Reimplement a simpler version of JSON.stringify.

src/json.js

 // Copyright 2009 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 73 matching lines @@
     var separator = ",\n" + indent;
     final = "[\n" + indent + partial.join(separator) + "\n" +
         stepback + "]";
   } else {
     final = "[]";
   }
   stack.pop();
   return final;
 }
 
 function SerializeObject(value, replacer, stack, indent, gap) {

[Toon Verwaest, 2012/10/17 17:52:50]

We should try the fast path here, rather than in JSONStringify below. If we do
the same on the C-side, we can jump back and forth as necessary, without giving
up work in between.

[Yang, 2012/10/18 12:27:33]

Will do in a later CL.

   if (!%PushIfAbsent(stack, value)) {
     throw MakeTypeError('circular_structure', $Array());
   }
   var stepback = indent;
   indent += gap;
   var partial = new InternalArray();
   if (IS_ARRAY(replacer)) {
     var length = replacer.length;
     for (var i = 0; i < length; i++) {
       if (%_CallFunction(replacer, i, ObjectHasOwnProperty)) {
@@ skipping 195 matching lines @@
       BasicSerializeArray(value, stack, builder);
     } else {
       BasicSerializeObject(value, stack, builder);
     }
   }
 }
 
 
 function JSONStringify(value, replacer, space) {
   if (%_ArgumentsLength() == 1) {
+    var result = %BasicJSONStringify(value);
+    if (result != 0) return result;

[Toon Verwaest, 2012/10/17 17:52:50]

If possible, also use IS_UNDEFINED here; like below.

[Yang, 2012/10/18 12:27:33]

I don't think this is necessary:
if nothing is written to the string, the return value of %BasicJSONStringify is
already undefined. Returning it has the same effect as the line

if (builder.length == 0) return;

The IS_UNDEFINED check is used to see whether %_FastAsciiArrayJoin bailed out
due to failed allocation in generated code. Undefined serves as a sentinel value
to signal using %StringBuilderConcat as fallback.

     var builder = new InternalArray();
     BasicJSONSerialize('', value, new InternalArray(), builder);
     if (builder.length == 0) return;
-    var result = %_FastAsciiArrayJoin(builder, "");
+    result = %_FastAsciiArrayJoin(builder, "");
     if (!IS_UNDEFINED(result)) return result;
     return %StringBuilderConcat(builder, builder.length, "");
   }
   if (IS_OBJECT(space)) {
     // Unwrap 'space' if it is wrapped
     if (IS_NUMBER_WRAPPER(space)) {
       space = ToNumber(space);
     } else if (IS_STRING_WRAPPER(space)) {
       space = ToString(space);
     }
@@ skipping 16 matching lines @@
 
 function SetUpJSON() {
   %CheckIsBootstrapping();
   InstallFunctions($JSON, DONT_ENUM, $Array(
     "parse", JSONParse,
     "stringify", JSONStringify
   ));
 }
 
 SetUpJSON();