Convert 'const string&' to 'string_view', as per C++17 recommendations. WIP.

src/cheat/BankRomCheat.cxx

@@ -21,11 +21,11 @@
 #include "BankRomCheat.hxx"
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-BankRomCheat::BankRomCheat(OSystem& os, const string& name, const string& code)
+BankRomCheat::BankRomCheat(OSystem& os, string_view name, string_view code)
   : Cheat(os, name, code)
 {
   if(myCode.length() == 7)
-    myCode = "0" + code;
+    myCode = "0" + string{code};
 
   bank = unhex(myCode.substr(0, 2));
   address = 0xf000 + unhex(myCode.substr(2, 3));

src/cheat/BankRomCheat.hxx

@@ -23,7 +23,7 @@
 class BankRomCheat : public Cheat
 {
   public:
-    BankRomCheat(OSystem& os, const string& name, const string& code);
+    BankRomCheat(OSystem& os, string_view name, string_view code);
     ~BankRomCheat() override = default;
 
     bool enable() override;

src/cheat/Cheat.hxx

@@ -25,7 +25,7 @@ class OSystem;
 class Cheat
 {
   public:
-    Cheat(OSystem& osystem, const string& name, const string& code)
+    Cheat(OSystem& osystem, string_view name, string_view code)
       : myOSystem{osystem},
         myName{name == "" ? code : name},
         myCode{code} { }
@@ -41,7 +41,7 @@ class Cheat
     virtual void evaluate() = 0;
 
   protected:
-    static uInt16 unhex(const string& hex)
+    static uInt16 unhex(string_view hex)
     {
       int ret = 0;
       for(const auto c: hex)

src/cheat/CheatManager.cxx

@@ -33,7 +33,7 @@ CheatManager::CheatManager(OSystem& osystem)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool CheatManager::add(const string& name, const string& code,
+bool CheatManager::add(string_view name, string_view code,
                        bool enable, int idx)
 {
   const shared_ptr<Cheat> cheat = createCheat(name, code);
@@ -79,7 +79,7 @@ void CheatManager::remove(int idx)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void CheatManager::addPerFrame(const string& name, const string& code, bool enable)
+void CheatManager::addPerFrame(string_view name, string_view code, bool enable)
 {
   // The actual cheat will always be in the main list; we look there first
   shared_ptr<Cheat> cheat;
@@ -117,7 +117,7 @@ void CheatManager::addPerFrame(const string& name, const string& code, bool enab
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void CheatManager::addOneShot(const string& name, const string& code)
+void CheatManager::addOneShot(string_view name, string_view code)
 {
   // Evaluate this cheat once, and then immediately discard it
   const shared_ptr<Cheat> cheat = createCheat(name, code);
@@ -126,7 +126,7 @@ void CheatManager::addOneShot(const string& name, const string& code)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-shared_ptr<Cheat> CheatManager::createCheat(const string& name, const string& code) const
+shared_ptr<Cheat> CheatManager::createCheat(string_view name, string_view code) const
 {
   if(!isValidCode(code))
     return nullptr;
@@ -143,7 +143,7 @@ shared_ptr<Cheat> CheatManager::createCheat(const string& name, const string& co
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void CheatManager::parse(const string& cheats)
+void CheatManager::parse(string_view cheats)
 {
   StringList s;
   string::size_type lastPos = cheats.find_first_not_of(',', 0);
@@ -198,7 +198,7 @@ void CheatManager::parse(const string& cheats)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void CheatManager::enable(const string& code, bool enable)
+void CheatManager::enable(string_view code, bool enable)
 {
   for(const auto& cheat: myCheatList)
   {
@@ -263,7 +263,7 @@ void CheatManager::saveCheatDatabase()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void CheatManager::loadCheats(const string& md5sum)
+void CheatManager::loadCheats(string_view md5sum)
 {
   myPerFrameList.clear();
   myCheatList.clear();
@@ -287,7 +287,7 @@ void CheatManager::loadCheats(const string& md5sum)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void CheatManager::saveCheats(const string& md5sum)
+void CheatManager::saveCheats(string_view md5sum)
 {
   ostringstream cheats;
   for(uInt32 i = 0; i < myCheatList.size(); ++i)
@@ -322,7 +322,7 @@ void CheatManager::saveCheats(const string& md5sum)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool CheatManager::isValidCode(const string& code)
+bool CheatManager::isValidCode(string_view code)
 {
   for(const auto c: code)
     if(!isxdigit(c))

src/cheat/CheatManager.hxx

@@ -49,7 +49,7 @@ class CheatManager
 
       @return  Whether the cheat was created and enabled.
     */
-    bool add(const string& name, const string& code,
+    bool add(string_view name, string_view code,
              bool enable = true, int idx = -1);
 
     /**
@@ -68,7 +68,7 @@ class CheatManager
       @param code    The actual cheatcode
       @param enable  Add or remove the cheat to the per-frame list
     */
-    void addPerFrame(const string& name, const string& code, bool enable);
+    void addPerFrame(string_view name, string_view code, bool enable);
 
     /**
       Creates and enables a one-shot cheat.  One-shot cheats are the
@@ -78,7 +78,7 @@ class CheatManager
       @param name  Name of the cheat (not absolutely required)
       @param code  The actual cheatcode (in hex)
     */
-    void addOneShot(const string& name, const string& code);
+    void addOneShot(string_view name, string_view code);
 
     /**
       Enable/disabled the cheat specified by the given code.
@@ -86,7 +86,7 @@ class CheatManager
       @param code    The actual cheatcode to search for
       @param enable  Enable/disable the cheat
     */
-    void enable(const string& code, bool enable);
+    void enable(string_view code, bool enable);
 
     /**
       Returns the game cheatlist.
@@ -111,17 +111,17 @@ class CheatManager
     /**
       Load cheats for ROM with given MD5sum to cheatlist(s).
     */
-    void loadCheats(const string& md5sum);
+    void loadCheats(string_view md5sum);
 
     /**
       Saves cheats for ROM with given MD5sum to cheat map.
     */
-    void saveCheats(const string& md5sum);
+    void saveCheats(string_view md5sum);
 
     /**
       Checks if a code is valid.
     */
-    static bool isValidCode(const string& code);
+    static bool isValidCode(string_view code);
 
   private:
     /**
@@ -132,14 +132,14 @@ class CheatManager
 
       @return  The cheat (if was created), else nullptr.
     */
-    shared_ptr<Cheat> createCheat(const string& name, const string& code) const;
+    shared_ptr<Cheat> createCheat(string_view name, string_view code) const;
 
     /**
       Parses a list of cheats and adds/enables each one.
 
       @param cheats  Comma-separated list of cheats (without any names)
     */
-    void parse(const string& cheats);
+    void parse(string_view cheats);
 
   private:
     OSystem& myOSystem;
@@ -147,7 +147,7 @@ class CheatManager
     CheatList myCheatList;
     CheatList myPerFrameList;
 
-    std::map<string,string> myCheatMap;
+    std::map<string,string, std::less<>> myCheatMap;
     string myCheatFile;
 
     // This is set each time a new cheat/ROM is loaded, for later

src/cheat/CheetahCheat.cxx

@@ -21,7 +21,7 @@
 #include "CheetahCheat.hxx"
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-CheetahCheat::CheetahCheat(OSystem& os, const string& name, const string& code)
+CheetahCheat::CheetahCheat(OSystem& os, string_view name, string_view code)
   : Cheat(os, name, code),
     address{static_cast<uInt16>(0xf000 + unhex(code.substr(0, 3)))},
     value{static_cast<uInt8>(unhex(code.substr(3, 2)))},

src/cheat/CheetahCheat.hxx

@@ -23,7 +23,7 @@
 class CheetahCheat : public Cheat
 {
   public:
-    CheetahCheat(OSystem& os, const string& name, const string& code);
+    CheetahCheat(OSystem& os, string_view name, string_view code);
     ~CheetahCheat() override = default;
 
     bool enable() override;

src/cheat/RamCheat.cxx

@@ -23,7 +23,7 @@
 #include "RamCheat.hxx"
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-RamCheat::RamCheat(OSystem& os, const string& name, const string& code)
+RamCheat::RamCheat(OSystem& os, string_view name, string_view code)
   : Cheat(os, name, code),
     address{static_cast<uInt16>(unhex(myCode.substr(0, 2)))},
     value{static_cast<uInt8>(unhex(myCode.substr(2, 2)))}

src/cheat/RamCheat.hxx

@@ -23,7 +23,7 @@
 class RamCheat : public Cheat
 {
   public:
-    RamCheat(OSystem& os, const string& name, const string& code);
+    RamCheat(OSystem& os, string_view name, string_view code);
     ~RamCheat() override = default;
 
     bool enable() override;

src/common/FBBackendSDL2.cxx

@@ -454,14 +454,14 @@ bool FBBackendSDL2::createRenderer()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void FBBackendSDL2::setTitle(const string& title)
+void FBBackendSDL2::setTitle(string_view title)
 {
   ASSERT_MAIN_THREAD;
 
   myScreenTitle = title;
 
   if(myWindow)
-    SDL_SetWindowTitle(myWindow, title.c_str());
+    SDL_SetWindowTitle(myWindow, string{title}.c_str());
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

src/common/FBBackendSDL2.hxx

@@ -78,7 +78,7 @@ class FBBackendSDL2 : public FBBackend
 
       @param title  The title of the application / window
     */
-    void setTitle(const string& title) override;
+    void setTitle(string_view title) override;
 
     /**
       Shows or hides the cursor based on the given boolean value.

src/common/FSNodeFactory.hxx

@@ -44,7 +44,7 @@ class FSNodeFactory
     enum class Type { SYSTEM, ZIP };
 
   public:
-    static unique_ptr<AbstractFSNode> create(const string& path, Type type)
+    static unique_ptr<AbstractFSNode> create(string_view path, Type type)
     {
       switch(type)
       {

src/common/FSNodeZIP.cxx

@@ -26,7 +26,7 @@
 #include "FSNodeZIP.hxx"
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-FSNodeZIP::FSNodeZIP(const string& p)
+FSNodeZIP::FSNodeZIP(string_view p)
 {
   // Extract ZIP file and virtual file (if specified)
   const size_t pos = BSPF::findIgnoreCase(p, ".zip");

src/common/FSNodeZIP.hxx

@@ -40,11 +40,11 @@ class FSNodeZIP : public AbstractFSNode
      *
      * @param path  String with the path the new node should point to.
      */
-    explicit FSNodeZIP(const string& path);
+    explicit FSNodeZIP(string_view path);
 
     bool exists() const override;
-    const string& getName() const override    { return _name; }
+    const string& getName() const override  { return _name; }
-    void setName(const string& name) override { _name = name; }
+    void setName(string_view name) override { _name = name; }
     const string& getPath() const override { return _path;      }
     string getShortPath() const   override { return _shortPath; }
     bool hasParent() const override   { return true; }
@@ -56,7 +56,7 @@ class FSNodeZIP : public AbstractFSNode
     //////////////////////////////////////////////////////////
     // For now, ZIP files cannot be modified in any way
     bool makeDir() override { return false; }
-    bool rename(const string& newfile) override { return false; }
+    bool rename(string_view) override { return false; }
     //////////////////////////////////////////////////////////
 
     size_t getSize() const override { return _size; }

src/common/HighScoresManager.cxx

@@ -537,9 +537,9 @@ HSM::ScoreAddresses HighScoresManager::getPropScoreAddr(const json& jprops)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-uInt16 HighScoresManager::fromHexStr(const string& addr)
+uInt16 HighScoresManager::fromHexStr(string_view addr)
 {
-  string naked = addr;
+  string naked{addr};
 
   if(const int pos = naked.find("0x") != std::string::npos)
     naked = naked.substr(pos + 1);

src/common/HighScoresManager.hxx

@@ -232,7 +232,7 @@ class HighScoresManager
                               uInt16 defVal = 0);
     static HSM::ScoreAddresses getPropScoreAddr(const json& jprops);
 
