xref: /frameworks/support/v4/java/android/support/v4/app/BackStackRecord.java

/*
 * Copyright (C) 2011 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.support.v4.app;

import android.os.Build;
import android.os.Parcel;
import android.os.Parcelable;
import android.support.v4.util.LogWriter;
import android.support.v4.util.Pair;
import android.text.TextUtils;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;

import java.io.FileDescriptor;
import java.io.PrintWriter;
import java.util.ArrayList;

final class BackStackState implements Parcelable {
    final int[] mOps;
    final int mTransition;
    final int mTransitionStyle;
    final String mName;
    final int mIndex;
    final int mBreadCrumbTitleRes;
    final CharSequence mBreadCrumbTitleText;
    final int mBreadCrumbShortTitleRes;
    final CharSequence mBreadCrumbShortTitleText;
    final int mCustomTransition;
    final int mSceneRoot;
    final ArrayList<String> mSharedElementSourceNames;
    final ArrayList<String> mSharedElementTargetNames;

    public BackStackState(FragmentManagerImpl fm, BackStackRecord bse) {
        int numRemoved = 0;
        BackStackRecord.Op op = bse.mHead;
        while (op != null) {
            if (op.removed != null) numRemoved += op.removed.size();
            op = op.next;
        }
        mOps = new int[bse.mNumOp*7 + numRemoved];

        if (!bse.mAddToBackStack) {
            throw new IllegalStateException("Not on back stack");
        }

        op = bse.mHead;
        int pos = 0;
        while (op != null) {
            mOps[pos++] = op.cmd;
            mOps[pos++] = op.fragment != null ? op.fragment.mIndex : -1;
            mOps[pos++] = op.enterAnim;
            mOps[pos++] = op.exitAnim;
            mOps[pos++] = op.popEnterAnim;
            mOps[pos++] = op.popExitAnim;
            if (op.removed != null) {
                final int N = op.removed.size();
                mOps[pos++] = N;
                for (int i=0; i<N; i++) {
                    mOps[pos++] = op.removed.get(i).mIndex;
                }
            } else {
                mOps[pos++] = 0;
            }
            op = op.next;
        }
        mTransition = bse.mTransition;
        mTransitionStyle = bse.mTransitionStyle;
        mName = bse.mName;
        mIndex = bse.mIndex;
        mBreadCrumbTitleRes = bse.mBreadCrumbTitleRes;
        mBreadCrumbTitleText = bse.mBreadCrumbTitleText;
        mBreadCrumbShortTitleRes = bse.mBreadCrumbShortTitleRes;
        mBreadCrumbShortTitleText = bse.mBreadCrumbShortTitleText;
        mCustomTransition = bse.mCustomTransition;
        mSceneRoot = bse.mSceneRoot;
        mSharedElementSourceNames = bse.mSharedElementSourceNames;
        mSharedElementTargetNames = bse.mSharedElementTargetNames;
    }

    public BackStackState(Parcel in) {
        mOps = in.createIntArray();
        mTransition = in.readInt();
        mTransitionStyle = in.readInt();
        mName = in.readString();
        mIndex = in.readInt();
        mBreadCrumbTitleRes = in.readInt();
        mBreadCrumbTitleText = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(in);
        mBreadCrumbShortTitleRes = in.readInt();
        mBreadCrumbShortTitleText = TextUtils.CHAR_SEQUENCE_CREATOR.createFromParcel(in);
        mCustomTransition = in.readInt();
        mSceneRoot = in.readInt();
        mSharedElementSourceNames = in.createStringArrayList();
        mSharedElementTargetNames = in.createStringArrayList();
    }

