3.0.14

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@push.rocks/smartstream",
-  "version": "3.0.3",
+  "version": "3.0.14",
   "private": false,
   "description": "simplifies access to node streams",
   "main": "dist_ts/index.js",
@@ -24,9 +24,10 @@
   "devDependencies": {
     "@git.zone/tsbuild": "^2.1.66",
     "@git.zone/tsrun": "^1.2.44",
-    "@git.zone/tstest": "^1.0.77",
-    "@push.rocks/smartfile": "^10.0.33",
-    "@push.rocks/tapbundle": "^5.0.15"
+    "@git.zone/tstest": "^1.0.84",
+    "@push.rocks/smartfile": "^11.0.0",
+    "@push.rocks/tapbundle": "^5.0.15",
+    "@types/node": "^20.9.0"
   },
   "dependencies": {
     "@push.rocks/smartpromise": "^4.0.3",

test/test.streamfunction.ts

@@ -10,21 +10,21 @@ tap.test('should handle a read stream', async (tools) => {
   const streamWrapper = new smartstream.StreamWrapper([
     smartfile.fsStream.createReadStream('./test/assets/readabletext.txt'),
     new smartstream.SmartDuplex({
-      writeAndTransformFunction: async (chunkStringArg: Buffer, streamTools) => {
+      writeFunction: async (chunkStringArg: Buffer, streamTools) => {
         // do something with the stream here
         const result = chunkStringArg.toString().substr(0, 100);
         streamTools.push('wow =========== \n');
         return Buffer.from(result);
       },
-      streamEndFunction: async (tools) => {
+      finalFunction: async (tools) => {
         return Buffer.from('this is the end');
       },
     }),
     new smartstream.SmartDuplex({
-      writeAndTransformFunction: async (chunkStringArg) => {
+      writeFunction: async (chunkStringArg) => {
         console.log(chunkStringArg.toString());
       },
-      streamEndFunction: async (tools) => {
+      finalFunction: async (tools) => {
         tools.push(null);
       },
     })
@@ -37,7 +37,7 @@ tap.test('should create a valid Intake', async (tools) => {
   testIntake.pipe(
       new smartstream.SmartDuplex({
         objectMode: true,
-        writeAndTransformFunction: async (chunkStringArg: string, streamTools) => {
+        writeFunction: async (chunkStringArg: string, streamTools) => {
           await tools.delayFor(100);
           console.log(chunkStringArg);
           return chunkStringArg;

ts/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartstream',
-  version: '3.0.3',
+  version: '3.0.14',
   description: 'simplifies access to node streams'
 }

ts/index.ts

@@ -2,3 +2,5 @@ export * from './smartstream.classes.passthrough.js';
 export * from './smartstream.classes.smartduplex.js';
 export * from './smartstream.classes.streamwrapper.js';
 export * from './smartstream.classes.streamintake.js';
+
+export * from './smartstream.functions.js'

ts/smartstream.classes.passthrough.ts

@@ -13,7 +13,9 @@ export class PassThrough extends plugins.stream.Duplex {
     if (this.push(chunk, encoding)) {
       callback();
     } else {
-      this.once('drain', callback);
+      this.once('drain', () => {
+        callback();
+      });
     }
   }
 }

ts/smartstream.classes.smartduplex.ts

@@ -6,18 +6,19 @@ export interface IStreamTools {
   push: (pipeObject: any) => void;
 }
 
-export interface IWriteAndTransformFunction<T, rT> {
+export interface IStreamWriteFunction<T, rT> {
   (chunkArg: T, toolsArg: IStreamTools): Promise<rT>;
 }
 
-export interface IStreamEndFunction<rT> {
+export interface IStreamFinalFunction<rT> {
   (toolsArg: IStreamTools): Promise<rT>;
 }
 
 export interface SmartStreamOptions<TInput, TOutput> extends DuplexOptions {
+  handleBackpressure?: boolean;
   readFunction?: () => Promise<void>;
-  writeAndTransformFunction?: IWriteAndTransformFunction<TInput, TOutput>;
-  streamEndFunction?: IStreamEndFunction<TOutput>;
+  writeFunction?: IStreamWriteFunction<TInput, TOutput>;
+  finalFunction?: IStreamFinalFunction<TOutput>;
   // Add other custom options if necessary
 }
 
