example2.cpp

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// 
// Copyright (c) 2009, Benjamin Kaufmann
// 
// This file is part of Clasp. See http://www.cs.uni-potsdam.de/clasp/ 
// 
// Clasp is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
// 
// Clasp is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with Clasp; if not, write to the Free Software
// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
//

// Add the libclasp directory to the list of 
// include directoies of your build system.
#include <clasp/clasp_facade.h>
#include <clasp/solver.h>
#include "example.h"

// This example uses the ClaspFacade to compute
// the stable models of the program
//    a :- not b.
//    b :- not a.
//
// The ClaspFacade is a convenient wrapper for the services of the clasp library.
// See clasp_facade.h for details.


// In order to get models from the ClaspFacade, we must provide a suitable
// event handler.
class ModelPrinter : public Clasp::EventHandler {
public:
        ModelPrinter() {}
        bool onModel(const Clasp::Solver& s, const Clasp::Model& m) {
                printModel(s.symbolTable(), m);
                return true;
        }
};

void example2() {
        // Aggregates configuration options.
        // Using config, you can control many parts of the search, e.g.
        // - the amount and kind of preprocessing
        // - the enumerator to use and the number of models to compute
        // - the heuristic used for decision making
        // - the restart strategy
        // - ...
        Clasp::ClaspConfig config;
        // We want to compute all models but
        // otherwise we use the default configuration.
        config.enumerate.numModels = 0;
        
        // The "interface" to the clasp library.
        Clasp::ClaspFacade libclasp;

        // LogicProgram provides the interface for defining logic programs.
        // The returned object is already setup and ready to use.
        // See logic_program.h for details.
        Clasp::Asp::LogicProgram& asp = libclasp.startAsp(config);
        asp.setAtomName(1, "a");
        asp.setAtomName(2, "b");
        asp.startRule(Clasp::Asp::BASICRULE).addHead(1).addToBody(2, false).endRule();
        asp.startRule(Clasp::Asp::BASICRULE).addHead(2).addToBody(1, false).endRule();
        
        // We are done with problem setup. 
        // Prepare the problem for solving.
        libclasp.prepare();

        // Start the actual solving process.
        ModelPrinter printer;
        libclasp.solve(&printer);
        std::cout << "No more models!" << std::endl;
}