1 files changed, 283 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/source/ShuffleOrder.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/source/ShuffleOrder.java
new file mode 100644
index 0000000000..f137054145
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/source/ShuffleOrder.java
@@ -0,0 +1,283 @@
+/*
+ * Copyright (C) 2017 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 org.mozilla.thirdparty.com.google.android.exoplayer2.source;
+
+import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
+import java.util.Arrays;
+import java.util.Random;
+
+/**
+ * Shuffled order of indices.
+ *
+ * <p>The shuffle order must be immutable to ensure thread safety.
+ */
+public interface ShuffleOrder {
+
+  /**
+   * The default {@link ShuffleOrder} implementation for random shuffle order.
+   */
+  class DefaultShuffleOrder implements ShuffleOrder {
+
+    private final Random random;
+    private final int[] shuffled;
+    private final int[] indexInShuffled;
+
+    /**
+     * Creates an instance with a specified length.
+     *
+     * @param length The length of the shuffle order.
+     */
+    public DefaultShuffleOrder(int length) {
+      this(length, new Random());
+    }
+
+    /**
+     * Creates an instance with a specified length and the specified random seed. Shuffle orders of
+     * the same length initialized with the same random seed are guaranteed to be equal.
+     *
+     * @param length The length of the shuffle order.
+     * @param randomSeed A random seed.
+     */
+    public DefaultShuffleOrder(int length, long randomSeed) {
+      this(length, new Random(randomSeed));
+    }
+
+    /**
+     * Creates an instance with a specified shuffle order and the specified random seed. The random
+     * seed is used for {@link #cloneAndInsert(int, int)} invocations.
+     *
+     * @param shuffledIndices The shuffled indices to use as order.
+     * @param randomSeed A random seed.
+     */
+    public DefaultShuffleOrder(int[] shuffledIndices, long randomSeed) {
+      this(Arrays.copyOf(shuffledIndices, shuffledIndices.length), new Random(randomSeed));
+    }
+
+    private DefaultShuffleOrder(int length, Random random) {
+      this(createShuffledList(length, random), random);
+    }
+
+    private DefaultShuffleOrder(int[] shuffled, Random random) {
+      this.shuffled = shuffled;
+      this.random = random;
+      this.indexInShuffled = new int[shuffled.length];
+      for (int i = 0; i < shuffled.length; i++) {
+        indexInShuffled[shuffled[i]] = i;
+      }
+    }
+
+    @Override
+    public int getLength() {
+      return shuffled.length;
+    }
+
+    @Override
+    public int getNextIndex(int index) {
+      int shuffledIndex = indexInShuffled[index];
+      return ++shuffledIndex < shuffled.length ? shuffled[shuffledIndex] : C.INDEX_UNSET;
+    }
+
+    @Override
+    public int getPreviousIndex(int index) {
+      int shuffledIndex = indexInShuffled[index];
+      return --shuffledIndex >= 0 ? shuffled[shuffledIndex] : C.INDEX_UNSET;
+    }
+
+    @Override
+    public int getLastIndex() {
+      return shuffled.length > 0 ? shuffled[shuffled.length - 1] : C.INDEX_UNSET;
+    }
+
+    @Override
+    public int getFirstIndex() {
+      return shuffled.length > 0 ? shuffled[0] : C.INDEX_UNSET;
+    }
+
+    @Override
+    public ShuffleOrder cloneAndInsert(int insertionIndex, int insertionCount) {
+      int[] insertionPoints = new int[insertionCount];
+      int[] insertionValues = new int[insertionCount];
+      for (int i = 0; i < insertionCount; i++) {
+        insertionPoints[i] = random.nextInt(shuffled.length + 1);
+        int swapIndex = random.nextInt(i + 1);
+        insertionValues[i] = insertionValues[swapIndex];
+        insertionValues[swapIndex] = i + insertionIndex;
+      }
+      Arrays.sort(insertionPoints);
+      int[] newShuffled = new int[shuffled.length + insertionCount];
+      int indexInOldShuffled = 0;
+      int indexInInsertionList = 0;
+      for (int i = 0; i < shuffled.length + insertionCount; i++) {
+        if (indexInInsertionList < insertionCount
+            && indexInOldShuffled == insertionPoints[indexInInsertionList]) {
+          newShuffled[i] = insertionValues[indexInInsertionList++];
+        } else {
+          newShuffled[i] = shuffled[indexInOldShuffled++];
+          if (newShuffled[i] >= insertionIndex) {
+            newShuffled[i] += insertionCount;
+          }
+        }
+      }
+      return new DefaultShuffleOrder(newShuffled, new Random(random.nextLong()));
+    }
+
+    @Override
+    public ShuffleOrder cloneAndRemove(int indexFrom, int indexToExclusive) {
+      int numberOfElementsToRemove = indexToExclusive - indexFrom;
+      int[] newShuffled = new int[shuffled.length - numberOfElementsToRemove];
+      int foundElementsCount = 0;
+      for (int i = 0; i < shuffled.length; i++) {
+        if (shuffled[i] >= indexFrom && shuffled[i] < indexToExclusive) {
+          foundElementsCount++;
+        } else {
+          newShuffled[i - foundElementsCount] =
+              shuffled[i] >= indexFrom ? shuffled[i] - numberOfElementsToRemove : shuffled[i];
+        }
+      }
+      return new DefaultShuffleOrder(newShuffled, new Random(random.nextLong()));
+    }
+
+    @Override
+    public ShuffleOrder cloneAndClear() {
+      return new DefaultShuffleOrder(/* length= */ 0, new Random(random.nextLong()));
+    }
+
+    private static int[] createShuffledList(int length, Random random) {
+      int[] shuffled = new int[length];
+      for (int i = 0; i < length; i++) {
+        int swapIndex = random.nextInt(i + 1);
+        shuffled[i] = shuffled[swapIndex];
+        shuffled[swapIndex] = i;
+      }
+      return shuffled;
+    }
+
+  }
+
+  /**
+   * A {@link ShuffleOrder} implementation which does not shuffle.
