feat: initial implementation of processorAsync (#205)

* feat: initial implementation of processorAsync

* feat: types

* docs: how to use

* feat: test

README.md

@@ -368,10 +368,10 @@ const options = {
   glob: {
 
     //To include hidden files (starting with a dot)
-    dot: true, 
+    dot: true,
 
     //To fix paths on Windows OS when path.join() is used to create paths
-    windowsPathsNoEscape: true, 
+    windowsPathsNoEscape: true,
   },
 }
 ```
@@ -437,6 +437,18 @@ const results = replaceInFileSync({
 })
 ```
 
+Alongside the `processor`, there is also `processorAsync` which is the equivalent for asynchronous processing. It should return a promise that resolves with the processed content:
+
+```js
+const results = await replaceInFile({
+  files: 'path/to/files/*.html',
+  processorAsync: async (input, file) => {
+    const asyncResult = await doAsyncOperation(input, file);
+    return input.replace(/foo/g, asyncResult)
+  },
+})
+```
+
 ### Using a custom file system API
 `replace-in-file` defaults to using `'node:fs/promises'` and `'node:fs'` to provide file reading and write APIs.
 You can provide an `fs` or `fsSync` object of your own to switch to a different file system, such as a mock file system for unit tests.

src/helpers/config.js

@@ -55,12 +55,17 @@ export function parseConfig(config) {
   config.glob = config.glob || {}
 
   //Extract data
-  const {files, getTargetFile, from, to, processor, ignore, encoding} = config
+  const {files, getTargetFile, from, to, processor, processorAsync, ignore, encoding} = config
   if (typeof processor !== 'undefined') {
     if (typeof processor !== 'function' && !Array.isArray(processor)) {
       throw new Error(`Processor should be either a function or an array of functions`)
     }
   }
+  else if (typeof processorAsync !== 'undefined') {
+    if (typeof processorAsync !== 'function' && !Array.isArray(processorAsync)) {
+      throw new Error(`ProcessorAsync should be either a function or an array of functions`)
+    }
+  }
   else {
     if (typeof files === 'undefined') {
       throw new Error('Must specify file or files')

src/helpers/config.spec.js

@@ -96,6 +96,15 @@ describe('helpers/config.js', () => {
       })).to.throw(Error)
     })
 
+    it('should error when an invalid `processorAsync` is specified', () => {
+      expect(() => parseConfig({
+        processorAsync: 'foo',
+        files: ['test1', 'test2', 'test3'],
+        from: [/re/g, /place/g],
+        to: ['b'],
+      })).to.throw(Error)
+    })
+
     it('should error when `files` are not specified', () => {
       expect(() => parseConfig({
         from: [/re/g, /place/g],

src/helpers/process.js

@@ -40,6 +40,28 @@ export function processSync(file, processor, config) {
   return result
 }
 
+/**
+ * Run processors (async)
+ */
+export async function runProcessorsAsync(contents, processorAsync, file) {
+
+  //Ensure array and prepare result
+  const processorAsyncs = Array.isArray(processorAsync) ? processorAsync : [processorAsync]
+
+  //Run processors
+  let newContents = contents
+  for (const processor of processorAsyncs) {
+    newContents = await processor(newContents, file)
+  }
+
+  //Check if contents changed and prepare result
+  const hasChanged = (newContents !== contents)
+  const result = {file, hasChanged}
+
+  //Return along with new contents
+  return [result, newContents]
+}
+
 /**
  * Helper to process in a single file (async)
  */
@@ -50,7 +72,7 @@ export async function processAsync(file, processor, config) {
   const contents = await fs.readFile(file, encoding)
 
   //Make replacements
-  const [result, newContents] = runProcessors(contents, processor, file)
+  const [result, newContents] = await runProcessorsAsync(contents, processor, file)
 
   //Contents changed and not a dry run? Write to file
   if (result.hasChanged && !dry) {

src/process-file.js

@@ -10,14 +10,14 @@ export async function processFile(config) {
 
   //Parse config
   config = parseConfig(config)
-  const {files, processor, dry, verbose} = config
+  const {files, processor, processorAsync, dry, verbose} = config
 
   //Dry run?
   logDryRun(dry && verbose)
 
   //Find paths and process them
   const paths = await pathsAsync(files, config)
-  const promises = paths.map(path => processAsync(path, processor, config))
+  const promises = paths.map(path => processAsync(path, processor ?? processorAsync, config))
   const results = await Promise.all(promises)
 
   //Return results

src/process-file.spec.js

@@ -72,6 +72,22 @@ describe('Process a file', () => {
       })
     })
 
+    it('should run processorAsync', done => {
+      processFile({
+        files: 'test1',
+        processorAsync: async (input) => {
+          const replaceValue = await Promise.resolve('b')
+          return input.replace(/re\splace/g, replaceValue)
+        },
+      }).then(() => {
+        const test1 = fs.readFileSync('test1', 'utf8')
+        const test2 = fs.readFileSync('test2', 'utf8')
+        expect(test1).to.equal('a b c')
+        expect(test2).to.equal(testData)
+        done()
+      })
+    })
+
     it('should replace contents in a single file with regex', done => {
       processFile(fromToToProcessor({
         files: 'test1',
@@ -400,7 +416,7 @@ describe('Process a file', () => {
       expect(results[0].hasChanged).to.equal(false)
     })
 
-    it('should return corret results for multiple files', function() {
+    it('should return correct results for multiple files', function() {
       const results = processFileSync(fromToToProcessor({
         files: ['test1', 'test2', 'test3'],
         from: /re\splace/g,

src/replace-in-file.js

@@ -10,7 +10,7 @@ import {processFile, processFileSync} from './process-file.js'
 export async function replaceInFile(config) {
 
   //If custom processor is provided use it instead
-  if (config && config.processor) {
+  if (config && (config.processor || config.processorAsync)) {
     return await processFile(config)
   }
 
@@ -35,6 +35,10 @@ export async function replaceInFile(config) {
  */
 export function replaceInFileSync(config) {
 
+  if (config && config.processorAsync) {
+    throw new Error('ProcessorAsync cannot be used in synchronous mode')
+  }
+
   //If custom processor is provided use it instead
   if (config && config.processor) {
     return processFileSync(config)

src/replace-in-file.spec.js

@@ -469,6 +469,16 @@ describe('Replace in file', () => {
    */
   describe('Sync', () => {
 
+    it('should error with processorAsync', function() {
+      return expect(() => replaceInFileSync({
+        files: 'test1',
+        processorAsync: async (input) => {
+          const replaceValue = await Promise.resolve('b')
+          return input.replace(/re\splace/g, replaceValue)
+        },
+      })).to.throw(Error)
+    })
+
     it('should replace contents in a single file with regex', function() {
       replaceInFileSync({
         files: 'test1',

types/index.d.ts

@@ -29,6 +29,7 @@ declare module 'replace-in-file' {
     dry?: boolean;
     glob?: object;
     processor?: ProcessorCallback | Array<ProcessorCallback>;
+    processorAsync?: ProcessorAsyncCallback | Array<ProcessorAsyncCallback>;
   }
 
   export interface ReplaceResult {
@@ -42,3 +43,4 @@ declare module 'replace-in-file' {
 type FromCallback = (file: string) => string | RegExp | (RegExp | string)[];
 type ToCallback = (match: string, file: string) => string | string[];
 type ProcessorCallback = (input: string, file: string) => string;
+type ProcessorAsyncCallback = (input: string, file: string) => Promise<string>;