Add MediaChunkListIterator

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=219472988

library/core/src/main/java/com/google/android/exoplayer2/source/chunk/BaseMediaChunkIterator.java

@@ -56,14 +56,14 @@ public abstract class BaseMediaChunkIterator implements MediaChunkIterator {
    *
    * @throws NoSuchElementException If the iterator does not point to a valid element.
    */
-  protected void checkInBounds() {
+  protected final void checkInBounds() {
     if (currentIndex < fromIndex || currentIndex > toIndex) {
       throw new NoSuchElementException();
     }
   }
 
   /** Returns the current index this iterator is pointing to. */
-  protected long getCurrentIndex() {
+  protected final long getCurrentIndex() {
     return currentIndex;
   }
 }

library/core/src/main/java/com/google/android/exoplayer2/source/chunk/MediaChunkListIterator.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2018 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 com.google.android.exoplayer2.source.chunk;
+
+import com.google.android.exoplayer2.upstream.DataSpec;
+import java.util.List;
+
+/** A {@link MediaChunkIterator} which iterates over a {@link List} of {@link MediaChunk}s. */
+public final class MediaChunkListIterator extends BaseMediaChunkIterator {
+
+  private final List<? extends MediaChunk> chunks;
+  private final boolean reverseOrder;
+
+  /**
+   * Creates iterator.
+   *
+   * @param chunks The list of chunks to iterate over.
+   * @param reverseOrder Whether to iterate in reverse order.
+   */
+  public MediaChunkListIterator(List<? extends MediaChunk> chunks, boolean reverseOrder) {
+    super(0, chunks.size() - 1);
+    this.chunks = chunks;
+    this.reverseOrder = reverseOrder;
+  }
+
+  @Override
+  public DataSpec getDataSpec() {
+    return getCurrentChunk().dataSpec;
+  }
+
+  @Override
+  public long getChunkStartTimeUs() {
+    return getCurrentChunk().startTimeUs;
+  }
+
+  @Override
+  public long getChunkEndTimeUs() {
+    return getCurrentChunk().endTimeUs;
+  }
+
+  private MediaChunk getCurrentChunk() {
+    int index = (int) super.getCurrentIndex();
+    if (reverseOrder) {
+      index = chunks.size() - 1 - index;
+    }
+    return chunks.get(index);
+  }
+}

library/core/src/test/java/com/google/android/exoplayer2/source/chunk/MediaChunkListIteratorTest.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2018 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 com.google.android.exoplayer2.source.chunk;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.android.exoplayer2.Format;
+import com.google.android.exoplayer2.testutil.FakeMediaChunk;
+import java.util.Arrays;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+
+/** Tests for {@link MediaChunkListIterator}. */
+@RunWith(RobolectricTestRunner.class)
+public class MediaChunkListIteratorTest {
+
+  private static final Format TEST_FORMAT = Format.createSampleFormat(null, null, 0);
+
+  private FakeMediaChunk testChunk1;
+  private FakeMediaChunk testChunk2;
+
+  @Before
+  public void setUp() {
+    testChunk1 = new FakeMediaChunk(TEST_FORMAT, 0, 10);
+    testChunk2 = new FakeMediaChunk(TEST_FORMAT, 10, 20);
+  }
+
+  @Test
+  public void iterator_reverseOrderFalse_returnsItemsInNormalOrder() {
+    MediaChunkListIterator iterator =
+        new MediaChunkListIterator(
+            Arrays.asList(testChunk1, testChunk2), /* reverseOrder= */ false);
+    assertThat(iterator.isEnded()).isFalse();
+    assertThat(iterator.next()).isTrue();
+    assertEqual(iterator, testChunk1);
+    assertThat(iterator.next()).isTrue();
+    assertEqual(iterator, testChunk2);
+    assertThat(iterator.next()).isFalse();
+    assertThat(iterator.isEnded()).isTrue();
+  }
+
+  @Test
+  public void iterator_reverseOrderTrue_returnsItemsInReverseOrder() {
+    MediaChunkListIterator iterator =
+        new MediaChunkListIterator(
+            Arrays.asList(testChunk1, testChunk2), /* reverseOrder= */ true);
+    assertThat(iterator.isEnded()).isFalse();
+    assertThat(iterator.next()).isTrue();
+    assertEqual(iterator, testChunk2);
+    assertThat(iterator.next()).isTrue();
+    assertEqual(iterator, testChunk1);
+    assertThat(iterator.next()).isFalse();
+    assertThat(iterator.isEnded()).isTrue();
+  }
+
+  private static void assertEqual(MediaChunkListIterator iterator, FakeMediaChunk chunk) {
+    assertThat(iterator.getChunkStartTimeUs()).isEqualTo(chunk.startTimeUs);
+    assertThat(iterator.getChunkEndTimeUs()).isEqualTo(chunk.endTimeUs);
+    assertThat(iterator.getDataSpec()).isEqualTo(chunk.dataSpec);
+  }
+}

