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Diffstat (limited to 'core/java/android/content/UndoManager.java')
| -rw-r--r-- | core/java/android/content/UndoManager.java | 932 |
1 files changed, 932 insertions, 0 deletions
diff --git a/core/java/android/content/UndoManager.java b/core/java/android/content/UndoManager.java new file mode 100644 index 0000000..1c2db47 --- /dev/null +++ b/core/java/android/content/UndoManager.java @@ -0,0 +1,932 @@ +/* + * 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; +import android.os.ParcelableParcel; +import android.text.TextUtils; + +import java.util.ArrayList; +import java.util.HashMap; + +/** + * Top-level class for managing and interacting with the global undo state for + * a document or application. This class supports both undo and redo and has + * helpers for merging undoable operations together as they are performed. + * + * <p>A single undoable operation is represented by {@link UndoOperation} which + * apps implement to define their undo/redo behavior. The UndoManager keeps + * a stack of undo states; each state can have one or more undo operations + * inside of it.</p> + * + * <p>Updates to the stack must be done inside of a {@link #beginUpdate}/{@link #endUpdate()} + * pair. During this time you can add new operations to the stack with + * {@link #addOperation}, retrieve and modify existing operations with + * {@link #getLastOperation}, control the label shown to the user for this operation + * with {@link #setUndoLabel} and {@link #suggestUndoLabel}, etc.</p> + * + * <p>Every {link UndoOperation} is associated with an {@link UndoOwner}, which identifies + * the data it belongs to. The owner is used to indicate how operations are dependent + * on each other -- operations with the same owner are dependent on others with the + * same owner. For example, you may have a document with multiple embedded objects. If the + * document itself and each embedded object use different owners, then you + * can provide undo semantics appropriate to the user's context: while within + * an embedded object, only edits to that object are seen and the user can + * undo/redo them without needing to impact edits in other objects; while + * within the larger document, all edits can be seen and the user must + * undo/redo them as a single stream.</p> + */ +public class UndoManager { + private final HashMap<String, UndoOwner> mOwners = new HashMap<String, UndoOwner>(); + private final ArrayList<UndoState> mUndos = new ArrayList<UndoState>(); + private final ArrayList<UndoState> mRedos = new ArrayList<UndoState>(); + private int mUpdateCount; + private int mHistorySize = 20; + private UndoState mWorking; + private int mCommitId = 1; + private boolean mInUndo; + private boolean mMerged; + + private int mStateSeq; + private int mNextSavedIdx; + private UndoOwner[] mStateOwners; + + /** + * Never merge with the last undo state. + */ + public static final int MERGE_MODE_NONE = 0; + + /** + * Allow merge with the last undo state only if it contains + * operations with the caller's owner. + */ + public static final int MERGE_MODE_UNIQUE = 1; + + /** + * Always allow merge with the last undo state, if possible. + */ + public static final int MERGE_MODE_ANY = 2; + + public UndoOwner getOwner(String tag, Object data) { + if (tag == null) { + throw new NullPointerException("tag can't be null"); + } + if (data == null) { + throw new NullPointerException("data can't be null"); + } + UndoOwner owner = mOwners.get(tag); + if (owner != null) { + if (owner.mData != data) { + if (owner.mData != null) { + throw new IllegalStateException("Owner " + owner + " already exists with data " + + owner.mData + " but giving different data " + data); + } + owner.mData = data; + } + return owner; + } + + owner = new UndoOwner(tag); + owner.mManager = this; + owner.mData = data; + mOwners.put(tag, owner); + return owner; + } + + void removeOwner(UndoOwner owner) { + // XXX need to figure out how to prune. + if (false) { + mOwners.remove(owner.mTag); + owner.mManager = null; + } + } + + /** + * Flatten the current undo state into a Parcelable object, which can later be restored + * with {@link #restoreInstanceState(android.os.Parcelable)}. + */ + public Parcelable saveInstanceState() { + if (mUpdateCount > 0) { + throw new IllegalStateException("Can't save