from-node-stream/example.js

"use strict";

const Promise = require("bluebird");
const fs = require("fs");
const through2 = require("through2");
const fromNodeStream = require("./");
const pipe = require("@promistream/pipe");
const collect = require("@promistream/collect");
const rangeNumbers = require("@promistream/range-numbers");
const bufferedMap = require("@promistream/buffered-map");
const map = require("@promistream/map");

let transform = through2.obj((chunk, encoding, callback) => {
	callback(null, chunk + 5);
});

return Promise.try(() => {
	return pipe([
		rangeNumbers(0, 10),
		fromNodeStream(transform),
		collect()
	]).read();
}).then((result) => {
	console.log("transform result:", result);
	
	return pipe([
		fromNodeStream(fs.createReadStream("example.js", { encoding: "utf8" })),
		bufferedMap((line) => line.split("\n")),
		collect()
	]).read();
}).then((result) => {
	console.log("read result:", result);
	
	return pipe([
		rangeNumbers(0, 10),
		map((number) => String(number) + "\n"),
		fromNodeStream(fs.createWriteStream("numbers.txt", { encoding: "utf8" }))
	]).read();
}).then((result) => {
	console.log("write result:", result);
	console.log("numbers.txt contents:");
	console.log(fs.readFileSync("numbers.txt", { encoding: "utf8" }));
});