ES6: Adding support for size to Set and Map

src/collection.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 70 matching lines @@
   }
   if (%SetHas(this, key)) {
     %SetDelete(this, key);
     return true;
   } else {
     return false;
   }
 }
 
 
+function SetGetSize() {
+  if (!IS_SET(this)) {
+    throw MakeTypeError('incompatible_method_receiver',
+                        ['Set.prototype.size', this]);
+  }
+  return %SetGetSize(this);
+}
+
+
 function MapConstructor() {
   if (%_IsConstructCall()) {
     %MapInitialize(this);
   } else {
     return new $Map();
   }
 }
 
 
 function MapGet(key) {
@@ skipping 37 matching lines @@
     throw MakeTypeError('incompatible_method_receiver',
                         ['Map.prototype.delete', this]);
   }
   if (IS_UNDEFINED(key)) {
     key = undefined_sentinel;
   }
   return %MapDelete(this, key);
 }
 
 
+function MapGetSize() {
+  if (!IS_MAP(this)) {
+    throw MakeTypeError('incompatible_method_receiver',
+                        ['Map.prototype.size', this]);
+  }
+  return %MapGetSize(this);
+}
+
+
 function WeakMapConstructor() {
   if (%_IsConstructCall()) {
     %WeakMapInitialize(this);
   } else {
     return new $WeakMap();
   }
 }
 
 
 function WeakMapGet(key) {
@@ skipping 50 matching lines @@
 
   // Set up the Set and Map constructor function.
   %SetCode($Set, SetConstructor);
   %SetCode($Map, MapConstructor);
 
   // Set up the constructor property on the Set and Map prototype object.
   %SetProperty($Set.prototype, "constructor", $Set, DONT_ENUM);
   %SetProperty($Map.prototype, "constructor", $Map, DONT_ENUM);
 
   // Set up the non-enumerable functions on the Set prototype object.
+  InstallGetter($Set.prototype, "size", SetGetSize);
   InstallFunctions($Set.prototype, DONT_ENUM, $Array(
     "add", SetAdd,
     "has", SetHas,
     "delete", SetDelete
   ));
 
   // Set up the non-enumerable functions on the Map prototype object.
+  InstallGetter($Map.prototype, "size", MapGetSize);
   InstallFunctions($Map.prototype, DONT_ENUM, $Array(
     "get", MapGet,
     "set", MapSet,
     "has", MapHas,
     "delete", MapDelete
   ));
 
   // Set up the WeakMap constructor function.
   %SetCode($WeakMap, WeakMapConstructor);
 
   // Set up the constructor property on the WeakMap prototype object.
   %SetProperty($WeakMap.prototype, "constructor", $WeakMap, DONT_ENUM);
 
   // Set up the non-enumerable functions on the WeakMap prototype object.
   InstallFunctions($WeakMap.prototype, DONT_ENUM, $Array(
     "get", WeakMapGet,
     "set", WeakMapSet,
     "has", WeakMapHas,
     "delete", WeakMapDelete
   ));
 })();