Replace map-stream with regular TransformStream

Reverts #11. According to #15 the returned map-stream doesn't implement the expected
Readable interface, thus we're switching back to node's TransformStream.

Fixes #15

lib/forkStdout.js

@@ -1,9 +1,10 @@
 "use strict";
 
 var os = require("os");
+var util = require("util");
 var ForkStream = require("fork-stream");
 var Linerstream = require("linerstream");
-var mapStream = require("map-stream");
+var Transform = require("stream").Transform;
 
 var messageToNode = "message to node: ";
 
@@ -36,13 +37,13 @@ function forkStdout(stdout) {
         .pipe(fork);
 
     // Removes the 'message to node: '-prefix from every chunk.
-    phridgeEndpoint = fork.a.pipe(mapStream(function(data, cb){
-        cb(null, data.slice(messageToNode.length));
+    phridgeEndpoint = fork.a.pipe(new CropPhridgePrefix({
+        encoding: "utf8"
     }));
 
     // We need to restore EOL-character in stdout stream
-    cleanStdoutEndpoint = fork.b.pipe(mapStream(function(data, cb){
-        cb(null, data + os.EOL);
+    cleanStdoutEndpoint = fork.b.pipe(new RestoreLineBreaks({
+        encoding: "utf8"
     }));
 
     return {
@@ -51,4 +52,38 @@ function forkStdout(stdout) {
     };
 }
 
+/**
+ * Appends an EOL-character to every chunk.
+ *
+ * @param options
+ * @constructor
+ * @private
+ */
+function RestoreLineBreaks(options) {
+    Transform.call(this, options);
+}
+util.inherits(RestoreLineBreaks, Transform);
+
+RestoreLineBreaks.prototype._transform = function (chunk, enc, cb) {
+    this.push(chunk + os.EOL);
+    cb();
+};
+
+/**
+ * Removes the 'message to node: '-prefix from every chunk.
+ *
+ * @param options
+ * @constructor
+ * @private
+ */
+function CropPhridgePrefix(options) {
+    Transform.call(this, options);
+}
+util.inherits(CropPhridgePrefix, Transform);
+
+CropPhridgePrefix.prototype._transform = function (chunk, enc, cb) {
+    this.push(chunk.slice(messageToNode.length));
+    cb();
+};
+
 module.exports = forkStdout;

package.json

@@ -20,7 +20,6 @@
   "dependencies": {
     "fork-stream": "^0.0.4",
     "linerstream": "^0.1.4",
-    "map-stream": "^0.1.0",
     "phantomjs": "^1.9.7-15",
     "temp": "^0.8.0",
     "when": "^3.4.2"