1 /*
2 * Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 #ifndef WEBRTC_COMMON_H_
12 #define WEBRTC_COMMON_H_
13
14 #include <map>
15
16 #include "webrtc/base/basictypes.h"
17
18 namespace webrtc {
19
20 // Only add new values to the end of the enumeration and never remove (only
21 // deprecate) to maintain binary compatibility.
22 enum class ConfigOptionID {
23 kMyExperimentForTest,
24 kAlgo1CostFunctionForTest,
25 kTemporalLayersFactory,
26 kNetEqCapacityConfig,
27 kNetEqFastAccelerate,
28 kVoicePacing,
29 kExtendedFilter,
30 kDelayAgnostic,
31 kExperimentalAgc,
32 kExperimentalNs,
33 kBeamforming,
34 kIntelligibility
35 };
36
37 // Class Config is designed to ease passing a set of options across webrtc code.
38 // Options are identified by typename in order to avoid incorrect casts.
39 //
40 // Usage:
41 // * declaring an option:
42 // struct Algo1_CostFunction {
43 // virtual float cost(int x) const { return x; }
44 // virtual ~Algo1_CostFunction() {}
45 // };
46 //
47 // * accessing an option:
48 // config.Get<Algo1_CostFunction>().cost(value);
49 //
50 // * setting an option:
51 // struct SqrCost : Algo1_CostFunction {
52 // virtual float cost(int x) const { return x*x; }
53 // };
54 // config.Set<Algo1_CostFunction>(new SqrCost());
55 //
56 // Note: This class is thread-compatible (like STL containers).
57 class Config {
58 public:
59 // Returns the option if set or a default constructed one.
60 // Callers that access options too often are encouraged to cache the result.
61 // Returned references are owned by this.
62 //
63 // Requires std::is_default_constructible<T>
64 template<typename T> const T& Get() const;
65
66 // Set the option, deleting any previous instance of the same.
67 // This instance gets ownership of the newly set value.
68 template<typename T> void Set(T* value);
69
Config()70 Config() {}
~Config()71 ~Config() {
72 // Note: this method is inline so webrtc public API depends only
73 // on the headers.
74 for (OptionMap::iterator it = options_.begin();
75 it != options_.end(); ++it) {
76 delete it->second;
77 }
78 }
79
80 private:
81 struct BaseOption {
~BaseOptionBaseOption82 virtual ~BaseOption() {}
83 };
84
85 template<typename T>
86 struct Option : BaseOption {
OptionOption87 explicit Option(T* v): value(v) {}
~OptionOption88 ~Option() {
89 delete value;
90 }
91 T* value;
92 };
93
94 template<typename T>
identifier()95 static ConfigOptionID identifier() {
96 return T::identifier;
97 }
98
99 // Used to instantiate a default constructed object that doesn't needs to be
100 // owned. This allows Get<T> to be implemented without requiring explicitly
101 // locks.
102 template<typename T>
default_value()103 static const T& default_value() {
104 RTC_DEFINE_STATIC_LOCAL(const T, def, ());
105 return def;
106 }
107
108 typedef std::map<ConfigOptionID, BaseOption*> OptionMap;
109 OptionMap options_;
110
111 // RTC_DISALLOW_COPY_AND_ASSIGN
112 Config(const Config&);
113 void operator=(const Config&);
114 };
115
116 template<typename T>
Get()117 const T& Config::Get() const {
118 OptionMap::const_iterator it = options_.find(identifier<T>());
119 if (it != options_.end()) {
120 const T* t = static_cast<Option<T>*>(it->second)->value;
121 if (t) {
122 return *t;
123 }
124 }
125 return default_value<T>();
126 }
127
128 template<typename T>
Set(T * value)129 void Config::Set(T* value) {
130 BaseOption*& it = options_[identifier<T>()];
131 delete it;
132 it = new Option<T>(value);
133 }
134
135 } // namespace webrtc
136
137 #endif // WEBRTC_COMMON_H_
138