| ExistsLoaderInterface | Empty interface for Twig 1.x compatibility. |
| LoaderInterface | Interface all loaders must implement. |
| SourceContextLoaderInterface | Empty interface for Twig 1.x compatibility. |
| ArrayLoader | Loads a template from an array. |
| ChainLoader | Loads templates from other loaders. |
| FilesystemLoader | Loads template from the filesystem. |
