Make VM TypedList not implement ByteBuffer.

runtime/lib/typed_data.dart

Index: runtime/lib/typed_data.dart
diff --git a/runtime/lib/typed_data.dart b/runtime/lib/typed_data.dart
index 376acb33bdc84a791d5644389e0dbfd48ffef9c9..a7910f83061463c845659e5d6d7dc9a98d34d6c8 100644
--- a/runtime/lib/typed_data.dart
+++ b/runtime/lib/typed_data.dart
@@ -298,7 +298,7 @@ patch class Int32x4 {
 patch class ByteData {
   /* patch */ factory ByteData(int length) {
     var list = new _Uint8Array(length);
-    return new _ByteDataView(list.buffer, 0, length);
+    return new _ByteDataView(list, 0, length);
   }
 
   /* patch */ factory ByteData.view(ByteBuffer buffer,
@@ -306,8 +306,13 @@ patch class ByteData {
     if (length == null) {
       length = buffer.lengthInBytes - offsetInBytes;
     }
-    return new _ByteDataView(buffer, offsetInBytes, length);
+    _ByteBuffer internalBuffer = buffer;
+    return new _ByteDataView(internalBuffer._typedData, offsetInBytes, length);
   }
+
+  // Called directly from C code.
+  factory ByteData._view(TypedData typedData, int offsetInBytes, int length)
+      => new _ByteDataView(typedData, offsetInBytes, length);
 }
 
 
@@ -554,11 +559,14 @@ abstract class _TypedListBase {
         if (needsClamping) {
           Lists.copy(from, skipCount, this, start, count);
           return;
-        } else if (this.buffer._setRange(
-                     start * elementSizeInBytes + this.offsetInBytes,
-                     count * elementSizeInBytes,
-                     from.buffer,
-                     skipCount * elementSizeInBytes + from.offsetInBytes)) {
+        }
+        _ByteBuffer buffer = this.buffer;
+        _ByteBuffer fromBuffer = from.buffer;
+        if (buffer._typedData._setRange(
+                start * elementSizeInBytes + this.offsetInBytes,
+                count * elementSizeInBytes,
+                fromBuffer._typedData,
+                skipCount * elementSizeInBytes + from.offsetInBytes)) {
           return;
         }
       } else if (from.buffer == this.buffer) {
@@ -607,7 +615,13 @@ abstract class _TypedListBase {
 }
 
 
-abstract class _TypedList extends _TypedListBase implements ByteBuffer {
+abstract class _TypedList extends _TypedListBase {
+  // The [buffer] getter should return the same value each time.
+  // Store it here the first time it is created.
+  // We don't want to store it on the object, since not all typed lists
+  // have a buffer extracted.

[Søren Gjesse, 2014/01/14 12:00:17]

Is this just to save an instance variable? You are probably right that most
types lists will never have .buffer called, but still...

[Lasse Reichstein Nielsen, 2014/01/14 12:19:17]

Yes.

+  static var _buffers = new Expando();
+
   // Default method implementing parts of the TypedData interface.
   int get offsetInBytes {
     return 0;
@@ -618,7 +632,12 @@ abstract class _TypedList extends _TypedListBase implements ByteBuffer {
   }
 
   ByteBuffer get buffer {
-    return this;
+    _ByteBuffer buffer = _buffers[this];
+    if (buffer == null) {
+      buffer = new _ByteBuffer(this);
+      _buffers[this] = buffer;
+    }
+    return buffer;
   }
 
   // Methods implementing the collection interface.
@@ -2334,11 +2353,14 @@ class _TypedListIterator<E> implements Iterator<E> {
 
 
 class _TypedListView extends _TypedListBase implements TypedData {
+  final TypedData _typedData;
+  final int offsetInBytes;
+  final int length;
+
   _TypedListView(ByteBuffer _buffer, int _offset, int _length)
-    : _typedData = _buffer,  // This assignment is type safe.
-      offsetInBytes = _offset,
-      length = _length {
-  }
+      : _typedData = (_buffer as _ByteBuffer)._typedData,
+        offsetInBytes = _offset,
+        length = _length;
 
   // Method(s) implementing the TypedData interface.
 
@@ -2349,10 +2371,6 @@ class _TypedListView extends _TypedListBase implements TypedData {
   ByteBuffer get buffer {
     return _typedData.buffer;
   }
-
-  final TypedData _typedData;
-  final int offsetInBytes;
-  final int length;
 }
 
 
@@ -3033,14 +3051,17 @@ class _Int32x4ArrayView extends _TypedListView implements Int32x4List {
 
 
 class _ByteDataView implements ByteData {
-  _ByteDataView(ByteBuffer _buffer, int _offsetInBytes, int _lengthInBytes)
-    : _typedData = _buffer,  // _buffer is guaranteed to be a TypedData here.
+  final TypedData _typedData;
+  final int _offset;
+  final int length;
+
+  _ByteDataView(TypedData typedData, int _offsetInBytes, int _lengthInBytes)
+    : _typedData = typedData,
       _offset = _offsetInBytes,
       length = _lengthInBytes {
-    _rangeCheck(_buffer.lengthInBytes, _offset, length);
+    _rangeCheck(typedData.lengthInBytes, _offset, length);
   }
 
-
   // Method(s) implementing TypedData interface.
 
   ByteBuffer get buffer {
@@ -3311,11 +3332,6 @@ class _ByteDataView implements ByteData {
       native "ByteData_ToEndianFloat32";
   static double _toEndianFloat64(double host_value, bool little_endian)
       native "ByteData_ToEndianFloat64";
-
-
-  final TypedData _typedData;
-  final int _offset;
-  final int length;
 }
 
 
@@ -3407,3 +3423,18 @@ void _throwRangeError(int index, int length) {
   String message = "$index must be in the range [0..$length)";
   throw new RangeError(message);
 }
+
+/**
+ * Internal implementation of [ByteBuffer].
+ */
+class _ByteBuffer implements ByteBuffer {
+  final _TypedList _typedData;
+
+  _ByteBuffer(this._typedData);
+
+  int get lengthInBytes => _typedData.lengthInBytes;
+
+  int get hashCode => _typedData.hashCode;
+  bool operator==(Object other) =>
+      other is _ByteBuffer && _typedData == other._typedData;
+}