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# @rollup/plugin-babel
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@rollup/plugin-babel provides seamless integration between Rollup and Babel, enabling developers to transpile ES6/7 code during the bundling process. It offers multiple helper handling strategies and supports both input and output transformation modes with comprehensive configuration options.
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## Package Information
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- **Package Name**: @rollup/plugin-babel
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- **Package Type**: npm
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- **Language**: JavaScript/TypeScript
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- **Installation**: `npm install @rollup/plugin-babel --save-dev`
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## Core Imports
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```javascript
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import { babel } from '@rollup/plugin-babel';
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```
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For specific functions:
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```javascript
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import { 
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  babel, 
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  getBabelInputPlugin, 
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  getBabelOutputPlugin,
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  createBabelInputPluginFactory,
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  createBabelOutputPluginFactory 
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} from '@rollup/plugin-babel';
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```
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Using default export:
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```javascript
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import babel from '@rollup/plugin-babel';
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// babel is an alias for getBabelInputPlugin
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```
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For CommonJS:
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```javascript
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const { babel, getBabelInputPlugin, getBabelOutputPlugin } = require('@rollup/plugin-babel');
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// or
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const babel = require('@rollup/plugin-babel').default;
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```
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## Basic Usage
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```javascript
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import { babel } from '@rollup/plugin-babel';
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const config = {
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  input: 'src/index.js',
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  output: {
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    dir: 'output',
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    format: 'es'
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  },
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  plugins: [babel({ babelHelpers: 'bundled' })]
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};
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export default config;
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```
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## Architecture
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@rollup/plugin-babel is built around several key components:
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- **Input Transformation**: `babel()` and `getBabelInputPlugin()` transform source files during the input phase
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- **Output Transformation**: `getBabelOutputPlugin()` transforms generated chunks during the output phase
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- **Helper Strategies**: Four different approaches for handling Babel helpers (bundled, runtime, inline, external)
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- **Factory Functions**: `createBabelInputPluginFactory()` and `createBabelOutputPluginFactory()` for custom plugin creation
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- **Configuration System**: Comprehensive options handling with validation and defaults
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- **Filter System**: Advanced file filtering with include/exclude patterns and custom filter functions
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## Capabilities
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### Input Plugin
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Primary plugin function for transforming source files during input processing. Supports comprehensive Babel configuration and file filtering.
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```javascript { .api }
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function babel(options?: RollupBabelInputPluginOptions): Plugin;
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function getBabelInputPlugin(options?: RollupBabelInputPluginOptions): Plugin;
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interface RollupBabelInputPluginOptions extends Omit<BabelTransformOptions, 'include' | 'exclude'> {
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  include?: FilterPattern;
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  exclude?: FilterPattern;
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  filter?: ReturnType<CreateFilter>;
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  extensions?: string[];
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  babelHelpers?: 'bundled' | 'runtime' | 'inline' | 'external';
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  skipPreflightCheck?: boolean;
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}
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```
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[Input Plugin](./input-plugin.md)
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### Output Plugin
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Plugin for transforming output chunks after bundle generation. Ideal for compatibility transformations and format-specific optimizations.
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```javascript { .api }
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function getBabelOutputPlugin(options?: RollupBabelOutputPluginOptions): Plugin;
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interface RollupBabelOutputPluginOptions extends Omit<BabelTransformOptions, 'include' | 'exclude'> {
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  allowAllFormats?: boolean;
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}
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```
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[Output Plugin](./output-plugin.md)
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### Custom Plugin Factories
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Advanced factory functions for creating custom Babel plugins with specialized configuration and processing logic.
