From 9ad5796bb371e045c8459a04cdf4b6a93f1eba7a Mon Sep 17 00:00:00 2001
From: Trevor Harwell <trevor.harwell@evisions.com>
Date: Wed, 25 Apr 2018 18:48:48 -0400
Subject: [PATCH] Add support to stream parsing node style

---
 .eslintrc.js        |  2 +-
 papaparse.js        | 53 ++++++++++++++++++++++++++++++++++++++++++---
 tests/node-tests.js | 30 +++++++++++++++++++++++++
 3 files changed, 81 insertions(+), 4 deletions(-)

diff --git a/.eslintrc.js b/.eslintrc.js
index f63bc09..3085f72 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -42,7 +42,7 @@ module.exports = {
 		"consistent-this": "off",
 		"curly": "off",
 		"default-case": "error",
-		"dot-location": "error",
+		"dot-location": "off",
 		"dot-notation": "error",
 		"eol-last": "error",
 		"eqeqeq": "error",
diff --git a/papaparse.js b/papaparse.js
index b7fa8db..75afb25 100755
--- a/papaparse.js
+++ b/papaparse.js
@@ -17,14 +17,14 @@
 		// Node. Does not work with strict CommonJS, but
 		// only CommonJS-like environments that support module.exports,
 		// like Node.
-		module.exports = factory();
+		module.exports = factory(require('stream'));
 	}
 	else
 	{
 		// Browser globals (root is window)
 		root.Papa = factory();
 	}
-}(this, function()
+}(this, function(streamModule)
 {
 	'use strict';
 
@@ -71,6 +71,7 @@
 	Papa.FileStreamer = FileStreamer;
 	Papa.StringStreamer = StringStreamer;
 	Papa.ReadableStreamStreamer = ReadableStreamStreamer;
+	Papa.createDuplexStream = createDuplexStream;
 
 	if (global.jQuery)
 	{
@@ -228,7 +229,13 @@
 		}
 
 		var streamer = null;
-		if (typeof _input === 'string')
+		if (_input === null && typeof streamModule !== 'undefined')
+		{
+			// create a node Duplex stream for use
+			// with .pipe
+			return createDuplexStream(_config);
+		}
+		else if (typeof _input === 'string')
 		{
 			if (_config.download)
 				streamer = new NetworkStreamer(_config);
@@ -838,6 +845,46 @@
 	ReadableStreamStreamer.prototype = Object.create(ChunkStreamer.prototype);
 	ReadableStreamStreamer.prototype.constructor = ReadableStreamStreamer;
 
+	function createDuplexStream(_config) {
+		var config = copy(_config);
+		config.step = function(results) {
+			results.data.forEach(function(item) {
+				duplexStream.push(item);
+			});
+		};
+		config.complete = function() {
+			duplexStream.push(null);
+		};
+
+		var chunkStreamer = new ChunkStreamer(config);
+
+		chunkStreamer._nextChunk = function() {
+			// empty function since this
+			// logic is handled by the Duplex class
+		};
+
+		// streamModule from node must exist
+		// for this to run
+		var duplexStream = new streamModule.Duplex({
+			readableObjectMode: true,
+			decodeStrings: false,
+			read: function(size) {
+				// since pausing controls the input into the parser
+				// we do not need to re-trigger the parser to continue
+			},
+			write: function(chunk, encoding, callback) {
+				chunkStreamer.parseChunk(typeof chunk === 'string' ? chunk : chunk.toString(config.encoding));
+				callback();
+			},
+			'final': function(callback) {
+				chunkStreamer._finished = true;
+				chunkStreamer.parseChunk('');
+				callback();
+			}
+		});
+
+		return duplexStream;
+	}
 
 	// Use one ParserHandle per entire CSV file or string
 	function ParserHandle(_config)
diff --git a/tests/node-tests.js b/tests/node-tests.js
index 44752ff..574f821 100644
--- a/tests/node-tests.js
+++ b/tests/node-tests.js
@@ -59,6 +59,36 @@ describe('PapaParse', function() {
 		});
 	});
 
+	it('piped streaming CSV should be correctly parsed', function(done) {
+		var data = [];
+		fs.createReadStream(__dirname + '/long-sample.csv', 'utf8')
+			.pipe(Papa.parse(null))
+			.on('data', function(item) {
+				data.push(item);
+			})
+			.on('end', function() {
+				assert.deepEqual(data[0], [
+					'Grant',
+					'Dyer',
+					'Donec.elementum@orciluctuset.example',
+					'2013-11-23T02:30:31-08:00',
+					'2014-05-31T01:06:56-07:00',
+					'Magna Ut Associates',
+					'ljenkins'
+				]);
+				assert.deepEqual(data[7], [
+					'Talon',
+					'Salinas',
+					'posuere.vulputate.lacus@Donecsollicitudin.example',
+					'2015-01-31T09:19:02-08:00',
+					'2014-12-17T04:59:18-08:00',
+					'Aliquam Iaculis Incorporate',
+					'Phasellus@Quisquetincidunt.example'
+				]);
+				done();
+			});
+	});
+
 	it('should support pausing and resuming on same tick when streaming', function(done) {
 		var rows = [];
 		Papa.parse(fs.createReadStream(__dirname + '/long-sample.csv', 'utf8'), {