[GiNaC-list] GiNaC::parser parses unary operators in the wrong order

[Richard B. Kreckel]

Dear Vitaly,

Thanks a lot for looking into the parsing issues.

On 6/12/23 17:59, Vitaly Magerya wrote:
> On 20/02/2023, I wrote:
>> Hi, all. When parsing expressions with sign in the exponent, GiNaC's
>> parses confuses the priorities somehow. Here are some examples:
>>
>>      3^2+1 is parsed as (3^2)+1, which is correct;
>>      3^+2+1 is parsed as 3^(+2+1), which is wrong;
>>      3^-2+1 is parsed as 3^(-2+1), which is wrong;
>>      3^+2/3 is parsed as 3^(+2/3), which is wrong;
>>      etc.
> 
> So after some more testing I found that GiNaC doesn't only
> misparse the exponentiation this way, but multiplication too.
> Things like "3*+2+1" are parsed wrong too. The handling of the
> unary operators is broken if they appear after other operators.
> 
> As a separate problem, parsing nested exponentiation, like
> "2^3^4", results in GiNaC throwing an exception, saying that
> "power should have exactly 2 operands", which is false: for
> example ginsh handles "2^3^4" easily and correctly.
> 
> So, with some work I was able to fix both of these problems. I'm
> attaching a proposed solution, with tests included. Would it be
> possible to commit this?

I reviewed your patch and the test vectors and they look good. They make 
sense. It is apparent that you cared very much for compatibility with 
ginsh. I have applied the patch.

> I would additionally like to request a point release after this
> fix; this parsing problem potentially affects our usage of GiNaC,
> and we'd rather stay with a release version than build our own
> release tarballs.

I understand that GiNaC's parsing is important for your project. Yes, we 
can do a release soonish.

All my best,
   -richy.
-- 
Richard B. Kreckel
<https://in.terlu.de/~kreckel/>