    public BackStackRecord instantiate(FragmentManagerImpl fm) {
        BackStackRecord bse = new BackStackRecord(fm);
        int pos = 0;
        int num = 0;
        while (pos < mOps.length) {
            BackStackRecord.Op op = new BackStackRecord.Op();
            op.cmd = mOps[pos++];
            if (FragmentManagerImpl.DEBUG) Log.v(FragmentManagerImpl.TAG,
                    "Instantiate " + bse + " op #" + num + " base fragment #" + mOps[pos]);
            int findex = mOps[pos++];
            if (findex >= 0) {
                Fragment f = fm.mActive.get(findex);
                op.fragment = f;
            } else {
                op.fragment = null;
            }
            op.enterAnim = mOps[pos++];
            op.exitAnim = mOps[pos++];
            op.popEnterAnim = mOps[pos++];
            op.popExitAnim = mOps[pos++];
            final int N = mOps[pos++];
            if (N > 0) {
                op.removed = new ArrayList<Fragment>(N);
                for (int i=0; i<N; i++) {
                    if (FragmentManagerImpl.DEBUG) Log.v(FragmentManagerImpl.TAG,
                            "Instantiate " + bse + " set remove fragment #" + mOps[pos]);
                    Fragment r = fm.mActive.get(mOps[pos++]);
                    op.removed.add(r);
                }
            }
            bse.addOp(op);
            num++;
        }
        bse.mTransition = mTransition;
        bse.mTransitionStyle = mTransitionStyle;
        bse.mName = mName;
        bse.mIndex = mIndex;
        bse.mAddToBackStack = true;
        bse.mBreadCrumbTitleRes = mBreadCrumbTitleRes;
        bse.mBreadCrumbTitleText = mBreadCrumbTitleText;
        bse.mBreadCrumbShortTitleRes = mBreadCrumbShortTitleRes;
        bse.mBreadCrumbShortTitleText = mBreadCrumbShortTitleText;
        bse.mCustomTransition = mCustomTransition;
        bse.mSceneRoot = mSceneRoot;
        bse.mSharedElementSourceNames = mSharedElementSourceNames;
        bse.mSharedElementTargetNames = mSharedElementTargetNames;
        bse.bumpBackStackNesting(1);
        return bse;
    }

    public int describeContents() {
        return 0;
    }

    public void writeToParcel(Parcel dest, int flags) {
        dest.writeIntArray(mOps);
        dest.writeInt(mTransition);
        dest.writeInt(mTransitionStyle);
        dest.writeString(mName);
        dest.writeInt(mIndex);
        dest.writeInt(mBreadCrumbTitleRes);
        TextUtils.writeToParcel(mBreadCrumbTitleText, dest, 0);
        dest.writeInt(mBreadCrumbShortTitleRes);
        TextUtils.writeToParcel(mBreadCrumbShortTitleText, dest, 0);
        dest.writeInt(mCustomTransition);
        dest.writeInt(mSceneRoot);
        dest.writeStringList(mSharedElementSourceNames);
        dest.writeStringList(mSharedElementTargetNames);
    }

    public static final Parcelable.Creator<BackStackState> CREATOR
            = new Parcelable.Creator<BackStackState>() {
        public BackStackState createFromParcel(Parcel in) {
            return new BackStackState(in);
        }

        public BackStackState[] newArray(int size) {
            return new BackStackState[size];
        }
    };
}

/**
 * @hide Entry of an operation on the fragment back stack.
 */
final class BackStackRecord extends FragmentTransaction implements
        FragmentManager.BackStackEntry, Runnable {
    static final String TAG = FragmentManagerImpl.TAG;

    final FragmentManagerImpl mManager;

    static final int OP_NULL = 0;
    static final int OP_ADD = 1;
    static final int OP_REPLACE = 2;
    static final int OP_REMOVE = 3;
    static final int OP_HIDE = 4;
    static final int OP_SHOW = 5;
    static final int OP_DETACH = 6;
    static final int OP_ATTACH = 7;

    static final class Op {
        Op next;
        Op prev;
        int cmd;
        Fragment fragment;
        int enterAnim;
        int exitAnim;
        int popEnterAnim;
        int popExitAnim;
        ArrayList<Fragment> removed;
    }

