stream: consolidate common code from push and unshift helper functions

Author: wa-Nadoo

lib/internal/streams/readable.js

@@ -367,6 +367,18 @@ Readable.prototype.push = function(chunk, encoding) {
   debug('push', chunk);
 
   const state = this._readableState;
+  if ((state[kState] & kEnded) !== 0) {
+    errorOrDestroy(this, new ERR_STREAM_PUSH_AFTER_EOF());
+    return false;
+  } else if ((state[kState] & (kDestroyed | kErrored)) !== 0)
+    return false;
+
+  state[kState] &= ~kReading;
+  if (chunk === null) {
+    onEofChunk(this, state);
+    return false;
+  }
+
   return (state[kState] & kObjectMode) === 0 ?
     readableAddChunkPushByteMode(this, state, chunk, encoding) :
     readableAddChunkPushObjectMode(this, state, chunk, encoding);
@@ -376,20 +388,25 @@ Readable.prototype.push = function(chunk, encoding) {
 Readable.prototype.unshift = function(chunk, encoding) {
   debug('unshift', chunk);
   const state = this._readableState;
+  if ((state[kState] & kEndEmitted) !== 0) {
+    errorOrDestroy(this, new ERR_STREAM_UNSHIFT_AFTER_END_EVENT());
+    return false;
+  } else if ((state[kState] & (kDestroyed | kErrored)) !== 0)
+    return false;
+
+  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);
 };
 
 
 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) {
@@ -418,34 +435,16 @@ function readableAddChunkUnshiftByteMode(stream, state, chunk, encoding) {
 }
 
 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)
-    errorOrDestroy(stream, new ERR_STREAM_UNSHIFT_AFTER_END_EVENT());
-  else if ((state[kState] & (kDestroyed | kErrored)) !== 0)
-    return false;
-  else
-    addChunk(stream, state, chunk, true);
+  addChunk(stream, state, chunk, true);
 
   return canPushMore(state);
 }
 
 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) {
@@ -464,22 +463,11 @@ function readableAddChunkPushByteMode(stream, state, chunk, encoding) {
   }
 
   if (!chunk || chunk.length <= 0) {
-    state[kState] &= ~kReading;
     maybeReadMore(stream, state);
 
     return canPushMore(state);
   }
 
-  if ((state[kState] & kEnded) !== 0) {
-    errorOrDestroy(stream, new ERR_STREAM_PUSH_AFTER_EOF());
-    return false;
-  }
-
-  if ((state[kState] & (kDestroyed | kErrored)) !== 0) {
-    return false;
-  }
-
-  state[kState] &= ~kReading;
   if ((state[kState] & kDecoder) !== 0 && !encoding) {
     chunk = state[kDecoderValue].write(chunk);
     if (chunk.length === 0) {
@@ -493,23 +481,6 @@ 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;
-  }
-
-  if ((state[kState] & (kDestroyed | kErrored)) !== 0) {
-    return false;
-  }
-
-  state[kState] &= ~kReading;
-
   if ((state[kState] & kDecoder) !== 0 && !encoding) {
     chunk = state[kDecoderValue].write(chunk);
   }