[ragel-users] Default actions that leave the machine

[Adrian Thurston]

Hi, does this do what you want?

main = (
           ('HELLO ' $^parse_error) 'WORLD' |
           any*
        );

I'm not sure how that fits into your overall plan. Try it out and we'll 
discuss further.

Regards,
  Adrian

On 11-01-31 03:50 PM, Murray Henderson wrote:
> Hello,
>
> Both local and global error actions transition to the error state. I
> am using Ragel 6.5. I can try with 6.6 when I get home.
>
> I made a quick example (based off S. Geist's example):
>
> http://pastebin.com/06ihRxQg
>
> Example output:
>
> HELLO WORLD
> read: HELLO WORLD
> len: 12, state: 12
> HELWORLD
> parse error
> read: HEL
> len: 3, state: 0
>
>
> Cheers,
> Murray
>
>
> On Tue, Feb 1, 2011 at 10:02 AM, Adrian Thurston<thurston at complang.org>  wrote:
>> Local error actions don't. Sorry I should have suggested just those.
>>
>> On 11-01-31 02:58 PM, Murray Henderson wrote:
>>>
>>> Hello,
>>>
>>> Local and global error actions transition to the error state.
>>>
>>> I want DEF to transition to the next machine (ie. behave like a final
>>> state), not the error state.
>>>
>>> The parser I am writing is permissive, all input must be accepted (I
>>> never want to goto the error state).
>>>
>>> I do not wish to use manual goto recovery, because the parser is large
>>> and complex, such manual tracking is a lot of work and error prone.
>>>
>>> Cheers,
>>> Murray
>>>
>>>
>>>
>>> On Tue, Feb 1, 2011 at 4:58 AM, Adrian Thurston
>>> <adrian.thurston at esentire.com>    wrote:
>>>>
>>>> Hi, have you looked at ragel's local and global error actions yet? These
>>>> may
>>>> do what you want.
>>>>
>>>> -Adrian
>>>>
>>>> On 11-01-26 08:08 PM, Murray Henderson wrote:
>>>>>
>>>>> Hello,
>>>>>
>>>>> I want to embed a default action into a machine that leaves the
>>>>> machine (without using manual a jump inside the action).
>>>>>
>>>>> For simplicities sake, I will call this operator $^^ (since it is
>>>>> similar to the Local Error operator).
>>>>>
>>>>>
>>>>> Example:
>>>>>
>>>>> action parse_error {}
>>>>> helloworld = ('HELLO ' %^^parse_error) 'WORLD';
>>>>>
>>>>> Non-error inputs include:
>>>>> HELLO WORLD
>>>>> HELLOWORLD (parse_error action occurs on 'O' ->      'W' transition)
>>>>> HELLWORLD (parse_error action occurs on 'L' ->      'W' transition)
>>>>> HELWORLD (parse_error action occurs on 'L' ->      'W' transition)
>>>>> HEWORLD (parse_error action occurs on 'E' ->      'W' transition)
>>>>> HWORLD (parse_error action occurs on 'H' ->      'W' transition)
>>>>> WORLD (parse_error action occurs on ->      'W' transition)
>>>>>
>>>>>
>>>>> I can simulate the above behavior with the '?' operator, but that is
>>>>> laborious, and there are other ways of using $^^ that I suspect cannot
>>>>> be simulated.
>>>>>
>>>>>
>>>>> I want this operator because I am trying to make a liberal parser that
>>>>> accepts all possible input. (Every state must have a default action)
>>>>> .I am creating a html5 parser that uses regular machines for
>>>>> tokenizing, and scanners built from the regular machines for parsing.
>>>>> Yes, I am mad.
>>>>>
>>>>> I cannot use manual jumps, because I don't want to jump out of the
>>>>> scanners mid-token.
>>>>>
>>>>>
>>>>> I am willing to try and add this operator into Ragel myself. I have
>>>>> grabbed the source code and tracked my way to fsmap.cpp, where the new
>>>>> operator would be added.
>>>>>
>>>>> Before I continue...
>>>>> Is there already a way to achieve my desired behavior that I am not
>>>>> aware
>>>>> of?
>>>>> Would such an operator be worthwhile? Is it even possible?
>>>>> Is there any knowledge that could be imparted that would help me make a
>>>>> patch?
>>>>>
>>>>> If I do end up making a patch, for symmetry purposes I will make
>>>>> global/local and start/any/final etc versions of the operator.
>>>>>
>>>>> After a brief look through the source, it looks like I would need to
>>>>> mod the FsmAp::fillGaps() function, passing in a (separate object for
>>>>> each?) final state into the FsmAp::attachNewTrans() instead of NULL.
>>>>>
>>>>> Ragel is a wonderful program by the way, thank you for creating it.
>>>>>
>>>>> Cheers,
>>>>> Murray
>>>>>
>>>>> _______________________________________________
>>>>> ragel-users mailing list
>>>>> ragel-users at complang.org
>>>>> http://www.complang.org/mailman/listinfo/ragel-users
>>>>>
>>>>
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