    Op mHead;
    Op mTail;
    int mNumOp;
    int mEnterAnim;
    int mExitAnim;
    int mPopEnterAnim;
    int mPopExitAnim;
    int mTransition;
    int mTransitionStyle;
    boolean mAddToBackStack;
    boolean mAllowAddToBackStack = true;
    String mName;
    boolean mCommitted;
    int mIndex = -1;

    int mBreadCrumbTitleRes;
    CharSequence mBreadCrumbTitleText;
    int mBreadCrumbShortTitleRes;
    CharSequence mBreadCrumbShortTitleText;

    int mCustomTransition;
    int mSceneRoot;
    ArrayList<String> mSharedElementSourceNames;
    ArrayList<String> mSharedElementTargetNames;

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder(128);
        sb.append("BackStackEntry{");
        sb.append(Integer.toHexString(System.identityHashCode(this)));
        if (mIndex >= 0) {
            sb.append(" #");
            sb.append(mIndex);
        }
        if (mName != null) {
            sb.append(" ");
            sb.append(mName);
        }
        sb.append("}");
        return sb.toString();
    }

    public void dump(String prefix, FileDescriptor fd, PrintWriter writer, String[] args) {
        dump(prefix, writer, true);
    }

    public void dump(String prefix, PrintWriter writer, boolean full) {
        if (full) {
            writer.print(prefix); writer.print("mName="); writer.print(mName);
                    writer.print(" mIndex="); writer.print(mIndex);
                    writer.print(" mCommitted="); writer.println(mCommitted);
            if (mTransition != FragmentTransaction.TRANSIT_NONE) {
                writer.print(prefix); writer.print("mTransition=#");
                        writer.print(Integer.toHexString(mTransition));
                        writer.print(" mTransitionStyle=#");
                        writer.println(Integer.toHexString(mTransitionStyle));
            }
            if (mEnterAnim != 0 || mExitAnim !=0) {
                writer.print(prefix); writer.print("mEnterAnim=#");
                        writer.print(Integer.toHexString(mEnterAnim));
                        writer.print(" mExitAnim=#");
                        writer.println(Integer.toHexString(mExitAnim));
            }
            if (mPopEnterAnim != 0 || mPopExitAnim !=0) {
                writer.print(prefix); writer.print("mPopEnterAnim=#");
                        writer.print(Integer.toHexString(mPopEnterAnim));
                        writer.print(" mPopExitAnim=#");
                        writer.println(Integer.toHexString(mPopExitAnim));
            }
            if (mBreadCrumbTitleRes != 0 || mBreadCrumbTitleText != null) {
                writer.print(prefix); writer.print("mBreadCrumbTitleRes=#");
                        writer.print(Integer.toHexString(mBreadCrumbTitleRes));
                        writer.print(" mBreadCrumbTitleText=");
                        writer.println(mBreadCrumbTitleText);
            }
            if (mBreadCrumbShortTitleRes != 0 || mBreadCrumbShortTitleText != null) {
                writer.print(prefix); writer.print("mBreadCrumbShortTitleRes=#");
                        writer.print(Integer.toHexString(mBreadCrumbShortTitleRes));
                        writer.print(" mBreadCrumbShortTitleText=");
                        writer.println(mBreadCrumbShortTitleText);
            }
        }

