stream: consolidate common code from push and unshift helper functions

Author: wa-Nadoo

lib/internal/streams/readable.js

@@ -368,6 +368,12 @@ Readable.prototype.push = function(chunk, encoding) {
   debug('push', chunk);
 
   const state = this._readableState;
+  if (chunk === null) {
+    state[kState] &= ~kReading;
+    onEofChunk(this, state);
+    return false;
+  }
+
   return (state[kState] & kObjectMode) === 0 ?
     readableAddChunkPushByteMode(this, state, chunk, encoding) :
     readableAddChunkPushObjectMode(this, state, chunk, encoding);
@@ -377,20 +383,19 @@ Readable.prototype.push = function(chunk, encoding) {
 Readable.prototype.unshift = function(chunk, encoding) {
   debug('unshift', chunk);
   const state = this._readableState;
+  if (chunk === null) {
+    state[kState] &= ~kReading;
+    onEofChunk(this, state);
+    return false;
+  }
+
   return (state[kState] & kObjectMode) === 0 ?
     readableAddChunkUnshiftByteMode(this, state, chunk, encoding) :
-    readableAddChunkUnshiftObjectMode(this, state, chunk);
+    readableAddChunkUnshiftValue(this, state, chunk);
 };
 
 
 function readableAddChunkUnshiftByteMode(stream, state, chunk, encoding) {
-  if (chunk === null) {
-    state[kState] &= ~kReading;
-    onEofChunk(stream, state);
-
-    return false;
-  }
-
   if (typeof chunk === 'string') {
     encoding = encoding || state.defaultEncoding;
     if (state.encoding !== encoding) {
@@ -418,21 +423,11 @@ function readableAddChunkUnshiftByteMode(stream, state, chunk, encoding) {
   return readableAddChunkUnshiftValue(stream, state, chunk);
 }
 
-function readableAddChunkUnshiftObjectMode(stream, state, chunk) {
-  if (chunk === null) {
-    state[kState] &= ~kReading;
-    onEofChunk(stream, state);
-
-    return false;
-  }
-
-  return readableAddChunkUnshiftValue(stream, state, chunk);
-}
-
 function readableAddChunkUnshiftValue(stream, state, chunk) {
-  if ((state[kState] & kEndEmitted) !== 0)
+  if ((state[kState] & kEndEmitted) !== 0) {
     errorOrDestroy(stream, new ERR_STREAM_UNSHIFT_AFTER_END_EVENT());
-  else if ((state[kState] & (kDestroyed | kErrored)) !== 0)
+    return false;
+  } else if ((state[kState] & (kDestroyed | kErrored)) !== 0)
     return false;
   else
     addChunk(stream, state, chunk, true);
@@ -441,12 +436,6 @@ function readableAddChunkUnshiftValue(stream, state, chunk) {
 }
 
 function readableAddChunkPushByteMode(stream, state, chunk, encoding) {
-  if (chunk === null) {
-    state[kState] &= ~kReading;
-    onEofChunk(stream, state);
-    return false;
-  }
-
   if (typeof chunk === 'string') {
     encoding = encoding || state.defaultEncoding;
     if (state.encoding !== encoding) {
@@ -464,7 +453,7 @@ function readableAddChunkPushByteMode(stream, state, chunk, encoding) {
     return false;
   }
 
-  if (!chunk || chunk.length <= 0) {
+  if (!chunk || chunk.length === 0) {
     state[kState] &= ~kReading;
     maybeReadMore(stream, state);
 
@@ -494,12 +483,6 @@ function readableAddChunkPushByteMode(stream, state, chunk, encoding) {
 }
 
 function readableAddChunkPushObjectMode(stream, state, chunk, encoding) {
-  if (chunk === null) {
-    state[kState] &= ~kReading;
-    onEofChunk(stream, state);
-    return false;
-  }
-
   if ((state[kState] & kEnded) !== 0) {
     errorOrDestroy(stream, new ERR_STREAM_PUSH_AFTER_EOF());
     return false;