Proto for Boost mailing list page: Re: [proto] Defining the result domain of a proto operator

Subject: Re: [proto] Defining the result domain of a proto operator
From: Eric Niebler (eric_at_[hidden])
Date: 2011-08-26 11:44:11

On 8/26/2011 11:23 AM, Joel Falcou wrote:
> On 26/08/2011 17:18, Eric Niebler wrote:
>> Why can't you use a grammar to recognize patterns like these and
>> take appropriate action?
> 
> we do. Another point is that container based operation in our system 
> need to know the number of dimension of the container. Domains carry 
> this dimensions informations as we dont want to mix different sized 
> container in a same expression. The containers we have are :
> 
> table which can have 1 to MAX_DIM dimesnions matrix which behave as
> table<2> when mixed with table covector and vector that act as a
> matrix when mixed with matrix adn table<2> with table.
> 
> The domain are then flagged with this dimension informations.

OK, then I'll just assume you guys know what you're doing ('cause you
clearly do).

The original questions was:

> Is there a mechanism in Proto to define how the domain of a node new
> should be computed depending on the tag and the domains of the
> children?

The answer is no, but you don't need that, I don't think. Proto will
compute the domain of m*v to be matrix. It will use matrix_domain's
generator to post-process the new expression. That generator can do
anything -- including placing the new expression in the vector domain.
In short, there is no requirement that a domain's generator must produce
expressions in that domain. Just hack matrix_domain's generator.

-- 
Eric Niebler
BoostPro Computing
http://www.boostpro.com