-    static uInt16 fromHexStr(const string& addr);
+    static uInt16 fromHexStr(string_view addr);
     static Int32 fromBCD(uInt8 bcd);
     string hash(const HSM::ScoresData& data) const;
 

src/common/Logger.cxx

@@ -26,44 +26,46 @@ Logger& Logger::instance()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Logger::log(const string& message, Level level)
+void Logger::log(string_view message, Level level)
 {
   instance().logMessage(message, level);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Logger::error(const string& message)
+void Logger::error(string_view message)
 {
   instance().logMessage(message, Level::ERR);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Logger::info(const string& message)
+void Logger::info(string_view message)
 {
   instance().logMessage(message, Level::INFO);
 }
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Logger::debug(const string& message)
+void Logger::debug(string_view message)
 {
   instance().logMessage(message, Level::DEBUG);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Logger::logMessage(const string& message, Level level)
+void Logger::logMessage(string_view message, Level level)
 {
   const std::lock_guard<std::mutex> lock(mutex);
 
   if(level == Logger::Level::ERR)
   {
     cout << message << endl << std::flush;
-    myLogMessages += message + "\n";
+    myLogMessages += message;
+    myLogMessages += "\n";
   }
   else if(static_cast<int>(level) <= myLogLevel ||
           level == Logger::Level::ALWAYS)
   {
     if(myLogToConsole)
       cout << message << endl << std::flush;
-    myLogMessages += message + "\n";
+    myLogMessages += message;
+    myLogMessages += "\n";
   }
 }
 

src/common/Logger.hxx

@@ -40,13 +40,13 @@ class Logger {
 
     static Logger& instance();
 
-    static void log(const string& message, Level level = Level::ALWAYS);
+    static void log(string_view message, Level level = Level::ALWAYS);
 
-    static void error(const string& message);
+    static void error(string_view message);
 
-    static void info(const string& message);
+    static void info(string_view message);
 
-    static void debug(const string& message);
+    static void debug(string_view message);
 
     void setLogParameters(int logLevel, bool logToConsole);
     void setLogParameters(Level logLevel, bool logToConsole);
@@ -66,7 +66,7 @@ class Logger {
     std::mutex mutex;
 
   private:
-    void logMessage(const string& message, Level level);
+    void logMessage(string_view message, Level level);
 
     Logger(const Logger&) = delete;
     Logger(Logger&&) = delete;

src/common/MouseControl.cxx

@@ -23,12 +23,12 @@
 #include "MouseControl.hxx"
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-MouseControl::MouseControl(Console& console, const string& mode)
+MouseControl::MouseControl(Console& console, string_view mode)
   : myProps{console.properties()},
     myLeftController{console.leftController()},
     myRightController{console.rightController()}
 {
-  istringstream m_axis(mode);
+  istringstream m_axis(string{mode});  // TODO: fixed in C++20
   string m_mode;
   m_axis >> m_mode;
 

src/common/MouseControl.hxx

@@ -55,7 +55,7 @@ class MouseControl
       @param console The console in use by the system
       @param mode    Contains information about how to use the mouse axes/buttons
     */
-    MouseControl(Console& console, const string& mode);
+    MouseControl(Console& console, string_view mode);
 
     /**
       Cycle through each available mouse control mode
@@ -85,10 +85,10 @@ class MouseControl
       int xid{-1}, yid{-1};
       string message;
 
-      explicit MouseMode(const string& msg = "") : message{msg} { }
+      explicit MouseMode(string_view msg = "") : message{msg} { }
       MouseMode(Controller::Type xt, int xi,
                 Controller::Type yt, int yi,
-                const string& msg)
+                string_view msg)
         : xtype{xt}, ytype{yt}, xid{xi}, yid{yi}, message{msg}  { }
 
       friend ostream& operator<<(ostream& os, const MouseMode& mm)

src/common/PJoystickHandler.cxx

@@ -217,7 +217,7 @@ bool PhysicalJoystickHandler::remove(int id)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool PhysicalJoystickHandler::remove(const string& name)
+bool PhysicalJoystickHandler::remove(string_view name)
 {
   const auto it = myDatabase.find(name);
   if(it != myDatabase.end() && it->second.joy == nullptr)
@@ -229,7 +229,7 @@ bool PhysicalJoystickHandler::remove(const string& name)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool PhysicalJoystickHandler::mapStelladaptors(const string& saport, int ID)
+bool PhysicalJoystickHandler::mapStelladaptors(string_view saport, int ID)
 {
   bool erased = false;
   // saport will have two values:

src/common/PJoystickHandler.hxx

@@ -73,8 +73,8 @@ class PhysicalJoystickHandler
     /** Return stick ID on success, -1 on failure. */
     int add(const PhysicalJoystickPtr& stick);
     bool remove(int id);
-    bool remove(const string& name);
+    bool remove(string_view name);
-    bool mapStelladaptors(const string& saport, int ID = -1);
+    bool mapStelladaptors(string_view saport, int ID = -1);
     bool hasStelladaptors() const;
     void setDefaultMapping(Event::Type event, EventMode mode);
 
@@ -126,7 +126,7 @@ class PhysicalJoystickHandler
     void changeDrivingSensitivity(int direction = +1);
 
   private:
-    using StickDatabase = std::map<string,StickInfo>;
+    using StickDatabase = std::map<string, StickInfo, std::less<>>;
     using StickList = std::map<int, PhysicalJoystickPtr>;
 
     OSystem& myOSystem;

src/common/PaletteHandler.cxx

@@ -29,7 +29,7 @@ PaletteHandler::PaletteHandler(OSystem& system)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-PaletteHandler::PaletteType PaletteHandler::toPaletteType(const string& name) const
+PaletteHandler::PaletteType PaletteHandler::toPaletteType(string_view name) const
 {
   if(name == SETTING_Z26)
     return PaletteType::Z26;
@@ -301,7 +301,7 @@ void PaletteHandler::getAdjustables(Adjustable& adjustable) const
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void PaletteHandler::setPalette(const string& name)
+void PaletteHandler::setPalette(string_view name)
 {
   myOSystem.settings().setValue("palette", name);
 

src/common/PaletteHandler.hxx

@@ -113,7 +113,7 @@ class PaletteHandler
 
       @param name  The palette to switch to
     */
-    void setPalette(const string& name);
+    void setPalette(string_view name);
 
     /**
       Sets the palette from current settings.
@@ -178,7 +178,7 @@ class PaletteHandler
 
       @return  The palette type
     */
-    PaletteType toPaletteType(const string& name) const;
+    PaletteType toPaletteType(string_view name) const;
 
     /**
       Convert enumeration to palette settings name.

src/common/Rect.hxx

@@ -37,9 +37,9 @@ struct Point
 
   constexpr Point() = default;
   explicit constexpr Point(Int32 x1, Int32 y1) : x{x1}, y{y1} { }
-  explicit Point(const string& p) {
+  explicit Point(string_view p) {
     char c = '\0';
-    istringstream buf(p);
+    istringstream buf(string{p});  // TODO: fixed in C++20
     buf >> x >> c >> y;
     if(c != 'x')
       x = y = 0;
@@ -60,9 +60,9 @@ struct Size
 
   constexpr Size() = default;
   explicit constexpr Size(uInt32 w1, uInt32 h1) : w{w1}, h{h1} { }
-  explicit Size(const string& s) {
+  explicit Size(string_view s) {
     char c = '\0';
-    istringstream buf(s);
+    istringstream buf(string{s});  // TODO: fixed in C++20
     buf >> w >> c >> h;
     if(c != 'x')
       w = h = 0;

src/common/RewindManager.cxx

@@ -96,7 +96,7 @@ void RewindManager::setup()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool RewindManager::addState(const string& message, bool timeMachine)
+bool RewindManager::addState(string_view message, bool timeMachine)
 {
   // only check for Time Machine states, ignore for debugger
   if(timeMachine && myStateList.currentIsValid())

src/common/RewindManager.hxx

@@ -107,7 +107,7 @@ class RewindManager
 
       @param message  Message to display when replaying this state
     */
-    bool addState(const string& message, bool timeMachine = false);
+    bool addState(string_view message, bool timeMachine = false);
 
     /**
       Rewind numStates levels of the state list, and display the message associated

src/common/StaggeredLogger.cxx

@@ -36,7 +36,7 @@ namespace {
 } // namespace
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-StaggeredLogger::StaggeredLogger(const string& message, Logger::Level level)
+StaggeredLogger::StaggeredLogger(string_view message, Logger::Level level)
   : myMessage{message},
     myLevel{level}
 {

src/common/StaggeredLogger.hxx

@@ -38,7 +38,7 @@ class StaggeredLogger
 {
   public:
 
-    StaggeredLogger(const string& message, Logger::Level level);
+    StaggeredLogger(string_view message, Logger::Level level);
     ~StaggeredLogger();
 
     void log();

src/common/StateManager.cxx

@@ -139,7 +139,7 @@ void StateManager::toggleTimeMachine()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool StateManager::addExtraState(const string& message)
+bool StateManager::addExtraState(string_view message)
 {
   if(myActiveMode == Mode::TimeMachine)
   {

src/common/StateManager.hxx

@@ -77,7 +77,7 @@ class StateManager
       Optionally adds one extra state when entering the Time Machine dialog;
       this uses the RewindManager for its functionality.
     */
-    bool addExtraState(const string& message);
+    bool addExtraState(string_view message);
 
     /**
       Rewinds states; this uses the RewindManager for its functionality.

src/common/StringParser.hxx

@@ -34,9 +34,9 @@ class StringParser
 
       @param str  The string to split
     */
-    explicit StringParser(const string& str)
+    explicit StringParser(string_view str)
     {
-      istringstream buf(str);
+      istringstream buf(string{str});  // TODO: fixed in C++20
       string line;
 
       while(std::getline(buf, line, '\n'))

src/common/Variant.hxx

@@ -45,6 +45,7 @@ class Variant
     Variant() = default;  // NOLINT
 
     Variant(const string& s) : data{s} { }
+    Variant(string_view s) : data{s} { }
     Variant(const char* s) : data{s} { }
 
     Variant(Int32 i)  { buf().str(""); buf() << i; data = buf().str(); }

src/common/bspf.hxx

@@ -193,6 +193,12 @@ namespace BSPF
   }
 
   // Convert string to integer, using default value on any error
+  inline int stringToInt(string_view s, const int defaultValue = 0)
+  {
+    try        { return std::stoi(string{s}); }
+    catch(...) { return defaultValue; }
+  }
+  // TODO: remove this once we reimplement stoi
   inline int stringToInt(const string& s, const int defaultValue = 0)
   {
     try        { return std::stoi(s); }
@@ -285,7 +291,7 @@ namespace BSPF
   //  (case sensitive for upper case characters in second string, except first one)
   // - the first character must match
   // - the following characters must appear in the order of the first string
-  inline bool matchesCamelCase(const string_view s1, const string_view s2)
+  inline bool matchesCamelCase(string_view s1, string_view s2)
   {
     // skip leading '_' for matching
     const uInt32 ofs = (s1[0] == '_' && s2[0] == '_') ? 1 : 0;
@@ -330,7 +336,7 @@ namespace BSPF
   // @param str      The searched string
   // @param pattern  The pattern to search for
   // @return  Position of pattern in string.
-  inline size_t matchWithJoker(const string& str, const string& pattern)
+  inline size_t matchWithJoker(string_view str, string_view pattern)
   {
     if(str.length() >= pattern.length())
     {
@@ -361,9 +367,9 @@ namespace BSPF
   // @param str      The searched string
   // @param pattern  The pattern to search for
   // @return  True if pattern was found.
-  inline bool matchWithWildcards(const string& str, const string& pattern)
+  inline bool matchWithWildcards(string_view str, string_view pattern)
   {
-    string pat = pattern;
+    string pat{pattern};  // TODO: don't use copy
 
     // remove leading and trailing '*'
     size_t i = 0;
@@ -394,7 +400,7 @@ namespace BSPF
   }
 
   // Modify 'str', replacing all occurrences of 'from' with 'to'
-  inline void replaceAll(string& str, const string& from, const string& to)
+  inline void replaceAll(string& str, string_view from, string_view to)
   {
     if(from.empty()) return;
     size_t start_pos = 0;
@@ -407,11 +413,11 @@ namespace BSPF
   }
 
   // Trim leading and trailing whitespace from a string
-  inline string trim(const string& str)
+  inline string trim(string_view str)
   {
     const auto first = str.find_first_not_of(' ');
     return (first == string::npos) ? EmptyString :
-            str.substr(first, str.find_last_not_of(' ')-first+1);
+            string{str.substr(first, str.find_last_not_of(' ')-first+1)};
   }
 
