Feature: add ability to pass in specific version of svelte

README.md

@@ -77,6 +77,16 @@ export default {
 
         // let Rollup handle all other warnings normally
         handler(warning);
+      },
+
+      // Pass in a specific version of Svelte, e.g. if you use
+      // npm aliases to install multiple versions you can import
+      // a specific version:
+      // import svelte1 from 'svelte1' // aliased version of [email protected]
+      svelte: {
+        compile: svelte1.compile,
+        preprocess: svelte1.preprocess,
+        major_version: 1
       }
     })
   ]

index.d.ts

@@ -23,6 +23,12 @@ declare class CssWriter {
   toString(): string;
 }
 
+interface Svelte {
+  compile: any;
+  preprocess: any;
+  major_version: number;
+}
+
 interface Options {
   /**
    * By default, all .svelte and .html files are compiled
@@ -80,6 +86,11 @@ interface Options {
    */
   customElement?: boolean;
 
+  /**
+   * Pass in a specific version of Svelte.
+   */
+  svelte?: Svelte;
+
   /**
    * let Rollup handle all other warnings normally
    */

index.js

@@ -1,16 +1,22 @@
 const fs = require('fs');
 const path = require('path');
 const relative = require('require-relative');
-const { version } = require('svelte/package.json');
 const { createFilter } = require('rollup-pluginutils');
 const { encode, decode } = require('sourcemap-codec');
 
-const major_version = +version[0];
 const pkg_export_errors = new Set();
 
-const { compile, preprocess } = major_version >= 3
-	? require('svelte/compiler.js')
-	: require('svelte');
+function loadDefaultSvelte() {
+	const { version } = require('svelte/package.json');
+
+	const major_version = +version[0];
+
+	const { compile, preprocess } = major_version >= 3
+		? require('svelte/compiler.js')
+		: require('svelte');
+
+	return { compile, preprocess, major_version };
+}
 
 function sanitize(input) {
 	return path
@@ -110,6 +116,7 @@ class CssWriter {
 }
 
 module.exports = function svelte(options = {}) {
+	const { compile, preprocess, major_version } = options.svelte || loadDefaultSvelte();
 	const filter = createFilter(options.include, options.exclude);
 
 	const extensions = options.extensions || ['.html', '.svelte'];