Prefs.h

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/**********************************************************************
 
  Audacity: A Digital Audio Editor
 
  Prefs.h
 
  Dominic Mazzoni
  Markus Meyer
 
  Audacity uses wxWidgets' wxFileConfig class to handle preferences.
  In Audacity versions prior to 1.3.1, it used wxConfig, which would
  store the prefs in a platform-dependent way (e.g. in the registry
  on Windows). Now it always stores the settings in a configuration file
  in the Audacity Data Directory.
 
  Every time we read a preference, we need to specify the default
  value for that preference, to be used if the preference hasn't
  been set before.
 
  So, to avoid code duplication, we provide functions in this file
  to read and write preferences which have a nonobvious default
  value, so that if we later want to change this value, we only
  have to change it in one place.
 
  See Prefs.cpp for a (complete?) list of preferences we keep
  track of...
 
**********************************************************************/
#ifndef __AUDACITY_PREFS__
#define __AUDACITY_PREFS__
 
#include <functional>
#include <set>
#include <vector>
 
// Increment this every time the prefs need to be reset
// the first part (before the r) indicates the version the reset took place
// the second part (after the r) indicates the number of times the prefs have been reset within the same version
#define AUDACITY_PREFS_VERSION_STRING "1.1.1r1"
 
#include <functional>
 
#include "ComponentInterfaceSymbol.h"
#include "wxArrayStringEx.h"
#include "FileConfig.h"
 
#include <memory>
 
class wxFileName;
 
PREFERENCES_API void InitPreferences( std::unique_ptr<FileConfig> uPrefs );
 
PREFERENCES_API void ResetPreferences();
PREFERENCES_API void FinishPreferences();
 
extern PREFERENCES_API FileConfig *gPrefs;
extern int gMenusDirty;
 
 
struct ByColumns_t{};
extern PREFERENCES_API ByColumns_t ByColumns;
 
struct SettingPath {
   RegistryPath mPath;
   operator const RegistryPath &() const { return mPath; }
};
 
/* The constructors are non-explicit for convenience */
class PREFERENCES_API SettingBase
{
public:
   SettingBase( const char *path ) : mPath{ path } {}
   SettingBase( const wxChar *path ) : mPath{ path } {}
   SettingBase( const wxString &path ) : mPath{ path } {}
 
   wxConfigBase *GetConfig() const;
 
   const SettingPath &GetPath() const { return mPath; }
 
   bool Delete();
 
protected:
   SettingBase( const SettingBase& ) = default;
   const SettingPath mPath;
};
 
class TransactionalSettingBase : public SettingBase
{
public:
   using SettingBase::SettingBase;
 
   virtual void Invalidate() = 0;
 
protected:
   // Methods below should only be callable
   // from within a transaction.
   friend class SettingTransaction;
   friend class SettingScope;
   
   virtual void EnterTransaction(size_t depth) = 0;
   virtual bool Commit() = 0;
   virtual void Rollback() noexcept = 0;
};
 
 
class PREFERENCES_API SettingScope /* not final */
{
public:
   SettingScope();
   ~SettingScope() noexcept;
   SettingScope(const SettingScope&) = delete;
   SettingScope &operator=(const SettingScope&) = delete;
 
   enum AddResult{ NotAdded, Added, PreviouslyAdded };
   static AddResult Add( TransactionalSettingBase& setting );
 
protected:
   std::set< TransactionalSettingBase * > mPending;
   bool mCommitted = false;
};
 
 
class PREFERENCES_API SettingTransaction final : public SettingScope
{
public:
 
   bool Commit();
};
 
template< typename T >
class CachingSettingBase : public TransactionalSettingBase
{
public:
   using TransactionalSettingBase::TransactionalSettingBase;
   explicit CachingSettingBase( const SettingBase &path )
      : TransactionalSettingBase{ path.GetPath() } {}
 
protected:
   CachingSettingBase( const CachingSettingBase & ) = default;
   mutable T mCurrentValue{};
   mutable bool mValid{false};
};
 
template< typename T >
class Setting : public CachingSettingBase< T >
{
public:
   using CachingSettingBase< T >::CachingSettingBase;
 
   using DefaultValueFunction = std::function< T() >;
 
   Setting( const SettingBase &path, const T &defaultValue )
      : CachingSettingBase< T >{ path }
      , mDefaultValue{ defaultValue }
   {}
 
   Setting( const SettingBase &path, DefaultValueFunction function )
      : CachingSettingBase< T >{ path }
      , mFunction{ function }
   {}
   
 
   const T& GetDefault() const
   {
      if ( mFunction )
         mDefaultValue = mFunction();
      return mDefaultValue;
   }
 
   bool Read( T *pVar ) const
   {
      return ReadWithDefault( pVar, GetDefault() );
   }
 
   bool ReadWithDefault( T *pVar, const T& defaultValue ) const
   {
      if ( pVar )
         *pVar = defaultValue;
      if ( pVar && this->mValid ) {
         *pVar = this->mCurrentValue;
         return true;
      }
      const auto config = this->GetConfig();
      if ( pVar && config ) {
         if ((this->mValid = config->Read( this->mPath, &this->mCurrentValue )))
            *pVar = this->mCurrentValue;
         return this->mValid;
      }
      return (this->mValid = false);
   }
 
