JSONNumber - optional decimal

Garrett Smith dhtmlkitchen at gmail.com
Tue Jun 8 23:56:57 PDT 2010


On 6/8/10, Oliver Hunt <oliver at apple.com> wrote:
> On Jun 8, 2010, at 8:46 PM, Garrett Smith wrote:
>

[...]

>> IF anyone has a correct JSON parser, I would appreciate it. Also, are
>> there any good test suites for JSON?
>
> I spent quite a bit of time ensuring JSC's JSON parser exactly matched the
> spec grammar, and hence exhibits this behaviour so I believe the parser in
> JSC is "correct" -- if you're interested the code can be found at  (note
> that it's under an MIT style license)
> http://trac.webkit.org/browser/trunk/JavaScriptCore/runtime/LiteralParser.cpp

I see, so \d. is no good.

I was more looking for a few regexps to fill in a tight function for
the FAQ.  While your C++ looks clean, transliterating that would
surely be a no-go for the FAQ. Strategy-outline:

// TODO: define validJSONExp.
var parseJSON = NATIVE_JSON_PARSE_SUPPORT ?
   function(responseText) {
    return JSON.parse(responseText);
   } :
   function(responseText) {
    if(validJSONExp.test(responseText)) {
      return new Function("return(" + responseText + ")")();
    } else {
      throw SyntaxError("JSON parse error");
    }
};

The goal is to essentially match exactly what JSON parse would do for
1 argument and for the FAQ, the code would be tighter to use a RegExp.
I'll figure it out.

> At the time I recall talking a bit with Hallvord Steen of Opera, and he was
> working on a testsuite of some sort but I can no longer recall the url.
>

OK. Good to know.

> That said I think allowing '1.' (etc) makes sense as it's fairly standard
> across multiple programming languages, and I am unaware of any specific
> reason for disallowing it.
>

It seems like it would have made sense. Now, well, no, not now; the
spec is released and implemented like that in at least two
implementations.

> In the long term I don't see changing the grammar to allow a trailing period
> as being harmful as it's a relaxation.  In the short term vendors that
> follow the spec may fail to parse content :-(
>

Changing it now would probably just create more confusion.


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