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/**************************************************************************************[SatELite.h]
Copyright (c) 2005-2010, Niklas Een, Niklas Sorensson

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
associated documentation files (the "Software"), to deal in the Software without restriction,
including without limitation the rights to use, copy, modify, merge, publish, distribute,
sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or
substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
**************************************************************************************************/

/**************************************************************************************************

A simple Chaff-like SAT-solver with support for incremental SAT.

**************************************************************************************************/

#ifndef SatELite_h
#define SatELite_h

#include "SolverTypes.h"
#include "VarOrder.h"

namespace SatELite {

extern bool opt_confl_1sub  ;
extern bool opt_confl_ksub  ;
extern bool opt_var_elim    ;
extern bool opt_0sub        ;
extern bool opt_1sub        ;
extern bool opt_2sub        ;
extern bool opt_repeated_sub;
extern bool opt_def_elim    ;
extern bool opt_unit_def    ;
extern bool opt_hyper1_res  ;
extern bool opt_pure_literal;
extern bool opt_asym_branch ;
extern bool opt_keep_all    ;
extern bool opt_no_random   ;
extern bool opt_pre_sat     ;
extern bool opt_ext_sat     ;
extern bool opt_niver       ;
extern cchar* input_file    ;
extern cchar* output_file   ;
extern cchar* varmap_file   ;
extern cchar* elimed_file   ;
extern cchar* model_file    ;

//#################################################################################################
// INLINED "Queue.h" HERE:
template <class T>
class Queue {
    vec<T>  elems;
    int     first;
public:
    Queue(void) : first(0) { }
    void insert(T x)   { elems.push(x); }
    T    dequeue(void) { return elems[first++]; }
    void clear(void)   { elems.clear(); first = 0; }
    int  size(void)    { return elems.size() - first; }
    bool has(T x) { for (int i = first; i < elems.size(); i++) if (elems[i] == x) return true; return false; }
};
//#################################################################################################


//#################################################################################################
// INLINED "TmpFiles.h" HERE:
FILE* createTmpFile(cchar* prefix, cchar* mode, char*& out_name = *(char**)NULL);
void  deleteTmpFile(cchar* prefix, bool exact = false);
void  deleteTmpFiles(void);
//#################################################################################################


#define BUMP_MORE


//=================================================================================================
// Clause:


class Solver;

struct Clause_t {
    int     id_;        // -1 = dynamic clause
    union {
        struct {
            uint64  abst_;
            uint    size_learnt;
        };
        struct {
            char    _vec[sizeof(vec<Lit>)];
        };
    };
    Lit     data[0];

    vec<Lit>&   Vec(void) const { return *((vec<Lit>*)&_vec); }

    // PUBLIC INTERFACE:
    //
    bool       dynamic     (void)      const { return id_ == -1; }
    int        size        (void)      const { return dynamic() ? Vec().size() : size_learnt >> 1;}
    Lit&       operator [] (int index)       { return dynamic() ? Vec()[index] : data[index]; }
    const Lit& operator [] (int index) const { return dynamic() ? Vec()[index] : data[index]; }
    Lit&       operator () (int index)       { assert(!dynamic()); return data[index]; }
    const Lit& operator () (int index) const { assert(!dynamic()); return data[index]; }
    void       push        (Lit p)           { assert(dynamic()); Vec().push(p); }
    void       clear       (void)            { assert(dynamic()); Vec().clear(); }
    vec<Lit>&  asVec       (void)      const { assert(dynamic()); return Vec(); }

    // Constructors:
    Clause_t(void) { id_ = -1; new (&Vec()) vec<Lit>(); }
   ~Clause_t(void) { assert(dynamic()); Vec().~vec<Lit>(); }
};


class Clause {
    Clause_t* ptr_;
public:
    Clause(void)        : ptr_(NULL) {}
    Clause(Clause_t& c) : ptr_(&c) {}
    Clause(Clause_t* c) : ptr_( c) {}
    Clause_t* ptr(void) const { return ptr_; }

    bool    operator == (Clause other)  const { return ptr_ == other.ptr_; }
    bool    null(void)                  const { return ptr_ == NULL; }
    void    zero(void)                        { ptr_ = NULL; }

    bool       dynamic     (void)       const { return ptr_->dynamic(); }
    int        size        (void)       const { return ptr_->size(); }
    Lit&       operator [] (int index)        { return (*ptr_)[index]; }
    const Lit& operator [] (int index)  const { return (*ptr_)[index]; }
    Lit&       operator () (int index)        { return (*ptr_)(index); }
    const Lit& operator () (int index)  const { return (*ptr_)(index); }

    // Dynamic:
    void       push        (Lit p)      const { return ptr_->push(p); }
    void       clear       (void)       const { return ptr_->clear(); }
    vec<Lit>&  asVec       (void)       const { return ptr_->asVec(); }