@@ -109,15 +110,17 @@ export class SmartDuplex<TInput = any, TOutput = any> extends Duplex {
 
   // INSTANCE
   private readFunction?: () => Promise<void>;
-  private writeAndTransformFunction?: IWriteAndTransformFunction<TInput, TOutput>;
-  private streamEndFunction?: IStreamEndFunction<TOutput>;
+  private handleBackpressure: boolean;
+  private writeFunction?: IStreamWriteFunction<TInput, TOutput>;
+  private finalFunction?: IStreamFinalFunction<TOutput>;
   private observableSubscription?: plugins.smartrx.rxjs.Subscription;
 
   constructor(optionsArg?: SmartStreamOptions<TInput, TOutput>) {
     super(optionsArg);
     this.readFunction = optionsArg?.readFunction;
-    this.writeAndTransformFunction = optionsArg?.writeAndTransformFunction;
-    this.streamEndFunction = optionsArg?.streamEndFunction;
+    this.writeFunction = optionsArg?.writeFunction;
+    this.finalFunction = optionsArg?.finalFunction;
+    this.handleBackpressure = optionsArg?.handleBackpressure ?? true;
   }
 
   public async _read(size: number): Promise<void> {
@@ -128,7 +131,7 @@ export class SmartDuplex<TInput = any, TOutput = any> extends Duplex {
 
   // Ensure the _write method types the chunk as TInput and encodes TOutput
   public async _write(chunk: TInput, encoding: string, callback: (error?: Error | null) => void) {
-    if (!this.writeAndTransformFunction) {
+    if (!this.writeFunction) {
       return callback(new Error('No stream function provided'));
     }
 
@@ -141,10 +144,14 @@ export class SmartDuplex<TInput = any, TOutput = any> extends Duplex {
     };
 
     try {
-      const modifiedChunk = await this.writeAndTransformFunction(chunk, tools);
+      const modifiedChunk = await this.writeFunction(chunk, tools);
       if (modifiedChunk) {
-        if (!this.push(modifiedChunk)) {
-          // Handle backpressure if necessary
+        if (!this.push(modifiedChunk) && this.handleBackpressure) {
+          this.pause();
+          // Listen for 'drain' event to resume
+          this.once('drain', () => {
+            this.resume(); // Resume the source of data
+          });
         }
       }
       callback();
@@ -154,24 +161,24 @@ export class SmartDuplex<TInput = any, TOutput = any> extends Duplex {
   }
 
   public async _final(callback: (error?: Error | null) => void) {
-    if (this.streamEndFunction) {
+    if (this.finalFunction) {
       const tools: IStreamTools = {
         truncate: () => callback(),
         push: (pipeObject) => this.push(pipeObject),
       };
 
       try {
-        const finalChunk = await this.streamEndFunction(tools);
+        const finalChunk = await this.finalFunction(tools);
         if (finalChunk) {
           this.push(finalChunk);
         }
-        callback();
       } catch (err) {
         callback(err);
       }
     } else {
-      this.push(null),
-      callback();
+      // nothing here
     }
+    this.push(null);
+    callback();
   }
 }

ts/smartstream.functions.ts

@@ -0,0 +1,26 @@
+import { Transform, type TransformCallback, type TransformOptions } from 'stream';
+
+export interface AsyncTransformFunction<TInput, TOutput> {
+  (chunkArg: TInput): Promise<TOutput>;
+}
+
+export function createTransformFunction<TInput, TOutput>(
+  asyncFunction: AsyncTransformFunction<TInput, TOutput>,
+  options?: TransformOptions
+): Transform {
+  const transformStream = new Transform({
+    ...options,
+    objectMode: true, // Ensure we operate in object mode
+    async transform(chunk: TInput, encoding: string, callback: TransformCallback) {
+      try {
+        const transformed = await asyncFunction(chunk);
+        this.push(transformed);
+        callback();
+      } catch (error) {
+        callback(error instanceof Error ? error : new Error(String(error)));
+      }
+    }
+  });
+
+  return transformStream;
+}