        if (mHead != null) {
            writer.print(prefix); writer.println("Operations:");
            String innerPrefix = prefix + "    ";
            Op op = mHead;
            int num = 0;
            while (op != null) {
                String cmdStr;
                switch (op.cmd) {
                    case OP_NULL: cmdStr="NULL"; break;
                    case OP_ADD: cmdStr="ADD"; break;
                    case OP_REPLACE: cmdStr="REPLACE"; break;
                    case OP_REMOVE: cmdStr="REMOVE"; break;
                    case OP_HIDE: cmdStr="HIDE"; break;
                    case OP_SHOW: cmdStr="SHOW"; break;
                    case OP_DETACH: cmdStr="DETACH"; break;
                    case OP_ATTACH: cmdStr="ATTACH"; break;
                    default: cmdStr="cmd=" + op.cmd; break;
                }
                writer.print(prefix); writer.print("  Op #"); writer.print(num);
                        writer.print(": "); writer.print(cmdStr);
                        writer.print(" "); writer.println(op.fragment);
                if (full) {
                    if (op.enterAnim != 0 || op.exitAnim != 0) {
                        writer.print(prefix); writer.print("enterAnim=#");
                                writer.print(Integer.toHexString(op.enterAnim));
                                writer.print(" exitAnim=#");
                                writer.println(Integer.toHexString(op.exitAnim));
                    }
                    if (op.popEnterAnim != 0 || op.popExitAnim != 0) {
                        writer.print(prefix); writer.print("popEnterAnim=#");
                                writer.print(Integer.toHexString(op.popEnterAnim));
                                writer.print(" popExitAnim=#");
                                writer.println(Integer.toHexString(op.popExitAnim));
                    }
                }
                if (op.removed != null && op.removed.size() > 0) {
                    for (int i=0; i<op.removed.size(); i++) {
                        writer.print(innerPrefix);
                        if (op.removed.size() == 1) {
                            writer.print("Removed: ");
                        } else {
                            if (i == 0) {
                                writer.println("Removed:");
                            }
                            writer.print(innerPrefix); writer.print("  #"); writer.print(i);
                                    writer.print(": ");
                        }
                        writer.println(op.removed.get(i));
                    }
                }
                op = op.next;
                num++;
            }
        }
    }

    public BackStackRecord(FragmentManagerImpl manager) {
        mManager = manager;
    }

    public int getId() {
        return mIndex;
    }

    public int getBreadCrumbTitleRes() {
        return mBreadCrumbTitleRes;
    }

    public int getBreadCrumbShortTitleRes() {
        return mBreadCrumbShortTitleRes;
    }

    public CharSequence getBreadCrumbTitle() {
        if (mBreadCrumbTitleRes != 0) {
            return mManager.mActivity.getText(mBreadCrumbTitleRes);
        }
        return mBreadCrumbTitleText;
    }

    public CharSequence getBreadCrumbShortTitle() {
        if (mBreadCrumbShortTitleRes != 0) {
            return mManager.mActivity.getText(mBreadCrumbShortTitleRes);
        }
        return mBreadCrumbShortTitleText;
    }

    void addOp(Op op) {
        if (mHead == null) {
            mHead = mTail = op;
        } else {
            op.prev = mTail;
            mTail.next = op;
            mTail = op;
        }
        op.enterAnim = mEnterAnim;
        op.exitAnim = mExitAnim;
        op.popEnterAnim = mPopEnterAnim;
        op.popExitAnim = mPopExitAnim;
        mNumOp++;
    }

    public FragmentTransaction add(Fragment fragment, String tag) {
        doAddOp(0, fragment, tag, OP_ADD);
        return this;
    }

    public FragmentTransaction add(int containerViewId, Fragment fragment) {
        doAddOp(containerViewId, fragment, null, OP_ADD);
        return this;
    }

    public FragmentTransaction add(int containerViewId, Fragment fragment, String tag) {
        doAddOp(containerViewId, fragment, tag, OP_ADD);
        return this;
    }

    private void doAddOp(int containerViewId, Fragment fragment, String tag, int opcmd) {
        fragment.mFragmentManager = mManager;

        if (tag != null) {
            if (fragment.mTag != null && !tag.equals(fragment.mTag)) {
                throw new IllegalStateException("Can't change tag of fragment "
                        + fragment + ": was " + fragment.mTag
                        + " now " + tag);
            }
            fragment.mTag = tag;
        }

        if (containerViewId != 0) {
            if (fragment.mFragmentId != 0 && fragment.mFragmentId != containerViewId) {
                throw new IllegalStateException("Can't change container ID of fragment "
                        + fragment + ": was " + fragment.mFragmentId
                        + " now " + containerViewId);
            }
            fragment.mContainerId = fragment.mFragmentId = containerViewId;
        }

