1 files changed, 110 insertions, 0 deletions
diff --git a/core/java/android/content/UndoOperation.java b/core/java/android/content/UndoOperation.java
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+++ b/core/java/android/content/UndoOperation.java
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+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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 android.content;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+
+/**
+ * A single undoable operation.  You must subclass this to implement the state
+ * and behavior for your operation.  Instances of this class are placed and
+ * managed in an {@link UndoManager}.
+ */
+public abstract class UndoOperation<DATA> implements Parcelable {
+    UndoOwner mOwner;
+
+    /**
+     * Create a new instance of the operation.
+     * @param owner Who owns the data being modified by this undo state; must be
+     * returned by {@link UndoManager#getOwner(String, Object) UndoManager.getOwner}.
+     */
+    public UndoOperation(UndoOwner owner) {
+        mOwner = owner;
+    }
+
+    /**
+     * Construct from a Parcel.
+     */
+    protected UndoOperation(Parcel src, ClassLoader loader) {
+    }
+
+    /**
+     * Owning object as given to {@link #UndoOperation(UndoOwner)}.
+     */
+    public UndoOwner getOwner() {
+        return mOwner;
+    }
+
+    /**
+     * Synonym for {@link #getOwner()}.{@link android.content.UndoOwner#getData()}.
+     */
+    public DATA getOwnerData() {
+        return (DATA)mOwner.getData();
+    }
+
+    /**
+     * Return true if this undo operation is a member of the given owner.
+     * The default implementation is <code>owner == getOwner()</code>.  You
+     * can override this to provide more sophisticated dependencies between
+     * owners.
+     */
+    public boolean matchOwner(UndoOwner owner) {
+        return owner == getOwner();
+    }
+
+    /**
+     * Return true if this operation actually contains modification data.  The
+     * default implementation always returns true.  If you return false, the
+     * operation will be dropped when the final undo state is being built.
+     */
+    public boolean hasData() {
+        return true;
+    }
+
+    /**
+     * Return true if this operation can be merged with a later operation.
+     * The default implementation always returns true.
+     */
+    public boolean allowMerge() {
+        return true;
+    }
+
+    /**
+     * Called when this undo state is being committed to the undo stack.
+     * The implementation should perform the initial edits and save any state that
+     * may be needed to undo them.
+     */
+    public abstract void commit();
+
+    /**
+     * Called when this undo state is being popped off the undo stack (in to
+     * the temporary redo stack).  The implementation should remove the original
+     * edits and thus restore the target object to its prior value.
+     */
+    public abstract void undo();
+
+    /**
+     * Called when this undo state is being pushed back from the transient
+     * redo stack to the main undo stack.  The implementation should re-apply
+     * the edits that were previously removed by {@link #undo}.
+     */
+    public abstract void redo();
+
+    public int describeContents() {
+        return 0;
+    }
+}