Reimplement import plugin registation without sequence numbers

src/import/Import.cpp

@@ -84,11 +84,33 @@ ImportPluginList &Importer::sImportPluginList()
    return theList;
 }
 
+namespace {
+static const auto PathStart = wxT("Importers");
+
+static Registry::GroupItem &sRegistry()
+{
+   static Registry::TransparentGroupItem<> registry{ PathStart };
+   return registry;
+}
+
+struct ImporterItem final : Registry::SingleItem {
+   ImporterItem( const Identifier &id, std::unique_ptr<ImportPlugin> pPlugin )
+      : SingleItem{ id }
+      , mpPlugin{ std::move( pPlugin ) }
+   {}
+
+   std::unique_ptr<ImportPlugin> mpPlugin;
+};
+}
+
 Importer::RegisteredImportPlugin::RegisteredImportPlugin(
-   std::unique_ptr<ImportPlugin> pPlugin )
+   const Identifier &id,
+   std::unique_ptr<ImportPlugin> pPlugin,
+   const Registry::Placement &placement )
 {
    if ( pPlugin )
-      sImportPluginList().emplace_back( std::move( pPlugin ) );
+      Registry::RegisterItem( sRegistry(), placement,
+         std::make_unique< ImporterItem >( id, std::move( pPlugin ) ) );
 }
 
 UnusableImportPluginList &Importer::sUnusableImportPluginList()
@@ -110,16 +132,29 @@ bool Importer::Initialize()
    // order is significant.  If none match, they will all be tried
    // in the order defined here.
 
-   // They were pushed on the array at static initialization time in an
-   // unspecified sequence.  Sort according to the sequence numbers they
-   // report to make the order determinate.
-   auto &list = sImportPluginList();
-   std::sort( list.begin(), list.end(),
-      []( const ImportPluginList::value_type &a,
-          const ImportPluginList::value_type &b ){
-         return a->SequenceNumber() < b->SequenceNumber();
+   using namespace Registry;
+   static OrderingPreferenceInitializer init{
+      PathStart,
+      { {wxT(""), wxT("PCM,OGG,FLAC,MP3,LOF,FFmpeg") } }
+      // QT and GStreamer are only conditionally compiled and would get
+      // placed at the end if present
+   };
+   
+   static struct MyVisitor final : Visitor {
+      MyVisitor()
+      {
+         // Once only, visit the registry to collect the plug-ins properly
+         // sorted
+         TransparentGroupItem<> top{ PathStart };
+         Registry::Visit( *this, &top, &sRegistry() );
       }
-   );
+
+      void Visit( SingleItem &item, const Path &path ) override
+      {
+         sImportPluginList().push_back(
+            static_cast<ImporterItem&>( item ).mpPlugin.get() );
+      }
+   } visitor;
 
    // Ordering of the unusable plugin list is not important.
 
@@ -292,7 +327,7 @@ void Importer::ReadImportItems()
          {
             if (importPlugin->GetPluginStringID() == new_item->filters[i])
             {
-               new_item->filter_objects.push_back(importPlugin.get());
+               new_item->filter_objects.push_back(importPlugin);
                found = true;
                break;
             }
@@ -307,7 +342,7 @@ void Importer::ReadImportItems()
          bool found = false;
          for (size_t i = 0; i < new_item->filter_objects.size(); i++)
          {
-            if (importPlugin.get() == new_item->filter_objects[i])
+            if (importPlugin == new_item->filter_objects[i])
             {
                found = true;
                break;
@@ -323,7 +358,7 @@ void Importer::ReadImportItems()
                new_item->filters.begin() + index,
                importPlugin->GetPluginStringID());
             new_item->filter_objects.insert(
-               new_item->filter_objects.begin() + index, importPlugin.get());
+               new_item->filter_objects.begin() + index, importPlugin);
             if (new_item->divider >= 0)
                new_item->divider++;
          }
@@ -402,7 +437,7 @@ std::unique_ptr<ExtImportItem> Importer::CreateDefaultImportItem()
    for (const auto &importPlugin : sImportPluginList())
    {
       new_item->filters.push_back(importPlugin->GetPluginStringID());
-      new_item->filter_objects.push_back(importPlugin.get());
+      new_item->filter_objects.push_back(importPlugin);
    }
    new_item->divider = -1;
    return new_item;
@@ -462,7 +497,7 @@ bool Importer::Import( AudacityProject &project,
          {
             // This plugin corresponds to user-selected filter, try it first.
             wxLogDebug(wxT("Inserting %s"),plugin->GetPluginStringID());
-            importPlugins.insert(importPlugins.begin(), plugin.get());
+            importPlugins.insert(importPlugins.begin(), plugin);
          }
       }
    }
@@ -532,14 +567,14 @@ bool Importer::Import( AudacityProject &project,
    // is not changed by user selection overrides or any other mechanism, but we include an assert
    // in case subsequent code revisions to the constructor should break this assumption that
    // libsndfile is first.
-   ImportPlugin *libsndfilePlugin = sImportPluginList().begin()->get();
+   ImportPlugin *libsndfilePlugin = *sImportPluginList().begin();
    wxASSERT(libsndfilePlugin->GetPluginStringID() == wxT("libsndfile"));
 