        Op op = new Op();
        op.cmd = opcmd;
        op.fragment = fragment;
        addOp(op);
    }

    public FragmentTransaction replace(int containerViewId, Fragment fragment) {
        return replace(containerViewId, fragment, null);
    }

    public FragmentTransaction replace(int containerViewId, Fragment fragment, String tag) {
        if (containerViewId == 0) {
            throw new IllegalArgumentException("Must use non-zero containerViewId");
        }

        doAddOp(containerViewId, fragment, tag, OP_REPLACE);
        return this;
    }

    public FragmentTransaction remove(Fragment fragment) {
        Op op = new Op();
        op.cmd = OP_REMOVE;
        op.fragment = fragment;
        addOp(op);

        return this;
    }

    public FragmentTransaction hide(Fragment fragment) {
        Op op = new Op();
        op.cmd = OP_HIDE;
        op.fragment = fragment;
        addOp(op);

        return this;
    }

    public FragmentTransaction show(Fragment fragment) {
        Op op = new Op();
        op.cmd = OP_SHOW;
        op.fragment = fragment;
        addOp(op);

        return this;
    }

    public FragmentTransaction detach(Fragment fragment) {
        Op op = new Op();
        op.cmd = OP_DETACH;
        op.fragment = fragment;
        addOp(op);

        return this;
    }

    public FragmentTransaction attach(Fragment fragment) {
        Op op = new Op();
        op.cmd = OP_ATTACH;
        op.fragment = fragment;
        addOp(op);

        return this;
    }

    public FragmentTransaction setCustomAnimations(int enter, int exit) {
        return setCustomAnimations(enter, exit, 0, 0);
    }

    public FragmentTransaction setCustomAnimations(int enter, int exit,
            int popEnter, int popExit) {
        mEnterAnim = enter;
        mExitAnim = exit;
        mPopEnterAnim = popEnter;
        mPopExitAnim = popExit;
        return this;
    }

    public FragmentTransaction setTransition(int transition) {
        mTransition = transition;
        return this;
    }

    @Override
    public FragmentTransaction setCustomTransition(int sceneRootId, int transitionId) {
        mSceneRoot = sceneRootId;
        mCustomTransition = transitionId;
        return this;
    }

    @Override
    public FragmentTransaction addSharedElement(View sharedElement, String name) {
        if (Build.VERSION.SDK_INT >= 21 || Build.VERSION.CODENAME.equals("L")) {
            String transitionName = FragmentTransitionCompat21.getTransitionName(sharedElement);
            if (transitionName == null) {
                throw new IllegalArgumentException("Unique transitionNames are required for all" +
                        " sharedElements");
            }
            if (mSharedElementSourceNames == null) {
                mSharedElementSourceNames = new ArrayList<String>();
                mSharedElementTargetNames = new ArrayList<String>();
            }

            mSharedElementSourceNames.add(transitionName);
            mSharedElementTargetNames.add(name);
        }
        return this;
    }

    public FragmentTransaction setTransitionStyle(int styleRes) {
        mTransitionStyle = styleRes;
        return this;
    }

    public FragmentTransaction addToBackStack(String name) {
        if (!mAllowAddToBackStack) {
            throw new IllegalStateException(
                    "This FragmentTransaction is not allowed to be added to the back stack.");
        }
        mAddToBackStack = true;
        mName = name;
        return this;
    }

    public boolean isAddToBackStackAllowed() {
        return mAllowAddToBackStack;
    }

    public FragmentTransaction disallowAddToBackStack() {
        if (mAddToBackStack) {
            throw new IllegalStateException(
                    "This transaction is already being added to the back stack");
        }
        mAllowAddToBackStack = false;
        return this;
    }

