[Gecode] IntVarProcessor question.

[Guido Tack]

Hi.

The VarProcessors are responsible for translating from Modification 
Events (MEs) to Propagation Conditions (PCs) and putting all 
propagators registered for certain PCs into the propagation queue.
The Processor iterates over all variables of its VarTypeID and, 
depending on a variable's ME, all propagators that are registered for 
the corresponding PC are "processed". The propagators are organized in 
an array that is sorted by the PCs they respond to. So for example, if 
you have ME_INT_MAX, all propagators registered for PC_INT_BND, 
PC_INT_MAX, and PC_INT_DOM have to be processed. The order of PCs for 
Int is VAL, BND, MIN, MAX, DOM. process_modified takes two PCs as its 
arguments. These are used as pointers into the propagator array: 
process_modified(x,PC_INT_MAX,PC_INT_DOM,ME_INT_MAX) means to process 
all propagators "between" DOM and MAX (incl.).
So basically, for implementing process, you just have to know the order 
of your PCs and which MEs should trigger which PCs. The rest can be 
copied from the IntVarProcessor.

Guido

> Hi all,
>
>
> I am trying to set up a constraint system over real numbers in gecode. 
>  I need
> to implement a method like IntVarProcessor::process but according with 
> the
> events of the new constraint system. Unfortunately i don't understand 
> what is
> this method intended for. This method is closely related to
> Space::process_modified which takes the variable, two propagation 
> conditions
> and a modification event as arguments, but a relationship between the 
> event
> which caused variable modification and the two propagation conditions 
> is not
> much clear to me.
>
> Would it be possible for any of you to provide a short description of 
> this?.
> In the following i list the propagation events declared for the new 
> system:
>
> ME_RI_VAL -> when a variable gets instantiated.
> ME_RI_BND -> both, lower and upper bounds where modified.
> ME_RI_MIN -> the lower bound was modified.
> ME_RI_MAX -> the upper bound was modified.
>
> I have also defined the corresponding PC_RI_* propagation conditions!.
>
> Thanks in advance.
>
> Gustavo Gutierrez
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