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/*
* 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
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