    public FragmentTransaction setBreadCrumbTitle(int res) {
        mBreadCrumbTitleRes = res;
        mBreadCrumbTitleText = null;
        return this;
    }

    public FragmentTransaction setBreadCrumbTitle(CharSequence text) {
        mBreadCrumbTitleRes = 0;
        mBreadCrumbTitleText = text;
        return this;
    }

    public FragmentTransaction setBreadCrumbShortTitle(int res) {
        mBreadCrumbShortTitleRes = res;
        mBreadCrumbShortTitleText = null;
        return this;
    }

    public FragmentTransaction setBreadCrumbShortTitle(CharSequence text) {
        mBreadCrumbShortTitleRes = 0;
        mBreadCrumbShortTitleText = text;
        return this;
    }

    void bumpBackStackNesting(int amt) {
        if (!mAddToBackStack) {
            return;
        }
        if (FragmentManagerImpl.DEBUG) Log.v(TAG, "Bump nesting in " + this
                + " by " + amt);
        Op op = mHead;
        while (op != null) {
            if (op.fragment != null) {
                op.fragment.mBackStackNesting += amt;
                if (FragmentManagerImpl.DEBUG) Log.v(TAG, "Bump nesting of "
                        + op.fragment + " to " + op.fragment.mBackStackNesting);
            }
            if (op.removed != null) {
                for (int i=op.removed.size()-1; i>=0; i--) {
                    Fragment r = op.removed.get(i);
                    r.mBackStackNesting += amt;
                    if (FragmentManagerImpl.DEBUG) Log.v(TAG, "Bump nesting of "
                            + r + " to " + r.mBackStackNesting);
                }
            }
            op = op.next;
        }
    }

    public int commit() {
        return commitInternal(false);
    }

    public int commitAllowingStateLoss() {
        return commitInternal(true);
    }

    int commitInternal(boolean allowStateLoss) {
        if (mCommitted) throw new IllegalStateException("commit already called");
        if (FragmentManagerImpl.DEBUG) {
            Log.v(TAG, "Commit: " + this);
            LogWriter logw = new LogWriter(TAG);
            PrintWriter pw = new PrintWriter(logw);
            dump("  ", null, pw, null);
        }
        mCommitted = true;
        if (mAddToBackStack) {
            mIndex = mManager.allocBackStackIndex(this);
        } else {
            mIndex = -1;
        }
        mManager.enqueueAction(this, allowStateLoss);
        return mIndex;
    }

    public void run() {
        if (FragmentManagerImpl.DEBUG) Log.v(TAG, "Run: " + this);

        if (mAddToBackStack) {
            if (mIndex < 0) {
                throw new IllegalStateException("addToBackStack() called after commit()");
            }
        }

        bumpBackStackNesting(1);

        Object state = beginTransition(mSharedElementSourceNames, mSharedElementTargetNames);

