+    Val<Boolean> redoAvailableProperty();
     boolean isRedoAvailable();
 
     /**

diff --git a/undofx/src/main/java/org/fxmisc/undo/impl/ChangeQueue.java b/undofx/src/main/java/org/fxmisc/undo/impl/ChangeQueue.java
@@ -10,8 +10,16 @@ interface QueuePosition {
 
     boolean hasPrev();
 
+    /** Returns the next item. Current position stays unchanged. */
+    C peekNext();
+
+    /** Returns the previous item. Current position stays unchanged. */
+    C peekPrev();
+
+    /** Returns the next item and increases the current position by 1. */
     C next();
 
+    /** Returns the previous item and decreases the current position by 1. */
     C prev();
 
     @SuppressWarnings({"unchecked"})

diff --git a/undofx/src/main/java/org/fxmisc/undo/impl/FixedSizeChangeQueue.java b/undofx/src/main/java/org/fxmisc/undo/impl/FixedSizeChangeQueue.java
@@ -74,23 +74,37 @@ public boolean hasPrev() {
     }
 
     @Override
-    public C next() {
+    public C peekNext() {
         if(currentPosition < size) {
-            return fetch(currentPosition++).getChange();
+            return fetch(currentPosition).getChange();
         } else {
             throw new NoSuchElementException();
         }
     }
 
     @Override
-    public C prev() {
+    public C next() {
+        C c = peekNext();
+        currentPosition += 1;
+        return c;
+    }
+
+    @Override
+    public C peekPrev() {
         if(currentPosition > 0) {
-            return fetch(--currentPosition).getChange();
+            return fetch(currentPosition - 1).getChange();
         } else {
             throw new NoSuchElementException();
         }
     }
 
+    @Override
+    public C prev() {
+        C c = peekPrev();
+        currentPosition -= 1;
+        return c;
+    }
+
     @Override
     public void forgetHistory() {
         zeroPositionRevision = fetchRevisionForPosition(currentPosition);

diff --git a/undofx/src/main/java/org/fxmisc/undo/impl/UndoManagerImpl.java b/undofx/src/main/java/org/fxmisc/undo/impl/UndoManagerImpl.java
@@ -11,9 +11,12 @@
 
 import org.fxmisc.undo.UndoManager;
 import org.fxmisc.undo.impl.ChangeQueue.QueuePosition;
+import org.reactfx.EventSource;
 import org.reactfx.EventStream;
 import org.reactfx.Subscription;
 import org.reactfx.SuspendableNo;
+import org.reactfx.value.Val;
+import org.reactfx.value.ValBase;
 
 public class UndoManagerImpl<C> implements UndoManager {
 
@@ -45,21 +48,21 @@ public boolean isValid() {
     private final Subscription subscription;
     private final SuspendableNo performingAction = new SuspendableNo();
 
-    private final BooleanBinding undoAvailable = new BooleanBinding() {
-        @Override
-        protected boolean computeValue() {
-            return queue.hasPrev();
-        }
+    private final EventSource<Void> invalidationRequests = new EventSource<Void>();
+
+    private final Val<C> nextToUndo = new ValBase<C>() {
+        @Override protected Subscription connect() { return invalidationRequests.subscribe(x -> invalidate()); }
+        @Override protected C computeValue() { return queue.hasPrev() ? queue.peekPrev() : null; }
     };
 
-    private final BooleanBinding redoAvailable = new BooleanBinding() {
-        @Override
-        protected boolean computeValue() {
-            return queue.hasNext();
-        }
+    private final Val<C> nextToRedo = new ValBase<C>() {
+        @Override protected Subscription connect() { return invalidationRequests.subscribe(x -> invalidate()); }
+        @Override protected C computeValue() { return queue.hasNext() ? queue.peekNext() : null; }
     };
 
     private final BooleanBinding atMarkedPosition = new BooleanBinding() {
+        { invalidationRequests.addObserver(x -> this.invalidate()); }
+
         @Override
         protected boolean computeValue() {
             return mark.equals(queue.getCurrentPosition());
@@ -96,9 +99,7 @@ public boolean undo() {
         if(isUndoAvailable()) {
             canMerge = false;
             performChange(invert.apply(queue.prev()));
-            undoAvailable.invalidate();
-            redoAvailable.invalidate();
-            atMarkedPosition.invalidate();
+            invalidateProperties();
             return true;
         } else {
             return false;
@@ -110,9 +111,7 @@ public boolean redo() {
         if(isRedoAvailable()) {
             canMerge = false;
             performChange(queue.next());
-            undoAvailable.invalidate();
-            redoAvailable.invalidate();
-            atMarkedPosition.invalidate();
+            invalidateProperties();
             return true;
         } else {
             return false;
@@ -121,22 +120,22 @@ public boolean redo() {
 
     @Override
     public boolean isUndoAvailable() {
-        return undoAvailable.get();
+        return nextToUndo.isPresent();
     }
 
     @Override
-    public ObservableBooleanValue undoAvailableProperty() {
-        return undoAvailable;
+    public Val<Boolean> undoAvailableProperty() {
+        return nextToUndo.map(c -> true).orElseConst(false);
     }
 
     @Override
     public boolean isRedoAvailable() {
-        return redoAvailable.get();
+        return nextToRedo.isPresent();
     }
 
     @Override
-    public ObservableBooleanValue redoAvailableProperty() {
-        return redoAvailable;
+    public Val<Boolean> redoAvailableProperty() {
+        return nextToRedo.map(c -> true).orElseConst(false);
     }
 
     @Override
@@ -172,7 +171,7 @@ public void preventMerge() {
     @Override
     public void forgetHistory() {
         queue.forgetHistory();
-        undoAvailable.invalidate();
+        invalidateProperties();
     }
 
     private void performChange(C change) {
@@ -220,8 +219,10 @@ private void addChange(C change) {
             queue.push(change);
             canMerge = true;
         }
-        undoAvailable.invalidate();
-        redoAvailable.invalidate();
-        atMarkedPosition.invalidate();
+        invalidateProperties();
+    }
+
+    private void invalidateProperties() {
+        invalidationRequests.push(null);
     }
 }
diff --git a/undofx/src/main/java/org/fxmisc/undo/impl/UnlimitedChangeQueue.java b/undofx/src/main/java/org/fxmisc/undo/impl/UnlimitedChangeQueue.java
@@ -56,11 +56,21 @@ public final boolean hasPrev() {
         return currentPosition > 0;
     }
 
+    @Override
+    public final C peekNext() {
+        return changes.get(currentPosition).getChange();
+    }
+
     @Override
     public final C next() {
         return changes.get(currentPosition++).getChange();
     }
 
+    @Override
+    public final C peekPrev() {
+        return changes.get(currentPosition - 1).getChange();
+    }
+
     @Override
     public final C prev() {
         return changes.get(--currentPosition).getChange();

diff --git a/undofx/src/main/java/org/fxmisc/undo/impl/ZeroSizeChangeQueue.java b/undofx/src/main/java/org/fxmisc/undo/impl/ZeroSizeChangeQueue.java
@@ -44,11 +44,21 @@ public boolean hasPrev() {
         return false;
     }
 
+    @Override
+    public C peekNext() {
+        throw new NoSuchElementException();
+    }
+
     @Override
     public C next() {
         throw new NoSuchElementException();
     }
 
+    @Override
+    public C peekPrev() {
+        throw new NoSuchElementException();
+    }
+
     @Override
     public C prev() {
         throw new NoSuchElementException();