library/core/src/test/java/com/google/android/exoplayer2/trackselection/AdaptiveTrackSelectionTest.java

@@ -23,19 +23,14 @@ import static org.mockito.Mockito.verifyZeroInteractions;
 import static org.mockito.Mockito.when;
 import static org.mockito.MockitoAnnotations.initMocks;
 
-import android.net.Uri;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.source.TrackGroup;
-import com.google.android.exoplayer2.source.chunk.MediaChunk;
 import com.google.android.exoplayer2.source.chunk.MediaChunkIterator;
 import com.google.android.exoplayer2.testutil.FakeClock;
+import com.google.android.exoplayer2.testutil.FakeMediaChunk;
 import com.google.android.exoplayer2.upstream.BandwidthMeter;
-import com.google.android.exoplayer2.upstream.DataSource;
-import com.google.android.exoplayer2.upstream.DataSpec;
-import com.google.android.exoplayer2.upstream.DefaultHttpDataSource;
 import com.google.android.exoplayer2.util.MimeTypes;
-import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -409,35 +404,4 @@ public final class AdaptiveTrackSelectionTest {
         /* drmInitData= */ null);
   }
 
-  private static final class FakeMediaChunk extends MediaChunk {
-
-    private static final DataSource DATA_SOURCE = new DefaultHttpDataSource("TEST_AGENT", null);
-
-    public FakeMediaChunk(Format trackFormat, long startTimeUs, long endTimeUs) {
-      super(
-          DATA_SOURCE,
-          new DataSpec(Uri.EMPTY),
-          trackFormat,
-          C.SELECTION_REASON_ADAPTIVE,
-          null,
-          startTimeUs,
-          endTimeUs,
-          0);
-    }
-
-    @Override
-    public void cancelLoad() {
-      // Do nothing.
-    }
-
-    @Override
-    public void load() throws IOException, InterruptedException {
-      // Do nothing.
-    }
-
-    @Override
-    public boolean isLoadCompleted() {
-      return true;
-    }
-  }
 }

testutils_robolectric/src/main/java/com/google/android/exoplayer2/testutil/FakeMediaChunk.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2018 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 com.google.android.exoplayer2.testutil;
+
+import android.net.Uri;
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.Format;
+import com.google.android.exoplayer2.source.chunk.MediaChunk;
+import com.google.android.exoplayer2.upstream.DataSource;
+import com.google.android.exoplayer2.upstream.DataSpec;
+import com.google.android.exoplayer2.upstream.DefaultHttpDataSource;
+import java.io.IOException;
+
+/** Fake {@link MediaChunk}. */
+public final class FakeMediaChunk extends MediaChunk {
+
+  private static final DataSource DATA_SOURCE = new DefaultHttpDataSource("TEST_AGENT", null);
+
+  public FakeMediaChunk(Format trackFormat, long startTimeUs, long endTimeUs) {
+    super(
+        DATA_SOURCE,
+        new DataSpec(Uri.EMPTY),
+        trackFormat,
+        C.SELECTION_REASON_ADAPTIVE,
+        /* trackSelectionData= */ null,
+        startTimeUs,
+        endTimeUs,
+        /* chunkIndex= */ 0);
+  }
+
+  @Override
+  public void cancelLoad() {
+    // Do nothing.
+  }
+
+  @Override
+  public void load() throws IOException, InterruptedException {
+    // Do nothing.
+  }
+
+  @Override
+  public boolean isLoadCompleted() {
+    return true;
+  }
+}