stream-compute

Combines several streams of events, and computes a value every time one changes

Install

npm install --save stream-compute

API

streamCompute(inputs, compute(data,cb))

• inputs is an array of strings that are the names of the dependencies for this computation
• compute(data, cb) is the function used for performing the computation.
  • data An object that contains keys that correspond to the inputs array that was passed in. The keys contain the last known value of that dependency. Computing only starts once all inputs have sent at least one value.
  • cb(err, result) is the callback which should be called after the computation has finished

The function returns an object that contains the following keys:

• input which is a map of Writable streams which are populated by the list of inputs
• output a Readable stream which has the results of computations

Example

var streamArray = require("stream-array");
var intervalStream = require("interval-stream");
var stdout = require("stdout");

var streamCompute = require("stream-compute");

var greeter = make_greeter();

var messages = streamArray(["Hello", "What's up", "Greetz"]);
var names = streamArray(["Alice", "Bob", "Eve"]);

greeter.output.pipe(stdout("Output:"));

messages.pipe(intervalStream(200)).pipe(greeter.input.message);
names.pipe(intervalStream(300)).pipe(greeter.input.name);

function make_greeter() {
	return streamCompute(["message", "name"], function(data, cb) {
		var name = data.name;
		var message = data.message;
		var result = {
			message: "Hey, " + name + ": " + message
		};
		cb(null, result);
	});
}