Initial StateMatrix idea using composition and void*

BUG=none
TEST=media_unittests

Review URL: http://codereview.chromium.org/3416001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@65128 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 140 insertions, 0 deletions

diff --git a/media/base/state_matrix.cc b/media/base/state_matrix.cc
new file mode 100644
index 0000000..f0ef07b
--- /dev/null
+++ b/media/base/state_matrix.cc
@@ -0,0 +1,26 @@
+// Copyright (c) 2010 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/state_matrix.h"
+
+#include "base/stl_util-inl.h"
+
+namespace media {
+
+StateMatrix::StateMatrix() {
+}
+
+StateMatrix::~StateMatrix() {
+  STLDeleteValues(&states_);
+}
+
+bool StateMatrix::IsStateDefined(int state) {
+  return states_.find(state) != states_.end();
+}
+
+int StateMatrix::ExecuteHandler(void* instance, int state) {
+  return states_.find(state)->second->ExecuteHandler(instance);
+}
+
+}  // namespace media
diff --git a/media/base/state_matrix.h b/media/base/state_matrix.h
new file mode 100644
index 0000000..779646f
--- /dev/null
+++ b/media/base/state_matrix.h
@@ -0,0 +1,61 @@
+// Copyright (c) 2010 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.
+
+#ifndef MEDIA_BASE_STATE_MATRIX_H_
+#define MEDIA_BASE_STATE_MATRIX_H_
+
+#include <map>
+
+#include "base/logging.h"
+
+namespace media {
+
+class StateMatrix {
+ public:
+  StateMatrix();
+  ~StateMatrix();
+
+  template <typename HandlerType>
+  void AddState(int state, int (HandlerType::* handler)()) {
+    CHECK(!IsStateDefined(state));
+    StateEntryBase* entry = new StateEntry<HandlerType>(handler);
+    states_.insert(std::make_pair(state, entry));
+  }
+
+  bool IsStateDefined(int state);
+
+  int ExecuteHandler(void* instance, int state);
+
+ private:
+  class StateEntryBase {
+   public:
+    StateEntryBase() {}
+    virtual ~StateEntryBase() {}
+
+    virtual int ExecuteHandler(void* instance) = 0;
+  };
+
+  template <typename HandlerType>
+  class StateEntry : public StateEntryBase {
+   public:
+    explicit StateEntry(int (HandlerType::* handler)()) : handler_(handler) {}
+    virtual ~StateEntry() {}
+
+    virtual int ExecuteHandler(void* instance) {
+      return (reinterpret_cast<HandlerType*>(instance)->*handler_)();
+    }
+
+   private:
+    int (HandlerType::* handler_)();
+  };
+
+  typedef std::map<int, StateEntryBase*> StateMap;
+  StateMap states_;
+
+  DISALLOW_COPY_AND_ASSIGN(StateMatrix);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_STATE_MATRIX_H_
diff --git a/media/base/state_matrix_unittest.cc b/media/base/state_matrix_unittest.cc
new file mode 100644
index 0000000..599ea6f
--- /dev/null
+++ b/media/base/state_matrix_unittest.cc
@@ -0,0 +1,53 @@
+// Copyright (c) 2010 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/state_matrix.h"
+#include "testing/gmock/include/gmock/gmock.h"
+
+using ::testing::Return;
+
+namespace media {
+
+class MockStateHandler {
+ public:
+  enum State {
+    A,
+    B,
+    C,
+  };
+
+  MOCK_METHOD0(HandleA, int());
+  MOCK_METHOD0(HandleB, int());
+  MOCK_METHOD0(HandleC, int());
+};
+
+TEST(StateMatrixTest, AddState) {
+  MockStateHandler handler;
+  StateMatrix sm;
+
+  EXPECT_FALSE(sm.IsStateDefined(MockStateHandler::A));
+  EXPECT_FALSE(sm.IsStateDefined(MockStateHandler::B));
+  EXPECT_FALSE(sm.IsStateDefined(MockStateHandler::C));
+
+  sm.AddState(MockStateHandler::A, &MockStateHandler::HandleA);
+
+  EXPECT_TRUE(sm.IsStateDefined(MockStateHandler::A));
+  EXPECT_FALSE(sm.IsStateDefined(MockStateHandler::B));
+  EXPECT_FALSE(sm.IsStateDefined(MockStateHandler::C));
+}
+
+TEST(StateMatrixTest, ExecuteHandler) {
+  MockStateHandler handler;
+  StateMatrix sm;
+
+  sm.AddState(MockStateHandler::A, &MockStateHandler::HandleA);
+
+  EXPECT_CALL(handler, HandleA())
+      .WillOnce(Return(MockStateHandler::B));
+
+  EXPECT_EQ(MockStateHandler::B,
+            sm.ExecuteHandler(&handler, MockStateHandler::A));
+}
+
+}  // namespace media