 
   T Read() const
   {
      return ReadWithDefault( GetDefault() );
   }
 
 
   T ReadWithDefault( const T &defaultValue ) const
   {
      if (this->mValid)
         return this->mCurrentValue;
      const auto config = this->GetConfig();
      if (config) {
         this->mCurrentValue =
            config->ReadObject(this->mPath, defaultValue);
         // If config file contains a value that agrees with the default, we
         // can't detect that, so assume invalidity still
         this->mValid = (this->mCurrentValue != defaultValue);
         return this->mCurrentValue;
      }
      else
         return T{};
   }
 
   bool Write( const T &value )
   {
      const auto config = this->GetConfig();
      
      if (config == nullptr)
         return false;
      
      switch ( SettingScope::Add( *this ) ) {
         // Eager writes, but not flushed, when there is no transaction
         default:
         case SettingTransaction::NotAdded: {
            this->mCurrentValue = value;
            return DoWrite();
         }
 
         // Deferred writes, with flush, if there is a commit later
         case SettingTransaction::Added:
         case SettingTransaction::PreviouslyAdded:
            this->mCurrentValue = value;
            this->mValid = true;
            return true;
      }
   }
 
   bool Reset()
   {
      return Write( GetDefault() );
   }
 
   void Invalidate() override
   {
      this->mValid = false;
   }
 
private:
   void EnterTransaction(size_t depth) override
   {
      const T value = Read();
 
      for (size_t i = mPreviousValues.size(); i < depth; ++i)
         this->mPreviousValues.emplace_back( value );
   }
 
   bool Commit() override
   {
      // This can be only called from within the transaction
      assert(!this->mPreviousValues.empty());
 
      if (this->mPreviousValues.empty())
         return false;
      
      const auto result = this->mPreviousValues.size() > 1 || DoWrite();
      mPreviousValues.pop_back();
 
      return result;
   }
 
   void Rollback() noexcept override
   {
      // This can be only called from within the transaction
      assert(!this->mPreviousValues.empty());
      
      if (!this->mPreviousValues.empty())
      {
         this->mCurrentValue = std::move(this->mPreviousValues.back());
         this->mPreviousValues.pop_back();
      }
   }
 
protected:
 
   bool DoWrite( )
   {
      const auto config = this->GetConfig();
      return this->mValid =
         config ? config->Write( this->mPath, this->mCurrentValue ) : false;
   }
 
   const DefaultValueFunction mFunction;
   mutable T mDefaultValue{};
   std::vector<T> mPreviousValues;
};
 
class PREFERENCES_API BoolSetting final : public Setting< bool >
{
public:
   using Setting::Setting;
 
   bool Toggle();
};
 
class IntSetting final : public Setting< int >
{
public:
   using Setting::Setting;
};
 
class DoubleSetting final : public Setting< double >
{
public:
   using Setting::Setting;
};
 
class StringSetting final : public Setting< wxString >
{
public:
   using Setting::Setting;
};
 
using EnumValueSymbol = ComponentInterfaceSymbol;
 
class PREFERENCES_API EnumValueSymbols : public std::vector< EnumValueSymbol >
{
public:
   EnumValueSymbols() = default;
   EnumValueSymbols( std::initializer_list<EnumValueSymbol> symbols )
     : vector( symbols )
   {}
   EnumValueSymbols( std::vector< EnumValueSymbol > symbols )
     : vector( symbols )
   {}
 
   // columnwise constructor; arguments must have same size
   // (Implicit constructor takes initial tag argument to avoid unintended
   // overload resolution to the inherited constructor taking
   // initializer_list, in the case that each column has exactly two strings)
   EnumValueSymbols(
      ByColumns_t,
      const TranslatableStrings &msgids,
      wxArrayStringEx internals
   );
 
   const TranslatableStrings &GetMsgids() const;
   const wxArrayStringEx &GetInternals() const;
 
private:
   mutable TranslatableStrings mMsgids;
   mutable wxArrayStringEx mInternals;
};
 
class PREFERENCES_API ChoiceSetting
{
public:
   ChoiceSetting(const SettingPath &, EnumValueSymbols, long = -1) = delete;
 
   ChoiceSetting(TransactionalSettingBase &key, EnumValueSymbols symbols,
      long defaultSymbol = -1)
      : mKey{ key.GetPath() }
      , mSymbols{ move(symbols) }
      , mpOtherSettings{ &key }
      , mDefaultSymbol{ defaultSymbol }
   {
      assert(defaultSymbol < static_cast<long>(mSymbols.size()));
   }
 