   // C++11 way to get local time

src/debugger/Debugger.cxx

@@ -119,8 +119,8 @@ FBInitStatus Debugger::initializeVideo()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool Debugger::start(const string& message, int address, bool read,
+bool Debugger::start(string_view message, int address, bool read,
-                     const string& toolTip)
+                     string_view toolTip)
 {
   if(myOSystem.eventHandler().enterDebugMode())
   {
@@ -139,7 +139,7 @@ bool Debugger::start(const string& message, int address, bool read,
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool Debugger::startWithFatalError(const string& message)
+bool Debugger::startWithFatalError(string_view message)
 {
   if(myOSystem.eventHandler().enterDebugMode())
   {
@@ -218,7 +218,7 @@ TrapArray& Debugger::writeTraps() const
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string Debugger::run(const string& command)
+string Debugger::run(string_view command)
 {
   return myParser->run(command);
 }
@@ -450,7 +450,7 @@ bool Debugger::writeTrap(uInt16 t) const
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Debugger::log(const string& triggerMsg)
+void Debugger::log(string_view triggerMsg)
 {
   const CartDebug::Disassembly& disasm = myCartDebug->disassembly();
   const int pc = myCpuDebug->pc();
@@ -719,7 +719,7 @@ string Debugger::showWatches()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-int Debugger::stringToValue(const string& stringval)
+int Debugger::stringToValue(string_view stringval)
 {
   return myParser->decipher_arg(stringval);
 }
@@ -745,7 +745,7 @@ void Debugger::saveOldState(bool clearDirtyPages)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Debugger::addState(const string& rewindMsg)
+void Debugger::addState(string_view rewindMsg)
 {
   // Add another rewind level to the Time Machine buffer
   RewindManager& r = myOSystem.state().rewindManager();
@@ -788,7 +788,7 @@ void Debugger::setQuitState()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool Debugger::addFunction(const string& name, const string& definition,
+bool Debugger::addFunction(string_view name, string_view definition,
                            Expression* exp, bool builtin)
 {
   myFunctions.emplace(name, unique_ptr<Expression>(exp));
@@ -798,14 +798,14 @@ bool Debugger::addFunction(const string& name, const string& definition,
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool Debugger::isBuiltinFunction(const string& name)
+bool Debugger::isBuiltinFunction(string_view name)
 {
   return std::any_of(ourBuiltinFunctions.cbegin(), ourBuiltinFunctions.cend(),
       [&](const auto& func) { return name == func.name; });
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool Debugger::delFunction(const string& name)
+bool Debugger::delFunction(string_view name)
 {
   const auto& iter = myFunctions.find(name);
   if(iter == myFunctions.end())
@@ -815,25 +815,25 @@ bool Debugger::delFunction(const string& name)
   if(isBuiltinFunction(name))
       return false;
 
-  myFunctions.erase(name);
+  myFunctions.erase(string{name});
 
   const auto& def_iter = myFunctionDefs.find(name);
   if(def_iter == myFunctionDefs.end())
     return false;
 
-  myFunctionDefs.erase(name);
+  myFunctionDefs.erase(string{name});
   return true;
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-const Expression& Debugger::getFunction(const string& name) const
+const Expression& Debugger::getFunction(string_view name) const
 {
   const auto& iter = myFunctions.find(name);
   return iter != myFunctions.end() ? *(iter->second) : EmptyExpression;
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-const string& Debugger::getFunctionDef(const string& name) const
+const string& Debugger::getFunctionDef(string_view name) const
 {
   const auto& iter = myFunctionDefs.find(name);
   return iter != myFunctionDefs.end() ? iter->second : EmptyString;

src/debugger/Debugger.hxx

@@ -67,8 +67,8 @@ class Debugger : public DialogContainer
   friend class M6502;
 
   public:
-    using FunctionMap = std::map<string, unique_ptr<Expression>>;
+    using FunctionMap = std::map<string, unique_ptr<Expression>, std::less<>>;
-    using FunctionDefMap = std::map<string, string>;
+    using FunctionDefMap = std::map<string, string, std::less<>>;
 
     /**
       Create a new debugger parent object
@@ -94,9 +94,9 @@ class Debugger : public DialogContainer
       @param message  Message to display when entering debugger
       @param address  An address associated with the message
     */
-    bool start(const string& message = "", int address = -1, bool read = true,
+    bool start(string_view message = "", int address = -1, bool read = true,
-               const string& toolTip = "");
+               string_view toolTip = "");
-    bool startWithFatalError(const string& message = "");
+    bool startWithFatalError(string_view message = "");
 
     /**
       Wrapper method for EventHandler::leaveDebugMode() for those classes
@@ -109,13 +109,13 @@ class Debugger : public DialogContainer
     */
     void quit();
 
-    bool addFunction(const string& name, const string& def,
+    bool addFunction(string_view name, string_view def,
                      Expression* exp, bool builtin = false);
-    static bool isBuiltinFunction(const string& name);
+    static bool isBuiltinFunction(string_view name);
-    bool delFunction(const string& name);
+    bool delFunction(string_view name);
-    const Expression& getFunction(const string& name) const;
+    const Expression& getFunction(string_view name) const;
 
-    const string& getFunctionDef(const string& name) const;
+    const string& getFunctionDef(string_view name) const;
     FunctionDefMap getFunctionDefMap() const;
     static string builtinHelp();
 
@@ -194,7 +194,7 @@ class Debugger : public DialogContainer
     /**
       Run the debugger command and return the result.
     */
-    string run(const string& command);
+    string run(string_view command);
 
     string autoExec(StringList* history);
 
@@ -204,7 +204,7 @@ class Debugger : public DialogContainer
       Convert between string->integer and integer->string, taking into
       account the current base format.
     */
-    int stringToValue(const string& stringval);
+    int stringToValue(string_view stringval);
 
     /* Convenience methods to get/set bit(s) in an 8-bit register */
     static uInt8 set_bit(uInt8 input, uInt8 bit, bool on)
@@ -296,7 +296,7 @@ class Debugger : public DialogContainer
     /**
       Saves a rewind state with the given message.
     */
-    void addState(const string& rewindMsg);
+    void addState(string_view rewindMsg);
 
     /**
       Set initial state before entering the debugger.
@@ -326,7 +326,7 @@ class Debugger : public DialogContainer
     bool readTrap(uInt16 t) const;
     bool writeTrap(uInt16 t) const;
     void clearAllTraps() const;
-    void log(const string& triggerMsg);
+    void log(string_view triggerMsg);
 
     // Set a bunch of RAM locations at once
     string setRAM(IntArray& args);

src/debugger/DebuggerExpressions.hxx

@@ -134,7 +134,7 @@ class EqualsExpression : public Expression
 class EquateExpression : public Expression
 {
   public:
-    EquateExpression(const string& label) : Expression(), myLabel{label} { }
+    EquateExpression(string_view label) : Expression(), myLabel{label} { }
     Int32 evaluate() const override
       { return Debugger::debugger().cartDebug().getAddress(myLabel); }
 
@@ -146,7 +146,7 @@ class EquateExpression : public Expression
 class FunctionExpression : public Expression
 {
   public:
-    FunctionExpression(const string& label) : Expression(), myLabel{label} { }
+    FunctionExpression(string_view label) : Expression(), myLabel{label} { }
     Int32 evaluate() const override
       { return Debugger::debugger().getFunction(myLabel).evaluate(); }
 

src/debugger/DebuggerParser.cxx

@@ -66,7 +66,7 @@ DebuggerParser::DebuggerParser(Debugger& d, Settings& s)
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 // main entry point: PromptWidget calls this method.
-string DebuggerParser::run(const string& command)
+string DebuggerParser::run(string_view command)
 {
 #if 0
   // this was our parser test code. Left for reference.
@@ -163,7 +163,7 @@ string DebuggerParser::exec(const FSNode& file, StringList* history)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void DebuggerParser::outputCommandError(const string& errorMsg, int command)
+void DebuggerParser::outputCommandError(string_view errorMsg, int command)
 {
   const string example = commands[command].extendedDesc.substr(commands[command].extendedDesc.find("Example:"));
 
@@ -190,10 +190,10 @@ void DebuggerParser::getCompletions(const char* in, StringList& completions)
 // they're valid, or -1 if they're not.
 // decipher_arg may be called by the GUI as needed. It is also called
 // internally by DebuggerParser::run()
-int DebuggerParser::decipher_arg(const string& str)
+int DebuggerParser::decipher_arg(string_view str)
 {
   bool derefByte=false, derefWord=false, lobyte=false, hibyte=false, bin=false, dec=false;
-  string arg = str;
+  string arg{str};
 
   const Base::Fmt defaultBase = Base::format();
 
@@ -330,7 +330,7 @@ string DebuggerParser::showWatches()
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool DebuggerParser::getArgs(const string& command, string& verb)
+bool DebuggerParser::getArgs(string_view command, string& verb)
 {
   ParseState state = ParseState::IN_COMMAND;
   size_t i = 0;
@@ -2456,7 +2456,7 @@ void DebuggerParser::executeTrapWriteIf()
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 // Wrapper function for trap(if)s
-void DebuggerParser::executeTraps(bool read, bool write, const string& command,
+void DebuggerParser::executeTraps(bool read, bool write, string_view command,
                                   bool hasCond)
 {
   const uInt32 ofs = hasCond ? 1 : 0,

src/debugger/DebuggerParser.hxx

@@ -35,7 +35,7 @@ class DebuggerParser
     DebuggerParser(Debugger& debugger, Settings& settings);
 
     /** Run the given command, and return the result */
-    string run(const string& command);
+    string run(string_view command);
 
     /** Execute parser commands given in 'file' */
     string exec(const FSNode& file, StringList* history = nullptr);
@@ -45,23 +45,23 @@ class DebuggerParser
     static void getCompletions(const char* in, StringList& completions);
 
     /** Evaluate the given expression using operators, current base, etc */
-    int decipher_arg(const string& str);
+    int decipher_arg(string_view str);
 
     /** String representation of all watches currently defined */
     string showWatches();
 
-    static inline string red(const string& msg = "")
+    static inline string red(string_view msg = "")
     {
-      return char(kDbgColorRed & 0xff) + msg;
+      return char(kDbgColorRed & 0xff) + string{msg};
     }
-    static inline string inverse(const string& msg = "")
+    static inline string inverse(string_view msg = "")
     {
       // ASCII DEL char, decimal 127
-      return "\177" + msg;
+      return "\177" + string{msg};
     }
 
   private:
-    bool getArgs(const string& command, string& verb);
+    bool getArgs(string_view command, string& verb);
     bool validateArgs(int cmd);
     string eval();
     string saveScriptFile(string file);
@@ -112,7 +112,7 @@ class DebuggerParser
       uInt32 end{0};
       string condition;
 
-      Trap(bool r, bool w, uInt32 b, uInt32 e, const string& c)
+      Trap(bool r, bool w, uInt32 b, uInt32 e, string_view c)
         : read(r), write(w), begin(b), end(e), condition(c) {}
     };
 
@@ -146,7 +146,7 @@ class DebuggerParser
     void listTimers();
 
     // output the error with the example provided for the command
-    void outputCommandError(const string& errorMsg, int command);
+    void outputCommandError(string_view errorMsg, int command);
 
     void executeDirective(Device::AccessType type);
 
@@ -252,7 +252,7 @@ class DebuggerParser
     void executeTrapReadIf();
     void executeTrapWrite();
     void executeTrapWriteIf();
-    void executeTraps(bool read, bool write, const string& command, bool cond = false);
+    void executeTraps(bool read, bool write, string_view command, bool cond = false);
     void executeTrapRW(uInt32 addr, bool read, bool write, bool add = true);  // not exposed by debugger
     void executeType();
     void executeUHex();

src/debugger/TIADebug.cxx

@@ -1037,7 +1037,7 @@ string TIADebug::audFreq(uInt8 dist, uInt8 div) const
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string TIADebug::stringOnly(const string& value, bool changed)
+string TIADebug::stringOnly(string_view value, bool changed)
 {
   ostringstream buf;
 
