Implement ES6 String.raw behind --harmony-templates

src/harmony-templates.js

Index: src/harmony-templates.js
diff --git a/src/harmony-templates.js b/src/harmony-templates.js
index dd122cce85f28ae5e478af25fb9a1a8c8bbb2c9c..712d8d3a12bbb996d1bd838c09d81fd9d180e3e6 100644
--- a/src/harmony-templates.js
+++ b/src/harmony-templates.js
@@ -12,3 +12,37 @@ function GetTemplateCallSite(siteObj, rawStrings) {
 
   return %ObjectFreeze(siteObj);
 }
+
+
+// ES6 Draft 10-14-2014, section 21.1.2.4
+function StringRaw(callSite) {
+  // TODO(caitp): Use rest parameters when implemented
+  var numberOfSubstitutions = %_ArgumentsLength();
+  var cooked = ToObject(callSite);
+  var raw = ToObject(cooked.raw);
+  var literalSegments = ToLength(raw.length);
+  if (literalSegments <= 0) return "";
+
+  var result = ToString(raw[0]);
+
+  for (var i = 1; i < literalSegments; ++i) {
+    if (i < numberOfSubstitutions) {
+      result += ToString(%_Arguments(i));
+    }
+    result += ToString(raw[i]);
+  }
+
+  return result;
+}
+
+
+function ExtendStringForTemplates() {
+  %CheckIsBootstrapping();
+
+  // Set up the non-enumerable functions on the String object.
+  InstallFunctions($String, DONT_ENUM, $Array(
+    "raw", StringRaw
+  ));
+}
+
+ExtendStringForTemplates();