stream: call helper function from push and unshift

PR-URL: #50173
Reviewed-By: Matteo Collina <[email protected]>
Reviewed-By: Robert Nagy <[email protected]>
Reviewed-By: Benjamin Gruenbaum <[email protected]>

Author: rluvaton

lib/internal/streams/readable.js

@@ -284,77 +284,164 @@ Readable.prototype[SymbolAsyncDispose] = function() {
 // similar to how Writable.write() returns true if you should
 // write() some more.
 Readable.prototype.push = function(chunk, encoding) {
-  return readableAddChunk(this, chunk, encoding, false);
+  debug('push', chunk);
+
+  const state = this._readableState;
+  return (state[kState] & kObjectMode) === 0 ?
+    readableAddChunkPushByteMode(this, state, chunk, encoding) :
+    readableAddChunkPushObjectMode(this, state, chunk, encoding);
 };
 
 // Unshift should *always* be something directly out of read().
 Readable.prototype.unshift = function(chunk, encoding) {
-  return readableAddChunk(this, chunk, encoding, true);
+  debug('unshift', chunk);
+  const state = this._readableState;
+  return (state[kState] & kObjectMode) === 0 ?
+    readableAddChunkUnshiftByteMode(this, state, chunk, encoding) :
+    readableAddChunkUnshiftObjectMode(this, state, chunk);
 };
 
-function readableAddChunk(stream, chunk, encoding, addToFront) {
-  debug('readableAddChunk', chunk);
-  const state = stream._readableState;
 
-  let err;
-  if ((state[kState] & kObjectMode) === 0) {
-    if (typeof chunk === 'string') {
-      encoding = encoding || state.defaultEncoding;
-      if (state.encoding !== encoding) {
-        if (addToFront && state.encoding) {
-          // When unshifting, if state.encoding is set, we have to save
-          // the string in the BufferList with the state encoding.
-          chunk = Buffer.from(chunk, encoding).toString(state.encoding);
-        } else {
-          chunk = Buffer.from(chunk, encoding);
-          encoding = '';
-        }
+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) {
+      if (state.encoding) {
+        // When unshifting, if state.encoding is set, we have to save
+        // the string in the BufferList with the state encoding.
+        chunk = Buffer.from(chunk, encoding).toString(state.encoding);
+      } else {
+        chunk = Buffer.from(chunk, encoding);
       }
-    } 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 if (Stream._isUint8Array(chunk)) {
+    chunk = Stream._uint8ArrayToBuffer(chunk);
+  } else if (chunk !== undefined && !(chunk instanceof Buffer)) {
+    errorOrDestroy(stream, new ERR_INVALID_ARG_TYPE(
+      'chunk', ['string', 'Buffer', 'Uint8Array'], chunk));
+    return false;
   }
 
-  if (err) {
-    errorOrDestroy(stream, err);
-  } else if (chunk === null) {
+
+  if (!(chunk && chunk.length > 0)) {
+    return canPushMore(state);
+  }
+
+  return readableAddChunkUnshiftValue(stream, state, chunk);
+}
+
+function readableAddChunkUnshiftObjectMode(stream, state, chunk) {
+  if (chunk === null) {
     state[kState] &= ~kReading;
     onEofChunk(stream, state);
-  } else if (((state[kState] & kObjectMode) !== 0) || (chunk && chunk.length > 0)) {
-    if (addToFront) {
-      if ((state[kState] & kEndEmitted) !== 0)
-        errorOrDestroy(stream, new ERR_STREAM_UNSHIFT_AFTER_END_EVENT());
-      else if (state.destroyed || state.errored)
-        return false;
-      else
-        addChunk(stream, state, chunk, true);
-    } else if (state.ended) {
-      errorOrDestroy(stream, new ERR_STREAM_PUSH_AFTER_EOF());
-    } else if (state.destroyed || state.errored) {
-      return false;
-    } else {
-      state[kState] &= ~kReading;
-      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);
-      }
+
+    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.destroyed || state.errored)
+    return false;
+  else
+    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) {
+      chunk = Buffer.from(chunk, encoding);
+      encoding = '';
     }
-  } else if (!addToFront) {
+  } else if (chunk instanceof Buffer) {
+    encoding = '';
+  } else if (Stream._isUint8Array(chunk)) {
+    chunk = Stream._uint8ArrayToBuffer(chunk);
+    encoding = '';
+  } else if (chunk !== undefined) {
+    errorOrDestroy(stream, new ERR_INVALID_ARG_TYPE(
+      'chunk', ['string', 'Buffer', 'Uint8Array'], chunk));
+    return false;
+  }
+
+  if (!chunk || chunk.length <= 0) {
     state[kState] &= ~kReading;
     maybeReadMore(stream, state);
+
+    return canPushMore(state);
+  }
+
+  if (state.ended) {
+    errorOrDestroy(stream, new ERR_STREAM_PUSH_AFTER_EOF());
+
+    return false;
+  }
+
+  if (state.destroyed || state.errored) {
+    return false;
+  }
+
+  state[kState] &= ~kReading;
+  if (state.decoder && !encoding) {
+    chunk = state.decoder.write(chunk);
+    if (chunk.length === 0) {
+      maybeReadMore(stream, state);
+
+      return canPushMore(state);
+    }
   }
 
+  addChunk(stream, state, chunk, false);
+  return canPushMore(state);
+}
+
+function readableAddChunkPushObjectMode(stream, state, chunk, encoding) {
+  if (chunk === null) {
+    state[kState] &= ~kReading;
+    onEofChunk(stream, state);
+
+    return false;
+  }
+
+  if (state.ended) {
+    errorOrDestroy(stream, new ERR_STREAM_PUSH_AFTER_EOF());
+    return false;
+  }
+
+  if (state.destroyed || state.errored) {
+    return false;
+  }
+
+  state[kState] &= ~kReading;
+  if (state.decoder && !encoding) {
+    chunk = state.decoder.write(chunk);
+  }
+
+  addChunk(stream, state, chunk, false);
+  return canPushMore(state);
+}
+
+function canPushMore(state) {
   // We can push more data if we are below the highWaterMark.
   // Also, if we have no data yet, we can stand some more bytes.
   // This is to work around cases where hwm=0, such as the repl.