[kelbt-users] [feature proposal] autocommit mode

[Adrian Thurston]

But how do you choose the production(s) to place the hold on? That's the 
problem I'm seeing. Every choice point in a backtracking LR is covered 
by many productions above it and I think a hold would need to be placed 
on every one of those.

Maybe we have different views of 'commit' at this point ... In kelbt a 
commit clears everything below it in the parse tree. Perhaps in the 
autocommit mode this should not be the case?

-Adrian

Elijah Epifanov wrote:
> Hey, sorry for the long delay.
> 
> I think it should be just a flag at the end of a rule (where commit is
> implied in autocommit mode).
> e.g.:
> 
> autocommit;
> 
> # Second level supports multiplication.
> F: tok_number tok_mult F hold try { ... };
> 
> I think hold is a correct antonym to commit in this case.
> 
> 2009/1/25 Adrian Thurston <thurston at complang.org>:
>> I'm curious if it would be hard to tell where to put the 'noncommit'
>> flags. What do you think?
>>
>> -Adrian
>>
>> Elijah Epifanov wrote:
>>> 2009/1/23 Adrian Thurston <thurston at complang.org>:
>>>> So let me see if I understand ... autocommit would cause all alternative
>>>> parses to be discarded on every reduction, with the option to disable it
>>>> on specific reductions? This would make Kelbt behave like standard Yacc
>>>> by default, with the kelbt behaviour turned on only where needed?
>>> exactly, like any ordinary lalr parser
>>>
>>>> -Adrian
>>>>
>>>> Elijah Epifanov wrote:
>>>>> There's no need to delay commit when parsing an unambiguous language,
>>>>> therefore every rule will need (if efficiency is of concern) to commit
>>>>> after reduce.
>>>>>
>>>>> It would be convenient to set an auto-commit mode on on per-grammar
>>>>> basis and (rarely, if at all) disable it for specific portions when
>>>>> needed.
>>>>>
>>>>> %%
>>>>> # Second level supports multiplication.
>>>>> F: tok_number tok_mult F commit try { ... };
>>>>> F: tok_number commit try { ... );
>>>>> };
>>>>> %%
>>>>> ->
>>>>> %%
>>>>> autocommit;
>>>>>
>>>>> # Second level supports multiplication.
>>>>> F: tok_number tok_mult F try { ... };
>>>>> F: tok_number try { ... };
>>>>> %%
>>>>>
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