stringify helpers before bundling

Author: Rich-Harris

package.json

@@ -17,10 +17,10 @@
     "precodecov": "npm run coverage",
     "lint": "eslint src test/*.js",
     "build": "npm run build:main && npm run build:shared && npm run build:ssr",
-    "build:main": "rollup -c rollup/rollup.config.main.js",
+    "build:main": "node shared/_build.js && rollup -c rollup/rollup.config.main.js",
     "build:shared": "rollup -c rollup/rollup.config.shared.js",
     "build:ssr": "rollup -c rollup/rollup.config.ssr.js",
-    "dev": "rollup -c rollup/rollup.config.main.js -w",
+    "dev": "node shared/_build.js && rollup -c rollup/rollup.config.main.js -w",
     "dev:shared": "rollup -c rollup/rollup.config.shared.js -w",
     "pretest": "npm run build",
     "prepublish": "npm run lint && npm run build"

src/generators/dom/index.js

@@ -6,7 +6,7 @@ import { walk } from 'estree-walker';
 import deindent from '../../utils/deindent.js';
 import CodeBuilder from '../../utils/CodeBuilder.js';
 import visit from './visit.js';
-import { nameMap, sharedMap } from './sharedNames.js';
+import shared from './shared.js';
 import Generator from '../Generator.js';
 import preprocess from './preprocess.js';
 
@@ -25,7 +25,7 @@ class DomGenerator extends Generator {
 	}
 
 	helper ( name ) {
-		if ( this.options.dev && sharedMap.has( `${name}Dev` ) ) {
+		if ( this.options.dev && `${name}Dev` in shared ) {
 			name = `${name}Dev`;
 		}
 
@@ -275,20 +275,20 @@ export default function dom ( parsed, source, options ) {
 		);
 	} else {
 		generator.uses.forEach( key => {
-			const str = sharedMap.get( key );
+			const str = shared[ key ];
 			const code = new MagicString( str );
-			const fn = parseExpressionAt( str, 0 );
+			const expression = parseExpressionAt( str, 0 );
 
-			let scope = annotateWithScopes( fn );
+			let scope = annotateWithScopes( expression );
 
-			walk( fn, {
+			walk( expression, {
 				enter ( node, parent ) {
 					if ( node._scope ) scope = node._scope;
 
 					if ( node.type === 'Identifier' && isReference( node, parent ) && !scope.has( node.name ) ) {
-						if ( nameMap.has( node.name ) ) {
+						if ( node.name in shared ) {
 							// this helper function depends on another one
-							const dependency = nameMap.get( node.name );
+							const dependency = node.name;
 							generator.uses.add( dependency );
 
 							const alias = generator.alias( dependency );
@@ -309,8 +309,8 @@ export default function dom ( parsed, source, options ) {
 					`var ${generator.alias( 'transitionManager' )} = window.${global} || ( window.${global} = ${code});`
 				);
 			} else {
-				const alias = generator.alias( fn.id.name );
-				if ( alias !== fn.id.name ) code.overwrite( fn.id.start, fn.id.end, alias );
+				const alias = generator.alias( expression.id.name );
+				if ( alias !== expression.id.name ) code.overwrite( expression.id.start, expression.id.end, alias );
 
 				builders.main.addBlock( code.toString() );
 			}

src/generators/dom/sharedNames.js

@@ -0,0 +1,36 @@
+const fs = require( 'fs' );
+const path = require( 'path' );
+const acorn = require( 'acorn' );
+
+const declarations = {};
+
+fs.readdirSync( __dirname ).forEach( file => {
+	if ( !/^[a-z]+\.js$/.test( file ) ) return;
+
+	const source = fs.readFileSync( path.join( __dirname, file ), 'utf-8' );
+	const ast = acorn.parse( source, {
+		ecmaVersion: 6,
+		sourceType: 'module'
+	});
+
+	ast.body.forEach( node => {
+		if ( node.type !== 'ExportNamedDeclaration' ) return;
+
+		const { declaration } = node;
+		if ( !declaration ) return;
+
+		const name = declaration.type === 'VariableDeclaration' ?
+			declaration.declarations[0].id.name :
+			declaration.id.name;
+
+		const value = declaration.type === 'VariableDeclaration' ?
+			declaration.declarations[0].init :
+			declaration;
+
+		const { start, end } = value;
+		declarations[ name ] = source.slice( start, end );
+	});
+});
+
+fs.writeFileSync( 'src/generators/dom/shared.js', `// this file is auto-generated, do not edit it
+export default ${JSON.stringify( declarations, null, '\t' )};` );