Added more const-correctness fixes.

Author: SimonCahill

include/libdbc/message.hpp

@@ -24,7 +24,7 @@ struct Message {
 	ParseSignalsStatus parse_signals(const std::vector<uint8_t>& data, std::vector<double>& values) const;
 
 	void append_signal(const Signal& signal);
-	std::vector<Signal> get_signals() const;
+	const std::vector<Signal>& get_signals() const;
 	uint32_t id() const;
 	uint8_t size() const;
 	const std::string& name() const;
@@ -33,11 +33,11 @@ struct Message {
 	virtual bool operator==(const Message& rhs) const;
 
 private:
-	uint32_t m_id;
-	std::string m_name;
-	uint8_t m_size;
-	std::string m_node;
-	std::vector<Signal> m_signals;
+	uint32_t m_id{};
+	std::string m_name{};
+	uint8_t m_size{};
+	std::string m_node{};
+	std::vector<Signal> m_signals{};
 
 	friend std::ostream& operator<<(std::ostream& out, const Message& msg);
 };

include/libdbc/signal.hpp

@@ -30,7 +30,7 @@ struct Signal {
 
 	Signal() = delete;
 	virtual ~Signal() = default;
-	explicit Signal(std::string name,
+	explicit Signal(const std::string& name,
 					bool is_multiplexed,
 					uint32_t start_bit,
 					uint32_t size,
@@ -40,8 +40,8 @@ struct Signal {
 					double offset,
 					double min,
 					double max,
-					std::string unit,
-					std::vector<std::string> receivers);
+					const std::string& unit,
+					const std::vector<std::string>& receivers);
 
 	virtual bool operator==(const Signal& rhs) const;
 	bool operator<(const Signal& rhs) const;

src/message.cpp

@@ -92,7 +92,7 @@ void Message::append_signal(const Signal& signal) {
 	m_signals.push_back(signal);
 }
 
-std::vector<Signal> Message::get_signals() const {
+const std::vector<Signal>& Message::get_signals() const {
 	return m_signals;
 }
 

src/signal.cpp

@@ -5,7 +5,7 @@
 #include <vector>
 
 namespace Libdbc {
-Signal::Signal(std::string name,
+Signal::Signal(const std::string& name,
 			   bool is_multiplexed,
 			   uint32_t start_bit,
 			   uint32_t size,
@@ -15,8 +15,8 @@ Signal::Signal(std::string name,
 			   double offset,
 			   double min,
 			   double max,
-			   std::string unit,
-			   std::vector<std::string> receivers)
+			   const std::string& unit,
+			   const std::vector<std::string>& receivers)
 	: name(name)
 	, is_multiplexed(is_multiplexed)
 	, start_bit(start_bit)