[gecode-users] Adding restart-based search to ECLiPSe's interface to Gecode

[Christian Schulte]

Hi Kish,

Here is a solution built on top of Gecode. It defines a type
Kish::EngineBase that can be passed around irrespective of which engine it
actual is. The other stuff is just for illustration and how to recast
Gecode's engines as engines of type Kish::EngineBase.

Hope this helps.

Best
Christian


namespace Kish {

  class EngineBase {
  public:
    EngineBase(void) {}
    virtual Gecode::Space* next(void) = 0;
    virtual Gecode::Search::Statistics statistics(void) const = 0;
    virtual bool stopped(void) const = 0;
    virtual ~EngineBase(void) {}
  };

  class DFS : public EngineBase {
  protected:
    Gecode::DFS<Gecode::Space> e;
  public:
    DFS(Gecode::Space* s, const Gecode::Search::Options& o)
      : e(s,o) {}
    virtual Gecode::Space* next(void) { 
      return e.next(); 
    }
    virtual Gecode::Search::Statistics statistics(void) const {
      return e.statistics();
    }
    virtual bool stopped(void) const {
      return e.stopped();
    }
    virtual ~DFS(void) {}
  };

  class BAB : public EngineBase {
  protected:
    Gecode::BAB<Gecode::Space> e;
  public:
    BAB(Gecode::Space* s, const Gecode::Search::Options& o)
      : e(s,o) {}
    virtual Gecode::Space* next(void) { 
      return e.next(); 
    }
    virtual Gecode::Search::Statistics statistics(void) const {
      return e.statistics();
    }
    virtual bool stopped(void) const {
      return e.stopped();
    }
    virtual ~BAB(void) {}
  };

  template<template<class> class E>
  class RBS : public EngineBase {
  protected:
    Gecode::RBS<E,Gecode::Space> e;
  public:
    RBS(Gecode::Space* s, const Gecode::Search::Options& o)
      : e(s,o) {}
    virtual Gecode::Space* next(void) { 
      return e.next(); 
    }
    virtual Gecode::Search::Statistics statistics(void) const {
      return e.statistics();
    }
    virtual bool stopped(void) const {
      return e.stopped();
    }
    virtual ~RBS(void) {}
  };

  enum WhichEngine {
    WE_DFS, WE_BAB, 
    WE_RBS_DFS, WE_RBS_BAB
  };

  EngineBase* engine(WhichEngine we,
                     Gecode::Space* s, 
                     const Gecode::Search::Options& o) {
    switch (we) {
    case WE_DFS: return new DFS(s,o);
    case WE_BAB: return new BAB(s,o);
    case WE_RBS_DFS: return new RBS<Gecode::DFS>(s,o);
    case WE_RBS_BAB: return new RBS<Gecode::BAB>(s,o);
    }
  }
}


--
Christian Schulte, Professor of Computer Science, KTH,
www.ict.kth.se/~cschulte/


-----Original Message-----
From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On Behalf
Of Christian Schulte
Sent: Thursday, August 22, 2013 9:50 AM
To: 'Kish Shen'
Cc: users at gecode.org
Subject: Re: [gecode-users] Adding restart-based search to ECLiPSe's
interface to Gecode

Hi Kish,

My bad... There is really no common basetype for search engines, the type I
mentioned is actually for the implementations and not the interfaces...

I think you will have to wait until I have added a common basetype (there is
a basetype, but it is not powerful enough), I might be able to do it until
the end of the week.

Sorry for the confusion!

Cheers
Christian

--
Christian Schulte, Professor of Computer Science, KTH,
www.ict.kth.se/~cschulte/



-----Original Message-----
From: Kish Shen [mailto:kisshen at cisco.com]
Sent: Thursday, August 22, 2013 9:45 AM
To: cschulte at kth.se
Cc: users at gecode.org
Subject: Re: [gecode-users] Adding restart-based search to ECLiPSe's
interface to Gecode

Hi Christian,

Thanks again!

On 21/08/2013 19:17, Christian Schulte wrote:
> Try to avoid the Gecode::Search::bab .... functions. Just create as
follows:
> 	Gecode::Search::Engine* e = new Gecode::BAB(...) Then it also will 
> work for RBS, and you do not have to create a second engine yourself, 
> this will the RBS class do for you.
>
> And do not forget to delete e eventually!
>

This is the part that I don't know how to do correct -- probably because of
my lack of C++ knowledge, but as far as I can tell, Gecode::DFS etc are not
of class Engine*, according to the doc:

template<class T>
class Gecode::DFS<T>

for subclasses T of Space

T is GecodeSpace in my case, I assume. I am not sure what class DFS is, but
I can't see how it could be Engine*.

Anway, I tried to do the assignment as you suggested:


Search::Engine* segine;
...
sengine = new DFS<GecodeSpace>(solver, o); and indeed I get the error

cannot convert 'Gecode::DFS<GecodeSpace>*' to 'Gecode::Search::Engine*'

(I first tried sengine = new DFS(solver, o) but got an error 'expected
type-specifier')

So I am not sure what to do -- do I need to change the type of sengine,
and/or the way I assign an engine to sengine?

Cheers,

Kish





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