    for (const auto &plugin : sImportPluginList())
    {
       // Make sure its not already in the list
       if (importPlugins.end() ==
-          std::find(importPlugins.begin(), importPlugins.end(), plugin.get()))
+          std::find(importPlugins.begin(), importPlugins.end(), plugin))
       {
          if (plugin->SupportsExtension(extension))
          {
@@ -562,7 +597,7 @@ bool Importer::Import( AudacityProject &project,
                }
             }
             wxLogDebug(wxT("Appending %s"),plugin->GetPluginStringID());
-            importPlugins.push_back(plugin.get());
+            importPlugins.push_back(plugin);
          }
       }
    }
@@ -577,10 +612,10 @@ bool Importer::Import( AudacityProject &project,
       {
          // Make sure its not already in the list
          if (importPlugins.end() ==
-             std::find(importPlugins.begin(), importPlugins.end(), plugin.get()))
+             std::find(importPlugins.begin(), importPlugins.end(), plugin))
          {
             wxLogDebug(wxT("Appending %s"),plugin->GetPluginStringID());
-            importPlugins.push_back(plugin.get());
+            importPlugins.push_back(plugin);
          }
       }
    }

src/import/Import.h

@@ -20,6 +20,8 @@
 #include "../widgets/wxPanelWrapper.h" // to inherit
 #include "../FileNames.h" // for FileType
 
+#include "../commands/CommandManager.h" // for Registry::Placement
+
 class wxArrayString;
 class wxListBox;
 class AudacityProject;
@@ -80,7 +82,10 @@ public:
    // Objects of this type are statically constructed in files implementing
    // subclasses of ImportPlugin
    struct RegisteredImportPlugin{
-      RegisteredImportPlugin( std::unique_ptr<ImportPlugin> );
+      RegisteredImportPlugin(
+         const Identifier &id, // an internal string naming the plug-in
+         std::unique_ptr<ImportPlugin>,
+         const Registry::Placement &placement = { wxEmptyString, {} } );
    };
 
    // Objects of this type are statically constructed in files, to identify

src/import/ImportFFmpeg.cpp

@@ -185,8 +185,6 @@ public:
    ///! Probes the file and opens it if appropriate
    std::unique_ptr<ImportFileHandle> Open(
       const FilePath &Filename, AudacityProject*) override;
-   
-   unsigned SequenceNumber() const override;
 };
 
 ///! Does acual import, returned by FFmpegImportPlugin::Open
@@ -335,12 +333,7 @@ std::unique_ptr<ImportFileHandle> FFmpegImportPlugin::Open(
    return std::move(handle);
 }
 
-unsigned FFmpegImportPlugin::SequenceNumber() const
-{
-   return 60;
-}
-
-static Importer::RegisteredImportPlugin registered{
+static Importer::RegisteredImportPlugin registered{ "FFmpeg",
    std::make_unique< FFmpegImportPlugin >()
 };
 

src/import/ImportFLAC.cpp

@@ -137,8 +137,6 @@ class FLACImportPlugin final : public ImportPlugin
    TranslatableString GetPluginFormatDescription() override;
    std::unique_ptr<ImportFileHandle> Open(
       const FilePath &Filename, AudacityProject*)  override;
-
-   unsigned SequenceNumber() const override;
 };
 
 
@@ -334,12 +332,7 @@ std::unique_ptr<ImportFileHandle> FLACImportPlugin::Open(
    return std::move(handle);
 }
 
-unsigned FLACImportPlugin::SequenceNumber() const
-{
-   return 30;
-}
-
-static Importer::RegisteredImportPlugin registered{
+static Importer::RegisteredImportPlugin registered{ "FLAC",
    std::make_unique< FLACImportPlugin >()
 };
 

src/import/ImportForwards.h

@@ -16,7 +16,7 @@ class ImportPlugin;
 class UnusableImportPlugin;
 
 using ImportPluginList =
-   std::vector< std::unique_ptr<ImportPlugin> >;
+   std::vector< ImportPlugin * >;
 using UnusableImportPluginList =
    std::vector< std::unique_ptr<UnusableImportPlugin> >;
 

src/import/ImportGStreamer.cpp

@@ -249,8 +249,6 @@ public:
    ///! Probes the file and opens it if appropriate
    std::unique_ptr<ImportFileHandle> Open(
       const wxString &Filename, AudacityProject*) override;
-
-   unsigned SequenceNumber() const override;
 };
 