state while updating"); + } + ParcelableParcel pp = new ParcelableParcel(getClass().getClassLoader()); + Parcel p = pp.getParcel(); + mStateSeq++; + if (mStateSeq <= 0) { + mStateSeq = 0; + } + mNextSavedIdx = 0; + p.writeInt(mHistorySize); + p.writeInt(mOwners.size()); + // XXX eventually we need to be smart here about limiting the + // number of undo states we write to not exceed X bytes. + int i = mUndos.size(); + while (i > 0) { + p.writeInt(1); + i--; + mUndos.get(i).writeToParcel(p); + } + i = mRedos.size(); + p.writeInt(i); + while (i > 0) { + p.writeInt(2); + i--; + mRedos.get(i).writeToParcel(p); + } + p.writeInt(0); + return pp; + } + + void saveOwner(UndoOwner owner, Parcel out) { + if (owner.mStateSeq == mStateSeq) { + out.writeInt(owner.mSavedIdx); + } else { + owner.mStateSeq = mStateSeq; + owner.mSavedIdx = mNextSavedIdx; + out.writeInt(owner.mSavedIdx); + out.writeString(owner.mTag); + mNextSavedIdx++; + } + } + + /** + * Restore an undo state previously created with {@link #saveInstanceState()}. This will + * restore the UndoManager's state to almost exactly what it was at the point it had + * been previously saved; the only information not restored is the data object + * associated with each {@link UndoOwner}, which requires separate calls to + * {@link #getOwner(String, Object)} to re-associate the owner with its data. + */ + public void restoreInstanceState(Parcelable state) { + if (mUpdateCount > 0) { + throw new IllegalStateException("Can't save state while updating"); + } + forgetUndos(null, -1); + forgetRedos(null, -1); + ParcelableParcel pp = (ParcelableParcel)state; + Parcel p = pp.getParcel(); + mHistorySize = p.readInt(); + mStateOwners = new UndoOwner[p.readInt()]; + + int stype; + while ((stype=p.readInt()) != 0) { + UndoState ustate = new UndoState(this, p, pp.getClassLoader()); + if (stype == 1) { + mUndos.add(0, ustate); + } else { + mRedos.add(0, ustate); + } + } + } + + UndoOwner restoreOwner(Parcel in) { + int idx = in.readInt(); + UndoOwner owner = mStateOwners[idx]; + if (owner == null) { + String tag = in.readString(); + owner = new UndoOwner(tag); + mStateOwners[idx] = owner; + mOwners.put(tag, owner); + } + return owner; + } + + /** + * Set the maximum number of undo states that will be retained. + */ + public void setHistorySize(int size) { + mHistorySize = size; + if (mHistorySize >= 0 && countUndos(null) > mHistorySize) { + forgetUndos(null, countUndos(null) - mHistorySize); + } + } + + /** + * Return the current maximum number of undo states. + */ + public int getHistorySize() { + return mHistorySize; + } + + /** + * Perform undo of last/top <var>count</var> undo states. The states impacted + * by this can be limited through <var>owners</var>. + * @param owners Optional set of owners that should be impacted. If null, all + * undo states will be visible and available for undo. If non-null, only those + * states that contain one of the owners specified here will be visible. + * @param count Number of undo states to pop. + * @return Returns the number of undo states that were actually popped. + */ + public int undo(UndoOwner[] owners, int count) { + if (mWorking != null) { + throw new IllegalStateException("Can't be called during an update"); + } + + int num = 0; + int i = -1; + + mInUndo = true; + + UndoState us = getTopUndo(null); + if (us != null) { + us.makeExecuted(); + } + + while (count > 0 && (i=findPrevState(mUndos, owners, i)) >= 0) { + UndoState state = mUndos.remove(i); + state.undo(); + mRedos.add(state); + count--; + num++; + } + + mInUndo = false; + + return num; + } + + /** + * Perform redo of last/top <var>count</var> undo states in the transient redo stack. + * The states impacted by this can be limited through <var>owners</var>. + * @param owners Optional set of owners that should be impacted. If null, all + * undo states will be visible and available for undo. If non-null, only those + * states that contain one of the owners specified here will be visible. + * @param count Number of undo states to pop. + * @return Returns the number of undo states that were actually redone. + */ + public int redo(UndoOwner[] owners, int count) { + if (mWorking != null) { + throw new IllegalStateException("Can't be called during an update"); + } + + int num = 0; + int i = -1; + + mInUndo = true; + + while (count > 0 && (i=findPrevState(mRedos, owners, i)) >= 0) { + UndoState state = mRedos.remove(i); + state.redo(); + mUndos.add(state); + count--; + num++; + } + + mInUndo = false; + + return num; + } + + /** + * Returns true if we are currently inside of an undo/redo operation. This is + * useful for editors to know whether they should be generating new undo state + * when they see edit operations happening. + */ + public boolean isInUndo() { + return mInUndo; + } + + public int forgetUndos(UndoOwner[] owners, int count) { + if (count < 0) { + count = mUndos.size(); + } + + int removed = 0; + for (int i=0; i<mUndos.size() && removed < count; i++) { + UndoState state = mUndos.get(i); + if (count > 0 && matchOwners(state, owners)) { + state.destroy(); + mUndos.remove(i); + removed++; + } + } + + return removed; + } + + public int forgetRedos(UndoOwner[] owners, int count) { + if (count < 0) { + count = mRedos.size(); + } + + int removed = 0; + for (int i=0; i<mRedos.size() && removed < count; i++) { + UndoState state = mRedos.get(i); + if (count > 0 && matchOwners(state, owners)) { + state.destroy(); + mRedos.remove(i); + removed++; + } + } + + return removed; + } + + /** + * Return the number of undo states on the undo stack. + * @param owners If non-null, only those states containing an operation with one of + * the owners supplied here will be counted. + */ + public int countUndos(UndoOwner[] owners) { + if (owners == null) { + return mUndos.size(); + } + + int count=0; + int i=0; + while ((i=findNextState(mUndos, owners, i)) >= 0) { + count++; + i++; + } + return count; + } + + /** + * Return the number of redo states on the undo stack. + * @param owners If non-null, only those states containing an operation with one of + * the owners supplied here will be counted. + */ + public int countRedos(UndoOwner[] owners) { + if (owners == null) { + return mRedos.size(); + } + + int count=0; + int i=0; + while ((i=findNextState(mRedos, owners, i)) >= 0) { + count++; + i++; + } + return count; + } + + /** + * Return the user-visible label for the top undo state on the stack. + * @param owners If non-null, will select the top-most undo state containing an + * operation with one of the owners supplied here. + */ + public CharSequence getUndoLabel(UndoOwner[] owners) { + UndoState state = getTopUndo(owners); + return state != null ? state.getLabel() : null; + } + + /** + * Return the user-visible label for the top redo state on the stack. + * @param owners If non-null, will select the top-most undo state containing an + * operation with one of the owners supplied here. + */ + public CharSequence getRedoLabel(UndoOwner[] owners) { + UndoState state = getTopRedo(owners); + return state != null ? state.getLabel() : null; + } + + /** + * Start creating a new undo state. Multiple calls to this function will nest until + * they are all matched by a later call to {@link #endUpdate}. + * @param label Optional user-visible label for this new undo state. + */ + public void beginUpdate(CharSequence label) { + if (mInUndo) { + throw new IllegalStateException("Can't being update while performing undo/redo"); + } + if (mUpdateCount <= 0) { + createWorkingState(); + mMerged = false; + mUpdateCount = 0; + } + + mWorking.updateLabel(label); + mUpdateCount++; + } + + private void createWorkingState() { + mWorking = new UndoState(this, mCommitId++); + if (mCommitId < 0) { + mCommitId = 1; + } + } + + /** + * Returns true if currently inside of a {@link #beginUpdate}. + */ + public boolean isInUpdate() { + return mUpdateCount > 0; + } + + /** + * Forcibly set a new for the new undo state being built within a {@link #beginUpdate}. + * Any existing label will be replaced with this one. + */ + public void setUndoLabel(CharSequence label) { + if (mWorking == null) { + throw new IllegalStateException("Must be called during an update"); + } + mWorking.setLabel(label); + } + + /** + * Set a new for the new undo state being built within a {@link #beginUpdate}, but + * only if there is not a label currently set for it. + */ + public void suggestUndoLabel(CharSequence label) { + if (mWorking == null) { + throw new IllegalStateException("Must be called during an update"); + } + mWorking.updateLabel(label); + } + + /** + * Return the number of times {@link #beginUpdate} has been called without a matching + * {@link #endUpdate} call. + */ + public int getUpdateNestingLevel() { + return mUpdateCount; + } + + /** + * Check whether there is an {@link UndoOperation} in the current {@link #beginUpdate} + * undo state. + * @param owner Optional owner of the operation to look for. If null, will succeed + * if there is any operation; if non-null, will only succeed if there is an operation + * with the given owner. + * @return Returns true if there is a matching operation in the current undo state. + */ + public boolean hasOperation(UndoOwner owner) { + if (mWorking == null) { + throw new IllegalStateException("Must be called during an update"); + } + return mWorking.hasOperation(owner); + } + + /** + * Return the most recent {@link UndoOperation} that was added to the update. + * @param mergeMode May be either {@link #MERGE_MODE_NONE} or {@link #MERGE_MODE_ANY}. + */ + public UndoOperation<?> getLastOperation(int mergeMode) { + return getLastOperation(null, null, mergeMode); + } + + /** + * Return the most recent {@link UndoOperation} that was added to the update and + * has the given owner. + * @param owner Optional owner of last operation to retrieve. If null, the last + * operation regardless of owner will be retrieved; if non-null, the last operation + * matching the given owner will be retrieved. + * @param mergeMode May be either {@link #MERGE_MODE_NONE}, {@link #MERGE_MODE_UNIQUE}, + * or {@link #MERGE_MODE_ANY}. + */ + public UndoOperation<?> getLastOperation(UndoOwner owner, int mergeMode) { + return getLastOperation(null, owner, mergeMode); + } + + /** + * Return the most recent {@link UndoOperation} that was added to the update and + * has the given owner. + * @param clazz Optional class of the last operation to retrieve. If null, the + * last operation regardless of class will be retrieved; if non-null, the last + * operation whose class is the same as the given class will be retrieved. + * @param owner Optional owner of last operation to retrieve. If null, the last + * operation regardless of owner will be retrieved; if non-null, the last operation + * matching the given owner will be retrieved. + * @param mergeMode May be either {@link #MERGE_MODE_NONE}, {@link #MERGE_MODE_UNIQUE}, + * or {@link #MERGE_MODE_ANY}. + */ + public <T extends UndoOperation> T getLastOperation(Class<T> clazz, UndoOwner owner, + int mergeMode) { + if (mWorking == null) { + throw new IllegalStateException("Must be called during an update"); + } + if (mergeMode != MERGE_MODE_NONE && !mMerged && !mWorking.hasData()) { + UndoState state = getTopUndo(null); + UndoOperation<?> last; + if (state != null && (mergeMode == MERGE_MODE_ANY || !state.hasMultipleOwners()) + && state.canMerge() && (last=state.getLastOperation(clazz, owner)) != null) { + if (last.allowMerge()) { + mWorking.destroy(); + mWorking = state; + mUndos.remove(state); + mMerged = true; + return (T)last; + } + } + } + + return mWorking.getLastOperation(clazz, owner); + } + + /** + * Add a new UndoOperation to the current update. + * @param op The new operation to add. + * @param mergeMode May be either {@link #MERGE_MODE_NONE}, {@link #MERGE_MODE_UNIQUE}, + * or {@link #MERGE_MODE_ANY}. + */ + public void addOperation(UndoOperation<?> op, int mergeMode) { + if (mWorking == null) { + throw new IllegalStateException("Must be called during an update"); + } + UndoOwner owner = op.getOwner(); + if (owner.mManager != this) { + throw new IllegalArgumentException( + "Given operation's owner is not in this undo manager."); + } + if (mergeMode != MERGE_MODE_NONE && !mMerged && !mWorking.hasData()) { + UndoState state = getTopUndo(null); + if (state != null && (mergeMode == MERGE_MODE_ANY || !state.hasMultipleOwners()) + && state.canMerge() && state.hasOperation(op.getOwner())) { + mWorking.destroy(); + mWorking = state; + mUndos.remove(state); + mMerged = true; + } + } + mWorking.addOperation(op); + } + + /** + * Finish the creation of an undo state, matching a previous call to + * {@link #beginUpdate}. + */ + public void endUpdate() { + if (mWorking == null) { + throw new IllegalStateException("Must be called during an update"); + } + mUpdateCount--; + + if (mUpdateCount == 0) { + pushWorkingState(); + } + } + + private void pushWorkingState() { + int N = mUndos.size() + 1; + + if (mWorking.hasData()) { + mUndos.add(mWorking); + forgetRedos(null, -1); + mWorking.commit(); + if (N >= 2) { + // The state before this one can no longer be merged, ever. + // The only way to get back to it is for the user to perform + // an undo. + mUndos.get(N-2).makeExecuted(); + } + } else { + mWorking.destroy(); + } + mWorking = null; + + if (mHistorySize >= 0 && N > mHistorySize) { + forgetUndos(null, N - mHistorySize); + } + } + + /** + * Commit the last finished undo state. This undo state can no longer be + * modified with further {@link #MERGE_MODE_UNIQUE} or + * {@link #MERGE_MODE_ANY} merge modes. If called while inside of an update, + * this will push any changes in the current update on to the undo stack + * and result with a fresh undo state, behaving as if {@link #endUpdate()} + * had been called enough to unwind the current update, then the last state + * committed, and {@link #beginUpdate} called to restore the update nesting. + * @param owner The optional owner to determine whether to perform the commit. + * If this is non-null, the commit will only execute if the current top undo + * state contains an operation with the given owner. + * @return Returns an integer identifier for the committed undo state, which + * can later be used to try to uncommit the state to perform further edits on it. + */ + public int commitState(UndoOwner owner) { + if (mWorking != null && mWorking.hasData()) { + if (owner == null || mWorking.hasOperation(owner)) { + mWorking.setCanMerge(false); + int commitId = mWorking.getCommitId(); + pushWorkingState(); + createWorkingState(); + mMerged = true; + return commitId; + } + } else { + UndoState state = getTopUndo(null); + if (state != null && (owner == null || state.hasOperation(owner))) { + state.setCanMerge(false); + return state.getCommitId(); + } + } + return -1; + } + + /** + * Attempt to undo a previous call to {@link #commitState}. This will work + * if the undo state at the top of the stack has the given id, and has not been + * involved in an undo operation. Otherwise false is returned. + * @param commitId The identifier for the state to be uncommitted, as returned + * by {@link #commitState}. + * @param owner Optional owner that must appear in the committed state. + * @return Returns true if the uncommit is successful, else false. + */ + public boolean uncommitState(int commitId, UndoOwner owner) { + if (mWorking != null && mWorking.getCommitId() == commitId) { + if (owner == null || mWorking.hasOperation(owner)) { + return mWorking.setCanMerge(true); + } + } else { + UndoState state = getTopUndo(null); + if (state != null && (owner == null || state.hasOperation(owner))) { + if (state.getCommitId() == commitId) { + return state.setCanMerge(true); + } + } + } + return false; + } + + UndoState getTopUndo(UndoOwner[] owners) { + if (mUndos.size() <= 0) { + return null; + } + int i = findPrevState(mUndos, owners, -1); + return i >= 0 ? mUndos.get(i) : null; + } + + UndoState getTopRedo(UndoOwner[] owners) { + if (mRedos.size() <= 0) { + return null; + } + int i = findPrevState(mRedos, owners, -1); + return i >= 0 ? mRedos.get(i) : null; + } + + boolean matchOwners(UndoState state, UndoOwner[] owners) { + if (owners == null) { + return true; + } + for (int i=0; i<owners.length; i++) { + if (state.matchOwner(owners[i])) { + return true; + } + } + return false; + } + + int findPrevState(ArrayList<UndoState> states, UndoOwner[] owners, int from) { + final int N = states.size(); + + if (from == -1) { + from = N-1; + } + if (from >= N) { + return -1; + } + if (owners == null) { + return from; + } + + while (from >= 0) { + UndoState state = states.get(from); + if (matchOwners(state, owners)) { + return from; + } + from--; + } + + return -1; + } + + int findNextState(ArrayList<UndoState> states, UndoOwner[] owners, int from) { + final int N = states.size(); + + if (from < 0) { + from = 0; + } + if (from >= N) { + return -1; + } + if (owners == null) { + return from; + } + + while (from < N) { + UndoState state = states.get(from); + if (matchOwners(state, owners)) { + return from; + } + from++; + } + + return -1; + } + + final static class UndoState { + private final UndoManager mManager; + private final int mCommitId; + private final ArrayList<UndoOperation<?>> mOperations = new ArrayList<UndoOperation<?>>(); + private ArrayList<UndoOperation<?