On Mar 19, 2013, at 2:58 PM, jahanian <[email protected]> wrote:
>
> On Mar 19, 2013, at 2:29 PM, Jordan Rose <[email protected]> wrote:
>
>>
>> On Mar 19, 2013, at 14:21 , jahanian <[email protected]> wrote:
>>
>>>
>>> On Mar 19, 2013, at 1:42 PM, Jordan Rose <[email protected]> wrote:
>>>
>>>>
>>>> Would it make sense to not just continue but to pretend instead that the
>>>> '}' is there? I feel like that will give us better recovery. (You'd
>>>> eliminate those last two errors: "expected '}'" and "missing '@end'".)
>>>
>>> I think by 'pretending' you mean insert a '}' before @end and continue. I
>>> thought about this but I did not want to introduce the bookkeeping
>>> overhead for the correct case. Do you have a suggestion how to pretend
>>> without adding this overhead?
>>
>> Hm, I see what you mean—right now we unilaterally consume a closing brace
>> when we exit the loop. The easiest way to solve this is to extract the
>> parsing loop and the T.consumeClose() into a helper function, with an early
>> return for the @end case...but that's not exactly pretty. I guess I'll let
>> you make the call (or stand by the call you already made).
>
> Problem is not avoiding calling of T.consumeClose() in the incorrect case.
> Problem is that '@' and 'end" are two tokens and we have consumed
> '@' already (this will cause parse error later). I see two solutions:
> 1. When seeing '@', lookahead for 'end' and exit the loop while skipping
> T.consumeClose() . I think this is what you are suggesting. But it involves
> unnecessary overhead for the common case.
> 2. If it is possible, I can insert a '}' two tokens before current token and
> reset the lexer to the inserted '}' for the incorrect case, then problem is
> solved without introducing any undue overhead for
> the common case.
You don't need to insert the '}' token. If you've consumed the '@' and see
something that doesn't belong in a list of instance variables (e.g.,
'property', 'end'), break out of the loop without calling consumeClose() and
then PP.EnterToken() the '@' to recover.
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