stream: simplify push

PR-URL: #31150
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

Author: ronag

lib/_stream_readable.js

@@ -223,8 +223,7 @@ function readableAddChunk(stream, chunk, encoding, addToFront) {
   debug('readableAddChunk', chunk);
   const state = stream._readableState;
 
-  let skipChunkCheck;
-
+  let err;
   if (!state.objectMode) {
     if (typeof chunk === 'string') {
       encoding = encoding || state.defaultEncoding;
@@ -236,54 +235,47 @@ function readableAddChunk(stream, chunk, encoding, addToFront) {
         chunk = Buffer.from(chunk, encoding);
         encoding = '';
       }
-      skipChunkCheck = true;
+    } else if (chunk instanceof Buffer) {
+      encoding = '';
+    } else if (Stream._isUint8Array(chunk)) {
+      chunk = Stream._uint8ArrayToBuffer(chunk);
+      encoding = '';
+    } else if (chunk != null) {
+      err = new ERR_INVALID_ARG_TYPE(
+        'chunk', ['string', 'Buffer', 'Uint8Array'], chunk);
     }
-  } else {
-    skipChunkCheck = true;
   }
 
-  if (chunk === null) {
+  if (err) {
+    errorOrDestroy(stream, err);
+  } else if (chunk === null) {
     state.reading = false;
     onEofChunk(stream, state);
-  } else {
-    var er;
-    if (!skipChunkCheck)
-      er = chunkInvalid(state, chunk);
-    if (er) {
-      errorOrDestroy(stream, er);
-    } else if (state.objectMode || (chunk && chunk.length > 0)) {
-      if (typeof chunk !== 'string' &&
-          !state.objectMode &&
-          // Do not use Object.getPrototypeOf as it is slower since V8 7.3.
-          !(chunk instanceof Buffer)) {
-        chunk = Stream._uint8ArrayToBuffer(chunk);
-      }
-
-      if (addToFront) {
-        if (state.endEmitted)
-          errorOrDestroy(stream, new ERR_STREAM_UNSHIFT_AFTER_END_EVENT());
+  } else if (state.objectMode || (chunk && chunk.length > 0)) {
+    if (addToFront) {
+      if (state.endEmitted)
+        errorOrDestroy(stream, new ERR_STREAM_UNSHIFT_AFTER_END_EVENT());
+      else
+        addChunk(stream, state, chunk, true);
+    } else if (state.ended) {
+      errorOrDestroy(stream, new ERR_STREAM_PUSH_AFTER_EOF());
+    } else if (state.destroyed) {
+      return false;
+    } else {
+      state.reading = false;
+      if (state.decoder && !encoding) {
+        chunk = state.decoder.write(chunk);
+        if (state.objectMode || chunk.length !== 0)
+          addChunk(stream, state, chunk, false);
         else
-          addChunk(stream, state, chunk, true);
-      } else if (state.ended) {
-        errorOrDestroy(stream, new ERR_STREAM_PUSH_AFTER_EOF());
-      } else if (state.destroyed) {
-        return false;
+          maybeReadMore(stream, state);
       } else {
-        state.reading = false;
-        if (state.decoder && !encoding) {
-          chunk = state.decoder.write(chunk);
-          if (state.objectMode || chunk.length !== 0)
-            addChunk(stream, state, chunk, false);
-          else
-            maybeReadMore(stream, state);
-        } else {
-          addChunk(stream, state, chunk, false);
-        }
+        addChunk(stream, state, chunk, false);
       }
-    } else if (!addToFront) {
-      state.reading = false;
-      maybeReadMore(stream, state);
     }
+  } else if (!addToFront) {
+    state.reading = false;
+    maybeReadMore(stream, state);
   }
 
   // We can push more data if we are below the highWaterMark.
@@ -317,17 +309,6 @@ function addChunk(stream, state, chunk, addToFront) {
   maybeReadMore(stream, state);
 }
 
-function chunkInvalid(state, chunk) {
-  if (!Stream._isUint8Array(chunk) &&
-      typeof chunk !== 'string' &&
-      chunk !== undefined &&
-      !state.objectMode) {
-    return new ERR_INVALID_ARG_TYPE(
-      'chunk', ['string', 'Buffer', 'Uint8Array'], chunk);
-  }
-}
-
-
 Readable.prototype.isPaused = function() {
   const state = this._readableState;
   return state[kPaused] === true || state.flowing === false;