third_party/WebKit/Source/modules/mediasource/TrackDefaultList.cpp

// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "modules/mediasource/TrackDefaultList.h"

#include "bindings/core/v8/ExceptionState.h"
#include "core/dom/ExceptionCode.h"
#include "wtf/text/AtomicStringHash.h"
#include "wtf/text/StringHash.h"

namespace blink {

TrackDefaultList* TrackDefaultList::create() {
  return new TrackDefaultList();
}

TrackDefaultList* TrackDefaultList::create(
    const HeapVector<Member<TrackDefault>>& trackDefaults,
    ExceptionState& exceptionState) {
  // Per 11 Dec 2014 Editor's Draft
  // https://w3c.github.io/media-source/#trackdefaultlist
  // When this method is invoked, the user agent must run the following steps:
  // 1. If |trackDefaults| contains two or more TrackDefault objects with the
  //    same type and the same byteStreamTrackID, then throw an
  //    InvalidAccessError and abort these steps.
  //    Note: This also applies when byteStreamTrackID contains an empty
  //    string and ensures that there is only one "byteStreamTrackID
  //    independent" default for each TrackDefaultType value.
  using TypeAndID = std::pair<AtomicString, String>;
  using TypeAndIDToTrackDefaultMap =
      HeapHashMap<TypeAndID, Member<TrackDefault>>;
  TypeAndIDToTrackDefaultMap typeAndIDToTrackDefaultMap;

  for (const auto& trackDefault : trackDefaults) {
    TypeAndID key =
        TypeAndID(trackDefault->type(), trackDefault->byteStreamTrackID());
    if (!typeAndIDToTrackDefaultMap.add(key, trackDefault).isNewEntry) {
      exceptionState.throwDOMException(
          InvalidAccessError, "Duplicate TrackDefault type (" + key.first +
                                  ") and byteStreamTrackID (" + key.second +
                                  ")");
      return nullptr;
    }
  }

  // 2. Store a shallow copy of |trackDefaults| in this new object so the values
  //    can be returned by the accessor methods.
  // This step is done in constructor initializer.
  return new TrackDefaultList(trackDefaults);
}

TrackDefault* TrackDefaultList::item(unsigned index) const {
  // Per 11 Dec 2014 Editor's Draft
  // https://w3c.github.io/media-source/#trackdefaultlist
  // When this method is invoked, the user agent must run the following steps:
  // 1. If |index| is greater than or equal to the length attribute then
  //    return undefined and abort these steps.
  if (index >= m_trackDefaults.size())
    return 0;

  // 2. Return the |index|'th TrackDefault object in the list.
  return m_trackDefaults[index].get();
}

TrackDefaultList::TrackDefaultList() {}

TrackDefaultList::TrackDefaultList(
    const HeapVector<Member<TrackDefault>>& trackDefaults)
    : m_trackDefaults(trackDefaults) {}

DEFINE_TRACE(TrackDefaultList) {
  visitor->trace(m_trackDefaults);
}

}  // namespace blink