Minimal implementation and tests of observable array methods

src/array.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 423 matching lines @@
                         ["Array.prototype.pop"]);
   }
 
   var n = TO_UINT32(this.length);
   if (n == 0) {
     this.length = n;
     return;
   }
   n--;
   var value = this[n];
+  delete this[n];

[adamk, 2012/11/09 12:06:30]

This change is required for proper operation, and is the proper ordering per the
spec:

http://ecma-international.org/ecma-262/5.1/#sec-15.4.4.6

   this.length = n;
-  delete this[n];
   return value;
 }
 
 
 // Appends the arguments to the end of the array and returns the new
 // length of the array. See ECMA-262, section 15.4.4.7.
 function ArrayPush() {
   if (IS_NULL_OR_UNDEFINED(this) && !IS_UNDETECTABLE(this)) {
     throw MakeTypeError("called_on_null_or_undefined",
                         ["Array.prototype.push"]);
@@ skipping 118 matching lines @@
 
   var len = TO_UINT32(this.length);
 
   if (len === 0) {
     this.length = 0;
     return;
   }
 
   var first = this[0];
 
-  if (IS_ARRAY(this)) {
+  if (IS_ARRAY(this) && !%IsObserved(this)) {
     SmartMove(this, 0, 1, len, 0);
   } else {
     SimpleMove(this, 0, 1, len, 0);
   }
 
   this.length = len - 1;
 
   return first;
 }
 
 
 function ArrayUnshift(arg1) {  // length == 1
   if (IS_NULL_OR_UNDEFINED(this) && !IS_UNDETECTABLE(this)) {
     throw MakeTypeError("called_on_null_or_undefined",
                         ["Array.prototype.unshift"]);
   }
 
   var len = TO_UINT32(this.length);
   var num_arguments = %_ArgumentsLength();
 
-  if (IS_ARRAY(this)) {
+  if (IS_ARRAY(this) && !%IsObserved(this)) {
     SmartMove(this, 0, 0, len, num_arguments);
   } else {
     SimpleMove(this, 0, 0, len, num_arguments);
   }
 
   for (var i = 0; i < num_arguments; i++) {
     this[i] = %_Arguments(i);
   }
 
   this.length = len + num_arguments;
@@ skipping 26 matching lines @@
     if (end_i < 0) end_i = 0;
   } else {
     if (end_i > len) end_i = len;
   }
 
   var result = [];
 
   if (end_i < start_i) return result;
 
   if (IS_ARRAY(this) &&
+      !%IsObserved(this) &&
       (end_i > 1000) &&
       (%EstimateNumberOfElements(this) < end_i)) {
     SmartSlice(this, start_i, end_i - start_i, len, result);
   } else {
     SimpleSlice(this, start_i, end_i - start_i, len, result);
   }
 
   result.length = end_i - start_i;
 
   return result;
@@ skipping 36 matching lines @@
   deleted_elements.length = del_count;
 
   // Number of elements to add.
   var num_additional_args = 0;
   if (num_arguments > 2) {
     num_additional_args = num_arguments - 2;
   }
 
   var use_simple_splice = true;
 
-  if (IS_ARRAY(this) && num_additional_args !== del_count) {
+  if (IS_ARRAY(this) &&
+      !%IsObserved(this) &&
+      num_additional_args !== del_count) {
     // If we are only deleting/moving a few things near the end of the
     // array then the simple version is going to be faster, because it
     // doesn't touch most of the array.
     var estimated_non_hole_elements = %EstimateNumberOfElements(this);
     if (len > 20 && (estimated_non_hole_elements >> 2) < (len - start_i)) {
       use_simple_splice = false;
     }
   }
 
   if (use_simple_splice) {
@@ skipping 832 matching lines @@
   SetUpLockedPrototype(InternalArray, $Array(), $Array(
     "indexOf", getFunction("indexOf", ArrayIndexOf),
     "join", getFunction("join", ArrayJoin),
     "pop", getFunction("pop", ArrayPop),
     "push", getFunction("push", ArrayPush),
     "splice", getFunction("splice", ArraySplice)
   ));
 }
 
 SetUpArray();