>> mRecent; + private CharSequence mLabel; + private boolean mCanMerge = true; + private boolean mExecuted; + + UndoState(UndoManager manager, int commitId) { + mManager = manager; + mCommitId = commitId; + } + + UndoState(UndoManager manager, Parcel p, ClassLoader loader) { + mManager = manager; + mCommitId = p.readInt(); + mCanMerge = p.readInt() != 0; + mExecuted = p.readInt() != 0; + mLabel = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(p); + final int N = p.readInt(); + for (int i=0; i<N; i++) { + UndoOwner owner = mManager.restoreOwner(p); + UndoOperation op = (UndoOperation)p.readParcelable(loader); + op.mOwner = owner; + mOperations.add(op); + } + } + + void writeToParcel(Parcel p) { + if (mRecent != null) { + throw new IllegalStateException("Can't save state before committing"); + } + p.writeInt(mCommitId); + p.writeInt(mCanMerge ? 1 : 0); + p.writeInt(mExecuted ? 1 : 0); + TextUtils.writeToParcel(mLabel, p, 0); + final int N = mOperations.size(); + p.writeInt(N); + for (int i=0; i<N; i++) { + UndoOperation op = mOperations.get(i); + mManager.saveOwner(op.mOwner, p); + p.writeParcelable(op, 0); + } + } + + int getCommitId() { + return mCommitId; + } + + void setLabel(CharSequence label) { + mLabel = label; + } + + void updateLabel(CharSequence label) { + if (mLabel != null) { + mLabel = label; + } + } + + CharSequence getLabel() { + return mLabel; + } + + boolean setCanMerge(boolean state) { + // Don't allow re-enabling of merging if state has been executed. + if (state && mExecuted) { + return false; + } + mCanMerge = state; + return true; + } + + void makeExecuted() { + mExecuted = true; + } + + boolean canMerge() { + return mCanMerge && !mExecuted; + } + + int countOperations() { + return mOperations.size(); + } + + boolean hasOperation(UndoOwner owner) { + final int N = mOperations.size(); + if (owner == null) { + return N != 0; + } + for (int i=0; i<N; i++) { + if (mOperations.get(i).getOwner() == owner) { + return true; + } + } + return false; + } + + boolean hasMultipleOwners() { + final int N = mOperations.size(); + if (N <= 1) { + return false; + } + UndoOwner owner = mOperations.get(0).getOwner(); + for (int i=1; i<N; i++) { + if (mOperations.get(i).getOwner() != owner) { + return true; + } + } + return false; + } + + void addOperation(UndoOperation<?> op) { + if (mOperations.contains(op)) { + throw new IllegalStateException("Already holds " + op); + } + mOperations.add(op); + if (mRecent == null) { + mRecent = new ArrayList<UndoOperation<?>>(); + mRecent.add(op); + } + op.mOwner.mOpCount++; + } + + <T extends UndoOperation> T getLastOperation(Class<T> clazz, UndoOwner owner) { + final int N = mOperations.size(); + if (clazz == null && owner == null) { + return N > 0 ? (T)mOperations.get(N-1) : null; + } + // First look for the top-most operation with the same owner. + for (int i=N-1; i>=0; i--) { + UndoOperation<?> op = mOperations.get(i); + if (owner != null && op.getOwner() != owner) { + continue; + } + // Return this operation if it has the same class that the caller wants. + // Note that we don't search deeper for the class, because we don't want + // to end up with a different order of operations for the same owner. + if (clazz != null && op.getClass() != clazz) { + return null; + } + return (T)op; + } + + return null; + } + + boolean matchOwner(UndoOwner owner) { + for (int i=mOperations.size()-1; i>=0; i--) { + if (mOperations.get(i).matchOwner(owner)) { + return true; + } + } + return false; + } + + boolean hasData() { + for (int i=mOperations.size()-1; i>=0; i--) { + if (mOperations.get(i).hasData()) { + return true; + } + } + return false; + } + + void commit() { + final int N = mRecent != null ? mRecent.size() : 0; + for (int i=0; i<N; i++) { + mRecent.get(i).commit(); + } + mRecent = null; + } + + void undo() { + for (int i=mOperations.size()-1; i>=0; i--) { + mOperations.get(i).undo(); + } + } + + void redo() { + final int N = mOperations.size(); + for (int i=0; i<N; i++) { + mOperations.get(i).redo(); + } + } + + void destroy() { + for (int i=mOperations.size()-1; i>=0; i--) { + UndoOwner owner = mOperations.get(i).mOwner; + owner.mOpCount--; + if (owner.mOpCount <= 0) { + if (owner.mOpCount < 0) { + throw new IllegalStateException("Underflow of op count on owner " + owner + + " in op " + mOperations.get(i)); + } + mManager.removeOwner(owner); + } + } + } + } +} |