PetitParser crash

The "optional" below crashes my Pharo 1.2.2 image, and user interrupt has no effect...

categoryName := $- asParser negate plus flatten, ($- asParser, #any asParser star flatten) optional star.
categoryName parse: 'SuperMe'.

Sean

This is a bug in your parser, causing a direct recursion with "optional star".

Also this is a bug in Pharo causing direct recursion to hang the image.

#optional is a parser that always succeeds. #star is an parser that
parsers 0 or more times eagerly. Thus #star loops forever.

Thus, you should remove the #optional parser in your grammar, #star
alone already makes the receiver optional.

Lukas

On 7 August 2011 18:08, Sean P. DeNigris <[hidden email]> wrote:


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Lukas Renggli wrote

Also this is a bug in Pharo causing direct recursion to hang the image.

I'll report it.

Lukas Renggli wrote

#optional is a parser that always succeeds. #star is an parser that
parsers 0 or more times eagerly. Thus #star loops forever.

Thanks, so "optional" is like the ? in other regex systems, meaning 0 or 1 times.

>> #optional is a parser that always succeeds. #star is an parser that
>> parsers 0 or more times eagerly. Thus #star loops forever.
>>
> Thanks, so "optional" is like the ? in other regex systems, meaning 0 or 1
> times.

Yes, 'x?*' is illegal in most regex engines. I guess PetitParser could
also try to prevent it, at least in simple cases.

Lukas

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