@barchart/common-node-js/stream/ArrayReadStream.js

Common classes, utilities, and functions for building Node.js servers

const assert = require('@barchart/common-js/lang/assert'),
	object = require('@barchart/common-js/lang/object');

const Stream = require('stream');

module.exports = (() => {
	'use strict';

	/**
	 * A super-simple Node.js {@link Stream.Readable} that emits an array's
	 * items. Please note, this stream has very limited use cases and
	 * in 99% of use cases, an actual streaming source should be used
	 * which does not require the entire stream to be pre-cached (in
	 * the form of an array).
	 *
	 * @public
	 * @extends {Steam.Readable}
	 * @param {Object=} options
	 */
	class ArrayReadStream extends Stream.Readable {
		constructor(data, options) {
			super(object.merge({ objectMode: true }, (options || { })));

			assert.argumentIsArray(data, 'data');

			this._data = data;
			this._index = 0;
		}

		_read(size) {
			let item;

			if (this._index < this._data.length) {
				item = this._data[this._index];

				this._index = this._index + 1;
			} else {
				item = null;
			}

			this.push(item);
		}

		toString() {
			return '[ArrayReadStream]';
		}
	}

	return ArrayReadStream;
})();