add input/output events

Author: arcticnotes

.github/workflows/ci.yaml

@@ -3,6 +3,7 @@ on:
   push:
     branches:
       - master
+      - dev
 jobs:
   build:
     runs-on: ubuntu-latest

lib/syncline.js

@@ -148,6 +148,8 @@ const LF = Buffer.from( [ 0x0A]);
 
 const EVENT_STDOUT = 'stdout';
 const EVENT_STDERR = 'stderr';
+const EVENT_INPUT  = 'input';
+const EVENT_OUTPUT = 'output';
 const EVENT_EXIT   = 'exit';
 
 const TRACE_LEVEL_OFF      = 0;
@@ -257,6 +259,7 @@ export class Syncline extends EventEmitter {
 			console.log( `${ performance.now()}: main: ${ this.#control[ INDEX_LENGTH]}B written, setting timeout=${ Math.max( 0, timeout)}ms, state=${ STATE_NAMES[ STATE_INPUT_COMPLETE]}`);
 		Atomics.store( this.#control, INDEX_STATE, STATE_INPUT_COMPLETE);
 		Atomics.notify( this.#control, INDEX_STATE, 1);
+		this.emit( EVENT_INPUT, inputLine);
 
 		// step 2. receive output
 		Atomics.wait( this.#control, INDEX_STATE, STATE_INPUT_COMPLETE);
@@ -277,7 +280,9 @@ export class Syncline extends EventEmitter {
 					if( this.#traceLevel >= TRACE_LEVEL_PROTOCOL)
 						console.log( `${ performance.now()}: main: state changed to ${ STATE_NAMES[ outputState]}, reading final ${ length}B and returning`);
 					buffer.push( Buffer.from( this.#shared, OFFSET_DATA, length));
-					return Buffer.concat( buffer).toString( 'utf-8');
+					const outputLine = Buffer.concat( buffer).toString( 'utf-8');
+					this.emit( EVENT_OUTPUT, outputLine);
+					return outputLine;
 				case STATE_ERROR:
 					if( this.#traceLevel >= TRACE_LEVEL_PROTOCOL)
 						console.log( `${ performance.now()}: main: state changed to ${ STATE_NAMES[ outputState]}, reading ${ length}B and throwing`);

package-lock.json

@@ -1,6 +1,6 @@
 {
 	"name": "@arcticnotes/syncline",
-	"version": "0.0.3",
+	"version": "0.0.4",
 	"description": "A Node.js library providing synchronous communication (without async/await, Promises, or callbacks) with child processes",
 	"author": "Paul <paul@arcticnotes.com>",
 	"license": "MIT",

package.json

@@ -4,6 +4,8 @@ import { Syncline} from '@arcticnotes/syncline';
 
 TEST( 'smoke test', async() => {
 	const syncline = await Syncline.spawn( 'stdbuf', [ '-oL', 'tr', 'a-z', 'A-Z'], { trace: 3});
+	syncline.on( 'input', line => console.log( `input (length=${ line.length}):`, line));
+	syncline.on( 'output', line => console.log( `output (length=${ line.length}):`, line));
 	ASSERT.equal( syncline.exchange( 'Hello, world!'), 'HELLO, WORLD!'); 
 	await new Promise( resolve => setTimeout( resolve, 500));
 	await syncline.close();