@@ -1051,7 +1051,7 @@ string TIADebug::stringOnly(const string& value, bool changed)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string TIADebug::decWithLabel(const string& label, uInt16 value,
+string TIADebug::decWithLabel(string_view label, uInt16 value,
                               bool changed, uInt16 width)
 {
   ostringstream buf;
@@ -1069,7 +1069,7 @@ string TIADebug::decWithLabel(const string& label, uInt16 value,
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string TIADebug::hexWithLabel(const string& label, uInt16 value,
+string TIADebug::hexWithLabel(string_view label, uInt16 value,
                               bool changed, uInt16 width)
 {
   ostringstream buf;
@@ -1087,7 +1087,7 @@ string TIADebug::hexWithLabel(const string& label, uInt16 value,
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string TIADebug::binWithLabel(const string& label, uInt16 value, bool changed)
+string TIADebug::binWithLabel(string_view label, uInt16 value, bool changed)
 {
   ostringstream buf;
 
@@ -1104,13 +1104,13 @@ string TIADebug::binWithLabel(const string& label, uInt16 value, bool changed)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string TIADebug::boolWithLabel(const string& label, bool value, bool changed)
+string TIADebug::boolWithLabel(string_view label, bool value, bool changed)
 {
   ostringstream buf;
 
   if(value)
   {
-    string l = label;
+    string l{label};
     buf << "\177" << BSPF::toUpperCase(l) << "\177";
     //return "+" + BSPF::toUpperCase(label);
   }

src/debugger/TIADebug.hxx

@@ -188,14 +188,14 @@ class TIADebug : public DebuggerSystem
     static string colorSwatch(uInt8 c);
 
     string audFreq(uInt8 dist, uInt8 div) const;
-    static string stringOnly(const string& value, bool changed = false);
+    static string stringOnly(string_view value, bool changed = false);
-    static string decWithLabel(const string& label, uInt16 value,
+    static string decWithLabel(string_view label, uInt16 value,
                                bool changed = false, uInt16 width = 3);
-    static string hexWithLabel(const string& label, uInt16 value,
+    static string hexWithLabel(string_view label, uInt16 value,
                                bool changed = false, uInt16 width = 2);
-    static string binWithLabel(const string& label, uInt16 value,
+    static string binWithLabel(string_view label, uInt16 value,
                                bool changed = false);
-    static string boolWithLabel(const string& label, bool value,
+    static string boolWithLabel(string_view label, bool value,
                                 bool changed = false);
 
   private:

src/debugger/gui/DataGridWidget.cxx

@@ -582,7 +582,7 @@ void DataGridWidget::handleCommand(CommandSender* sender, int cmd,
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void DataGridWidget::setToolTip(int column, int row, const string& text)
+void DataGridWidget::setToolTip(int column, int row, string_view text)
 {
   if(row >= 0 && row < _rows && column >= 0 && column < _cols)
     _toolTipList[row * _cols + column] = text;

src/debugger/gui/DataGridWidget.hxx

@@ -85,7 +85,7 @@ class DataGridWidget : public EditableWidget
     void setCrossed(bool enable);
 
     using EditableWidget::setToolTip;
-    void setToolTip(int column, int row, const string& text);
+    void setToolTip(int column, int row, string_view text);
     string getToolTip(const Common::Point& pos) const override;
     bool changedToolTip(const Common::Point& oldPos, const Common::Point& newPos) const override;
 

src/debugger/gui/DebuggerDialog.cxx

@@ -434,7 +434,7 @@ void DebuggerDialog::createFont()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void DebuggerDialog::showFatalMessage(const string& msg)
+void DebuggerDialog::showFatalMessage(string_view msg)
 {
   myFatalError = make_unique<GUI::MessageBox>(this, *myLFont, msg, _w-20, _h-20,
                                               kDDExitFatalCmd, "Exit ROM", "Continue", "Fatal error");

src/debugger/gui/DebuggerDialog.hxx

@@ -49,7 +49,7 @@ class DebuggerDialog : public Dialog
 {
   public:
     // Note: these sizes make sure that all major tabs are fully visible
-    //  cart dependend information (e.g. DPC+) may require more space
+    //       cart dependend information (e.g. DPC+) may require more space
     enum {
       kSmallFontMinW  = 1090, kSmallFontMinH  = 720,
       kMediumFontMinW = 1160, kMediumFontMinH = 770,
@@ -73,7 +73,7 @@ class DebuggerDialog : public Dialog
     ButtonWidget& rewindButton() const { return *myRewindButton; }
     ButtonWidget& unwindButton() const { return *myUnwindButton; }
 
-    void showFatalMessage(const string& msg);
+    void showFatalMessage(string_view msg);
     void saveConfig() override;
 
   private:

src/debugger/gui/PromptWidget.cxx

@@ -569,10 +569,10 @@ int PromptWidget::historyDir(int& index, int direction)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void PromptWidget::historyAdd(const string& entry)
+void PromptWidget::historyAdd(string_view entry)
 {
   if(_historyIndex >= static_cast<int>(_history.size()))
-    _history.push_back(entry);
+    _history.emplace_back(entry);
   else
     _history[_historyIndex] = entry;
 }
@@ -882,7 +882,7 @@ void PromptWidget::putcharIntern(int c)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void PromptWidget::print(const string& str)
+void PromptWidget::print(string_view str)
 {
   for(const auto c: str)
     putcharIntern(c);

src/debugger/gui/PromptWidget.hxx

@@ -42,7 +42,7 @@ class PromptWidget : public Widget, public CommandSender
     ~PromptWidget() override = default;
 
   public:
-    void print(const string& str);
+    void print(string_view str);
     void printPrompt();
     string saveBuffer(const FSNode& file);
 
@@ -134,7 +134,7 @@ class PromptWidget : public Widget, public CommandSender
     bool _exitedEarly{false};
 
     int historyDir(int& index, int direction);
-    void historyAdd(const string& entry);
+    void historyAdd(string_view entry);
 
   private:
     // Following constructors and assignment operators not supported

src/debugger/gui/RamWidget.cxx

@@ -31,7 +31,7 @@
 RamWidget::RamWidget(GuiObject* boss, const GUI::Font& lfont, const GUI::Font& nfont,
                      int x, int y, int w, int h,
                      uInt32 ramsize, uInt32 numrows, uInt32 pagesize,
-                     const string& helpAnchor)
+                     string_view helpAnchor)
   : Widget(boss, lfont, x, y, w, h),
     CommandSender(boss),
     _nfont{nfont},
@@ -393,7 +393,7 @@ void RamWidget::showInputBox(int cmd)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string RamWidget::doSearch(const string& str)
+string RamWidget::doSearch(string_view str)
 {
   bool comparisonSearch = true;
 
@@ -450,7 +450,7 @@ string RamWidget::doSearch(const string& str)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string RamWidget::doCompare(const string& str)
+string RamWidget::doCompare(string_view str)
 {
   bool comparativeSearch = false;
   int searchVal = 0, offset = 0;
@@ -475,7 +475,7 @@ string RamWidget::doCompare(const string& str)
     if(str[0] == '-')
       negative = true;
 
-    string tmp = str;
+    string tmp{str};
     tmp.erase(0, 1);  // remove the operator
     offset = instance().debugger().stringToValue(tmp);
     if(negative)

src/debugger/gui/RamWidget.hxx

@@ -36,7 +36,7 @@ class RamWidget : public Widget, public CommandSender
     RamWidget(GuiObject* boss, const GUI::Font& lfont, const GUI::Font& nfont,
               int x, int y, int w, int h,
               uInt32 ramsize, uInt32 numrows, uInt32 pagesize,
-              const string& helpAnchor);
+              string_view helpAnchor);
     ~RamWidget() override;
 
     void loadConfig() override;
@@ -60,8 +60,8 @@ class RamWidget : public Widget, public CommandSender
     void fillGrid(bool updateOld);
 
     void showInputBox(int cmd);
-    string doSearch(const string& str);
+    string doSearch(string_view str);
-    string doCompare(const string& str);
+    string doCompare(string_view str);
     void doRestart();
     void showSearchResults();
 

src/emucore/Cart.cxx

@@ -27,12 +27,12 @@
 #include "Cart.hxx"
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-Cartridge::Cartridge(const Settings& settings, const string& md5)
+Cartridge::Cartridge(const Settings& settings, string_view md5)
   : mySettings{settings}
 {
-  const auto to_uInt32 = [](const string& s, uInt32 pos) {
+  const auto to_uInt32 = [](string_view s, uInt32 pos) {
-    return static_cast<uInt32>(std::stoul(s.substr(pos, 8), nullptr, 16));
+    return static_cast<uInt32>(std::stoul(string{s.substr(pos, 8)}, nullptr, 16));
-  };
+  };  // FIXME: convert to string_view by replacing std::stoul
 
   const uInt32 seed = to_uInt32(md5, 0)  ^ to_uInt32(md5, 8) ^
                       to_uInt32(md5, 16) ^ to_uInt32(md5, 24);
@@ -44,8 +44,7 @@ Cartridge::Cartridge(const Settings& settings, const string& md5)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Cartridge::setAbout(const string& about, const string& type,
+void Cartridge::setAbout(string_view about, string_view type, string_view id)
-                         const string& id)
 {
   myAbout = about;
   myDetectedType = type;

src/emucore/Cart.hxx

@@ -63,13 +63,13 @@ class Cartridge : public Device
       @param settings  A reference to the various settings (read-only)
       @param md5       The md5sum of the cart image
     */
-    Cartridge(const Settings& settings, const string& md5);
+    Cartridge(const Settings& settings, string_view md5);
     ~Cartridge() override = default;
 
     /**
       Set/query some information about this cartridge.
     */
-    void setAbout(const string& about, const string& type, const string& id);
+    void setAbout(string_view about, string_view type, string_view id);
     const string& about() const { return myAbout; }
     const string& detectedType() const { return myDetectedType; }
     const string& multiCartID() const  { return myMultiCartID;  }
@@ -295,10 +295,9 @@ class Cartridge : public Device
       Informs the cartridge about the name of the nvram file it will
       use; not all carts support this.
 
-      @param nvramdir  The full path of the nvram directory
+      @param path  The full path of the nvram file
-      @param romfile   The name of the cart from ROM properties
     */
-    virtual void setNVRamFile(const string& nvramdir, const string& romfile) { }
+    virtual void setNVRamFile(string_view path) { }
 
     /**
       Thumbulator only supports 16-bit ARM code.  Some Harmony/Melody drivers,

src/emucore/CartARM.cxx

@@ -20,7 +20,7 @@
 #include "CartARM.hxx"
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-CartridgeARM::CartridgeARM(const string& md5, const Settings& settings)
+CartridgeARM::CartridgeARM(const Settings& settings, string_view md5)
   : Cartridge(settings, md5)
 {
 }

src/emucore/CartARM.hxx

@@ -32,7 +32,7 @@ class CartridgeARM : public Cartridge
   friend class CartridgeARMWidget;
 
   public:
-    CartridgeARM(const string& md5, const Settings& settings);
+    CartridgeARM(const Settings& settings, string_view md5);
     ~CartridgeARM() override = default;
 
     /**

src/emucore/CartBUS.cxx

@@ -46,8 +46,8 @@ static constexpr uInt32 getUInt32(const uInt8* _array, size_t _address) {
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 CartridgeBUS::CartridgeBUS(const ByteBuffer& image, size_t size,
-                           const string& md5, const Settings& settings)
+                           string_view md5, const Settings& settings)
-  : CartridgeARM(md5, settings),
+  : CartridgeARM(settings, md5),
     myImage{make_unique<uInt8[]>(32_KB)}
 {
   // Copy the ROM image into my buffer

src/emucore/CartBUS.hxx

@@ -59,7 +59,7 @@ class CartridgeBUS : public CartridgeARM
       @param md5       The md5sum of the ROM image
       @param settings  A reference to the various settings (read-only)
     */
-    CartridgeBUS(const ByteBuffer& image, size_t size, const string& md5,
+    CartridgeBUS(const ByteBuffer& image, size_t size, string_view md5,
                  const Settings& settings);
     ~CartridgeBUS() override = default;
 

src/emucore/CartCDF.cxx

@@ -62,8 +62,8 @@ namespace {
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 CartridgeCDF::CartridgeCDF(const ByteBuffer& image, size_t size,
-                           const string& md5, const Settings& settings)
+                           string_view md5, const Settings& settings)
-  : CartridgeARM(md5, settings)
+  : CartridgeARM(settings, md5)
 {
   // Copy the ROM image into my buffer
   mySize = std::min(size, 512_KB);

src/emucore/CartCDF.hxx

@@ -82,7 +82,7 @@ class CartridgeCDF : public CartridgeARM
       @param md5       The md5sum of the ROM image
       @param settings  A reference to the various settings (read-only)
     */
-    CartridgeCDF(const ByteBuffer& image, size_t size, const string& md5,
+    CartridgeCDF(const ByteBuffer& image, size_t size, string_view md5,
                  const Settings& settings);
     ~CartridgeCDF() override = default;
 

src/emucore/CartCTY.cxx

@@ -357,9 +357,9 @@ bool CartridgeCTY::load(Serializer& in)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void CartridgeCTY::setNVRamFile(const string& nvramdir, const string& romfile)
+void CartridgeCTY::setNVRamFile(string_view path)
 {
-  myEEPROMFile = nvramdir + romfile + "_eeprom.dat";
+  myEEPROMFile = string{path} + "_eeprom.dat";
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

src/emucore/CartCTY.hxx

@@ -210,10 +210,9 @@ class CartridgeCTY : public Cartridge
     /**
       Informs the cartridge about the name of the nvram file it will use.
 