   ChoiceSetting(const SettingBase &key, EnumValueSymbols symbols,
      long defaultSymbol = -1)
      : mKey{ key.GetPath() }
      , mSymbols{ move(symbols) }
      , mDefaultSymbol{ defaultSymbol }
   {
      assert(defaultSymbol < static_cast<long>(mSymbols.size()));
   }
 
   const wxString &Key() const { return mKey; }
   const EnumValueSymbol &Default() const;
   const EnumValueSymbols &GetSymbols() const { return mSymbols; }
 
   wxString Read() const;
 
   // new direct use is discouraged but it may be needed in legacy code:
   // use a default in case the preference is not defined, which may not be
   // the default-default stored in this object.
   wxString ReadWithDefault( const wxString & ) const;
 
   bool Write( const wxString &value ); // you flush gPrefs afterward
 
   void SetDefault( long value );
 
protected:
   size_t Find( const wxString &value ) const;
   virtual void Migrate( wxString& );
 
   const wxString mKey;
   const EnumValueSymbols mSymbols;
   TransactionalSettingBase *const mpOtherSettings{};
 
   // stores an internal value
   mutable bool mMigrated { false };
 
   long mDefaultSymbol;
};
 
class PREFERENCES_API EnumSettingBase : public ChoiceSetting {
public:
   template<typename Key>
   EnumSettingBase(
      Key &&key, // moved string, or lvalue reference to another Setting
      EnumValueSymbols symbols,
      long defaultSymbol,
 
      std::vector<int> intValues, // must have same size as symbols
      const wxString &oldKey = {}
   )  : ChoiceSetting{ std::forward<Key>(key), move(symbols), defaultSymbol }
      , mIntValues{ move(intValues) }
      , mOldKey{ oldKey }
   {
      assert (mIntValues.size() == mSymbols.size());
   }
 
protected:
 
   // Read and write the encoded values
   int ReadInt() const;
 
   // new direct use is discouraged but it may be needed in legacy code:
   // use a default in case the preference is not defined, which may not be
   // the default-default stored in this object.
   int ReadIntWithDefault( int defaultValue ) const;
 
   bool WriteInt( int code ); // you flush gPrefs afterward
 
   size_t FindInt( int code ) const;
   void Migrate( wxString& ) override;
 
private:
   std::vector<int> mIntValues;
   const wxString mOldKey;
};
 
template< typename Enum >
class EnumSetting : public EnumSettingBase
{
public:
 
   template<typename Key>
   EnumSetting(
      Key &&key, // moved string, or lvalue reference to another Setting
      EnumValueSymbols symbols,
      long defaultSymbol,
 
      std::vector< Enum > values, // must have same size as symbols
      const wxString &oldKey = {}
   )
      : EnumSettingBase{
         std::forward<Key>(key), move(symbols), defaultSymbol,
         ConvertValues(values), oldKey
      }
   {}
 
   // Wrap ReadInt() and ReadIntWithDefault() and WriteInt()
   Enum ReadEnum() const
   { return static_cast<Enum>( ReadInt() ); }
 
   // new direct use is discouraged but it may be needed in legacy code:
   // use a default in case the preference is not defined, which may not be
   // the default-default stored in this object.
   Enum ReadEnumWithDefault( Enum defaultValue ) const
   {
      auto integer = static_cast<int>(defaultValue);
      return static_cast<Enum>( ReadIntWithDefault( integer ) );
   }
 
   bool WriteEnum( Enum value )
   { return WriteInt( static_cast<int>( value ) ); }
 
private:
   std::vector<int> ConvertValues( const std::vector< Enum > &values)
   {
      // To convert scoped enums.  This would be easier with std::ranges
      std::vector<int> result;
      result.reserve(values.size());
      for (auto value : values)
         result.push_back(static_cast<int>(value));
      return result;
   }
};
 
class PREFERENCES_API PrefsListener
{
public:
 
   static void Broadcast(int id = 0);
 
   PrefsListener();
   virtual ~PrefsListener();
 
   // Called when all preferences should be updated.
   // PrefsListener::UpdatePrefs() is defined, and does nothing
   virtual void UpdatePrefs() = 0;
 
protected:
   // Called when only selected preferences are to be updated.
   // id is some value generated by wxNewId() that identifies the portion
   // of preferences.
   // Default function does nothing.
   virtual void UpdateSelectedPrefs( int id );
 
private:
   struct Impl;
   std::unique_ptr<Impl> mpImpl;
};
 
PREFERENCES_API
wxString WarningDialogKey(const wxString &internalDialogName);
 
struct PREFERENCES_API PreferenceInitializer {
   PreferenceInitializer();
   virtual ~PreferenceInitializer();
   virtual void operator () () = 0;
 
   static void ReinitializeAll();
};
 
// Special extra-sticky settings
extern PREFERENCES_API BoolSetting DefaultUpdatesCheckingFlag;
 
#endif