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1 // Copyright 2014 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #ifndef MEDIA_BASE_TEXT_RANGES_H_ | |
6 #define MEDIA_BASE_TEXT_RANGES_H_ | |
7 | |
8 #include <map> | |
9 | |
10 #include "base/macros.h" | |
11 #include "base/time/time.h" | |
12 #include "media/base/media_export.h" | |
13 | |
14 namespace media { | |
15 | |
16 class MEDIA_EXPORT TextRanges { | |
acolwell GONE FROM CHROMIUM
2014/02/07 18:30:52
nit: Add class comment. Probably something around
Matthew Heaney (Chromium)
2014/02/07 18:49:07
Done.
| |
17 public: | |
18 TextRanges(); | |
19 | |
20 // Reset the current range pointer, such that we bind to a new range | |
21 // (either one that exists already, or one that is freshly-created) | |
22 // during the next AddCue(). | |
23 void Reset(); | |
24 | |
25 // Given a cue with starting timestamp |start_time|, add its start | |
26 // time to the time ranges. (Note that following a Reset(), cue | |
27 // times are assumed to be monotonically increasing.) If this time | |
28 // has already been added to the time ranges, then AddCue() returns | |
29 // false and clients should not push the cue downstream. Otherwise, | |
30 // the time is added to the time ranges and AddCue() returns true, | |
31 // meaning that the cue should be pushed downstream. | |
32 bool AddCue(base::TimeDelta start_time); | |
33 | |
34 // Returns a count of the number of time ranges, intended for use by | |
35 // the unit test module to vet proper time range merge behavior. | |
36 size_t RangeCountForTesting() const; | |
37 | |
38 private: | |
39 // Describes a range of times for cues that have already been | |
40 // pushed downstream. | |
41 class Range { | |
42 public: | |
43 // Initialize last_time count. | |
44 void ResetCount(base::TimeDelta start_time); | |
45 | |
46 // Set last_time and associated counts. | |
47 void SetLastTime(base::TimeDelta last_time); | |
48 | |
49 // Adjust time range state to mark the cue as having been seen, | |
50 // returning true if we have not seen |start_time| already and | |
51 // false otherwise. | |
52 bool AddCue(base::TimeDelta start_time); | |
53 | |
54 // Returns the value of the last time in the range. | |
55 base::TimeDelta last_time() const; | |
56 | |
57 private: | |
58 // The last timestamp of this range. | |
59 base::TimeDelta last_time_; | |
60 | |
61 // The number of cues we have detected so far, for this range, | |
62 // whose timestamp matches last_time. | |
63 int max_count_; | |
64 | |
65 // The number of cues we have seen since the most recent Reset(), | |
66 // whose timestamp matches last_time. | |
67 int count_; | |
68 }; | |
69 | |
70 typedef std::map<base::TimeDelta, Range> RangeMap; | |
71 | |
72 // NewRange() is used to create a new time range when AddCue() is | |
73 // called immediately following a Reset(), and no existing time | |
74 // range contains the indicated |start_time| of the cue. | |
75 void NewRange(base::TimeDelta start_time); | |
76 | |
77 // Coalesce curr_range with the range that immediately follows. | |
78 void Merge(Range& curr_range, const RangeMap::iterator& next_range_itr); | |
79 | |
80 // The collection of time ranges, each of which is bounded | |
81 // (inclusive) by the key and Range::last_time. | |
82 RangeMap range_map_; | |
83 | |
84 // The time range to which we bind following a Reset(). | |
85 RangeMap::iterator curr_range_itr_; | |
86 | |
87 DISALLOW_COPY_AND_ASSIGN(TextRanges); | |
88 }; | |
89 | |
90 } // namespace media | |
91 | |
92 #endif // MEDIA_BASE_TEXT_RANGES_H_ | |
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