extensions/typescript-language-features/src/languageProvider.ts/LanguageProvider/handles
class LanguageProvider:	public handles(resource: vscode.Uri, doc: vscode.TextDocument): boolean {
		if (doc && this.description.modeIds.indexOf(doc.languageId) >= 0) {
			return true;
		}

		const base = basename(resource.fsPath);
		return !!base && (!!this.description.configFilePattern && this.description.configFilePattern.test(base));
	}