        int transitionStyle = state != null ? 0 : mTransitionStyle;
        int transition = state != null ? 0 : mTransition;
        Op op = mHead;
        while (op != null) {
            int enterAnim = state != null ? 0 : op.enterAnim;
            int exitAnim = state != null ? 0 : op.exitAnim;
            switch (op.cmd) {
                case OP_ADD: {
                    Fragment f = op.fragment;
                    f.mNextAnim = enterAnim;
                    mManager.addFragment(f, false);
                } break;
                case OP_REPLACE: {
                    Fragment f = op.fragment;
                    if (mManager.mAdded != null) {
                        for (int i=0; i<mManager.mAdded.size(); i++) {
                            Fragment old = mManager.mAdded.get(i);
                            if (FragmentManagerImpl.DEBUG) Log.v(TAG,
                                    "OP_REPLACE: adding=" + f + " old=" + old);
                            if (f == null || old.mContainerId == f.mContainerId) {
                                if (old == f) {
                                    op.fragment = f = null;
                                } else {
                                    if (op.removed == null) {
                                        op.removed = new ArrayList<Fragment>();
                                    }
                                    op.removed.add(old);
                                    old.mNextAnim = exitAnim;
                                    if (mAddToBackStack) {
                                        old.mBackStackNesting += 1;
                                        if (FragmentManagerImpl.DEBUG) Log.v(TAG, "Bump nesting of "
                                                + old + " to " + old.mBackStackNesting);
                                    }
                                    mManager.removeFragment(old, transition, transitionStyle);
                                }
                            }
                        }
                    }
                    if (f != null) {
                        f.mNextAnim = enterAnim;
                        mManager.addFragment(f, false);
                    }
                } break;
                case OP_REMOVE: {
                    Fragment f = op.fragment;
                    f.mNextAnim = exitAnim;
                    mManager.removeFragment(f, transition, transitionStyle);
                } break;
                case OP_HIDE: {
                    Fragment f = op.fragment;
                    f.mNextAnim = exitAnim;
                    mManager.hideFragment(f, transition, transitionStyle);
                } break;
                case OP_SHOW: {
                    Fragment f = op.fragment;
                    f.mNextAnim = enterAnim;
                    mManager.showFragment(f, transition, transitionStyle);
                } break;
                case OP_DETACH: {
                    Fragment f = op.fragment;
                    f.mNextAnim = exitAnim;
                    mManager.detachFragment(f, transition, transitionStyle);
                } break;
                case OP_ATTACH: {
                    Fragment f = op.fragment;
                    f.mNextAnim = enterAnim;
                    mManager.attachFragment(f, transition, transitionStyle);
                } break;
                default: {
                    throw new IllegalArgumentException("Unknown cmd: " + op.cmd);
                }
            }

            op = op.next;
        }

        mManager.moveToState(mManager.mCurState, transition, transitionStyle, true);

        if (mAddToBackStack) {
            mManager.addBackStackState(this);
        }

        if (state != null) {
            updateTransitionEndState(state, mSharedElementTargetNames);
        }
    }

    private Object beginTransition(ArrayList<String> sourceNames, ArrayList<String> targetNames) {
        Object state = null;
        if ((Build.VERSION.SDK_INT >= 21 || Build.VERSION.CODENAME.equals("L"))
                && mCustomTransition != 0 && mSceneRoot != 0) {
            View rootView = mManager.mContainer.findViewById(mSceneRoot);
            if (!(rootView instanceof ViewGroup)) {
                throw new IllegalArgumentException("SceneRoot is not a ViewGroup");
            }
            ArrayList<View> hiddenFragmentViews = new ArrayList<View>();
            if (mManager.mAdded != null) {
                for (int i = mManager.mAdded.size() - 1; i >= 0; i--) {
                    Fragment fragment = mManager.mAdded.get(i);
                    if (fragment.mView != null) {
                        if (fragment.mHidden) {
                            hiddenFragmentViews.add(fragment.mView);
                        }
                    }
                }
            }
            state = FragmentTransitionCompat21.beginTransition(mManager.mActivity,
                    mCustomTransition, (ViewGroup) rootView, hiddenFragmentViews,
                    sourceNames, targetNames);
        }
        return state;
    }

    private void updateTransitionEndState(Object stateObj, ArrayList<String> targetNames) {
        if ((Build.VERSION.SDK_INT >= 21 || Build.VERSION.CODENAME.equals("L"))
                && stateObj != null) {
            ArrayList<View> hiddenFragmentViews = new ArrayList<View>();
            ArrayList<View> shownFragmentViews = new ArrayList<View>();
            if (mManager.mAdded != null) {
                for (int i = mManager.mAdded.size() - 1; i >= 0; i--) {
                    Fragment fragment = mManager.mAdded.get(i);
                    if (fragment.mView != null) {
                        if (fragment.mHidden) {
                            hiddenFragmentViews.add(fragment.mView);
                        } else {
                            shownFragmentViews.add(fragment.mView);
                        }
                    }
                }
            }
            FragmentTransitionCompat21.updateTransitionEndState(mManager.mActivity,
                    shownFragmentViews, hiddenFragmentViews, stateObj, targetNames);
        }
    }

