Convert asynchronously

README.md

@@ -38,12 +38,16 @@ convert({
 // convert multiple files & write them to disk
 convert({
   source: ['./src/**/*{.js,.ts}', './bin/main.ts'], 
+  onConverted: (file) => file.saveSync()
 });
 
-// convert multiple files from another TypeScript project & write them to disk
+// convert multiple files from a TypeScript project & asynchronously write them to disk
 convert({
   sourceTsConfig: '/path/to/project/tsconfig.json',
-});
+  onConverted: async (file) => file.save()
+})
+  .then(() => console.log('All files written successfully!'))
+  .catch(console.error);
 ```
 
 ### CLI

package.json

@@ -28,6 +28,7 @@
   },
   "dependencies": {
     "commander": "^9.0.0",
+    "is-promise": "^4.0.0",
     "ts-morph": "^13.0.3"
   },
   "devDependencies": {

src/converter.test.ts

@@ -4,15 +4,19 @@ import {runInNewContext as evalInVm} from 'vm';
 
 const testData = './tests/data/';
 
-const convertCode = (code: string, options?: Omit<Options, 'onConverted'>) => {
+const convertCode = (code: string, options?: Options) => {
   let result = '';
-  convert({...options, sourceCode: code, onConverted: (file) => result += file.getFullText()});
+  convert({...options, sourceCode: code, onConverted: (file) => {
+    result += file.getFullText();
+  }});
   return result;
 }
 
 const convertFiles = (files: string | readonly string[]) => {
   let output = '';
-  convert({source: files, onConverted: (file) => output += file.getFullText()})
+  convert({source: files, onConverted: (file) => {
+    output += file.getFullText()
+  }})
   return output;
 };
 
@@ -253,3 +257,17 @@ test('it should convert parenthesis', () => {
     expect(cmp(input, output, true)).toBe(true);
   }
 });
+
+test('it should support async', async () => {
+  const expected = 'Big(1).plus(1)';
+  let actual = '';
+  await convert({
+    sourceCode: '1 + 1',
+    onConverted: async (file) => {
+      const p = Promise.resolve(1);
+      await p;
+      actual = file.getText();
+    },
+  });
+  expect(actual).toBe(expected);
+});

src/converter.ts

@@ -1,4 +1,5 @@
 import { Node, Project, SourceFile, SyntaxKind } from "ts-morph";
+import { isPromise } from 'util/types';
 import { mapSyntaxKind } from './mappings';
 
 export type Options = {
@@ -54,25 +55,34 @@ export type Options = {
    * Thus, in order to fix the example above you should specify `{..., variables: ['total']}` in your `Options` object..
    */
   variables?: string[];
-
-  /**
-   * Called when an input file has been transformed to Bigs.
-   * 
-   * Saves the input file to disk by default.
-   */
-  onConverted?: (file: SourceFile) => void;
 };
 
+/**
+ * Function to call when an input file has been converted to Bigs.
+ */
+type OnConverted = (file: SourceFile) => void | Promise<void>;
+
 /**
  * The name of the filename when raw source code was given via the `sourceCode` option.
  */
 export const sourceCodeFileName = 'n2b-source.ts';
 
 export class Converter {
   private readonly options: Options;
+  private readonly project: Project;
 
   constructor(options: Options) {
+    this.project = new Project();
     this.options = options;
+
+    if (options.sourceCode)
+      this.project.createSourceFile(sourceCodeFileName, options.sourceCode);
+
+    if (options.source)
+      this.project.addSourceFilesAtPaths(options.source);
+
+    if (options.sourceTsConfig)
+      this.project.addSourceFilesFromTsConfig(options.sourceTsConfig);
   }
 
   private createBig(content: string | number) {
@@ -196,30 +206,27 @@ export class Converter {
     });
   }
 
-  convert() {
-    const project = new Project();
-
-    if (this.options.sourceCode)
-      project.createSourceFile(sourceCodeFileName, this.options.sourceCode);
+  convert(onConverted: OnConverted = (file) => file.saveSync()) {
+    const files = this.project.getSourceFiles();
 
-    if (this.options.source)
-      project.addSourceFilesAtPaths(this.options.source);
-
-    if (this.options.sourceTsConfig)
-      project.addSourceFilesFromTsConfig(this.options.sourceTsConfig);
-
-    if (!this.options.onConverted)
-      this.options.onConverted = (file) => file.saveSync();
+    for (const file of files) {
+      this.traverse(file);
+      onConverted(file);
+    }
+  }
 
-    const files = project.getSourceFiles();
+  async convertAsync(onConverted: OnConverted = (file) => file.save()) {
+    const files = this.project.getSourceFiles();
 
     for (const file of files) {
       this.traverse(file);
-      this.options.onConverted(file);
+      await onConverted(file);
     }
   }
 }
 
-export function convert(options: Options) {
-  return new Converter(options).convert();
+export function convert({onConverted, ...options}: Options & {onConverted?: OnConverted}) {
+  const converter = new Converter(options);
+  const async = isPromise(onConverted);
+  return async ? converter.convertAsync(onConverted) : converter.convert(onConverted);
 }