/******************************************
Copyright (c) 2016, Mate Soos

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of this software and associated documentation files (the "Software"), to deal
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The above copyright notice and this permission notice shall be included in
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***********************************************/

#ifndef CLAUSEALLOCATOR_H
#define CLAUSEALLOCATOR_H


#include "constants.h"
#include "cloffset.h"
#include "watched.h"
#include "clause.h"

#include <stdlib.h>
#include <map>
#include <vector>

namespace CMSat {

class Clause;
class Solver;
class PropEngine;

using std::map;
using std::vector;

/**
@brief Allocates memory for (xor) clauses

This class allocates memory in large chunks, then distributes it to clauses when
needed. When instructed, it consolidates the unused space (i.e. clauses free()-ed).
Essentially, it is a stack-like allocator for clauses. It is useful to have
this, because this way, we can address clauses according to their number,
which is 32-bit, instead of their address, which might be 64-bit
*/
class ClauseAllocator {
    public:
        ClauseAllocator();
        ~ClauseAllocator();

        template<class T>
        Clause* Clause_new(const T& ps, const uint32_t conflictNum
            #ifdef STATS_NEEDED
            , const int64_t ID
            #endif
        ) {
            void* mem = allocEnough(ps.size());
            memset(mem, 0, sizeof(Clause)+sizeof(Lit)*ps.size());
            Clause* real = new (mem) Clause(ps, conflictNum
            #ifdef STATS_NEEDED
            , ID
            #endif
            );

            return real;
        }

        ClOffset get_offset(const Clause* ptr) const;

        inline Clause* ptr(const ClOffset offset) const
        {
            return (Clause*)(&dataStart[offset]);
        }

        void clauseFree(Clause* c); ///Frees memory and associated clause number
        void clauseFree(ClOffset offset);

        void consolidate(
            Solver* solver
            , const bool force = false
        );

        size_t mem_used() const;

    private:
        void update_offsets(vector<ClOffset>& offsets);

        ClOffset move_cl(
            ClOffset* newDataStart
            , ClOffset*& new_ptr
            , Clause* old
        ) const;

        BASE_DATA_TYPE* dataStart; ///<Stack starts at these positions
        uint64_t size; ///<The number of BASE_DATA_TYPE datapieces currently used in each stack
        /**
        @brief Clauses in the stack had this size when they were allocated
        This my NOT be their current size: the clauses may be shrinked during
        the running of the solver. Therefore, it is imperative that their orignal
        size is saved. This way, we can later move clauses around.
        */
        uint64_t capacity; ///<The number of BASE_DATA_TYPE datapieces allocated
        /**
        @brief The estimated used size of the stack
        This is incremented by clauseSize each time a clause is allocated, and
        decremetented by clauseSize each time a clause is deallocated. The
        problem is, that clauses can shrink, and thus this value will be an
        overestimation almost all the time
        */
        uint64_t currentlyUsedSize;

        void* allocEnough(const uint32_t num_lits);
};

} //end namespace

#endif //CLAUSEALLOCATOR_H