[Draft] RtpPacket sketched.

webrtc/modules/rtp_rtcp/source/rtp_header_extensions_manager.h

+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#ifndef WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_HEADER_EXTENSIONS_MANAGER_H_
+#define WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_HEADER_EXTENSIONS_MANAGER_H_
+
+#include <memory>
+#include <string>
+
+#include "webrtc/base/basictypes.h"
+#include "webrtc/base/checks.h"
+#include "webrtc/base/constructormagic.h"
+#include "webrtc/base/thread_checker.h"
+#include "webrtc/call.h"
+
+namespace webrtc {
+
+class RtpHeaderExtensionsManager {
+ public:
+  using ExtensionType = const char*;
+
+  static constexpr uint8_t kInvalidId = 0;
+  static constexpr uint8_t kMinId = 1;
+  static constexpr uint8_t kMaxId = 14;
+  static constexpr ExtensionType kInvalidType = nullptr;
+
+  RtpHeaderExtensionsManager();
+
+  // Rtp header extensions.
+  template <typename Extension>
+  bool Register(uint8_t id) {
+    return Register(Extension::kId, id);
+  }
+  bool RegisterByName(const std::string& name, MediaType type, uint8_t id);
+
+  // Return kInvalidId if type is not found.
+  uint8_t GetId(ExtensionType type) const;
+  template <typename Extension>
+  bool IsRegistered() const {
+    return IsRegistered(Extension::kId);
+  }
+  bool IsRegistered(ExtensionType type) const {
+    return GetId(type) != kInvalidId;
+  }
+  // Return kInvalidExtension if no extension registered for given id.
+  ExtensionType GetType(uint8_t id) const {
+    RTC_DCHECK(kMinId <= id && id <= kMaxId);
+    return id_to_type_[id - 1];
+  }
+
+ private:
+  template <typename Extesnsion>
+  bool TryRegister(const std::string& name, MediaType type, uint8_t id);
+  bool Register(ExtensionType type, uint8_t id);
+
+  rtc::ThreadChecker configuration_thread_checker_;
+  ExtensionType id_to_type_[kMaxId - kMinId + 1];
+  RTC_DISALLOW_COPY_AND_ASSIGN(RtpHeaderExtensionsManager);
+};
+
+template <typename Extension>
+bool RtpHeaderExtensionsManager::TryRegister(const std::string& name,
+                                             MediaType type,
+                                             uint8_t id) {
+  return Extension::IsSupportedFor(type) && name == Extension::kId &&
+         Register<Extension>(id);
+}
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_HEADER_EXTENSIONS_MANAGER_H_