Added a config class to ease passing a set of options across webrtc.
Its main design reason is to expose control of experimental webrtc features.
R=niklas.enbom@webrtc.org
Review URL: https://webrtc-codereview.appspot.com/1450009
git-svn-id: http://webrtc.googlecode.com/svn/trunk@4004 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc.gyp b/webrtc.gyp
index 3c57425..6d2e04f 100644
--- a/webrtc.gyp
+++ b/webrtc.gyp
@@ -40,4 +40,21 @@
],
},
],
+ 'conditions': [
+ ['include_tests==1', {
+ 'targets': [
+ {
+ 'target_name': 'common_unittests',
+ 'type': 'executable',
+ 'dependencies': [
+ '<(DEPTH)/testing/gtest.gyp:gtest',
+ '<(webrtc_root)/test/test.gyp:test_support_main',
+ ],
+ 'sources': [
+ 'webrtc/common_unittest.cc',
+ ],
+ },
+ ], # targets
+ }], # include_tests
+ ],
}
diff --git a/webrtc/common.h b/webrtc/common.h
new file mode 100644
index 0000000..766f5b5
--- /dev/null
+++ b/webrtc/common.h
@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2013 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_COMMON_H
+#define WEBRTC_COMMON_H
+
+#include <map>
+
+namespace webrtc {
+
+// Class Config is designed to ease passing a set of options across webrtc code.
+// Options are identified by typename in order to avoid incorrect casts.
+//
+// Usage:
+// * declaring an option:
+// struct Algo1_CostFunction {
+// virtual float cost(int x) const { return x; }
+// virtual ~Algo1_CostFunction() {}
+// };
+//
+// * accessing an option:
+// config.Get<Algo1_CostFunction>().cost(value);
+//
+// * setting an option:
+// struct SqrCost : Algo1_CostFunction {
+// virtual float cost(int x) const { return x*x; }
+// };
+// config.Set<Algo1_CostFunction>(new SqrCost());
+//
+// Note: This class is thread-compatible (like STL containers).
+class Config {
+ public:
+ // Returns the option if set or a default constructed one.
+ // Callers that access options to often are encouraged to cache the result.
+ // Returned references are owned by this.
+ //
+ // Requires std::is_default_constructible<T>
+ template<typename T> const T& Get() const;
+
+ // Set the option, deleting any previous instance of the same.
+ // This instance gets ownership of the newly setted value.
+ template<typename T> void Set(T* value);
+
+ Config() {}
+ ~Config() {
+ // Note: this method is inline so webrtc public API depends only
+ // on the headers.
+ for (OptionMap::iterator it = options_.begin();
+ it != options_.end(); ++it) {
+ delete it->second;
+ }
+ }
+
+ private:
+ typedef void* OptionIdentifier;
+
+ struct BaseOption {
+ virtual ~BaseOption() {}
+ };
+
+ template<typename T>
+ struct Option : BaseOption {
+ explicit Option(T* v): value(v) {}
+ ~Option() {
+ delete value;
+ }
+ T* value;
+ };
+
+ // Own implementation of rtti-subset to avoid depending on rtti and its costs.
+ template<typename T>
+ static OptionIdentifier identifier() {
+ static char id_placeholder;
+ return &id_placeholder;
+ }
+
+ // Used to instantiate a default constructed object that doesn't needs to be
+ // owned. This allows Get<T> to be implemented without requiring explicitly
+ // locks.
+ template<typename T>
+ static const T& default_value() {
+ static const T def;
+ return def;
+ }
+
+ typedef std::map<OptionIdentifier, BaseOption*> OptionMap;
+ OptionMap options_;
+
+ // DISALLOW_COPY_AND_ASSIGN
+ Config(const Config&);
+ void operator=(const Config&);
+};
+
+template<typename T>
+const T& Config::Get() const {
+ OptionMap::const_iterator it = options_.find(identifier<T>());
+ if (it != options_.end()) {
+ const T* t = static_cast<Option<T>*>(it->second)->value;
+ if (t) {
+ return *t;
+ }
+ }
+ return default_value<T>();
+}
+
+template<typename T>
+void Config::Set(T* value) {
+ BaseOption*& it = options_[identifier<T>()];
+ delete it;
+ it = new Option<T>(value);
+}
+} // namespace webrtc
+#endif // WEBRTC_COMMON_H
diff --git a/webrtc/common_unittest.cc b/webrtc/common_unittest.cc
new file mode 100644
index 0000000..e672f1d
--- /dev/null
+++ b/webrtc/common_unittest.cc
@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2013 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.
+ */
+#include "common.h" // NOLINT
+
+#include "gtest/gtest.h"
+
+namespace webrtc {
+namespace {
+
+struct MyExperiment {
+ enum { kDefaultFactor = 1 };
+ enum { kDefaultOffset = 2 };
+
+ MyExperiment()
+ : factor(kDefaultFactor), offset(kDefaultOffset) {}
+
+ MyExperiment(int factor, int offset)
+ : factor(factor), offset(offset) {}
+
+ int factor;
+ int offset;
+};
+
+TEST(Config, ReturnsDefaultInstanceIfNotConfigured) {
+ Config config;
+ const MyExperiment& my_exp = config.Get<MyExperiment>();
+ EXPECT_EQ(MyExperiment::kDefaultFactor, my_exp.factor);
+ EXPECT_EQ(MyExperiment::kDefaultOffset, my_exp.offset);
+}
+
+TEST(Config, ReturnOptionWhenSet) {
+ Config config;
+ config.Set<MyExperiment>(new MyExperiment(5, 1));
+ const MyExperiment& my_exp = config.Get<MyExperiment>();
+ EXPECT_EQ(5, my_exp.factor);
+ EXPECT_EQ(1, my_exp.offset);
+}
+
+TEST(Config, SetNullSetsTheOptionBackToDefault) {
+ Config config;
+ config.Set<MyExperiment>(new MyExperiment(5, 1));
+ config.Set<MyExperiment>(NULL);
+ const MyExperiment& my_exp = config.Get<MyExperiment>();
+ EXPECT_EQ(MyExperiment::kDefaultFactor, my_exp.factor);
+ EXPECT_EQ(MyExperiment::kDefaultOffset, my_exp.offset);
+}
+
+struct Algo1_CostFunction {
+ Algo1_CostFunction() {}
+
+ virtual int cost(int x) const {
+ return x;
+ }
+
+ virtual ~Algo1_CostFunction() {}
+};
+
+struct SqrCost : Algo1_CostFunction {
+ virtual int cost(int x) const {
+ return x*x;
+ }
+};
+
+TEST(Config, SupportsPolimorphism) {
+ Config config;
+ config.Set<Algo1_CostFunction>(new SqrCost());
+ EXPECT_EQ(25, config.Get<Algo1_CostFunction>().cost(5));
+}
+} // namespace
+} // namespace webrtc
