support adding header packet to remove final buffer.copy call

lib/writer.js

@@ -1,18 +1,15 @@
 var Writer = function(size) {
   this.size = size || 1024;
-  this.buffer = new Buffer(this.size);
-  this.offset = 0;
+  this.buffer = new Buffer(this.size + 5);
+  this.offset = 5;
 };
 
 var p = Writer.prototype;
 
-p._remaining = function() {
-  return this.buffer.length - this.offset;
-}
-
 //resizes internal buffer if not enough size left
 p._ensure = function(size) {
-  if(this._remaining() < size) {
+  var remaining = this.buffer.length - this.offset;
+  if(remaining < size) {
     var oldBuffer = this.buffer;
     this.buffer = Buffer(oldBuffer.length + size);
     oldBuffer.copy(this.buffer);
@@ -52,10 +49,6 @@ p.addChar = function(char) {
   return this;
 }
 
-p.join = function() {
-  return this.buffer.slice(0, this.offset);
-}
-
 p.addString = function(string) {
   var string = string || "";
   var len = Buffer.byteLength(string);
@@ -66,7 +59,7 @@ p.addString = function(string) {
 }
 
 p.getByteLength = function() {
-  return this.offset;
+  return this.offset - 5;
 }
 
 p.add = function(otherBuffer) {
@@ -77,11 +70,24 @@ p.add = function(otherBuffer) {
 }
 
 p.clear = function() {
-  this.offset=0;
+  this.offset=5;
 }
 
-p.flush = function() {
-  var result = this.join();
+p.join = function(code) {
+  if(code) {
+    var end = this.offset;
+    this.offset = 0;
+    this.buffer[this.offset++] = code;
+    //write the length which is length of entire packet not including
+    //message type code byte
+    this.addInt32(end - 1);
+    this.offset = end;
+  }
+  return this.buffer.slice(code ? 0 : 5, this.offset);
+}
+
+p.flush = function(code) {
+  var result = this.join(code);
   this.clear();
   return result;
 }

test/unit/writer-tests.js

@@ -155,3 +155,23 @@ test("resizing to much larger", function() {
   var result = subject.addCString(string).flush();
   assert.equalBuffers(result, [33, 33, 33, 33, 33, 33, 33, 33, 0])
 })
+
+test("header", function() {
+  test('added as a hex code to a full writer', function() {
+    var subject = new Writer(2);
+    var result = subject.addCString("!").flush(0x50)
+    assert.equalBuffers(result, [0x50, 0, 0, 0, 6, 33, 0]);
+  })
+
+  test('added as a hex code to a non-full writer', function() {
+    var subject = new Writer(10).addCString("!");
+    var joinedResult = subject.join(0x50);
+    var result = subject.flush(0x50);
+    assert.equalBuffers(result, [0x50, 0, 0, 0, 6, 33, 0]);
+  })
+
+  test('added as a hex code to a buffer which requires resizing', function() {
+    var result = new Writer(2).addCString("!!!!!!!!").flush(0x50);
+    assert.equalBuffers(result, [0x50, 0, 0, 0, 0x0D, 33, 33, 33, 33, 33, 33, 33, 33, 0]);
+  })
+})