    public Object popFromBackStack(boolean doStateMove, Object state) {
        if (FragmentManagerImpl.DEBUG) {
            Log.v(TAG, "popFromBackStack: " + this);
            LogWriter logw = new LogWriter(TAG);
            PrintWriter pw = new PrintWriter(logw);
            dump("  ", null, pw, null);
        }

        if (state == null) {
            state = beginTransition(mSharedElementTargetNames, mSharedElementSourceNames);
        } else if (Build.VERSION.SDK_INT >= 21 || Build.VERSION.CODENAME.equals("L")) {
            FragmentTransitionCompat21.setNameOverrides(state, mSharedElementTargetNames,
                    mSharedElementSourceNames);
        }

        bumpBackStackNesting(-1);

        int transitionStyle = state != null ? 0 : mTransitionStyle;
        int transition = state != null ? 0 : mTransition;
        Op op = mTail;
        while (op != null) {
            int popEnterAnim = state != null ? 0 : op.popEnterAnim;
            int popExitAnim= state != null ? 0 : op.popExitAnim;
            switch (op.cmd) {
                case OP_ADD: {
                    Fragment f = op.fragment;
                    f.mNextAnim = popExitAnim;
                    mManager.removeFragment(f,
                            FragmentManagerImpl.reverseTransit(transition), transitionStyle);
                } break;
                case OP_REPLACE: {
                    Fragment f = op.fragment;
                    if (f != null) {
                        f.mNextAnim = popExitAnim;
                        mManager.removeFragment(f,
                                FragmentManagerImpl.reverseTransit(transition), transitionStyle);
                    }
                    if (op.removed != null) {
                        for (int i=0; i<op.removed.size(); i++) {
                            Fragment old = op.removed.get(i);
                            old.mNextAnim = popEnterAnim;
                            mManager.addFragment(old, false);
                        }
                    }
                } break;
                case OP_REMOVE: {
                    Fragment f = op.fragment;
                    f.mNextAnim = popEnterAnim;
                    mManager.addFragment(f, false);
                } break;
                case OP_HIDE: {
                    Fragment f = op.fragment;
                    f.mNextAnim = popEnterAnim;
                    mManager.showFragment(f,
                            FragmentManagerImpl.reverseTransit(transition), transitionStyle);
                } break;
                case OP_SHOW: {
                    Fragment f = op.fragment;
                    f.mNextAnim = popExitAnim;
                    mManager.hideFragment(f,
                            FragmentManagerImpl.reverseTransit(transition), transitionStyle);
                } break;
                case OP_DETACH: {
                    Fragment f = op.fragment;
                    f.mNextAnim = popEnterAnim;
                    mManager.attachFragment(f,
                            FragmentManagerImpl.reverseTransit(transition), transitionStyle);
                } break;
                case OP_ATTACH: {
                    Fragment f = op.fragment;
                    f.mNextAnim = popEnterAnim;
                    mManager.detachFragment(f,
                            FragmentManagerImpl.reverseTransit(transition), transitionStyle);
                } break;
                default: {
                    throw new IllegalArgumentException("Unknown cmd: " + op.cmd);
                }
            }

            op = op.prev;
        }

        if (doStateMove) {
            mManager.moveToState(mManager.mCurState,
                    FragmentManagerImpl.reverseTransit(transition), transitionStyle, true);
            if (state != null) {
                updateTransitionEndState(state, mSharedElementSourceNames);
                state = null;
            }
        }

        if (mIndex >= 0) {
            mManager.freeBackStackIndex(mIndex);
            mIndex = -1;
        }
        return state;
    }

    public String getName() {
        return mName;
    }

    public int getTransition() {
        return mTransition;
    }

    public int getTransitionStyle() {
        return mTransitionStyle;
    }

    public boolean isEmpty() {
        return mNumOp == 0;
    }
}