From 1bd586aad7fadeb4bdc6ed0f1f9d94040889e938 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Sat, 23 Jun 2018 22:15:37 +0200
Subject: [PATCH] Cache preflight check results per plugin's instance (#224)

---
 packages/rollup-plugin-babel/src/index.js     |  3 +-
 .../rollup-plugin-babel/src/preflightCheck.js | 62 ++++++++++---------
 2 files changed, 34 insertions(+), 31 deletions(-)

diff --git a/packages/rollup-plugin-babel/src/index.js b/packages/rollup-plugin-babel/src/index.js
index 044a5184f..e69000396 100644
--- a/packages/rollup-plugin-babel/src/index.js
+++ b/packages/rollup-plugin-babel/src/index.js
@@ -1,7 +1,7 @@
 import { dirname } from 'path';
 import { buildExternalHelpers, transform } from '@babel/core';
 import { createFilter } from 'rollup-pluginutils';
-import preflightCheck from './preflightCheck.js';
+import createPreflightCheck from './preflightCheck.js';
 import helperPlugin from './helperPlugin.js';
 import { warnOnce } from './utils.js';
 import { RUNTIME, EXTERNAL, HELPERS } from './constants.js';
@@ -30,6 +30,7 @@ export default function babel ( options ) {
 	} = unpackOptions(options);
 
 	const filter = createFilter( include, exclude );
+	const preflightCheck = createPreflightCheck();
 
 	return {
 		name: 'babel',
diff --git a/packages/rollup-plugin-babel/src/preflightCheck.js b/packages/rollup-plugin-babel/src/preflightCheck.js
index cc47d8a3b..f71fcb073 100644
--- a/packages/rollup-plugin-babel/src/preflightCheck.js
+++ b/packages/rollup-plugin-babel/src/preflightCheck.js
@@ -12,43 +12,45 @@ function fallbackClassTransform () {
 	};
 }
 
-let preflightCheckResults = {};
+export default function createPreflightCheck () {
+	let preflightCheckResults = {};
 
-export default function preflightCheck ( ctx, options, dir ) {
-	if ( !preflightCheckResults[ dir ] ) {
-		let helpers;
+	return ( ctx, options, dir ) => {
+		if ( !preflightCheckResults[ dir ] ) {
+			let helpers;
 
-		options = Object.assign( {}, options );
-		delete options.only;
-		delete options.ignore;
+			options = Object.assign( {}, options );
+			delete options.only;
+			delete options.ignore;
 
-		options.filename = join( dir, 'x.js' );
+			options.filename = join( dir, 'x.js' );
 
-		const inputCode = 'class Foo extends Bar {};\nexport default Foo;';
-		let check = transform( inputCode, options ).code;
+			const inputCode = 'class Foo extends Bar {};\nexport default Foo;';
+			let check = transform( inputCode, options ).code;
 
-		if ( ~check.indexOf('class ') ) {
-			options.plugins = (options.plugins || []).concat( fallbackClassTransform );
-			check = transform( inputCode, options ).code;
-		}
+			if ( ~check.indexOf('class ') ) {
+				options.plugins = (options.plugins || []).concat( fallbackClassTransform );
+				check = transform( inputCode, options ).code;
+			}
 
-		if ( ~check.indexOf( 'import _inherits' ) ) helpers = RUNTIME;
-		else if ( ~check.indexOf( 'function _inherits' ) ) helpers = INLINE;
-		else if ( ~check.indexOf( 'babelHelpers' ) ) helpers = EXTERNAL;
-		else {
-			ctx.error( 'An unexpected situation arose. Please raise an issue at https://github.com/rollup/rollup-plugin-babel/issues. Thanks!' );
-		}
+			if ( ~check.indexOf( 'import _inherits' ) ) helpers = RUNTIME;
+			else if ( ~check.indexOf( 'function _inherits' ) ) helpers = INLINE;
+			else if ( ~check.indexOf( 'babelHelpers' ) ) helpers = EXTERNAL;
+			else {
+				ctx.error( 'An unexpected situation arose. Please raise an issue at https://github.com/rollup/rollup-plugin-babel/issues. Thanks!' );
+			}
 
-		if (
-			!~check.indexOf( 'export default' ) &&
-			!~check.indexOf( 'export default Foo' ) &&
-			!~check.indexOf( 'export { Foo as default }' )
-		) {
-			ctx.error( 'It looks like your Babel configuration specifies a module transformer. Please disable it. See https://github.com/rollup/rollup-plugin-babel#configuring-babel for more information' );
-		}
+			if (
+				!~check.indexOf( 'export default' ) &&
+				!~check.indexOf( 'export default Foo' ) &&
+				!~check.indexOf( 'export { Foo as default }' )
+			) {
+				ctx.error( 'It looks like your Babel configuration specifies a module transformer. Please disable it. See https://github.com/rollup/rollup-plugin-babel#configuring-babel for more information' );
+			}
 
-		preflightCheckResults[ dir ] = helpers;
-	}
+			preflightCheckResults[ dir ] = helpers;
+		}
 
-	return preflightCheckResults[ dir ];
+		return preflightCheckResults[ dir ];
+	};
 }