Reimplement Maps and Sets in JS

src/harmony-templates.js

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 "use strict";
 
 var callSiteCache = new $Map;
 
 function SameCallSiteElements(rawStrings, other) {
   var length = rawStrings.length;
   var other = other.raw;
 
   if (length !== other.length) return false;
 
   for (var i = 0; i < length; ++i) {
     if (rawStrings[i] !== other[i]) return false;
   }
 
   return true;
 }
 
 
 function GetCachedCallSite(siteObj, hash) {
-  var obj = %MapGet(callSiteCache, hash);
+  var obj = %_CallFunction(callSiteCache, hash, $MapGet);

[caitp (gmail), 2015/03/25 12:56:27]

Couldn't we just call MapGet() (and others) directly here?

[adamk, 2015/03/25 15:43:06]

MapGet is now inside a closure, so it's not visible here.

[caitp (gmail), 2015/03/25 15:46:24]

I mean, you have a reference to $MapGet, otherwise %_CallFunction() wouldn't
work either.

[adamk, 2015/03/25 16:13:36]

Not sure what you're saying. I could have called "$MapGet" "MapGet" instead, but
$MapGet seemed a little clearer to me.

[adamk, 2015/03/25 16:14:24]

Or are you asking about the use of %_CallFunction()? That's necessary because
MapGet expects its first argument to be in |this|.

[caitp (gmail), 2015/03/25 16:31:50]

OH --- derp, you're right. Course, this map here is private, so $MapGet could be
assigned to the map instance --- anyway, do it how you want to do it

 
   if (IS_UNDEFINED(obj)) return;
 
   var length = obj.length;
   for (var i = 0; i < length; ++i) {
     if (SameCallSiteElements(siteObj, obj[i])) return obj[i];
   }
 }
 
 
 function SetCachedCallSite(siteObj, hash) {
-  var obj = %MapGet(callSiteCache, hash);
+  var obj = %_CallFunction(callSiteCache, hash, $MapGet);
   var array;
 
   if (IS_UNDEFINED(obj)) {
     array = new InternalArray(1);
     array[0] = siteObj;
-    %MapSet(callSiteCache, hash, array);
+    %_CallFunction(callSiteCache, hash, array, $MapSet);
   } else {
     obj.push(siteObj);
   }
 
   return siteObj;
 }
 
 
 function GetTemplateCallSite(siteObj, rawStrings, hash) {
   var cached = GetCachedCallSite(rawStrings, hash);
@@ skipping 32 matching lines @@
 function ExtendStringForTemplates() {
   %CheckIsBootstrapping();
 
   // Set up the non-enumerable functions on the String object.
   InstallFunctions($String, DONT_ENUM, $Array(
     "raw", StringRaw
   ));
 }
 
 ExtendStringForTemplates();