Move btif_state_machine to common/StateMachine
In Bluetooth native infrastructure refactor plan, we need a state
machine class for entire stack
Test: manual
Change-Id: I0e6671e42570482d9a9466b117054b3aadb3e9cc
diff --git a/common/state_machine.h b/common/state_machine.h
new file mode 100644
index 0000000..62d92d2
--- /dev/null
+++ b/common/state_machine.h
@@ -0,0 +1,214 @@
+/*
+ * Copyright 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <map>
+#include <utility>
+
+#include <base/logging.h>
+
+namespace bluetooth {
+
+namespace common {
+
+/**
+ * State machine used by Bluetooth native stack.
+ */
+class StateMachine {
+ public:
+ enum { kStateInvalid = -1 };
+
+ /**
+ * A class to represent the state in the State Machine.
+ */
+ class State {
+ friend class StateMachine;
+
+ public:
+ /**
+ * Constructor.
+ *
+ * @param sm the State Machine to use
+ * @param state_id the unique State ID. It should be a non-negative number.
+ */
+ State(StateMachine& sm, int state_id) : sm_(sm), state_id_(state_id) {}
+
+ virtual ~State() = default;
+
+ /**
+ * Process an event.
+ * TODO: The arguments are wrong - used for backward compatibility.
+ * Will be replaced later.
+ *
+ * @param event the event type
+ * @param p_data the event data
+ * @return true if the processing was completed, otherwise false
+ */
+ virtual bool ProcessEvent(uint32_t event, void* p_data) = 0;
+
+ /**
+ * Get the State ID.
+ *
+ * @return the State ID
+ */
+ int StateId() const { return state_id_; }
+
+ protected:
+ /**
+ * Called when a state is entered.
+ */
+ virtual void OnEnter() {}
+
+ /**
+ * Called when a state is exited.
+ */
+ virtual void OnExit() {}
+
+ /**
+ * Transition the State Machine to a new state.
+ *
+ * @param dest_state_id the state ID to transition to. It must be one
+ * of the unique state IDs when the corresponding state was created.
+ */
+ void TransitionTo(int dest_state_id) { sm_.TransitionTo(dest_state_id); }
+
+ /**
+ * Transition the State Machine to a new state.
+ *
+ * @param dest_state the state to transition to. It cannot be nullptr.
+ */
+ void TransitionTo(StateMachine::State* dest_state) {
+ sm_.TransitionTo(dest_state);
+ }
+
+ private:
+ StateMachine& sm_;
+ int state_id_;
+ };
+
+ StateMachine()
+ : initial_state_(nullptr),
+ previous_state_(nullptr),
+ current_state_(nullptr) {}
+ ~StateMachine() {
+ for (auto& kv : states_) delete kv.second;
+ }
+
+ /**
+ * Start the State Machine operation.
+ */
+ void Start() { TransitionTo(initial_state_); }
+
+ /**
+ * Quit the State Machine operation.
+ */
+ void Quit() { previous_state_ = current_state_ = nullptr; }
+
+ /**
+ * Get the current State ID.
+ *
+ * @return the current State ID
+ */
+ int StateId() const {
+ if (current_state_ != nullptr) {
+ return current_state_->StateId();
+ }
+ return kStateInvalid;
+ }
+
+ /**
+ * Get the previous current State ID.
+ *
+ * @return the previous State ID
+ */
+ int PreviousStateId() const {
+ if (previous_state_ != nullptr) {
+ return previous_state_->StateId();
+ }
+ return kStateInvalid;
+ }
+
+ /**
+ * Process an event.
+ * TODO: The arguments are wrong - used for backward compatibility.
+ * Will be replaced later.
+ *
+ * @param event the event type
+ * @param p_data the event data
+ * @return true if the processing was completed, otherwise false
+ */
+ bool ProcessEvent(uint32_t event, void* p_data) {
+ if (current_state_ == nullptr) return false;
+ return current_state_->ProcessEvent(event, p_data);
+ }
+
+ /**
+ * Transition the State Machine to a new state.
+ *
+ * @param dest_state_id the state ID to transition to. It must be one
+ * of the unique state IDs when the corresponding state was created.
+ */
+ void TransitionTo(int dest_state_id) {
+ auto it = states_.find(dest_state_id);
+
+ CHECK(it != states_.end()) << "Unknown State ID: " << dest_state_id;
+ State* dest_state = it->second;
+ TransitionTo(dest_state);
+ }
+
+ /**
+ * Transition the State Machine to a new state.
+ *
+ * @param dest_state the state to transition to. It cannot be nullptr.
+ */
+ void TransitionTo(StateMachine::State* dest_state) {
+ if (current_state_ != nullptr) {
+ current_state_->OnExit();
+ }
+ previous_state_ = current_state_;
+ current_state_ = dest_state;
+ current_state_->OnEnter();
+ }
+
+ /**
+ * Add a state to the State Machine.
+ * The state machine takes ownership on the state - i.e., the state will
+ * be deleted by the State Machine itself.
+ *
+ * @param state the state to add
+ */
+ void AddState(State* state) {
+ states_.insert(std::make_pair(state->StateId(), state));
+ }
+
+ /**
+ * Set the initial state of the State Machine.
+ *
+ * @param initial_state the initial state
+ */
+ void SetInitialState(State* initial_state) { initial_state_ = initial_state; }
+
+ private:
+ State* initial_state_;
+ State* previous_state_;
+ State* current_state_;
+ std::map<int, State*> states_;
+};
+
+} // namespace common
+
+} // namespace bluetooth