Array.observe emit splices for array length change and update index >= length

test/mjsunit/harmony/object-observe.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 939 matching lines @@
 }
 
 
 // Observing array length (including truncation)
 reset();
 var arr = ['a', 'b', 'c', 'd'];
 var arr2 = ['alpha', 'beta'];
 var arr3 = ['hello'];
 arr3[2] = 'goodbye';
 arr3.length = 6;
-var slow_arr = new Array(1000000000);
-slow_arr[500000000] = 'hello';
 Object.defineProperty(arr, '0', {configurable: false});
 Object.defineProperty(arr, '2', {get: function(){}});
 Object.defineProperty(arr2, '0', {get: function(){}, configurable: false});
 Object.observe(arr, observer.callback);
+Array.observe(arr, observer2.callback);
 Object.observe(arr2, observer.callback);
+Array.observe(arr2, observer2.callback);
 Object.observe(arr3, observer.callback);
-Object.observe(slow_arr, observer.callback);
+Array.observe(arr3, observer2.callback);
 arr.length = 2;
 arr.length = 0;
 arr.length = 10;
 Object.defineProperty(arr, 'length', {writable: false});
 arr2.length = 0;
 arr2.length = 1; // no change expected
 Object.defineProperty(arr2, 'length', {value: 1, writable: false});
 arr3.length = 0;
 ++arr3.length;
 arr3.length++;
 arr3.length /= 2;
 Object.defineProperty(arr3, 'length', {value: 5});
-Object.defineProperty(arr3, 'length', {value: 10, writable: false});
-slow_arr.length = 100;
+arr3[4] = 5;
+Object.defineProperty(arr3, 'length', {value: 1, writable: false});
 Object.deliverChangeRecords(observer.callback);
 observer.assertCallbackRecords([
   { object: arr, name: '3', type: 'deleted', oldValue: 'd' },
   { object: arr, name: '2', type: 'deleted' },
   { object: arr, name: 'length', type: 'updated', oldValue: 4 },
   { object: arr, name: '1', type: 'deleted', oldValue: 'b' },
   { object: arr, name: 'length', type: 'updated', oldValue: 2 },
   { object: arr, name: 'length', type: 'updated', oldValue: 1 },
   { object: arr, name: 'length', type: 'reconfigured' },
   { object: arr2, name: '1', type: 'deleted', oldValue: 'beta' },
   { object: arr2, name: 'length', type: 'updated', oldValue: 2 },
-  { object: arr2, name: 'length', type: 'reconfigured', oldValue: 1 },
+  { object: arr2, name: 'length', type: 'reconfigured' },
   { object: arr3, name: '2', type: 'deleted', oldValue: 'goodbye' },
   { object: arr3, name: '0', type: 'deleted', oldValue: 'hello' },
   { object: arr3, name: 'length', type: 'updated', oldValue: 6 },
   { object: arr3, name: 'length', type: 'updated', oldValue: 0 },
   { object: arr3, name: 'length', type: 'updated', oldValue: 1 },
   { object: arr3, name: 'length', type: 'updated', oldValue: 2 },
   { object: arr3, name: 'length', type: 'updated', oldValue: 1 },
-  { object: arr3, name: 'length', type: 'reconfigured', oldValue: 5 },
+  { object: arr3, name: '4', type: 'new' },
+  { object: arr3, name: '4', type: 'deleted', oldValue: 5 },
+  // TODO(rafaelw): It breaks spec compliance to get two records here.
+  // When the TODO in v8natives.js::DefineArrayProperty is addressed
+  // which prevents DefineProperty from over-writing the magic length
+  // property, these will collapse into a single record.
+  { object: arr3, name: 'length', type: 'updated', oldValue: 5 },
+  { object: arr3, name: 'length', type: 'reconfigured' }
+]);
+Object.deliverChangeRecords(observer2.callback);
+observer2.assertCallbackRecords([
+  { object: arr, type: 'splice', index: 2, removed: [, 'd'], addedCount: 0 },
+  { object: arr, type: 'splice', index: 1, removed: ['b'], addedCount: 0 },
+  { object: arr, type: 'splice', index: 1, removed: [], addedCount: 9 },
+  { object: arr2, type: 'splice', index: 1, removed: ['beta'], addedCount: 0 },
+  { object: arr3, type: 'splice', index: 0, removed: ['hello',, 'goodbye',,,,], addedCount: 0 },
+  { object: arr3, type: 'splice', index: 0, removed: [], addedCount: 1 },
+  { object: arr3, type: 'splice', index: 1, removed: [], addedCount: 1 },
+  { object: arr3, type: 'splice', index: 1, removed: [,], addedCount: 0 },
+  { object: arr3, type: 'splice', index: 1, removed: [], addedCount: 4 },
+  { object: arr3, name: '4', type: 'new' },
+  { object: arr3, type: 'splice', index: 1, removed: [,,,5], addedCount: 0 }
+]);
+
+
+// Updating length on large (slow) array
+reset();
+var slow_arr = new Array(1000000000);
+slow_arr[500000000] = 'hello';
+Object.observe(slow_arr, observer.callback);
+var spliceRecords;
+function slowSpliceCallback(records) {
+  spliceRecords = records;
+}
+Array.observe(slow_arr, slowSpliceCallback);
+slow_arr.length = 100;
+Object.deliverChangeRecords(observer.callback);
+observer.assertCallbackRecords([
   { object: slow_arr, name: '500000000', type: 'deleted', oldValue: 'hello' },
   { object: slow_arr, name: 'length', type: 'updated', oldValue: 1000000000 },
 ]);
+Object.deliverChangeRecords(slowSpliceCallback);
+assertEquals(spliceRecords.length, 1);
+// Have to custom assert this splice record because the removed array is huge.
+var splice = spliceRecords[0];
+assertSame(splice.object, slow_arr);
+assertEquals(splice.type, 'splice');
+assertEquals(splice.index, 100);
+assertEquals(splice.addedCount, 0);
+var array_keys = %GetArrayKeys(splice.removed, splice.removed.length);
+assertEquals(array_keys.length, 1);
+assertEquals(array_keys[0], 499999900);
+assertEquals(splice.removed[499999900], 'hello');
+assertEquals(splice.removed.length, 999999900);
 
