Re: [boost] [gacap]Is any interesting to "Generating All Combinations and Permutations"？

From: Hervé Brönnimann (hervebronnimann_at_[hidden])
Date: 2007-11-13 02:08:09

Ben: Before you do any substantial work, please check my proposal.  I  
have tried to provide background / explanations, and a set of  
coherent interfaces.  Please look at:

http://photon.poly.edu/~hbr/boost/combinations.html

The code in the .hpp (linked) is only temporary and not debugged.  I  
am in the process of writing test cases.  I'm happy to send it to you  
too...  Keep in mind it is work in progress.  I have a job and am  
spending far too much time on this at the moment :)
--HB

PS: I am not sure about the Incrementor/Decrementor interfaces,  
unless I can come up with a convincing example where the underlying  
type is not int and does not have operator++ and operator--,  but it  
still makes sense to count with it...

On Nov 13, 2007, at 1:50 AM, Ben Bear wrote:

> 2007/11/13, Hervé Brönnimann <hervebronnimann_at_[hidden]>:
>> Ben:  the naming partial_permutation would be a very good idea.  I
>> like it.  Am I correct that your (very cute!) idea would be extended
>> to prev_ as follows:
>>
>> bool next_partial_permutation(first, middle, last)
>> {
>>    reverse (middle, last);
>>    return next_permutation(first, last);
>> }
>>
>> prev_partial_permutation (
>> {
>>    bool result = next_permutation(first, last);
>
> oh,  here should be:-)
>       bool result = prev_permutation(first, last);
>
>>    reverse (middle, last);
>>    return result;
>> }
>>
>> That's all good, then.  BTW, you *should* assume that the client has
>> already sorted the range.  In other words, garbage in, garbage out,
>> and that's OK.  There's not reason to penalize those who keep their
>> ranges sorted.  It simply needs to be documented as a Requirement:
>> and given again as a Post-condition: (since the functions maintain
>> the sorted range invariant).
>>
>
> ok, I will prepare a resume source code that contains
> partial_permutation and combination, but without initializatons.  It
> will be very simple, against gacap.
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