ES6: Add support for Map.prototype.forEach and Set.prototype.forEach

src/collection.js

Index: src/collection.js
diff --git a/src/collection.js b/src/collection.js
index 9054187a12d0372ef1e028569a197059579f26ba..a9b87c07434c9a8f7332a1c6cb496a52112b28f0 100644
--- a/src/collection.js
+++ b/src/collection.js
@@ -113,8 +113,33 @@ function SetClear() {
     throw MakeTypeError('incompatible_method_receiver',
                         ['Set.prototype.clear', this]);
   }
-  // Replace the internal table with a new empty table.
-  %SetInitialize(this);
+  %SetClear(this);
+}
+
+
+// Matches OrderedHashTableIterator::Kind enum values.
+var SET_ITERATOR_KIND_VALUES = 2;
+
+
+function SetForEach(f, receiver) {
+  if (!IS_SET(this)) {
+    throw MakeTypeError('incompatible_method_receiver',
+                        ['Set.prototype.forEach', this]);
+  }
+
+  if (typeof f !== 'function') {

[adamk, 2014/04/14 19:15:42]

I think you want IS_SPEC_FUNCTION(f) here, which is a macro expanding to:

%_ClassOf(arg) === 'Function'

[arv (Not doing code reviews), 2014/04/14 19:51:49]

IS_SPEC_FUNCTION is not correct any more. It tests that the instance is a true
function. What we really care about is Callable. Most of the IS_SPEC function
have been removed in the spec and now the spec checks for Callable instead.

[rossberg, 2014/04/15 10:49:29]

They are testing the same thing (whether the instance type is either JS_FUNCTION
or JS_FUNCTION_PROXY -- there are no other callables in V8). However,
IS_SPEC_FUNCTION does not require a runtime call, so is preferable.

Somebody should fix the misleading comment in macros.py :)

+    throw MakeTypeError('called_non_callable', [f]);
+  }
+
+  var iterator = %SetCreateIterator(this, SET_ITERATOR_KIND_VALUES);
+  var entry;
+  try {
+    while (!(entry = %SetIteratorNext(iterator)).done) {
+      %_CallFunction(receiver, entry.value, entry.value, this, f);

[adamk, 2014/04/14 19:15:42]

Can you add a test that throws in its forEach function (both for set and maps)?

[arv (Not doing code reviews), 2014/04/14 19:51:49]

Done.

+    }
+  } finally {
+    %SetIteratorClose(iterator);
+  }
 }
 
 
@@ -127,13 +152,16 @@ function SetUpSet() {
   %FunctionSetPrototype($Set, new $Object());
   %SetProperty($Set.prototype, "constructor", $Set, DONT_ENUM);
 
+  %FunctionSetLength(SetForEach, 1);
+
   // 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,
-    "clear", SetClear
+    "clear", SetClear,
+    "forEach", SetForEach
   ));
 }
 
@@ -202,8 +230,33 @@ function MapClear() {
     throw MakeTypeError('incompatible_method_receiver',
                         ['Map.prototype.clear', this]);
   }
-  // Replace the internal table with a new empty table.
-  %MapInitialize(this);
+  %MapClear(this);
+}
+
+
+// Matches OrderedHashTableIterator::Kind enum values.
+var MAP_ITERATOR_KIND_ENTRIES = 3;
+
+
+function MapForEach(f, receiver) {
+  if (!IS_MAP(this)) {
+    throw MakeTypeError('incompatible_method_receiver',

[adamk, 2014/04/14 19:15:42]

Can you add tests for this and the other error cases?

[arv (Not doing code reviews), 2014/04/14 19:51:49]

Done.

+                        ['Map.prototype.forEach', this]);
+  }
+
+  if (typeof f !== 'function') {

[adamk, 2014/04/14 19:15:42]

IS_SPEC_FUNCTION

+    throw MakeTypeError('called_non_callable', [f]);
+  }
+
+  var iterator = %MapCreateIterator(this, MAP_ITERATOR_KIND_ENTRIES);
+  var entry;
+  try {
+    while (!(entry = %MapIteratorNext(iterator)).done) {
+      %_CallFunction(receiver, entry.value[1], entry.value[0], this, f);
+    }
+  } finally {
+    %MapIteratorClose(iterator);
+  }
 }
 
 
@@ -216,6 +269,8 @@ function SetUpMap() {
   %FunctionSetPrototype($Map, new $Object());
   %SetProperty($Map.prototype, "constructor", $Map, DONT_ENUM);
 
+  %FunctionSetLength(MapForEach, 1);
+
   // Set up the non-enumerable functions on the Map prototype object.
   InstallGetter($Map.prototype, "size", MapGetSize);
   InstallFunctions($Map.prototype, DONT_ENUM, $Array(
@@ -223,7 +278,8 @@ function SetUpMap() {
     "set", MapSet,
     "has", MapHas,
     "delete", MapDelete,
-    "clear", MapClear
+    "clear", MapClear,
+    "forEach", MapForEach
   ));
 }