TextRenderer only pushes new cues downstream

media/base/text_ranges.cc

Index: media/base/text_ranges.cc
diff --git a/media/base/text_ranges.cc b/media/base/text_ranges.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7eab0accf50473fb1f76d6c961d524f8bd35c488
--- /dev/null
+++ b/media/base/text_ranges.cc
@@ -0,0 +1,134 @@
+// 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 "media/base/text_ranges.h"
+
+#include "base/logging.h"
+
+namespace media {
+
+TextRanges::TextRanges() {
+  Reset();
+}
+
+void TextRanges::Reset() {
+  curr_range_itr_ = range_map_.end();
+}
+
+bool TextRanges::AddCue(base::TimeDelta start_time) {
+  typedef RangeMap::iterator Itr;
+
+  if (curr_range_itr_ == range_map_.end()) {
+    // There is no active time range, so this is the first AddCue()
+    // attempt that follows a Reset().
+
+    if (range_map_.empty()) {
+      NewRange(start_time);
+      return true;
+    }
+
+    if (start_time < range_map_.begin()->first) {
+      NewRange(start_time);
+      return true;
+    }
+
+    const Itr itr = --Itr(range_map_.upper_bound(start_time));
+    DCHECK(start_time >= itr->first);
+
+    Range& range = itr->second;
+
+    if (start_time > range.last_time) {
+      NewRange(start_time);
+      return true;
+    }
+
+    range.ResetCount(start_time);
+    curr_range_itr_ = itr;
+    return false;
+  }
+
+  DCHECK(start_time >= curr_range_itr_->first);
+
+  Range& curr_range = curr_range_itr_->second;
+
+  if (start_time <= curr_range.last_time)
+    return curr_range.AddCue(start_time);
+
+  const Itr next_range_itr = ++Itr(curr_range_itr_);
+
+  if (next_range_itr != range_map_.end()) {
+    DCHECK(next_range_itr->first > curr_range.last_time);
+    DCHECK(start_time <= next_range_itr->first);
+
+    if (start_time == next_range_itr->first) {
+      // We have walked off the curr range, and onto the next one.

[acolwell GONE FROM CHROMIUM, 2014/02/07 01:44:18]

nit:s/curr range/current range/ or s/curr range/|curr_range|/

[Matthew Heaney (Chromium), 2014/02/07 03:24:35]

Done.

+      // There is now no ambiguity about where the curr time range
+      // ends, and so we coalesce the curr and next ranges.

[acolwell GONE FROM CHROMIUM, 2014/02/07 01:44:18]

ditto. Either use "current" or the actual variable names with appropriate ||
wrapping.

[Matthew Heaney (Chromium), 2014/02/07 03:24:35]

Done.

+
+      Merge(curr_range, next_range_itr);
+      return false;
+    }
+  }
+
+  // Either curr is the last range in the map, or there is a next

[acolwell GONE FROM CHROMIUM, 2014/02/07 01:44:18]

ditto for this comment as well.

[Matthew Heaney (Chromium), 2014/02/07 03:24:35]

Done.

+  // range beyond the curr range, but its start time is ahead of this
+  // cue's start time.  In either case, this cue becomes the new
+  // last_time for the curr range.  Eventually we will see a cue whose
+  // time matches the start time of the next range, in which case we
+  // coalesce the curr and next ranges.
+
+  curr_range.SetLastTime(start_time);
+  return true;
+}
+
+size_t TextRanges::RangeCountForTesting() const {
+  return range_map_.size();
+}
+
+void TextRanges::NewRange(base::TimeDelta start_time) {
+  Range range;
+  range.SetLastTime(start_time);
+
+  std::pair<RangeMap::iterator, bool> result =
+      range_map_.insert(std::make_pair(start_time, range));
+  DCHECK(result.second);
+
+  curr_range_itr_ = result.first;
+}
+
+void TextRanges::Merge(
+    Range& curr_range,
+    RangeMap::iterator next_range_itr) {

[acolwell GONE FROM CHROMIUM, 2014/02/07 01:44:18]

nit: make const&

[Matthew Heaney (Chromium), 2014/02/07 03:24:35]

Done.

+  curr_range = next_range_itr->second;
+  curr_range.ResetCount(next_range_itr->first);
+  range_map_.erase(next_range_itr);
+}
+
+void TextRanges::Range::ResetCount(base::TimeDelta start_time) {
+  count = (start_time < last_time) ? 0 : 1;
+}
+
+void TextRanges::Range::SetLastTime(base::TimeDelta start_time) {

[acolwell GONE FROM CHROMIUM, 2014/02/07 01:44:18]

nit: s/start_time/last_time/

[Matthew Heaney (Chromium), 2014/02/07 03:24:35]

Done.

+  last_time = start_time;
+  count = 1;
+  max_count = 1;
+}
+
+bool TextRanges::Range::AddCue(base::TimeDelta start_time) {
+  if (start_time < last_time) {
+    DCHECK_EQ(count, 0);
+    return false;
+  }
+
+  DCHECK(start_time == last_time);
+
+  ++count;
+  if (count <= max_count)
+    return false;
+
+  ++max_count;
+  return true;
+}
+
+}  // namespace media