-      @param nvramdir  The full path of the nvram directory
+      @param path  The full path of the nvram file
-      @param romfile   The name of the cart from ROM properties
     */
-    void setNVRamFile(const string& nvramdir, const string& romfile) override;
+    void setNVRamFile(string_view path) override;
 
   #ifdef DEBUGGER_SUPPORT
     /**

src/emucore/CartDPCPlus.cxx

@@ -26,8 +26,8 @@
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 CartridgeDPCPlus::CartridgeDPCPlus(const ByteBuffer& image, size_t size,
-                                   const string& md5, const Settings& settings)
+                                   string_view md5, const Settings& settings)
-  : CartridgeARM(md5, settings),
+  : CartridgeARM(settings, md5),
     myImage{make_unique<uInt8[]>(32_KB)},
     mySize{std::min(size, 32_KB)}
 {

src/emucore/CartDPCPlus.hxx

@@ -55,7 +55,7 @@ class CartridgeDPCPlus : public CartridgeARM
       @param md5       The md5sum of the ROM image
       @param settings  A reference to the various settings (read-only)
     */
-    CartridgeDPCPlus(const ByteBuffer& image, size_t size, const string& md5,
+    CartridgeDPCPlus(const ByteBuffer& image, size_t size, string_view md5,
                      const Settings& settings);
     ~CartridgeDPCPlus() override = default;
 

src/emucore/CartFA2.cxx

@@ -79,9 +79,9 @@ bool CartridgeFA2::poke(uInt16 address, uInt8 value)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void CartridgeFA2::setNVRamFile(const string& nvramdir, const string& romfile)
+void CartridgeFA2::setNVRamFile(string_view path)
 {
-  myFlashFile = nvramdir + romfile + "_flash.dat";
+  myFlashFile = string{path} + "_flash.dat";
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

src/emucore/CartFA2.hxx

@@ -74,10 +74,9 @@ class CartridgeFA2 : public CartridgeFA
     /**
       Informs the cartridge about the name of the nvram file it will use.
 
-      @param nvramdir  The full path of the nvram directory
+      @param path  The full path of the nvram file
-      @param romfile   The name of the cart from ROM properties
     */
-    void setNVRamFile(const string& nvramdir, const string& romfile) override;
+    void setNVRamFile(string_view path) override;
 
   #ifdef DEBUGGER_SUPPORT
     /**

src/emucore/CartMVC.cxx

@@ -56,7 +56,7 @@ class StreamReader : public Serializable
   public:
     StreamReader() { myBuffer1.fill(0);  myBuffer2.fill(0); }
 
-    bool open(const string& path) {
+    bool open(string_view path) {
       myFile = Serializer(path, Serializer::Mode::ReadOnly);
       if(myFile)
         myFileSize = myFile.size();
@@ -738,7 +738,7 @@ class MovieCart : public Serializable
   public:
     MovieCart() { myROM.fill(0); }
 
-    bool init(const string& path);
+    bool init(string_view path);
     bool process(uInt16 address);
 
     bool save(Serializer& out) const override;
@@ -837,7 +837,7 @@ class MovieCart : public Serializable
 };
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool MovieCart::init(const string& path)
+bool MovieCart::init(string_view path)
 {
   std::copy_n(kernelROM, 1_KB, myROM.data());
 

src/emucore/Console.cxx

@@ -149,7 +149,7 @@ Console::Console(OSystem& osystem, unique_ptr<Cartridge>& cart,
 
   // Let the cart know how to query for the 'Cartridge.StartBank' property
   myCart->setStartBankFromPropsFunc([this]() {
-    const string& startbank = myProperties.get(PropType::Cart_StartBank);
+    const string_view startbank = myProperties.get(PropType::Cart_StartBank);
     return (startbank == EmptyString || BSPF::equalsIgnoreCase(startbank, "AUTO"))
         ? -1 : BSPF::stringToInt(startbank);
   });
@@ -169,8 +169,7 @@ Console::Console(OSystem& osystem, unique_ptr<Cartridge>& cart,
 
   // Add the real controllers for this system
   // This must be done before the debugger is initialized
-  const string& md5 = myProperties.get(PropType::Cart_MD5);
+  setControllers(myProperties.get(PropType::Cart_MD5));
-  setControllers(md5);
 
   // Pause audio and clear framebuffer while autodetection runs
   myOSystem.sound().pause(true);
@@ -238,7 +237,7 @@ Console::Console(OSystem& osystem, unique_ptr<Cartridge>& cart,
   myConsoleInfo.BankSwitch = myCart->about();
 
   // Some carts have an associated nvram file
-  myCart->setNVRamFile(myOSystem.nvramDir().getPath(), myConsoleInfo.CartName);
+  myCart->setNVRamFile(myOSystem.nvramDir().getPath() + myConsoleInfo.CartName);
 
   // Let the other devices know about the new console
   mySystem->consoleChanged(myConsoleTiming);
@@ -360,13 +359,13 @@ string Console::formatFromFilename() const
   }};
 
   // Get filename, and search using regex's above
-  const string& filename = myOSystem.romFile().getName();
+  const string_view filename = myOSystem.romFile().getName();
   for(const auto& pat: Pattern)
   {
     try
     {
       const std::regex rgx(pat[0], std::regex_constants::icase);
-      if(std::regex_search(filename, rgx))
+      if(std::regex_search(filename.cbegin(), filename.cend(), rgx))
         return pat[1];
     }
     catch(...)
@@ -676,7 +675,7 @@ FBInitStatus Console::initializeVideo(bool full)
       Common::Size(2 * myTIA->width(), myTIA->height());
 
     const bool devSettings = myOSystem.settings().getBool("dev.settings");
-    const string& title = string("Stella ") + STELLA_VERSION +
+    const string title = string{"Stella "} + STELLA_VERSION +
                    ": \"" + myProperties.get(PropType::Cart_Name) + "\"";
     fbstatus = myOSystem.frameBuffer().createDisplay(title,
         BufferType::Emulator, size, false);
@@ -837,7 +836,7 @@ void Console::createAudioQueue()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Console::setControllers(const string& romMd5)
+void Console::setControllers(string_view romMd5)
 {
   // Check for CompuMate scheme; it is special in that a handler creates both
   // controllers for us, and associates them with the bankswitching class
@@ -942,9 +941,8 @@ void Console::changeRightController(int direction)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-unique_ptr<Controller> Console::getControllerPort(const Controller::Type type,
+unique_ptr<Controller> Console::getControllerPort(
-                                                  const Controller::Jack port,
+    const Controller::Type type, const Controller::Jack port, string_view romMd5)
-                                                  const string& romMd5)
 {
   unique_ptr<Controller> controller;
 
@@ -1002,7 +1000,8 @@ unique_ptr<Controller> Console::getControllerPort(const Controller::Type type,
     {
       FSNode nvramfile = myOSystem.nvramDir();
       nvramfile /= "atarivox_eeprom.dat";
-      const Controller::onMessageCallback callback = [&os = myOSystem](const string& msg)
+      const Controller::onMessageCallback callback = [&os = myOSystem]
+      (string_view msg)
       {
         const bool devSettings = os.settings().getBool("dev.settings");
         if(os.settings().getBool(devSettings ? "dev.extaccess" : "plr.extaccess"))
@@ -1016,7 +1015,8 @@ unique_ptr<Controller> Console::getControllerPort(const Controller::Type type,
     {
       FSNode nvramfile = myOSystem.nvramDir();
       nvramfile /= "savekey_eeprom.dat";
-      const Controller::onMessageCallback callback = [&os = myOSystem](const string& msg)
+      const Controller::onMessageCallback callback = [&os = myOSystem]
+      (string_view msg)
       {
         const bool devSettings = os.settings().getBool("dev.settings");
         if(os.settings().getBool(devSettings ? "dev.extaccess" : "plr.extaccess"))
@@ -1031,8 +1031,8 @@ unique_ptr<Controller> Console::getControllerPort(const Controller::Type type,
 
     case Controller::Type::KidVid:
     {
-      const Controller::onMessageCallbackForced callback =
+      const Controller::onMessageCallbackForced callback = [&os = myOSystem]
-      [&os = myOSystem](const string& msg, bool force) {
+      (string_view msg, bool force) {
         const bool devSettings = os.settings().getBool("dev.settings");
         if(force || os.settings().getBool(devSettings ? "dev.extaccess" : "plr.extaccess"))
           os.frameBuffer().showTextMessage(msg);
@@ -1241,10 +1241,11 @@ void Console::toggleDeveloperSet(bool toggle)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Console::toggleTIABit(TIABit bit, const string& bitname, bool show, bool toggle) const
+void Console::toggleTIABit(TIABit bit, string_view bitname,
+                           bool show, bool toggle) const
 {
   const bool result = myTIA->toggleBit(bit, toggle ? 2 : 3);
-  const string message = bitname + (result ? " enabled" : " disabled");
+  const string message = string{bitname} + (result ? " enabled" : " disabled");
 
   myOSystem.frameBuffer().showTextMessage(message);
 }
@@ -1259,10 +1260,12 @@ void Console::toggleBits(bool toggle) const
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Console::toggleTIACollision(TIABit bit, const string& bitname, bool show, bool toggle) const
+void Console::toggleTIACollision(TIABit bit, string_view bitname,
+                                 bool show, bool toggle) const
 {
   const bool result = myTIA->toggleCollision(bit, toggle ? 2 : 3);
-  const string message = bitname + (result ? " collision enabled" : " collision disabled");
+  const string message = string{bitname} +
+      (result ? " collision enabled" : " collision disabled");
 
   myOSystem.frameBuffer().showTextMessage(message);
 }

src/emucore/Console.hxx

@@ -81,7 +81,7 @@ class Console : public Serializable, public ConsoleIO
     /**
       Sets the left and right controllers for the console.
     */
-    void setControllers(const string& romMd5);
+    void setControllers(string_view romMd5);
 
     /**
       Get the controller plugged into the specified jack
@@ -424,11 +424,12 @@ class Console : public Serializable, public ConsoleIO
       Selects the left or right controller depending on ROM properties
     */
     unique_ptr<Controller> getControllerPort(const Controller::Type type,
-                                             const Controller::Jack port, const string& romMd5);
+                                             const Controller::Jack port,
+                                             string_view romMd5);
 
-    void toggleTIABit(TIABit bit, const string& bitname,
+    void toggleTIABit(TIABit bit, string_view bitname,
                       bool show = true, bool toggle = true) const;
-    void toggleTIACollision(TIABit bit, const string& bitname,
+    void toggleTIACollision(TIABit bit, string_view bitname,
                             bool show = true, bool toggle = true) const;
 
   private:

src/emucore/Control.cxx

@@ -134,15 +134,12 @@ string Controller::getPropName(const Type type)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-Controller::Type Controller::getType(const string& propName)
+Controller::Type Controller::getType(string_view propName)
 {
   for(int i = 0; i < static_cast<int>(Type::LastType); ++i)
-  {
     if (BSPF::equalsIgnoreCase(propName, getPropName(Type{i})))
-    {
       return Type{i};
-    }
+
-  }
   // special case
   if(BSPF::equalsIgnoreCase(propName, "KEYPAD"))
     return Type::Keyboard;

src/emucore/Control.hxx

@@ -279,7 +279,7 @@ class Controller : public Serializable
     /**
       Returns the controller type of the given property name
     */
-    static Type getType(const string& propName);
+    static Type getType(string_view propName);
 
