Add a new incremental parsing API

Change-Id: I6b921766836d58df0281fb23b2add3f62a478e14

webm_parser/src/segment_parser.cc

@@ -0,0 +1,86 @@
+// Copyright (c) 2016 The WebM 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.
+#include "src/segment_parser.h"
+
+#include "src/chapters_parser.h"
+#include "src/cluster_parser.h"
+#include "src/cues_parser.h"
+#include "src/info_parser.h"
+#include "src/seek_head_parser.h"
+#include "src/skip_callback.h"
+#include "src/tags_parser.h"
+#include "src/tracks_parser.h"
+#include "webm/id.h"
+
+namespace webm {
+
+SegmentParser::SegmentParser()
+    : MasterParser(MakeChild<ChaptersParser>(Id::kChapters),
+                   MakeChild<ClusterParser>(Id::kCluster),
+                   MakeChild<CuesParser>(Id::kCues),
+                   MakeChild<InfoParser>(Id::kInfo),
+                   MakeChild<SeekHeadParser>(Id::kSeekHead),
+                   MakeChild<TagsParser>(Id::kTags),
+                   MakeChild<TracksParser>(Id::kTracks)) {}
+
+Status SegmentParser::Init(const ElementMetadata& metadata,
+                           std::uint64_t max_size) {
+  assert(metadata.size == kUnknownElementSize || metadata.size <= max_size);
+
+  begin_done_ = false;
+  parse_completed_ = false;
+  return MasterParser::Init(metadata, max_size);
+}
+
+void SegmentParser::InitAfterSeek(const Ancestory& child_ancestory,
+                                  const ElementMetadata& child_metadata) {
+  MasterParser::InitAfterSeek(child_ancestory, child_metadata);
+
+  begin_done_ = true;
+  parse_completed_ = false;
+  action_ = Action::kRead;
+}
+
+Status SegmentParser::Feed(Callback* callback, Reader* reader,
+                           std::uint64_t* num_bytes_read) {
+  assert(callback != nullptr);
+  assert(reader != nullptr);
+  assert(num_bytes_read != nullptr);
+
+  *num_bytes_read = 0;
+
+  if (!begin_done_) {
+    const ElementMetadata metadata{Id::kSegment, header_size(), size(),
+                                   position()};
+    const Status status = callback->OnSegmentBegin(metadata, &action_);
+    if (!status.completed_ok()) {
+      return status;
+    }
+    begin_done_ = true;
+  }
+
+  SkipCallback skip_callback;
+  if (action_ == Action::kSkip) {
+    callback = &skip_callback;
+  }
+
+  if (!parse_completed_) {
+    const Status status = MasterParser::Feed(callback, reader, num_bytes_read);
+    if (!status.completed_ok()) {
+      return status;
+    }
+    parse_completed_ = true;
+  }
+
+  return callback->OnSegmentEnd(
+      {Id::kSegment, header_size(), size(), position()});
+}
+
+bool SegmentParser::WasSkipped() const { return action_ == Action::kSkip; }
+
+}  // namespace webm