streams2: Abstract out onread function

Author: isaacs

lib/_stream_readable.js

@@ -28,7 +28,7 @@ var StringDecoder;
 
 util.inherits(Readable, Stream);
 
-function ReadableState(options) {
+function ReadableState(options, stream) {
   options = options || {};
 
   this.bufferSize = options.bufferSize || 16 * 1024;
@@ -45,6 +45,8 @@ function ReadableState(options) {
   this.ended = false;
   this.endEmitted = false;
   this.reading = false;
+  this.sync = false;
+  this.onread = onread.bind(stream);
 
   // whenever we return null, then we set a flag to say
   // that we're awaiting a 'readable' event emission.
@@ -144,59 +146,10 @@ Readable.prototype.read = function(n) {
   if (doRead) {
     var sync = true;
     state.reading = true;
+    state.sync = true;
     // call internal read method
-    this._read(state.bufferSize, function onread(er, chunk) {
-      state.reading = false;
-      if (er)
-        return this.emit('error', er);
-
-      if (!chunk || !chunk.length) {
-        // eof
-        state.ended = true;
-        if (state.decoder) {
-          chunk = state.decoder.end();
-          if (chunk && chunk.length) {
-            state.buffer.push(chunk);
-            state.length += chunk.length;
-          }
-        }
-        // if we've ended and we have some data left, then emit
-        // 'readable' now to make sure it gets picked up.
-        if (!sync) {
-          if (state.length > 0)
-            this.emit('readable');
-          else
-            endReadable(this);
-        }
-        return;
-      }
-
-      if (state.decoder)
-        chunk = state.decoder.write(chunk);
-
-      // update the buffer info.
-      if (chunk) {
-        state.length += chunk.length;
-        state.buffer.push(chunk);
-      }
-
-      // if we haven't gotten enough to pass the lowWaterMark,
-      // and we haven't ended, then don't bother telling the user
-      // that it's time to read more data.  Otherwise, that'll
-      // probably kick off another stream.read(), which can trigger
-      // another _read(n,cb) before this one returns!
-      if (state.length <= state.lowWaterMark) {
-        state.reading = true;
-        this._read(state.bufferSize, onread.bind(this));
-        return;
-      }
-
-      if (state.needReadable && !sync) {
-        state.needReadable = false;
-        this.emit('readable');
-      }
-    }.bind(this));
-    sync = false;
+    this._read(state.bufferSize, state.onread);
+    state.sync = false;
   }
 
   // If _read called its callback synchronously, then `reading`
@@ -221,6 +174,61 @@ Readable.prototype.read = function(n) {
   return ret;
 };
 
+function onread(er, chunk) {
+  var state = this._readableState;
+  var sync = state.sync;
+
+  state.reading = false;
+  if (er)
+    return this.emit('error', er);
+
+  if (!chunk || !chunk.length) {
+    // eof
+    state.ended = true;
+    if (state.decoder) {
+      chunk = state.decoder.end();
+      if (chunk && chunk.length) {
+        state.buffer.push(chunk);
+        state.length += chunk.length;
+      }
+    }
+    // if we've ended and we have some data left, then emit
+    // 'readable' now to make sure it gets picked up.
+    if (!sync) {
+      if (state.length > 0)
+        this.emit('readable');
+      else
+        endReadable(this);
+    }
+    return;
+  }
+
+  if (state.decoder)
+    chunk = state.decoder.write(chunk);
+
+  // update the buffer info.
+  if (chunk) {
+    state.length += chunk.length;
+    state.buffer.push(chunk);
+  }
+
+  // if we haven't gotten enough to pass the lowWaterMark,
+  // and we haven't ended, then don't bother telling the user
+  // that it's time to read more data.  Otherwise, that'll
+  // probably kick off another stream.read(), which can trigger
+  // another _read(n,cb) before this one returns!
+  if (state.length <= state.lowWaterMark) {
+    state.reading = true;
+    this._read(state.bufferSize, state.onread);
+    return;
+  }
+
+  if (state.needReadable && !sync) {
+    state.needReadable = false;
+    this.emit('readable');
+  }
+}
+
 // abstract method.  to be overridden in specific implementation classes.
 // call cb(er, data) where data is <= n in length.
 // for virtual (non-string, non-buffer) streams, "length" is somewhat