include/dlvhex2/InternalGrounder.h

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/* dlvhex -- Answer-Set Programming with external interfaces.
 * Copyright (C) 2005-2007 Roman Schindlauer
 * Copyright (C) 2006-2015 Thomas Krennwallner
 * Copyright (C) 2009-2016 Peter Schüller
 * Copyright (C) 2011-2016 Christoph Redl
 * Copyright (C) 2015-2016 Tobias Kaminski
 * Copyright (C) 2015-2016 Antonius Weinzierl
 *
 * This file is part of dlvhex.
 *
 * dlvhex is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * dlvhex 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with dlvhex; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA.
 */

#ifndef INTERNALGROUNDER_HPP_INCLUDED__09122011
#define INTERNALGROUNDER_HPP_INCLUDED__09122011

#include "dlvhex2/ID.h"
#include "dlvhex2/Interpretation.h"
#include "dlvhex2/ProgramCtx.h"
#include "dlvhex2/Printhelpers.h"
#include "dlvhex2/OrdinaryASPProgram.h"
#include "dlvhex2/Set.h"

#include <vector>
#include <map>
#include <boost/foreach.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/unordered_map.hpp>
#include "dlvhex2/GenuineSolver.h"

DLVHEX_NAMESPACE_BEGIN

class InternalGrounder : public GenuineGrounder
{
    public:
        enum OptLevel
        {
            full,
            builtin,
            none
        };

    protected:
        typedef boost::unordered_map<ID, ID> Substitution;
        typedef boost::unordered_map<ID, int> Binder;

        OrdinaryASPProgram inputprogram;
        OrdinaryASPProgram groundProgram;
        ProgramCtx& ctx;
        RegistryPtr reg;
        OptLevel optlevel;

        // dependency graph
        typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::bidirectionalS, ID> DepGraph;
        typedef DepGraph::vertex_descriptor Node;
        boost::unordered_map<ID, Node> depNodes;
        DepGraph depGraph;
        std::vector<Set<ID> > depSCC;

        // strata dependencies
        typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::bidirectionalS, int> SCCDepGraph;
        SCCDepGraph compDependencies;
        std::vector<std::set<ID> > predicatesOfStratum;
        std::vector<std::set<ID> > rulesOfStratum;
        boost::unordered_map<ID, int> stratumOfPredicate;

        ID globallyNewAtom;
        boost::unordered_map<ID, std::vector<ID> > derivableAtomsOfPredicate;
        boost::unordered_map<ID, std::set<std::pair<int, int> > > positionsOfPredicate;

        InterpretationPtr trueAtoms;

        std::vector<ID> groundRules;
        std::vector<ID> nonGroundRules;

        std::set<ID> groundedPredicates;
        std::set<ID> solvedPredicates;

        // initialization members
        void computeDepGraph();
        ID preprocessRule(ID ruleID);
        void computeStrata();

        void buildPredicateIndex();
        void loadStratum(int index);

        // grounding members
        void groundStratum(int index);

        void groundRule(ID ruleID, Substitution& s, std::vector<ID>& groundedRules, Set<ID>& newDerivableAtoms);
        void buildGroundInstance(ID ruleID, Substitution s, std::vector<ID>& groundedRules, Set<ID>& newDerivableAtoms);

        bool match(ID literalID, ID patternLiteral, Substitution& s);
        bool matchOrdinary(ID literalID, ID patternAtom, Substitution& s);
        bool matchBuiltin(ID literalID, ID patternAtom, Substitution& s);
        int matchNextFromExtension(ID literalID, Substitution& s, int startSearchIndex);
        int matchNextFromExtensionOrdinary(ID literalID, Substitution& s, int startSearchIndex);
        int matchNextFromExtensionBuiltin(ID literalID, Substitution& s, int startSearchIndex);
        int matchNextFromExtensionBuiltinUnary(ID literalID, Substitution& s, int startSearchIndex);
        int matchNextFromExtensionBuiltinBinary(ID literalID, Substitution& s, int startSearchIndex);
        int matchNextFromExtensionBuiltinTernary(ID literalID, Substitution& s, int startSearchIndex);
        int backtrack(ID ruleID, Binder& binders, int currentIndex);

        void setToTrue(ID atom);
        void addDerivableAtom(ID atom, std::vector<ID>& groundRules, Set<ID>& newDerivableAtoms);

        // helper members
        ID applySubstitutionToAtom(Substitution s, ID atomID);
        ID applySubstitutionToOrdinaryAtom(Substitution s, ID atomID);
        ID applySubstitutionToBuiltinAtom(Substitution s, ID atomID);
        std::string atomToString(ID atomID);
        std::string ruleToString(ID ruleID);
        ID getPredicateOfAtom(ID atomID);
        bool isGroundRule(ID ruleID);
        bool isPredicateGrounded(ID pred);
        bool isPredicateSolved(ID pred);
        bool isAtomDerivable(ID atom);
        int getStratumOfRule(ID ruleID);
        void computeGloballyNewAtom();

        Binder getBinderOfRule(std::vector<ID>& body);
        int getClosestBinder(std::vector<ID>& body, int litIndex, std::set<ID> variables);
        std::set<ID> getFreeVars(std::vector<ID>& body, int litIndex);
        std::set<ID> getOutputVariables(ID ruleID);
        std::vector<ID> reorderRuleBody(ID ruleID);
        bool biDependency(ID bi1, ID bi2);

        enum AppDir
        {
            x_op_y_eq_ret,
            x_op_ret_eq_y,
            ret_op_y_eq_x,
        };
        int applyIntFunction(AppDir ad, ID op, int x, int y);
    public:
        InternalGrounder(ProgramCtx& ctx, const OrdinaryASPProgram& p, OptLevel = full);

        const OrdinaryASPProgram& getGroundProgram();
        const OrdinaryASPProgram& getNongroundProgram();
        std::string getGroundProgramString();
        std::string getNongroundProgramString();

        typedef boost::shared_ptr<InternalGrounder> Ptr;
        typedef boost::shared_ptr<const InternalGrounder> ConstPtr;
};

typedef InternalGrounder::Ptr InternalGrounderPtr;
typedef InternalGrounder::ConstPtr InternalGrounderConstPtr;

DLVHEX_NAMESPACE_END
#endif

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