feat: add support for custom fs provider

We're looking to add our own providers for `user` and `cache` fs so they
can be persisted between sessions. With this change, we don't break the
existing API but we can allow for adding custom filesystems for these
providers.

src/service-override/files.ts

@@ -457,30 +457,51 @@ class DelegateFileSystemProvider implements IFileSystemProvider {
 const fileSystemProvider = new OverlayFileSystemProvider()
 fileSystemProvider.register(0, new MkdirpOnWriteInMemoryFileSystemProvider())
 
+interface CustomFileSystemProviders {
+  [scheme: string]: IFileSystemProvider
+}
+
 const extensionFileSystemProvider = new RegisteredFileSystemProvider(true)
 class MemoryFileService extends FileService {
-  constructor (@ILogService logService: ILogService) {
+  constructor (@ILogService logService: ILogService, additionalProviders: CustomFileSystemProviders = {}) {
     super(logService)
 
-    const userMemoryFileSystem = new InMemoryFileSystemProvider()
-
-    this.registerProvider('user', userMemoryFileSystem)
-    this.registerProvider('extension', extensionFileSystemProvider)
-    this.registerProvider('cache', new InMemoryFileSystemProvider())
-    this.registerProvider('logs', new InMemoryFileSystemProvider())
-    this.registerProvider(Schemas.vscodeUserData, new InMemoryFileSystemProvider())
-    this.registerProvider(Schemas.tmp, new InMemoryFileSystemProvider())
-    let fileSystemProviderDisposable = this.registerProvider('file', fileSystemProvider)
-    fileSystemProvider.onDidChangeOverlays(() => {
-      fileSystemProviderDisposable.dispose()
-      fileSystemProviderDisposable = this.registerProvider('file', fileSystemProvider)
-    })
+    if (additionalProviders.user == null) {
+      const userMemoryFileSystem = new InMemoryFileSystemProvider()
+      this.registerProvider('user', userMemoryFileSystem)
+    }
+    if (additionalProviders.extension == null) {
+      this.registerProvider('extension', extensionFileSystemProvider)
+    }
+    if (additionalProviders.cache == null) {
+      this.registerProvider('cache', new InMemoryFileSystemProvider())
+    }
+    if (additionalProviders.logs == null) {
+      this.registerProvider('logs', new InMemoryFileSystemProvider())
+    }
+    if (additionalProviders[Schemas.vscodeUserData] == null) {
+      this.registerProvider(Schemas.vscodeUserData, new InMemoryFileSystemProvider())
+    }
+    if (additionalProviders[Schemas.tmp] == null) {
+      this.registerProvider(Schemas.tmp, new InMemoryFileSystemProvider())
+    }
+    if (additionalProviders.file == null) {
+      let fileSystemProviderDisposable = this.registerProvider('file', fileSystemProvider)
+      fileSystemProvider.onDidChangeOverlays(() => {
+        fileSystemProviderDisposable.dispose()
+        fileSystemProviderDisposable = this.registerProvider('file', fileSystemProvider)
+      })
+    }
+
+    for (const [scheme, provider] of Object.entries(additionalProviders)) {
+      this.registerProvider(scheme, provider)
+    }
   }
 }
 
-export default function getServiceOverride (): IEditorOverrideServices {
+export default function getServiceOverride (customProviders?: CustomFileSystemProviders): IEditorOverrideServices {
   return {
-    [IFileService.toString()]: new SyncDescriptor(MemoryFileService, [], true)
+    [IFileService.toString()]: new SyncDescriptor(MemoryFileService, [customProviders], true)
   }
 }
 
@@ -504,6 +525,7 @@ export function registerFileSystemOverlay (priority: number, provider: IFileSyst
 }
 
 export {
+  CustomFileSystemProviders,
   IFileSystemProviderWithFileReadWriteCapability,
   FileSystemProviderCapabilities,
   FileType,