     /**
       Sets the dead zone amount for real analog joysticks.

src/emucore/DispatchResult.cxx

@@ -31,8 +31,9 @@ void DispatchResult::setOk(uInt64 cycles)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void DispatchResult::setDebugger(uInt64 cycles, const string& message,
+void DispatchResult::setDebugger(uInt64 cycles, string_view message,
-                                 const string& tooltip, int address, bool wasReadTrap)
+                                 string_view tooltip, int address,
+                                 bool wasReadTrap)
 {
   myStatus = Status::debugger;
   myCycles = cycles;
@@ -51,7 +52,7 @@ void DispatchResult::setFatal(uInt64 cycles)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void DispatchResult::setMessage(const string& message)
+void DispatchResult::setMessage(string_view message)
 {
   myMessage = message;
 }

src/emucore/DispatchResult.hxx

@@ -31,34 +31,45 @@ class DispatchResult
 
     uInt64 getCycles() const { return myCycles; }
 
-    const string& getMessage() const { assertStatus(Status::debugger, Status::fatal); return myMessage; }
+    const string& getMessage() const {
+      assertStatus(Status::debugger, Status::fatal);
+      return myMessage;
+    }
 
-    int getAddress() const { assertStatus(Status::debugger); return myAddress; }
+    int getAddress() const {
+      assertStatus(Status::debugger);
+      return myAddress;
+    }
 
-    bool wasReadTrap() const { assertStatus(Status::debugger); return myWasReadTrap; }
+    bool wasReadTrap() const {
+      assertStatus(Status::debugger);
+      return myWasReadTrap;
+    }
 
-    const string& getToolTip() const { assertStatus(Status::debugger, Status::fatal); return myToolTip; }
+    const string& getToolTip() const {
+      assertStatus(Status::debugger, Status::fatal);
+      return myToolTip;
+    }
 
     bool isSuccess() const;
 
     void setOk(uInt64 cycles);
 
-    void setDebugger(uInt64 cycles, const string& message = "",
+    void setDebugger(uInt64 cycles, string_view message = "",
-                     const string& tooltip = "", int address = -1, bool wasReadTrap = true);
+                     string_view tooltip = "", int address = -1,
+                     bool wasReadTrap = true);
 
     void setFatal(uInt64 cycles);
 
-    void setMessage(const string& message);
+    void setMessage(string_view message);
 
   private:
 
-    void assertStatus(Status status) const
+    void assertStatus(Status status) const {
-    {
       if (myStatus != status) throw runtime_error("invalid status for operation");
     }
 
-    template<typename ...Ts> void assertStatus(Status status, Ts... more) const
+    template<typename ...Ts> void assertStatus(Status status, Ts... more) const {
-    {
       if (myStatus == status) return;
 
       assertStatus(more...);

src/emucore/EventHandler.cxx

@@ -181,7 +181,7 @@ void EventHandler::removePhysicalJoystick(int id)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void EventHandler::mapStelladaptors(const string& saport)
+void EventHandler::mapStelladaptors(string_view saport)
 {
 #ifdef JOYSTICK_SUPPORT
   myPJoyHandler->mapStelladaptors(saport);
@@ -1767,7 +1767,7 @@ void EventHandler::handleConsoleStartupEvents()
   if(myOSystem.settings().getBool("holdselect"))
     handleEvent(Event::ConsoleSelect);
 
-  const string& holdjoy0 = myOSystem.settings().getString("holdjoy0");
+  const string_view holdjoy0 = myOSystem.settings().getString("holdjoy0");
 
   if(BSPF::containsIgnoreCase(holdjoy0, "U"))
     handleEvent(Event::LeftJoystickUp);
@@ -1780,7 +1780,7 @@ void EventHandler::handleConsoleStartupEvents()
   if(BSPF::containsIgnoreCase(holdjoy0, "F"))
     handleEvent(Event::LeftJoystickFire);
 
-  const string& holdjoy1 = myOSystem.settings().getString("holdjoy1");
+  const string_view holdjoy1 = myOSystem.settings().getString("holdjoy1");
   if(BSPF::containsIgnoreCase(holdjoy1, "U"))
     handleEvent(Event::RightJoystickUp);
   if(BSPF::containsIgnoreCase(holdjoy1, "D"))
@@ -2056,7 +2056,7 @@ json EventHandler::convertLegacyComboMapping(string list)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void EventHandler::removePhysicalJoystickFromDatabase(const string& name)
+void EventHandler::removePhysicalJoystickFromDatabase(string_view name)
 {
 #ifdef JOYSTICK_SUPPORT
   myPJoyHandler->remove(name);
@@ -2496,7 +2496,7 @@ string EventHandler::keyAtIndex(int idx, Event::Group group)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void EventHandler::setMouseControllerMode(const string& enable)
+void EventHandler::setMouseControllerMode(string_view enable)
 {
   if(myOSystem.hasConsole())
   {

src/emucore/EventHandler.hxx

@@ -79,7 +79,7 @@ class EventHandler
 
       @param saport  How to map the ports ('lr' or 'rl')
     */
-    void mapStelladaptors(const string& saport);
+    void mapStelladaptors(string_view saport);
 
     /**
       Toggles if all four joystick directions are allowed at once
@@ -145,7 +145,7 @@ class EventHandler
                      Currently, this will be one of the following values:
                      'always', 'analog', 'never'
     */
-    void setMouseControllerMode(const string& enable);
+    void setMouseControllerMode(string_view enable);
     void changeMouseControllerMode(int direction = +1);
     void changeMouseCursor(int direction = +1);
 
@@ -338,7 +338,7 @@ class EventHandler
       Remove the physical joystick identified by 'name' from the joystick
       database, only if it is not currently active.
     */
-    void removePhysicalJoystickFromDatabase(const string& name);
+    void removePhysicalJoystickFromDatabase(string_view name);
 
     /**
       Enable/disable text events (distinct from single-key events).

src/emucore/FBBackend.hxx

@@ -88,7 +88,7 @@ class FBBackend
 
       @param title   The title of the application / window
     */
-    virtual void setTitle(const string& title) = 0;
+    virtual void setTitle(string_view title) = 0;
 
     /**
       Shows or hides the cursor based on the given boolean value.

src/emucore/FBSurface.cxx

@@ -297,7 +297,7 @@ void FBSurface::frameRect(uInt32 x, uInt32 y, uInt32 w, uInt32 h,
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void FBSurface::splitString(const GUI::Font& font, const string& s, int w,
+void FBSurface::splitString(const GUI::Font& font, string_view s, int w,
                             string& left, string& right)
 {
 #ifdef GUI_SUPPORT
@@ -335,7 +335,7 @@ void FBSurface::splitString(const GUI::Font& font, const string& s, int w,
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-int FBSurface::drawString(const GUI::Font& font, const string& s,
+int FBSurface::drawString(const GUI::Font& font, string_view s,
                           int x, int y, int w, int h,
                           ColorId color, TextAlign align,
                           int deltax, bool useEllipsis, ColorId shadowColor,
@@ -344,7 +344,7 @@ int FBSurface::drawString(const GUI::Font& font, const string& s,
   int lines = 0;
 
 #ifdef GUI_SUPPORT
-  string inStr = s;
+  string inStr{s};
 
   // draw multiline string
   while(inStr.length() && h >= font.getFontHeight() * 2)
@@ -374,7 +374,7 @@ int FBSurface::drawString(const GUI::Font& font, const string& s,
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-int FBSurface::drawString(const GUI::Font& font, const string& s,
+int FBSurface::drawString(const GUI::Font& font, string_view s,
                           int x, int y, int w,
                           ColorId color, TextAlign align,
                           int deltax, bool useEllipsis, ColorId shadowColor,

src/emucore/FBSurface.hxx

@@ -228,10 +228,13 @@ class FBSurface
       @return       Number of lines drawn
     */
 
-    virtual int drawString(const GUI::Font& font, const string& s, int x, int y, int w, int h,
+    virtual int drawString(const GUI::Font& font, string_view s, int x, int y,
-                           ColorId color, TextAlign align = TextAlign::Left,
+                           int w, int h, ColorId color,
-                           int deltax = 0, bool useEllipsis = true, ColorId shadowColor = kNone,
+                           TextAlign align = TextAlign::Left,
-                           size_t linkStart = string::npos, size_t linkLen = string::npos,
+                           int deltax = 0, bool useEllipsis = true,
+                           ColorId shadowColor = kNone,
+                           size_t linkStart = string::npos,
+                           size_t linkLen = string::npos,
                            bool underline = false);
 
     /**
@@ -254,10 +257,12 @@ class FBSurface
       @return    x coordinate of end of string
 
     */
-    virtual int drawString(const GUI::Font& font, const string& s, int x, int y, int w,
+    virtual int drawString(const GUI::Font& font, string_view s, int x, int y,
-                           ColorId color, TextAlign align = TextAlign::Left,
+                           int w, ColorId color, TextAlign align = TextAlign::Left,
-                           int deltax = 0, bool useEllipsis = true, ColorId shadowColor = kNone,
+                           int deltax = 0, bool useEllipsis = true,
-                           size_t linkStart = string::npos, size_t linkLen = string::npos,
+                           ColorId shadowColor = kNone,
+                           size_t linkStart = string::npos,
+                           size_t linkLen = string::npos,
                            bool underline = false);
 
     /**
@@ -269,7 +274,7 @@ class FBSurface
       @param left   The left part of the split string
       @param right  The right part of the split string
     */
-    static void splitString(const GUI::Font& font, const string& s, int w,
+    static void splitString(const GUI::Font& font, string_view s, int w,
                             string& left, string& right);
 
     /**

src/emucore/FSNode.cxx

@@ -26,13 +26,13 @@ FSNode::FSNode(const AbstractFSNodePtr& realNode)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-FSNode::FSNode(const string& path)
+FSNode::FSNode(string_view path)
 {
   setPath(path);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void FSNode::setPath(const string& path)
+void FSNode::setPath(string_view path)
 {
   // Only create a new object when necessary
   if (path == getPath())
@@ -48,7 +48,7 @@ void FSNode::setPath(const string& path)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-FSNode& FSNode::operator/=(const string& path)
+FSNode& FSNode::operator/=(string_view path)
 {
   if (path != EmptyString)
   {
@@ -230,7 +230,7 @@ const string& FSNode::getName() const
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void FSNode::setName(const string& name)
+void FSNode::setName(string_view name)
 {
   if (_realNode)
     _realNode->setName(name);
@@ -249,7 +249,7 @@ string FSNode::getShortPath() const
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string FSNode::getNameWithExt(const string& ext) const
+string FSNode::getNameWithExt(string_view ext) const
 {
   if (!_realNode)
     return EmptyString;
@@ -259,11 +259,13 @@ string FSNode::getNameWithExt(const string& ext) const
         _realNode->getName().substr(pos+1);
 
   pos = s.find_last_of('.');
-  return (pos != string::npos) ? s.replace(pos, string::npos, ext) : s + ext;
+  return (pos != string::npos)
+    ? s.replace(pos, string::npos, ext)
+    : s + string{ext};
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string FSNode::getPathWithExt(const string& ext) const
+string FSNode::getPathWithExt(string_view ext) const
 {
   if (!_realNode)
     return EmptyString;
@@ -271,7 +273,9 @@ string FSNode::getPathWithExt(const string& ext) const
   string s = _realNode->getPath();
 
   const size_t pos = s.find_last_of('.');
-  return (pos != string::npos) ? s.replace(pos, string::npos, ext) : s + ext;
+  return (pos != string::npos)
+    ? s.replace(pos, string::npos, ext)
+    : s + string{ext};
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -321,7 +325,7 @@ bool FSNode::makeDir()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool FSNode::rename(const string& newfile)
+bool FSNode::rename(string_view newfile)
 {
   return (_realNode && _realNode->exists()) ? _realNode->rename(newfile) : false;
 }

src/emucore/FSNode.hxx

@@ -83,7 +83,7 @@ class FSNode
      * operating system doesn't support the concept), some other directory is
      * used (usually the root directory).
      */
-    explicit FSNode(const string& path);
+    explicit FSNode(string_view path);
 
