[kelbt-users] [feature proposal] autocommit mode

[Elijah Epifanov]

I think the rule of least surprise wins here:

In autocommit mode:
append `commit` to every production except those marked with `hold`.

It's that simple... both for user and for kelbt.

2009/2/15 Adrian Thurston <thurston at complang.org>:
> 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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