Define EnumSetting and EncodedEnumSetting

src/Prefs.h

@@ -30,6 +30,7 @@
 #define __AUDACITY_PREFS__
 
 #include "Audacity.h"
+#include "../include/audacity/IdentInterface.h"
 
 #include <wx/config.h>
 #include <wx/fileconf.h>
@@ -40,4 +41,84 @@ void FinishPreferences();
 extern AUDACITY_DLL_API wxFileConfig *gPrefs;
 extern int gMenusDirty;
 
+// Packages a table of user-visible choices each with an internal code string,
+// a preference key path,
+// and a default choice
+class EnumSetting
+{
+public:
+   EnumSetting(
+      const wxString &key,
+      const IdentInterfaceSymbol symbols[], size_t nSymbols,
+      size_t defaultSymbol
+   )
+      : mKey{ key }
+
+      , mSymbols{ symbols }
+      , mnSymbols{ nSymbols }
+
+      , mDefaultSymbol{ defaultSymbol }
+   {
+      wxASSERT( defaultSymbol < nSymbols );
+   }
+
+   const wxString &Key() const { return mKey; }
+   const IdentInterfaceSymbol &Default() const
+      { return mSymbols[mDefaultSymbol]; }
+   const IdentInterfaceSymbol *begin() const { return mSymbols; }
+   const IdentInterfaceSymbol *end() const { return mSymbols + mnSymbols; }
+
+   wxString Read() const;
+   bool Write( const wxString &value ); // you flush gPrefs afterward
+
+protected:
+   size_t Find( const wxString &value ) const;
+   virtual void Migrate( wxString& );
+
+   const wxString mKey;
+
+   const IdentInterfaceSymbol *mSymbols;
+   const size_t mnSymbols;
+
+   // stores an internal value
+   mutable bool mMigrated { false };
+
+   const size_t mDefaultSymbol;
+};
+
+// Extends EnumSetting with a corresponding table of integer codes
+// (generally not equal to their table positions),
+// and optionally an old preference key path that stored integer codes, to be
+// migrated into one that stores internal string values instead
+class EncodedEnumSetting : public EnumSetting
+{
+public:
+   EncodedEnumSetting(
+      const wxString &key,
+      const IdentInterfaceSymbol symbols[], size_t nSymbols,
+      size_t defaultSymbol,
+
+      const int intValues[] = nullptr, // must have same size as symbols
+      const wxString &oldKey = {}
+   )
+      : EnumSetting{ key, symbols, nSymbols, defaultSymbol }
+      , mIntValues{ intValues }
+      , mOldKey{ oldKey }
+   {
+      wxASSERT( mIntValues );
+   }
+
+   // Read and write the encoded values
+   virtual int ReadInt() const;
+   bool WriteInt( int code ); // you flush gPrefs afterward
+
+protected:
+   size_t FindInt( int code ) const;
+   void Migrate( wxString& ) override;
+
+private:
+   const int *mIntValues;
+   const wxString mOldKey;
+};
+
 #endif