[Draft] RTCP Parser sketched.

webrtc/modules/rtp_rtcp/source/rtcp_packet/parsing_container.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_RTCP_PACKET_PARSING_CONTAINER_H_
+#define WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_PACKET_PARSING_CONTAINER_H_
+
+#include "webrtc/modules/rtp_rtcp/source/rtcp_packet/common_header.h"
+
+namespace webrtc {
+namespace rtcp {
+/* ParsingContainer, with help of ParsingPacket class make raw buffer
+   look like container of Packets, i.e. foreach loop can be used on this class
+   Used in Sample2 only.
+*/
+
+class ParsingContainer {
+ public:
+  class value_type : public CommonHeader {
+   public:
+    bool valid() const { return valid_; }
+    bool Parse(const uint8_t* buffer, size_t length) {
+      return valid_ = CommonHeader::Parse(buffer, length);
+    }
+
+   private:
+    bool valid_ = false;
+  };
+
+  class const_iterator {
+   public:
+    const_iterator(const uint8_t* buffer, size_t length)
+        : buffer_end_(buffer + length) {
+      packet_.Parse(buffer, length);
+    }
+    bool operator==(const const_iterator& other) {
+      if (!packet_.valid() && !other.packet_.valid())
+        // All invalid headers are the same.
+        return true;
+      return
+          packet_.valid() == other.packet_.valid() &&
+          packet_.payload() == other.packet_.payload();
+    }
+    bool operator!=(const const_iterator& other) { return !(*this == other); }
+    const_iterator& operator++() {
+      if (!packet_.valid()) {
+        packet_.Parse(buffer_end_, 0);
+      } else {
+        const uint8_t* next_packet = packet_.NextPacket();
+        packet_.Parse(next_packet, buffer_end_ - next_packet);
+      }
+      return *this;
+    }
+    const value_type& operator*() const { return packet_; }
+    const value_type* operator->() const { return &packet_; }
+
+   private:
+    value_type packet_;
+    const uint8_t* buffer_end_;
+  };
+  ParsingContainer(const uint8_t* buffer, size_t length)
+      : begin_(buffer), length_(length) {}
+  const_iterator begin() const { return const_iterator(begin_, length_); }
+  const_iterator end() const { return const_iterator(begin_ + length_, 0); }
+
+ private:
+  const uint8_t* begin_ = nullptr;
+  const size_t length_ = 0;
+};
+
+}  // namespace rtcp
+}  // namespace webrtc
+#endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTCP_PACKET_PARSING_CONTAINER_H_