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```javascript { .api }
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function createBabelInputPluginFactory(
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  customCallback?: RollupBabelCustomInputPluginBuilder
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): typeof getBabelInputPlugin;
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function createBabelOutputPluginFactory(
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  customCallback?: RollupBabelCustomOutputPluginBuilder
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): typeof getBabelOutputPlugin;
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type RollupBabelCustomInputPluginBuilder = (
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  babel: typeof babelCore
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) => RollupBabelCustomInputPlugin;
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type RollupBabelCustomOutputPluginBuilder = (
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  babel: typeof babelCore
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) => RollupBabelCustomOutputPlugin;
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```
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[Custom Plugin Factories](./custom-plugin-factories.md)
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## Core Types
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```javascript { .api }
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// From @rollup/pluginutils
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type FilterPattern = string | RegExp | Array<string | RegExp>;
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type CreateFilter = (include?: FilterPattern, exclude?: FilterPattern, options?: FilterOptions) => (id: string | unknown) => boolean;
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interface FilterOptions {
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  resolve?: string | false | null;
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}
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// From rollup
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interface Plugin {
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  name: string;
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  options?(): void;
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  resolveId?(id: string): string | null;
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  load?(id: string): string | null;
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  transform?(code: string, filename: string): TransformResult | null;
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  renderStart?(outputOptions: OutputOptions): void;
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  renderChunk?(code: string, chunk: RenderedChunk, outputOptions: OutputOptions): TransformResult | null;
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}
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interface TransformPluginContext {
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  error(message: string): never;
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  warn(message: string): void;
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  // ... other context methods
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}
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interface PluginContext {
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  error(message: string): never;
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  warn(message: string): void;
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  // ... other context methods
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}
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interface TransformResult {
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  code: string;
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  map?: SourceMap;
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}
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interface SourceMap {
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  version: number;
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  sources: string[];
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  names: string[];
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  mappings: string;
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  file?: string;
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  sourcesContent?: string[];
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}
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// From @babel/core
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interface BabelTransformOptions {
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  filename?: string;
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  filenameRelative?: string;
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  presets?: any[];
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  plugins?: any[];
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  sourceMaps?: boolean;
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  sourceType?: 'script' | 'module' | 'unambiguous';
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  // ... other Babel options
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}
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interface BabelPartialConfig {
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  options: BabelTransformOptions;
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  hasFilesystemConfig(): boolean;
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}
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interface BabelFileResult {
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  code: string;
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  map?: object;
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  ast?: object;
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}
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// Custom plugin interfaces
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interface RollupBabelCustomInputPlugin {
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  options?: RollupBabelCustomInputPluginOptions;
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  config?: RollupBabelCustomInputPluginConfig;
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  result?: RollupBabelCustomInputPluginResult;
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}
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interface RollupBabelCustomOutputPlugin {
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  options?: RollupBabelCustomOutputPluginOptions;
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  config?: RollupBabelCustomOutputPluginConfig;
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  result?: RollupBabelCustomOutputPluginResult;
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}
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type RollupBabelCustomInputPluginOptions = (
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  options: RollupBabelInputPluginOptions & Record<string, any>
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) => {
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  customOptions: Record<string, any>;
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  pluginOptions: RollupBabelInputPluginOptions;
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};
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type RollupBabelCustomOutputPluginOptions = (
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  options: RollupBabelOutputPluginOptions & Record<string, any>
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) => {
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  customOptions: Record<string, any>;
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  pluginOptions: RollupBabelOutputPluginOptions;
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};
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interface RollupBabelCustomPluginConfigOptions {
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  code: string;
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  customOptions: Record<string, any>;
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}
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interface RollupBabelCustomPluginResultOptions {
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  code: string;
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  customOptions: Record<string, any>;
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  config: BabelPartialConfig;
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  transformOptions: BabelTransformOptions;
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}
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type RollupBabelCustomInputPluginConfig = (
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  this: TransformPluginContext,
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  cfg: BabelPartialConfig,
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  options: RollupBabelCustomPluginConfigOptions
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) => BabelTransformOptions;
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type RollupBabelCustomInputPluginResult = (
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  this: TransformPluginContext,
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  result: BabelFileResult,
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  options: RollupBabelCustomPluginResultOptions
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) => BabelFileResult;
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type RollupBabelCustomOutputPluginConfig = (
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  this: PluginContext,
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  cfg: BabelPartialConfig,
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  options: RollupBabelCustomPluginConfigOptions
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) => BabelTransformOptions;
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type RollupBabelCustomOutputPluginResult = (
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  this: PluginContext,
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  result: BabelFileResult,
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  options: RollupBabelCustomPluginResultOptions
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) => BabelFileResult;
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```