 
 // Assignments in loops (checking different IC states).
 reset();
 var obj = {};
 Object.observe(obj, observer.callback);
 for (var i = 0; i < 5; i++) {
   obj["a" + i] = i;
 }
 Object.deliverChangeRecords(observer.callback);
@@ skipping 14 matching lines @@
 Object.deliverChangeRecords(observer.callback);
 observer.assertCallbackRecords([
   { object: obj, name: "0", type: "new" },
   { object: obj, name: "1", type: "new" },
   { object: obj, name: "2", type: "new" },
   { object: obj, name: "3", type: "new" },
   { object: obj, name: "4", type: "new" },
 ]);
 
 
-// Adding elements past the end of an array should notify on length
+// Adding elements past the end of an array should notify on length for
+// Object.observe and emit "splices" for Array.observe.
 reset();
 var arr = [1, 2, 3];
 Object.observe(arr, observer.callback);
+Array.observe(arr, observer2.callback);
 arr[3] = 10;
 arr[100] = 20;
 Object.defineProperty(arr, '200', {value: 7});
 Object.defineProperty(arr, '400', {get: function(){}});
 arr[50] = 30; // no length change expected
 Object.deliverChangeRecords(observer.callback);
 observer.assertCallbackRecords([
   { object: arr, name: '3', type: 'new' },
   { object: arr, name: 'length', type: 'updated', oldValue: 3 },
   { object: arr, name: '100', type: 'new' },
   { object: arr, name: 'length', type: 'updated', oldValue: 4 },
   { object: arr, name: '200', type: 'new' },
   { object: arr, name: 'length', type: 'updated', oldValue: 101 },
   { object: arr, name: '400', type: 'new' },
   { object: arr, name: 'length', type: 'updated', oldValue: 201 },
   { object: arr, name: '50', type: 'new' },
 ]);
+Object.deliverChangeRecords(observer2.callback);
+observer2.assertCallbackRecords([
+  { object: arr, type: 'splice', index: 3, removed: [], addedCount: 1 },
+  { object: arr, type: 'splice', index: 4, removed: [], addedCount: 97 },
+  { object: arr, type: 'splice', index: 101, removed: [], addedCount: 100 },
+  { object: arr, type: 'splice', index: 201, removed: [], addedCount: 200 },
+  { object: arr, type: 'new', name: '50' },
+]);
 
 
 // Tests for array methods, first on arrays and then on plain objects
 //
 // === ARRAYS ===
 //
 // Push
 reset();
 var array = [1, 2];
 Object.observe(array, observer.callback);
@@ skipping 380 matching lines @@
     for (var n1 = 0; n1 < 3; ++n1)
       for (var n2 = 0; n2 < 3; ++n2)
         for (var i in mutation)
           TestFastElementsLength(mutation[i], b1 != 0, b2 != 0, 20*n1, 20*n2);
 
 for (var b1 = 0; b1 < 2; ++b1)
   for (var b2 = 0; b2 < 2; ++b2)
     for (var n = 0; n < 3; ++n)
       for (var i in mutationByIncr)
         TestFastElementsLength(mutationByIncr[i], b1 != 0, b2 != 0, 7*n, 7*n+1);