Fixed Stream decode C0 byte (nil) processing error (#68)

* Fixed Stream decode processing error:
after C0 byte (nil) stream switched to "End of stream state",
added test.
Minor changes made in modules formatting to satisfy modules
formatting rules checked in tests.

* Added stream decoder wrap option, default value is false for compatibility reasons.
When wrap is true decoded items are passed in form of {value: data} instead of data.
Using wrap=true for decoder stream allows decoding of C0 byte (nil).

* Added wrap option for decoder and encoder streams.
When wrap = true decoder stream outputs {value:data} instead of data,
encoder stream encodes data extracted from {value:data}.

* Added tests for encoder stream with wrap options,
encoder/decoder streams chain with wrap options.

Wrap option for encoder/decoder streams documented in readme.md

* encoder property _unwrap renamed to _wrap.
Minor changes in documentation for wrap option of encoder/decoder.

Author: i-kovalyov

README.md

@@ -177,17 +177,25 @@ This is just a commodity that calls
 -------------------------------------------------------
 <a name="encoder"></a>
 
-### encoder()
+### encoder(options)
 
 Builds a stream in object mode that encodes msgpack.
 
+Supported options:
+* `wrap`, objects should be passed to encoder in wrapped object {value: data}. Wrap option should be used if you need to pass null to encoder.
+
+
 -------------------------------------------------------
 <a name="decoder"></a>
 
-### decoder()
+### decoder(options)
 
 Builds a stream in object mode that decodes msgpack.
 
+Supported options:
+* `wrap`, decoded objects returned in wrapped object {value: data}. Wrap option should be used if stream contains msgpack nil.
+
+
 LevelUp Support
 ---------------
 

lib/streams.js

@@ -25,6 +25,7 @@ function Encoder (opts) {
   }
 
   Base.call(this, opts)
+  this._wrap = ('wrap' in opts) && opts.wrap
 }
 
 inherits(Encoder, Base)
@@ -33,7 +34,7 @@ Encoder.prototype._transform = function (obj, enc, done) {
   var buf = null
 
   try {
-    buf = this._msgpack.encode(obj).slice(0)
+    buf = this._msgpack.encode(this._wrap ? obj.value : obj).slice(0)
   } catch (err) {
     this.emit('error', err)
     return done()
@@ -53,6 +54,7 @@ function Decoder (opts) {
   Base.call(this, opts)
 
   this._chunks = bl()
+  this._wrap = ('wrap' in opts) && opts.wrap
 }
 
 inherits(Decoder, Base)
@@ -64,6 +66,9 @@ Decoder.prototype._transform = function (buf, enc, done) {
 
   try {
     var result = this._msgpack.decode(this._chunks)
+    if (this._wrap) {
+      result = {value: result}
+    }
     this.push(result)
   } catch (err) {
     if (err instanceof this._msgpack.IncompleteBufferError) {

test/streams.js

@@ -182,3 +182,80 @@ test('concatenated buffers work', function (t) {
 
   encoder.end()
 })
+
+test('nil processing works', function (t) {
+  t.plan(3)
+
+  var pack = msgpack()
+  var decoder = pack.decoder({wrap: true})
+  var decodedItemIndex = 0
+
+  decoder.on('data', function (chunk) {
+    decodedItemIndex++
+    t.deepEqual(chunk.value, decodedItemIndex === 1 ? null : false)
+  })
+
+  decoder.on('end', function () {
+    t.equal(decodedItemIndex, 2)
+  })
+
+  decoder.write(new Buffer([0xc0, 0xc2]))
+  decoder.end()
+})
+
+test('encoder wrap mode works', function (t) {
+  t.plan(1)
+
+  var pack = msgpack()
+  var encoder = pack.encoder({wrap: true})
+  var decoder = pack.decoder()
+  var data = { hello: 'world' }
+  var wrappedData = {value: data}
+
+  encoder.pipe(decoder)
+
+  decoder.on('data', function (chunk) {
+    t.deepEqual(chunk, data)
+  })
+
+  encoder.end(wrappedData)
+})
+
+test('encoder/decoder wrap mode must send an object through', function (t) {
+  t.plan(1)
+
+  var pack = msgpack()
+  var encoder = pack.encoder({wrap: true})
+  var decoder = pack.decoder({wrap: true})
+  var data = {value: { hello: 'world' }}
+
+  encoder.pipe(decoder)
+
+  decoder.on('data', function (chunk) {
+    t.deepEqual(chunk, data)
+  })
+
+  encoder.end(data)
+})
+
+test('encoder pack null', function (t) {
+  t.plan(2)
+  var pack = msgpack()
+  var encoder = pack.encoder({wrap: true})
+  var decoder = pack.decoder({wrap: true})
+
+  encoder.pipe(decoder)
+
+  var decodedItemIndex = 0
+  decoder.on('data', function (chunk) {
+    decodedItemIndex++
+    t.deepEqual(chunk.value, null)
+  })
+
+  decoder.on('end', function () {
+    t.equal(decodedItemIndex, 1)
+  })
+
+  encoder.write({value: null})
+  encoder.end()
+})