 // ============================================================================
@@ -261,7 +259,8 @@ public:
 // Instantiate GStreamerImportPlugin and add to the list of known importers
 
 static
-Importer::RegisteredImportPlugin{ []() -> std::unique_ptr< ImportPlugin > {
+Importer::RegisteredImportPlugin{ "GStreamer",
+   []() -> std::unique_ptr< ImportPlugin > {
    wxLogMessage(_TS("Audacity is built against GStreamer version %d.%d.%d-%d"),
                 GST_VERSION_MAJOR,
                 GST_VERSION_MINOR,
@@ -1152,11 +1151,6 @@ GStreamerImportFileHandle::Import(TrackFactory *trackFactory,
    return updateResult;
 }
 
-unsigned GStreamerImportPlugin::SequenceNumber() const
-{
-   return 80;
-}
-
 // ----------------------------------------------------------------------------
 // Message handlers
 // ----------------------------------------------------------------------------

src/import/ImportLOF.cpp

@@ -116,8 +116,6 @@ public:
    TranslatableString GetPluginFormatDescription() override;
    std::unique_ptr<ImportFileHandle> Open(
       const FilePath &Filename, AudacityProject *pProject) override;
-
-   unsigned SequenceNumber() const override;
 };
 
 
@@ -272,12 +270,7 @@ ProgressResult LOFImportFileHandle::Import(
    return ProgressResult::Success;
 }
 
-unsigned LOFImportPlugin::SequenceNumber() const
-{
-   return 50;
-}
-
-static Importer::RegisteredImportPlugin registered{
+static Importer::RegisteredImportPlugin registered{ "LOF",
    std::make_unique< LOFImportPlugin >()
 };
 

src/import/ImportMP3.cpp

@@ -117,8 +117,6 @@ public:
    TranslatableString GetPluginFormatDescription() override;
    std::unique_ptr<ImportFileHandle> Open(
       const FilePath &Filename, AudacityProject*) override;
-
-   unsigned SequenceNumber() const override;
 };
 
 class MP3ImportFileHandle final : public ImportFileHandle
@@ -257,12 +255,7 @@ ProgressResult MP3ImportFileHandle::Import(
    return privateData.updateResult;
 }
 
-unsigned MP3ImportPlugin::SequenceNumber() const
-{
-   return 40;
-}
-
-static Importer::RegisteredImportPlugin registered{
+static Importer::RegisteredImportPlugin registered{ "MP3",
    std::make_unique< MP3ImportPlugin >()
 };
 

src/import/ImportOGG.cpp

@@ -91,8 +91,6 @@ public:
    TranslatableString GetPluginFormatDescription() override;
    std::unique_ptr<ImportFileHandle> Open(
       const FilePath &Filename, AudacityProject*) override;
-
-   unsigned SequenceNumber() const override;
 };
 
 
@@ -215,12 +213,7 @@ std::unique_ptr<ImportFileHandle> OggImportPlugin::Open(
    return std::make_unique<OggImportFileHandle>(filename, std::move(file), std::move(vorbisFile));
 }
 
-unsigned OggImportPlugin::SequenceNumber() const
-{
-   return 20;
-}
-
-static Importer::RegisteredImportPlugin registered{
+static Importer::RegisteredImportPlugin registered{ "OGG",
    std::make_unique< OggImportPlugin >()
 };
 

src/import/ImportPCM.cpp

@@ -89,8 +89,6 @@ public:
    TranslatableString GetPluginFormatDescription() override;
    std::unique_ptr<ImportFileHandle> Open(
       const FilePath &Filename, AudacityProject*) override;
-
-   unsigned SequenceNumber() const override;
 };
 
 
@@ -192,12 +190,7 @@ std::unique_ptr<ImportFileHandle> PCMImportPlugin::Open(
    return std::make_unique<PCMImportFileHandle>(filename, std::move(file), info);
 }
 
-unsigned PCMImportPlugin::SequenceNumber() const
-{
-   return 10;
-}
-
-static Importer::RegisteredImportPlugin registered{
+static Importer::RegisteredImportPlugin registered{ "PCM",
    std::make_unique< PCMImportPlugin >()
 };
 

src/import/ImportPlugin.h

@@ -96,8 +96,6 @@ public:
    virtual std::unique_ptr<ImportFileHandle> Open(
       const FilePath &Filename, AudacityProject*) = 0;
 
-   virtual unsigned SequenceNumber() const = 0;
-
    virtual ~ImportPlugin() { }
 
 protected:

src/import/ImportQT.cpp

@@ -125,8 +125,6 @@ class QTImportPlugin final : public ImportPlugin
    std::unique_ptr<ImportFileHandle> Open(
       const wxString & Filename, AudacityProject*) override;
 
-   unsigned SequenceNumber() const override;
-
  private:
    bool mInitialized;
 };
@@ -222,12 +220,7 @@ std::unique_ptr<ImportFileHandle> QTImportPlugin::Open(
    return std::make_unique<QTImportFileHandle>(Filename, theMovie);
 }
 
-unsigned QTImportPlugin::SequenceNumber() const
-{
-   return 70;
-}
-
-static Importer::RegisteredImportPlugin registered{
+static Importer::RegisteredImportPlugin registered{ "QT",
    std::make_unique< QTImportPlugin >()
 };