+   */
+  final class UnshuffledShuffleOrder implements ShuffleOrder {
+
+    private final int length;
+
+    /**
+     * Creates an instance with a specified length.
+     *
+     * @param length The length of the shuffle order.
+     */
+    public UnshuffledShuffleOrder(int length) {
+      this.length = length;
+    }
+
+    @Override
+    public int getLength() {
+      return length;
+    }
+
+    @Override
+    public int getNextIndex(int index) {
+      return ++index < length ? index : C.INDEX_UNSET;
+    }
+
+    @Override
+    public int getPreviousIndex(int index) {
+      return --index >= 0 ? index : C.INDEX_UNSET;
+    }
+
+    @Override
+    public int getLastIndex() {
+      return length > 0 ? length - 1 : C.INDEX_UNSET;
+    }
+
+    @Override
+    public int getFirstIndex() {
+      return length > 0 ? 0 : C.INDEX_UNSET;
+    }
+
+    @Override
+    public ShuffleOrder cloneAndInsert(int insertionIndex, int insertionCount) {
+      return new UnshuffledShuffleOrder(length + insertionCount);
+    }
+
+    @Override
+    public ShuffleOrder cloneAndRemove(int indexFrom, int indexToExclusive) {
+      return new UnshuffledShuffleOrder(length - indexToExclusive + indexFrom);
+    }
+
+    @Override
+    public ShuffleOrder cloneAndClear() {
+      return new UnshuffledShuffleOrder(/* length= */ 0);
+    }
+  }
+
+  /**
+   * Returns length of shuffle order.
+   */
+  int getLength();
+
+  /**
+   * Returns the next index in the shuffle order.
+   *
+   * @param index An index.
+   * @return The index after {@code index}, or {@link C#INDEX_UNSET} if {@code index} is the last
+   *     element.
+   */
+  int getNextIndex(int index);
+
+  /**
+   * Returns the previous index in the shuffle order.
+   *
+   * @param index An index.
+   * @return The index before {@code index}, or {@link C#INDEX_UNSET} if {@code index} is the first
+   *     element.
+   */
+  int getPreviousIndex(int index);
+
+  /**
+   * Returns the last index in the shuffle order, or {@link C#INDEX_UNSET} if the shuffle order is
+   * empty.
+   */
+  int getLastIndex();
+
+  /**
+   * Returns the first index in the shuffle order, or {@link C#INDEX_UNSET} if the shuffle order is
+   * empty.
+   */
+  int getFirstIndex();
+
+  /**
+   * Returns a copy of the shuffle order with newly inserted elements.
+   *
+   * @param insertionIndex The index in the unshuffled order at which elements are inserted.
+   * @param insertionCount The number of elements inserted at {@code insertionIndex}.
+   * @return A copy of this {@link ShuffleOrder} with newly inserted elements.
+   */
+  ShuffleOrder cloneAndInsert(int insertionIndex, int insertionCount);
+
+  /**
+   * Returns a copy of the shuffle order with a range of elements removed.
+   *
+   * @param indexFrom The starting index in the unshuffled order of the range to remove.
+   * @param indexToExclusive The smallest index (must be greater or equal to {@code indexFrom}) that
+   *     will not be removed.
+   * @return A copy of this {@link ShuffleOrder} without the elements in the removed range.
+   */
+  ShuffleOrder cloneAndRemove(int indexFrom, int indexToExclusive);
+
+  /** Returns a copy of the shuffle order with all elements removed. */
+  ShuffleOrder cloneAndClear();
+}