     /**
      * Assignment operators.
@@ -106,7 +106,7 @@ class FSNode
      * Append the given path to the node, adding a directory separator
      * when necessary.  Modelled on the C++17 fs::path API.
      */
-    FSNode& operator/=(const string& path);
+    FSNode& operator/=(string_view path);
 
     /**
      * By default, the output operator simply outputs the fully-qualified
@@ -159,7 +159,7 @@ class FSNode
      * @return the file name
      */
     const string& getName() const;
-    void setName(const string& name);
+    void setName(string_view name);
 
     /**
      * Return a string representation of the file which can be passed to fopen().
@@ -241,7 +241,7 @@ class FSNode
      *
      * @return bool true if the node was renamed, false otherwise.
      */
-    bool rename(const string& newfile);
+    bool rename(string_view newfile);
 
     /**
      * Get the size of the current node path.
@@ -302,13 +302,13 @@ class FSNode
      * and replace the extension (if present) with the given one.  If no
      * extension is present, the given one is appended instead.
      */
-    string getNameWithExt(const string& ext = "") const;
+    string getNameWithExt(string_view ext = "") const;
-    string getPathWithExt(const string& ext = "") const;
+    string getPathWithExt(string_view ext = "") const;
 
   private:
     explicit FSNode(const AbstractFSNodePtr& realNode);
     AbstractFSNodePtr _realNode;
-    void setPath(const string& path);
+    void setPath(string_view path);
 };
 
 
@@ -370,7 +370,7 @@ class AbstractFSNode
      *       implementation for more information.
      */
     virtual const string& getName() const = 0;
-    virtual void setName(const string& name) = 0;
+    virtual void setName(string_view name) = 0;
 
     /**
      * Returns the 'path' of the current node, usable in fopen().
@@ -443,7 +443,7 @@ class AbstractFSNode
      *
      * @return bool true if the node was renamed, false otherwise.
      */
-    virtual bool rename(const string& newfile) = 0;
+    virtual bool rename(string_view newfile) = 0;
 
     /**
      * Get the size of the current node path.
@@ -504,12 +504,12 @@ class AbstractFSNode
      * @param str  String containing the path.
      * @return  Pointer to the first char of the last component inside str.
      */
-    static const char* lastPathComponent(const string& str)
+    static const char* lastPathComponent(string_view str)
     {
       if(str.empty())
         return "";
 
-      const char* const start = str.c_str();
+      const char* const start = str.data();
       const char* cur = start + str.size() - 2;
 
       while (cur >= start && !(*cur == '/' || *cur == '\\'))

src/emucore/FrameBuffer.cxx

@@ -174,7 +174,7 @@ void FrameBuffer::setupFonts()
       GUI::consoleDesc, GUI::consoleMediumDesc, GUI::stellaMediumDesc,
       GUI::stellaLargeDesc, GUI::stella12x24tDesc, GUI::stella14x28tDesc,
       GUI::stella16x32tDesc};
-    const string& dialogFont = myOSystem.settings().getString("dialogfont");
+    const string_view dialogFont = myOSystem.settings().getString("dialogfont");
     const FontDesc fd = getFontDesc(dialogFont);
 
     // The general font used in all UI elements
@@ -202,13 +202,13 @@ void FrameBuffer::setupFonts()
   }
 
   // The font used by the ROM launcher
-  const string& lf = myOSystem.settings().getString("launcherfont");
+  const string_view lf = myOSystem.settings().getString("launcherfont");
 
   myLauncherFont = make_unique<GUI::Font>(getFontDesc(lf));       //  8x13
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-FontDesc FrameBuffer::getFontDesc(const string& name)
+FontDesc FrameBuffer::getFontDesc(string_view name)
 {
   if(name == "small")
     return GUI::consoleDesc;        //  8x13
@@ -228,7 +228,7 @@ FontDesc FrameBuffer::getFontDesc(const string& name)
 #endif
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-FBInitStatus FrameBuffer::createDisplay(const string& title, BufferType type,
+FBInitStatus FrameBuffer::createDisplay(string_view title, BufferType type,
                                         Common::Size size, bool honourHiDPI)
 {
   ++myInitializedCount;
@@ -609,7 +609,8 @@ void FrameBuffer::updateInEmulationMode(float framesPerSecond)
 
 #ifdef GUI_SUPPORT
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void FrameBuffer::createMessage(const string& message, MessagePosition position, bool force)
+void FrameBuffer::createMessage(string_view message, MessagePosition position,
+                                bool force)
 {
   // Only show messages if they've been enabled
   if(myMsg.surface == nullptr || !(force || myOSystem.settings().getBool("uimessages")))
@@ -637,8 +638,8 @@ void FrameBuffer::createMessage(const string& message, MessagePosition position,
 #endif
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void FrameBuffer::showTextMessage(const string& message, MessagePosition position,
+void FrameBuffer::showTextMessage(string_view message,
-                                  bool force)
+                                  MessagePosition position, bool force)
 {
 #ifdef GUI_SUPPORT
   const int fontWidth = font().getMaxCharWidth();
@@ -653,7 +654,7 @@ void FrameBuffer::showTextMessage(const string& message, MessagePosition positio
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void FrameBuffer::showGaugeMessage(const string& message, const string& valueText,
+void FrameBuffer::showGaugeMessage(string_view message, string_view valueText,
                                    float value, float minValue, float maxValue)
 {
 #ifdef GUI_SUPPORT

src/emucore/FrameBuffer.hxx

@@ -83,7 +83,7 @@ class FrameBuffer
 
       @return  Status of initialization (see FBInitStatus 'enum')
     */
-    FBInitStatus createDisplay(const string& title, BufferType type,
+    FBInitStatus createDisplay(string_view title, BufferType type,
                                Common::Size size, bool honourHiDPI = true);
 
     /**
@@ -109,7 +109,7 @@ class FrameBuffer
       @param position Onscreen position for the message
       @param force    Force showing this message, even if messages are disabled
     */
-    void showTextMessage(const string& message,
+    void showTextMessage(string_view message,
                          MessagePosition position = MessagePosition::BottomCenter,
                          bool force = false);
     /**
@@ -121,7 +121,7 @@ class FrameBuffer
       @param minValue   The minimal value of the gauge bar
       @param maxValue   The maximal value of the gauge bar
     */
-    void showGaugeMessage(const string& message, const string& valueText,
+    void showGaugeMessage(string_view message, string_view valueText,
                           float value, float minValue = 0.F, float maxValue = 100.F);
 
     bool messageShown() const;
@@ -324,7 +324,7 @@ class FrameBuffer
 
       @return  The description of the font
     */
-    static FontDesc getFontDesc(const string& name);
+    static FontDesc getFontDesc(string_view name);
   #endif
 
     /**
@@ -407,7 +407,7 @@ class FrameBuffer
       @param position Onscreen position for the message
       @param force    Force showing this message, even if messages are disabled
     */
-    void createMessage(const string& message, MessagePosition position,
+    void createMessage(string_view message, MessagePosition position,
                        bool force = false);
   #endif
 

src/emucore/KidVid.cxx

@@ -26,7 +26,7 @@
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 KidVid::KidVid(Jack jack, const Event& event, const OSystem& osystem,
-               const System& system, const string& romMd5,
+               const System& system, string_view romMd5,
                const onMessageCallbackForced& callback)
   : Controller(jack, event, system, Controller::Type::KidVid),
     myEnabled{myJack == Jack::Right},

src/emucore/KidVid.hxx

@@ -49,7 +49,7 @@ class KidVid : public Controller
       @param callback  Called to pass messages back to the parent controller
     */
     KidVid(Jack jack, const Event& event, const OSystem& osystem,
-           const System& system, const string& romMd5,
+           const System& system, string_view romMd5,
            const onMessageCallbackForced& callback);
     ~KidVid() override = default;
 

src/emucore/Lightgun.cxx

@@ -27,7 +27,7 @@
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 Lightgun::Lightgun(Jack jack, const Event& event, const System& system,
-                   const string& romMd5, const FrameBuffer& frameBuffer)
+                   string_view romMd5, const FrameBuffer& frameBuffer)
   : Controller(jack, event, system, Controller::Type::Lightgun),
     myFrameBuffer{frameBuffer}
 {

src/emucore/Lightgun.hxx

@@ -43,7 +43,7 @@ class Lightgun : public Controller
 
     */
     Lightgun(Jack jack, const Event& event, const System& system,
-             const string& romMd5, const FrameBuffer& frameBuffer);
+             string_view romMd5, const FrameBuffer& frameBuffer);
     ~Lightgun() override = default;
 
   public:

src/emucore/M6502.cxx

@@ -568,10 +568,10 @@ void M6502::attach(Debugger& debugger)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-uInt32 M6502::addCondBreak(Expression* e, const string& name, bool oneShot)
+uInt32 M6502::addCondBreak(Expression* e, string_view name, bool oneShot)
 {
   myCondBreaks.emplace_back(e);
-  myCondBreakNames.push_back(name);
+  myCondBreakNames.emplace_back(name);
 
   updateStepStateByInstruction();
 
@@ -609,10 +609,10 @@ const StringList& M6502::getCondBreakNames() const
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-uInt32 M6502::addCondSaveState(Expression* e, const string& name)
+uInt32 M6502::addCondSaveState(Expression* e, string_view name)
 {
   myCondSaveStates.emplace_back(e);
-  myCondSaveStateNames.push_back(name);
+  myCondSaveStateNames.emplace_back(name);
 
   updateStepStateByInstruction();
 
@@ -650,10 +650,10 @@ const StringList& M6502::getCondSaveStateNames() const
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-uInt32 M6502::addCondTrap(Expression* e, const string& name)
+uInt32 M6502::addCondTrap(Expression* e, string_view name)
 {
   myTrapConds.emplace_back(e);
-  myTrapCondNames.push_back(name);
+  myTrapCondNames.emplace_back(name);
 
   updateStepStateByInstruction();
 

src/emucore/M6502.hxx

@@ -236,19 +236,19 @@ class M6502 : public Serializable
     BreakpointMap& breakPoints() { return myBreakPoints; }
 
     // methods for 'breakif' handling
-    uInt32 addCondBreak(Expression* e, const string& name, bool oneShot = false);
+    uInt32 addCondBreak(Expression* e, string_view name, bool oneShot = false);
     bool delCondBreak(uInt32 idx);
     void clearCondBreaks();
     const StringList& getCondBreakNames() const;
 
     // methods for 'savestateif' handling
-    uInt32 addCondSaveState(Expression* e, const string& name);
+    uInt32 addCondSaveState(Expression* e, string_view name);
     bool delCondSaveState(uInt32 idx);
     void clearCondSaveStates();
     const StringList& getCondSaveStateNames() const;
 
     // methods for 'trapif' handling
-    uInt32 addCondTrap(Expression* e, const string& name);
+    uInt32 addCondTrap(Expression* e, string_view name);
     bool delCondTrap(uInt32 idx);
     void clearCondTraps();
     const StringList& getCondTrapNames() const;

src/emucore/MD5.cxx

@@ -301,11 +301,9 @@ static void Decode(uInt32* output, const uInt8* const input, uInt32 len)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string hash(const string& buffer)
+string hash(string_view buffer)
 {
-  std::vector<uint8_t> vec(buffer.begin(), buffer.end());
+  return hash(reinterpret_cast<const uInt8*>(buffer.data()), buffer.size());
-
-  return hash(vec.data(), vec.size());
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

src/emucore/MD5.hxx

@@ -47,7 +47,7 @@ namespace MD5 {
 
     @return   The message - digest
   */
-  string hash(const string& buffer);
+  string hash(string_view buffer);
 
 } // namespace MD5
 

src/emucore/OSystem.cxx

@@ -207,7 +207,7 @@ bool OSystem::initialize(const Settings::Options& options)
   // Detect serial port for AtariVox-USB
   // If a previously set port is defined, use it;
   // otherwise use the first one found (if any)
-  const string& avoxport = mySettings->getString("avoxport");
+  const string_view avoxport = mySettings->getString("avoxport");
   const StringList ports = MediaFactory::createSerialPort()->portNames();
 
   if(avoxport.empty() && !ports.empty())
@@ -277,7 +277,7 @@ void OSystem::setConfigPaths()
   // Make sure all required directories actually exist
   const auto buildDirIfRequired = [](FSNode& path,
                                      const FSNode& initialPath,
-                                     const string& pathToAppend = EmptyString)
+                                     string_view pathToAppend = EmptyString)
   {
     path = initialPath;
     if(pathToAppend != EmptyString)
@@ -293,7 +293,7 @@ void OSystem::setConfigPaths()
 #endif
 
