mathjs/examples/node_modules/is-stream/index.js

Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser with support for symbolic computation, comes with a large set of built-in functions and constants, and offers an integrated solution to work with dif

'use strict';

const isStream = stream =>
	stream !== null &&
	typeof stream === 'object' &&
	typeof stream.pipe === 'function';

isStream.writable = stream =>
	isStream(stream) &&
	stream.writable !== false &&
	typeof stream._write === 'function' &&
	typeof stream._writableState === 'object';

isStream.readable = stream =>
	isStream(stream) &&
	stream.readable !== false &&
	typeof stream._read === 'function' &&
	typeof stream._readableState === 'object';

isStream.duplex = stream =>
	isStream.writable(stream) &&
	isStream.readable(stream);

isStream.transform = stream =>
	isStream.duplex(stream) &&
	typeof stream._transform === 'function' &&
	typeof stream._transformState === 'object';

module.exports = isStream;