refactor: 💡 simplify transformer calls

Author: kaisermann

src/autoProcess.ts

@@ -1,19 +1,18 @@
 import stripIndent from 'strip-indent';
-import { version } from 'svelte/package.json';
 
 import {
   PreprocessorGroup,
-  TransformerOptions,
   Preprocessor,
   Options,
   Processed,
+  TransformerArgs,
+  TransformerOptions,
 } from './types';
 import { hasPostCssInstalled } from './modules/hasPostcssInstalled';
 import { concat } from './modules/concat';
 import { parseFile } from './modules/parseFile';
 import { addLanguageAlias } from './modules/language';
-import { runTransformer } from './modules/transformers';
-import { throwUnsupportedError } from './modules/errors';
+import { throwUnsupportedError, throwError } from './modules/errors';
 
 interface Transformers {
   typescript?: TransformerOptions<Options.Typescript>;
@@ -33,14 +32,6 @@ type AutoPreprocessOptions = Transformers & {
   markupTagName?: string;
   aliases?: Array<[string, string]>;
   preserve?: string[];
-  // workaround while we don't have this
-  // https://github.com/microsoft/TypeScript/issues/17867
-  [languageName: string]:
-    | string
-    | Promise<string>
-    | Array<[string, string]>
-    | string[]
-    | TransformerOptions;
 };
 
 const ALIAS_OPTION_OVERRIDES: Record<string, any> = {
@@ -49,6 +40,35 @@ const ALIAS_OPTION_OVERRIDES: Record<string, any> = {
   },
 };
 
+export const runTransformer = async (
+  name: string,
+  options: TransformerOptions,
+  { content, map, filename, attributes }: TransformerArgs<any>,
+): Promise<Processed> => {
+  // remove any unnecessary indentation (useful for coffee, pug and sugarss)
+  content = stripIndent(content);
+
+  if (typeof options === 'function') {
+    return options({ content, map, filename, attributes });
+  }
+
+  try {
+    const { transformer } = await import(`./transformers/${name}`);
+
+    return transformer({
+      content,
+      filename,
+      map,
+      attributes,
+      options: typeof options === 'boolean' ? null : options,
+    });
+  } catch (e) {
+    throwError(
+      `Error transforming '${name}'.\n\nMessage:\n${e.message}\n\nStack:\n${e.stack}`,
+    );
+  }
+};
+
 export function autoPreprocess(
   {
     aliases,

src/modules/transformers.ts

@@ -4,7 +4,7 @@ import { parseFile } from '../modules/parseFile';
 
 export default (options?: Options.Babel): PreprocessorGroup => ({
   async script(svelteFile) {
-    const { default: transformer } = await import('../transformers/babel');
+    const { transformer } = await import('../transformers/babel');
 
     const { content, filename, dependencies, attributes } = await parseFile(
       svelteFile,

src/processors/babel.ts

@@ -4,9 +4,7 @@ import { concat } from '../modules/concat';
 
 export default (options?: Options.Coffeescript): PreprocessorGroup => ({
   async script(svelteFile) {
-    const { default: transformer } = await import(
-      '../transformers/coffeescript'
-    );
+    const { transformer } = await import('../transformers/coffeescript');
 
     const {
       content,

src/processors/coffeescript.ts

@@ -3,9 +3,7 @@ import { PreprocessorGroup } from '../types';
 export default (): PreprocessorGroup => {
   return {
     async style({ content, attributes, filename }) {
-      const { default: transformer } = await import(
-        '../transformers/globalStyle'
-      );
+      const { transformer } = await import('../transformers/globalStyle');
 
       if (!attributes.global) return { code: content };
 

src/processors/globalStyle.ts

@@ -4,7 +4,7 @@ import { concat } from '../modules/concat';
 
 export default (options?: Options.Less): PreprocessorGroup => ({
   async style(svelteFile) {
-    const { default: transformer } = await import('../transformers/less');
+    const { transformer } = await import('../transformers/less');
     const {
       content,
       filename,

src/processors/less.ts

@@ -5,7 +5,7 @@ import { concat } from '../modules/concat';
 /** Adapted from https://github.com/TehShrike/svelte-preprocess-postcss */
 export default (options?: Options.Postcss): PreprocessorGroup => ({
   async style(svelteFile) {
-    const { default: transformer } = await import('../transformers/postcss');
+    const { transformer } = await import('../transformers/postcss');
     const { content, filename, attributes, dependencies } = await parseFile(
       svelteFile,
       'css',

src/processors/postcss.ts

@@ -2,7 +2,7 @@ import { Options, PreprocessorGroup } from '../types';
 