 #ifdef IMAGE_SUPPORT
-  const string& ssSaveDir = mySettings->getString("snapsavedir");
+  const string_view ssSaveDir = mySettings->getString("snapsavedir");
   if(ssSaveDir == EmptyString)
     mySnapshotSaveDir = userDir();
   else
@@ -301,7 +301,7 @@ void OSystem::setConfigPaths()
   if(!mySnapshotSaveDir.isDirectory())
     mySnapshotSaveDir.makeDir();
 
-  const string& ssLoadDir = mySettings->getString("snaploaddir");
+  const string_view ssLoadDir = mySettings->getString("snaploaddir");
   if(ssLoadDir == EmptyString)
     mySnapshotLoadDir = userDir();
   else
@@ -315,7 +315,7 @@ void OSystem::setConfigPaths()
 
 #if 0
   // Debug code
-  auto dbgPath = [](const string& desc, const FSNode& location)
+  auto dbgPath = [](string_view desc, const FSNode& location)
   {
     cerr << desc << ": " << location << endl;
   };
@@ -331,7 +331,7 @@ void OSystem::setConfigPaths()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void OSystem::setUserDir(const string& path)
+void OSystem::setUserDir(string_view path)
 {
   mySettings->setValue("userdir", path);
 
@@ -416,8 +416,7 @@ void OSystem::createSound()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-string OSystem::createConsole(const FSNode& rom, const string& md5sum,
+string OSystem::createConsole(const FSNode& rom, string_view md5sum, bool newrom)
-                              bool newrom)
 {
   bool showmessage = false;
 
@@ -567,7 +566,7 @@ bool OSystem::hasConsole() const
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool OSystem::createLauncher(const string& startdir)
+bool OSystem::createLauncher(string_view startdir)
 {
   closeConsole();
 
@@ -666,7 +665,7 @@ unique_ptr<Console> OSystem::openConsole(const FSNode& romfile, string& md5)
     // Now create the cartridge
     string cartmd5 = md5;
     const string& type = props.get(PropType::Cart_Type);
-    const Cartridge::messageCallback callback = [&os = *this](const string& msg)
+    const Cartridge::messageCallback callback = [&os = *this](string_view msg)
     {
       const bool devSettings = os.settings().getBool("dev.settings");
 

src/emucore/OSystem.hxx

@@ -365,7 +365,7 @@ class OSystem
 
       @return  String indicating any error message (EmptyString for no errors)
     */
-    string createConsole(const FSNode& rom, const string& md5 = "",
+    string createConsole(const FSNode& rom, string_view md5 = "",
                          bool newrom = true);
 
     /**
@@ -386,7 +386,7 @@ class OSystem
 
       @return  True on successful creation, otherwise false
     */
-    bool createLauncher(const string& startdir = "");
+    bool createLauncher(string_view startdir = "");
 
     /**
       Answers whether the ROM launcher was actually successfully used
@@ -455,11 +455,11 @@ class OSystem
       Again, this is not supported on all systems, so it may be simply
       ignored.
     */
-    static void overrideBaseDir(const string& path) { ourOverrideBaseDir = path; }
+    static void overrideBaseDir(string_view path) { ourOverrideBaseDir = path; }
     static void overrideBaseDirWithApp() { ourOverrideBaseDirWithApp = true; }
 
     // Update the path of the user directory
-    void setUserDir(const string& path);
+    void setUserDir(string_view path);
 
   public:
     //////////////////////////////////////////////////////////////////////
@@ -505,7 +505,7 @@ class OSystem
                         they are free to ignore it
     */
     virtual void getBaseDirectories(string& basedir, string& homedir,
-                                    bool useappdir, const string& usedir) = 0;
+                                    bool useappdir, string_view usedir) = 0;
 
     virtual void initPersistence(FSNode& basedir) = 0;
 

src/emucore/OSystemStandalone.cxx

@@ -51,6 +51,6 @@ shared_ptr<CompositeKeyValueRepositoryAtomic> OSystemStandalone::getHighscoreRep
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 void OSystemStandalone::getBaseDirectories(
-    string& basedir, string& homedir, bool useappdir, const string& usedir)
+    string& basedir, string& homedir, bool useappdir, string_view usedir)
 {
 }

src/emucore/OSystemStandalone.hxx

@@ -41,7 +41,7 @@ class OSystemStandalone : public OSystem
     string describePresistence() override;
 
     void getBaseDirectories(string& basedir, string& homedir,
-                                    bool useappdir, const string& usedir) override;
+                            bool useappdir, string_view usedir) override;
 
   private:
 

src/emucore/PlusROM.cxx

@@ -47,7 +47,7 @@ using std::chrono::milliseconds;
 class PlusROMRequest {
   public:
     struct Destination {
-      Destination(const string& _host, const string& _path)
+      Destination(string_view _host, string_view _path)
         : host{_host}, path{_path} {}
 
       string host;
@@ -55,7 +55,7 @@ class PlusROMRequest {
     };
 
     struct PlusStoreId {
-      PlusStoreId(const string& _nick, const string& _id)
+      PlusStoreId(string_view _nick, string_view _id)
         : nick{_nick}, id{_id} {}
 
       string nick;
@@ -369,7 +369,7 @@ void PlusROM::reset()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool PlusROM::isValidHost(const string& host)
+bool PlusROM::isValidHost(string_view host)
 {
   // TODO: This isn't 100% either, as we're supposed to check for the length
   //       of each part between '.' in the range 1 .. 63
@@ -377,11 +377,11 @@ bool PlusROM::isValidHost(const string& host)
   //  library we decide to use
   static const std::regex rgx(R"(^(([a-z0-9]|[a-z0-9][a-z0-9\-]*[a-z0-9])\.)*([a-z0-9]|[a-z0-9][a-z0-9\-]*[a-z0-9])$)", std::regex_constants::icase);
 
-  return std::regex_match(host, rgx);
+  return std::regex_match(host.cbegin(), host.cend(), rgx);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool PlusROM::isValidPath(const string& path)
+bool PlusROM::isValidPath(string_view path)
 {
   // TODO: This isn't 100%
   //  Perhaps a better function will be included with whatever network

src/emucore/PlusROM.hxx

@@ -157,8 +157,8 @@ class PlusROM : public Serializable
     }
 
   private:
-    static bool isValidHost(const string& host);
+    static bool isValidHost(string_view host);
-    static bool isValidPath(const string& path);
+    static bool isValidPath(string_view path);
 
     /**
       Receive data from all requests that have completed.

src/emucore/Props.cxx

@@ -61,7 +61,7 @@ bool Properties::save(KeyValueRepository& repo) const
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Properties::set(PropType key, const string& value)
+void Properties::set(PropType key, string_view value)
 {
   const auto pos = static_cast<size_t>(key);
   if(pos < myProperties.size())
@@ -137,7 +137,7 @@ Properties& Properties::operator=(const Properties& properties)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Properties::setDefault(PropType key, const string& value)
+void Properties::setDefault(PropType key, string_view value)
 {
   ourDefaultProperties[static_cast<size_t>(key)] = value;
 }
@@ -200,7 +200,7 @@ void Properties::setDefaults()
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-PropType Properties::getPropType(const string& name)
+PropType Properties::getPropType(string_view name)
 {
   for(size_t i = 0; i < NUM_PROPS; ++i)
     if(ourPropertyNames[i] == name)

src/emucore/Props.hxx

@@ -106,7 +106,7 @@ class Properties
       @param key      The key of the property to set
       @param value    The value to assign to the property
     */
-    void set(PropType key, const string& value);
+    void set(PropType key, string_view value);
 
     /**
       Print the attributes of this properties object
@@ -148,7 +148,7 @@ class Properties
       @param key      The key of the property to set
       @param value    The value to assign to the property
     */
-    static void setDefault(PropType key, const string& value);
+    static void setDefault(PropType key, string_view value);
 
   private:
     /**
@@ -165,7 +165,7 @@ class Properties
 
       @param name  The PropType key associated with the given string
     */
-    static PropType getPropType(const string& name);
+    static PropType getPropType(string_view name);
 
     /**
       When printing each collection of ROM properties, it is useful to

src/emucore/QuadTari.cxx

@@ -70,7 +70,7 @@ unique_ptr<Controller> QuadTari::addController(const Controller::Type type, bool
 {
   FSNode nvramfile = myOSystem.nvramDir();
   const Controller::onMessageCallback callback = [&os = myOSystem]
-    (const string& msg) {
+    (string_view msg) {
       const bool devSettings = os.settings().getBool("dev.settings");
       if(os.settings().getBool(devSettings ? "dev.extaccess" : "plr.extaccess"))
         os.frameBuffer().showTextMessage(msg);

src/emucore/Serializer.cxx

@@ -22,14 +22,15 @@ using std::ios;
 using std::ios_base;
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-Serializer::Serializer(const string& filename, Mode m)
+Serializer::Serializer(string_view filename, Mode m)
 {
   if(m == Mode::ReadOnly)
   {
     const FSNode node(filename);
     if(node.isFile() && node.isReadable())
     {
-      unique_ptr<fstream> str = make_unique<fstream>(filename, ios::in | ios::binary);
+      unique_ptr<fstream> str = make_unique<fstream>(
+          string{filename}, ios::in | ios::binary);
       if(str && str->is_open())
       {
         myStream = std::move(str);
@@ -48,13 +49,14 @@ Serializer::Serializer(const string& filename, Mode m)
     // So we open in write and append mode - the write creates the file
     // when necessary, and the append doesn't delete any data if it
     // already exists
-    fstream temp(filename, ios::out | ios::app);
+    string f{filename};
+    fstream temp(f, ios::out | ios::app);
     temp.close();
 
     ios_base::openmode stream_mode = ios::in | ios::out | ios::binary;
     if(m == Mode::ReadWriteTrunc)
       stream_mode |= ios::trunc;
-    unique_ptr<fstream> str = make_unique<fstream>(filename, stream_mode);
+    unique_ptr<fstream> str = make_unique<fstream>(f, stream_mode);
     if(str && str->is_open())
     {
       myStream = std::move(str);
@@ -236,11 +238,10 @@ void Serializer::putDouble(double value)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-void Serializer::putString(const string& str)
+void Serializer::putString(string_view str)
 {
-  const auto len = static_cast<uInt32>(str.length());
+  putInt(static_cast<uInt32>(str.size()));
-  putInt(len);
+  myStream->write(str.data(), str.size());
-  myStream->write(str.data(), len);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

src/emucore/Serializer.hxx

@@ -49,7 +49,7 @@ class Serializer
       The valid() method must immediately be called to verify the stream
       was correctly initialized.
     */
-    explicit Serializer(const string& filename, Mode m = Mode::ReadWrite);
+    explicit Serializer(string_view filename, Mode m = Mode::ReadWrite);
     Serializer();
 
   public:
@@ -207,11 +207,11 @@ class Serializer
     void putDouble(double value);
 
     /**
-      Writes a string to the current output stream.
+      Writes a string(view) to the current output stream.
 
       @param str The string to write to the output stream.
     */
-    void putString(const string& str);
+    void putString(string_view str);
 
     /**
       Writes a boolean value to the current output stream.

src/emucore/Settings.cxx

@@ -192,7 +192,6 @@ Settings::Settings()
   setPermanent("confirmexit", false);
   setPermanent("autopause", false);
 
-
   // Misc options
   setPermanent("loglevel", static_cast<int>(Logger::Level::INFO));
   setPermanent("logtoconsole", "0");

src/emucore/tia/TIA.cxx

@@ -1185,14 +1185,9 @@ bool TIA::enableFixedColors(bool enable)
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-bool TIA::setFixedColorPalette(const string& colors)
+bool TIA::setFixedColorPalette(string_view colors)
 {
-  string s = colors;
+  for(size_t i = 0; i < std::max<size_t>(6, colors.size()); ++i)
-  sort(s.begin(), s.end());
-  if(s != "bgopry")
-    return false;
-
-  for(int i = 0; i < 6; ++i)
   {
     switch(colors[i])
     {