From 5b8887e60b09b8eda0d96f4a8e19005de5adf263 Mon Sep 17 00:00:00 2001
From: Vasiliy Loginevskiy <yeti-or@yandex-team.ru>
Date: Fri, 27 Mar 2015 14:00:59 +0300
Subject: [PATCH] No need in Duplex stream. Rewrite to Readable.

---
 lib/index.js                | 28 +++++++++++-----------------
 test/schemes/flat.test.js   | 11 ++++++-----
 test/schemes/nested.test.js | 11 ++++++-----
 3 files changed, 23 insertions(+), 27 deletions(-)

diff --git a/lib/index.js b/lib/index.js
index a524a6a..a13fd37 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -1,13 +1,13 @@
 var fs = require('fs'),
     path = require('path'),
     bemNaming = require('bem-naming'),
-    PassThrough = require('stream').PassThrough,
+    Readable = require('stream').Readable,
     schemes = require('./schemes');
 
 module.exports = function (levels, options) {
     options || (options = {});
 
-    var output = new PassThrough({ objectMode: true }),
+    var output = new Readable({ objectMode: true }),
         defaultScheme = options.scheme || schemes.nested,
         defaultNaming = options.naming ? bemNaming(options.naming) : bemNaming;
 
@@ -27,7 +27,7 @@ module.exports = function (levels, options) {
     });
 
     function add(obj) {
-        output.write(obj);
+        output.push(obj);
     }
 
     function scan(level, callback) {
@@ -72,22 +72,16 @@ module.exports = function (levels, options) {
         }
     }
 
-    var n = 0,
-        l = levels.length;
+    var n = levels.length;
 
-    if (l === 0) {
-        output.end();
-    } else {
-        for (var i = 0; i < l; ++i) {
-            scan(levels[i], scancb);
-        }
-    }
+    output._read = function () {
+        n || output.push(null);
 
-    function scancb(err) {
-        err && output.emit('error', err);
-
-        ++n === l && output.end();
-    }
+        levels.length && scan(levels.shift(), function (err) {
+            err && output.emit('error', err);
+            --n || output.push(null);
+        });
+    };
 
     return output;
 };
diff --git a/test/schemes/flat.test.js b/test/schemes/flat.test.js
index ed773f0..0485420 100644
--- a/test/schemes/flat.test.js
+++ b/test/schemes/flat.test.js
@@ -22,11 +22,12 @@ describe('flat scheme', function () {
     it('must throw error if levels is not found', function (done) {
         var walker = walk(['not-existing-level']);
 
-        walker.on('error', function (err) {
-            err.must.throw();
-            done();
-        })
-        .resume();
+        walker
+            .on('error', function (err) {
+                err.must.throw();
+                done();
+            })
+            .resume();
     });
 
     describe('ignore', function () {
diff --git a/test/schemes/nested.test.js b/test/schemes/nested.test.js
index 2d70f4c..d920aad 100644
--- a/test/schemes/nested.test.js
+++ b/test/schemes/nested.test.js
@@ -22,11 +22,12 @@ describe('nested scheme', function () {
     it('must throw error if levels is not found', function (done) {
         var walker = walk(['not-existing-level']);
 
-        walker.on('error', function (err) {
-            err.must.throw();
-            done();
-        })
-        .resume();
+        walker
+            .on('error', function (err) {
+                err.must.throw();
+                done();
+            })
+            .resume();
     });
 
     describe('ignore', function () {