 export default (options?: Options.Pug): PreprocessorGroup => ({
   async markup({ content, filename }) {
-    const { default: transformer } = await import('../transformers/pug');
+    const { transformer } = await import('../transformers/pug');
 
     return transformer({ content, filename, options });
   },

src/processors/pug.ts

@@ -2,7 +2,7 @@ import { PreprocessorGroup, Options } from '../types';
 
 export default (options: Options.Replace): PreprocessorGroup => ({
   async markup({ content, filename }) {
-    const { default: transformer } = await import('../transformers/replace');
+    const { transformer } = await import('../transformers/replace');
 
     return transformer({ content, filename, options });
   },

src/processors/replace.ts

@@ -4,7 +4,7 @@ import { concat } from '../modules/concat';
 
 export default (options?: Options.Sass): PreprocessorGroup => ({
   async style(svelteFile) {
-    const { default: transformer } = await import('../transformers/scss');
+    const { transformer } = await import('../transformers/scss');
     const {
       content,
       filename,

src/processors/scss.ts

@@ -4,7 +4,7 @@ import { concat } from '../modules/concat';
 
 export default (options?: Options.Stylus): PreprocessorGroup => ({
   async style(svelteFile) {
-    const { default: transformer } = await import('../transformers/stylus');
+    const { transformer } = await import('../transformers/stylus');
     const {
       content,
       filename,

src/processors/stylus.ts

@@ -4,7 +4,7 @@ import { concat } from '../modules/concat';
 
 export default (options?: Options.Typescript): PreprocessorGroup => ({
   async script(svelteFile) {
-    const { default: transformer } = await import('../transformers/typescript');
+    const { transformer } = await import('../transformers/typescript');
     const {
       content,
       filename,

src/processors/typescript.ts

@@ -30,4 +30,4 @@ const transformer: Transformer<Options.Babel> = async ({
   };
 };
 
-export default transformer;
+export { transformer };

src/transformers/babel.ts

@@ -17,4 +17,4 @@ const transformer: Transformer<Options.Coffeescript> = ({
   return { code, map };
 };
 
-export default transformer;
+export { transformer };

src/transformers/coffeescript.ts

@@ -78,4 +78,4 @@ const transformer: Transformer<Options.GlobalStyle> = async ({
   return { code: css, map: newMap };
 };
 
-export default transformer;
+export { transformer };

src/transformers/globalStyle.ts

@@ -26,4 +26,4 @@ const transformer: Transformer<Options.Less> = async ({
   };
 };
 
-export default transformer;
+export { transformer };

src/transformers/less.ts

@@ -68,4 +68,4 @@ const transformer: Transformer<Options.Postcss> = async ({
   return process(options, content, filename, map);
 };
 
-export default transformer;
+export { transformer };

src/transformers/postcss.ts

@@ -68,4 +68,4 @@ const transformer: Transformer<Options.Pug> = async ({
   };
 };
 
-export default transformer;
+export { transformer };

src/transformers/pug.ts

@@ -15,4 +15,4 @@ const transformer: Transformer<Options.Replace> = async ({
   };
 };
 
-export default transformer;
+export { transformer };

src/transformers/replace.ts

@@ -61,4 +61,4 @@ const transformer: Transformer<Options.Sass> = async ({
   });
 };
 
-export default transformer;
+export { transformer };

src/transformers/scss.ts

@@ -37,4 +37,4 @@ const transformer: Transformer<Options.Stylus> = ({
   });
 };
 
-export default transformer;
+export { transformer };

src/transformers/stylus.ts

@@ -382,4 +382,4 @@ const transformer: Transformer<Options.Typescript> = ({
   };
 };
 
-export default transformer;
+export { transformer };

src/transformers/typescript.ts

@@ -5,7 +5,7 @@ import { CompilerOptions } from 'typescript';
 import { TransformOptions as BabelOptions } from '@babel/core';
 
 export type Replace = Array<
-  [RegExp, (substring: string, ...args: any[]) => string | string]
+  [RegExp, string] | [RegExp, (substring: string, ...args: any[]) => string]
 >;
 
 export interface Coffeescript {

src/types/options.ts

@@ -1,7 +1,8 @@
 import autoProcess from '../../src';
 import { preprocess } from '../utils';
+import { Options } from '../../src/types';
 
-const options = [
+const options: Options.Replace = [
   [/@if\s*\((.*?)\)$/gim, '{#if $1}'],
   [/@elseif\s*\((.*?)\)$/gim, '{:else if $1}'],
   [/@else$/gim, '{:else}'],