Asset System: Asset Library Loader

Moved to T103188: Asset System: Asset Library Loader.

• All loader methods should be expected to run in a thread.
• Loaders may instantiate and use other loaders. E.g. a CurrentFileAssetLibraryLoader.

class AbstractAssetLibraryLoader {
  /** The asset library to load into. */
  AssetLibrary &library_;
  
public:
  AssetLibraryLoader(AssetLibrary &library);
  virtual ~AssetLibraryLoader() = default;
  
  virtual load_asset_representations() const = 0;
  virtual load_asset_preview(const AssetRepresentation &asset) const = 0;
  virtual load_catalog_definitions() const = 0;

  /** Actually load the asset for applying or import. */
  virtual load_asset(const AssetRepresentation &asset) const = 0;
  
protected:
  AssetRepresentation &add_asset_representation(AssetIdentifier identifier, ID &) const;
  AssetRepresentation &add_asset_representation(
      AssetIdentifier identifier,
      /* Name to be presented to the user. */
      StringRef name,
      unique_ptr<AssetMetaData> metadata) const;
  
  void add_asset_catalog_definition_file(
    AssetCatalogDefinitionFile &definiton_file,
    /* Optional to support writing catalogs back. Otherwise catalogs are read-only. */
    unique_ptr<AbstractAssetCatalogDefinitionWriter> writer = nullptr) const;
};

class AssetLibrary {
  /* ... */
   
  /** The loader for this asset library. */
  unique_ptr<AbstractAssetLibraryLoader> loader_;

public:
  AssetLibrary(unique_ptr<AbstractAssetLibraryLoader> loader);
  
  static AssetLibrary *load(unique_ptr<AbstractAssetLibraryLoader> loader);
};

Future

• Register libraries?
  ​​void AssetSystem::register_library(
  ​​    StringRef ui_name,
  ​​    AssetLibraryLocation default_location, 
  ​​    unique_ptr<AbstractAssetLibraryLoader> loader);