src/vs/workbench/browser/parts/editor/breadcrumbsPicker.ts/FileFilter/filter
class FileFilter:	filter(element: IWorkspaceFolder | IFileStat, _parentVisibility: TreeVisibility): boolean {
		if (isWorkspaceFolder(element)) {
			// not a file
			return true;
		}
		const folder = this._workspaceService.getWorkspaceFolder(element.resource);
		if (!folder || !this._cachedExpressions.has(folder.uri.toString())) {
			// no folder or no filer
			return true;
		}

		const expression = this._cachedExpressions.get(folder.uri.toString())!;
		return !expression(element.resource.path, basename(element.resource));
	}