[ragel-users] JavaScript code generation for Ragel

[Adrian Thurston]

Ya as far as Ragel code generation goes you shouldn't need to p, pe, or 
data available in the write init context. If I remember right that was 
due to a combination of Ruby variable scoping/declaration rules and the 
typical usage pattern of Ragel+Ruby. The Ruby code generator really is a 
special case for a number of reasons. What we need to a Ragel and Ruby 
expert to sort it out. I'm not both of those things.

There is also some strange stuff in the java code generator too. Java 
doesn't have static array data. It makes functions that set the values. 
But large arrays overflow the max function size so you can't have large 
static arrays. To get around this the arrays are made using functions 
(like the compiler does), but they are broken down into smaller parts 
and concatenated. Ugh. I'm not sure if this would apply to javascript as 
well.

-Adrian

On 10-10-11 12:14 PM, Dominic Marks wrote:
> Hey Adrian,
>
> I haven't but I will do. Thank you.
>
> I'm not sure if the RubyCodeGen::writeInit function is incorrect but
> it's quite divergent from the CDCodeGen version. The only problem I had
> doing the work, besides a few missed semicolons, was that the write init
> directive was trying to initialise pe to the data length. In my testing
> script the initialisation and execution stages are in separate functions
> and this produced invalid JavaScript (data being undefined at that point).
>
> I assumed I had misunderstood something about the options that can be
> given to write init and write exec but after that turned up a blank I
> looked at CDCodeGen. I was surprised to find that it didn't include
> similar code relating to the end directive. I made my writeInit function
> more like CDCodeGen and my problem was resolved.
>
> The code in question:
>
> http://github.com/dominicmarks/ragel-js/commit/7a8e554f2829fbebe04a26837ebb5512314c376b#diff-0
>
>
> The difference might be related to the concessions you mention, I didn't
> look into it too much.
>
> Thanks for Ragel, it's a great piece of software!
>
> Dominic
>
> On 11/10/2010 19:54, Adrian Thurston wrote:
>> Great, thanks for working on this!
>>
>> Did you have a look at the java code generator? There were a few
>> concessions that had to be made in the Ruby code generator that might
>> not need to be made in JS.
>>
>> -Adrian
>>
>> On 10-10-11 04:07 AM, Dominic Marks wrote:
>>> Hi all,
>>>
>>> I've got the table code generation strategy working. I'm going to work
>>> on building a set of RL files for testing purposes and then have a crack
>>> at writing a code generation backend that targets modern JavaScript VMs
>>> (e.g. produces JavaScript that best suits a JIT/tracer). If anyone would
>>> like to help with any part of this process, I'd be most grateful.
>>>
>>> I've forked Ragel trunk into a github repo while I work on this. There
>>> is a sample script (I translated the maillbox.rl file from the Ragel
>>> distribution) which you can play with if you install Node.js (a
>>> JavaScript application framework powered by Google's V8 VM). Note that
>>> while the sample script uses Node.js for IO, but the code generated is
>>> plain JavaScript. I look forward to being able to use Ragel in the
>>> browser soon too.
>>>
>>> Github:
>>>
>>> http://github.com/dominicmarks/ragel-js
>>>
>>> A diff against Ragel trunk is here:
>>>
>>> http://goodforbusiness.co.uk/~dom/ragel-js-20101011.diff
>>> <http://goodforbusiness.co.uk/%7Edom/ragel-js-20101011.diff>
>>>
>>> The code is mostly a cut-paste-and-replace from Ruby at the moment. I'll
>>> be tidying it up over the next few weeks, as my time allows. However, it
>>> does at least run one Ragel state machine correctly already.
>>>
>>> Mailbox.rl/Mailbox.js:
>>>
>>> http://goodforbusiness.co.uk/~dom/mailbox.js
>>> <http://goodforbusiness.co.uk/%7Edom/mailbox.js> (Requires Node.js).
>>>
>>> Cheers,
>>> Dom
>>>
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>>> ragel-users at complang.org
>>> http://www.complang.org/mailman/listinfo/ragel-users
>>
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