    // Non-dynamic:
    int        id          (void)       const { assert(!dynamic()); return ptr_->id_; }
    uint64     abst        (void)       const { assert(!dynamic()); return ptr_->abst_; }
    bool       learnt      (void)       const { assert(!dynamic()); return ptr_->size_learnt & 1; }
    float&     activity    (void)       const { assert(learnt()); return *((float*)&ptr_->data[size()]); }   // (learnt clauses only)
};

const Clause Clause_NULL = Clause();

macro bool operator < (Clause c1, Clause c2) { return (intp)c1.ptr() < (intp)c2.ptr(); }
macro uint hash(Clause c) { return (int)c.id(); }



//=================================================================================================
// Clause Subset:


class CSet {
    vec<int>    where;  // Map clause ID to position in 'which'.
    vec<Clause> which;  // List of clauses (for fast iteration). May contain 'Clause_NULL'.
    vec<int>    free;   // List of positions holding 'Clause_NULL'.

public:
    Clause  operator [] (int index) const { return which[index]; }
    int     size        (void)      const { return which.size(); }
    int     nElems      (void)      const { return which.size() - free.size(); }

    bool    add(Clause c) {
        assert(!c.null());
        where.growTo(c.id()+1, -1);
        if (where[c.id()] != -1)
            return true;
        if (free.size() > 0){
            where[c.id()] = free.last();
            which[free.last()] = c;
            free.pop();
        }else{
            where[c.id()] = which.size();
            which.push(c);
        }
        return false;
    }

    bool    exclude(Clause c) {
        assert(!c.null());
        if (c.id() >= where.size() || where[c.id()] == -1)
            return false;
        free.push(where[c.id()]);
        which[where[c.id()]] = Clause_NULL;
        where[c.id()] = -1;
        return true;
    }

    void    clear(void) {
        for (int i = 0; i < which.size(); i++)
            if (!which[i].null())
                where[which[i].id()] = -1;
        which.clear();
        free .clear();
    }
};



//=================================================================================================
// Helpers:


template <class T>
macro void remove(vec<T>& ws, const T& elem)
{
    int j = 0;
    for (; ws[j] != elem  ; j++) assert(j < ws.size());
    for (; j < ws.size()-1; j++) ws[j] = ws[j+1];
    ws.pop();
}

template <class T> macro void maybeRemove(vec<T>& ws, const T& elem) { if (ws.size() > 0) remove(ws, elem); }


macro int find(Clause c, Lit p) {
    for (int i = 0;; i++){
        assert(i < c.size());
        if (c[i] == p) return i; } }

template <class T>
macro int find(const vec<T>& ws, const T& elem) {   // 'find' has pre-condition that the element exists in the vector.
    for (int i = 0;; i++){
        assert(i < ws.size());
        if (ws[i] == elem) return i; } }


//=================================================================================================
// Solver -- the main class:


struct SolverStats : public BasicSolverStats {
    int64   reduceDBs;
    SolverStats(void) : reduceDBs(0) {}
};


struct SearchParams {
    double  var_decay, clause_decay, random_var_freq;    // (reasonable values are: 0.95, 0.999, 0.02)
    bool    simplify;
    SearchParams(double v = 1, double c = 1, double r = 0, bool s = true) : var_decay(v), clause_decay(c), random_var_freq(r), simplify(s) {}
};

enum OccurMode { occ_Off, occ_Permanent, occ_All };


struct Solver {

// INTERNAL

    bool                ok;             // If FALSE, the constraints are already unsatisfiable. No part of the solver state may be used!
    vec<Clause>         constrs;        // Set of problem clauses.
    vec<int>            constrs_free;   // Free list for problem clauses.
    vec<Clause>         learnts;        // Set of learnt clauses.
    vec<int>            learnts_free;   // Free list for learnt clauses.
    double              cla_inc;        // Amount to bump next clause with.
    double              cla_decay;      // INVERSE decay factor for clause activity: stores 1/decay.
    int                 n_literals;     // Literal count -- for output mainly. Only includes *problem* clauses.
    FILE*               elim_out;       // File storing eliminated clauses (needed to calculate model).
    char*               elim_out_file;  // (name of file)
    vec<vec<Clause>*>   iter_vecs;      // Vectors currently used for iterations. Removed clauses will be looked up and replaced by 'Clause_NULL'.
    vec<CSet*>          iter_sets;      // Sets currently used for iterations.

    vec<double>         activity;       // A heuristic measurement of the activity of a variable.
    vec<char>           polarity_sug;   // Suggestion (from user of Solver) for initial polarity to branch on. An 'lbool' coded as a 'char'.
    double              var_inc;        // Amount to bump next variable with.
    double              var_decay;      // INVERSE decay factor for variable activity: stores 1/decay. Use negative value for static variable order.
  #ifdef VAR_ORDER_2
    vec<double>         lt_activity;    // Long term activity.
    VarOrder2           order;          // Keeps track of the decision variable order.
  #else
    VarOrder            order;          // Keeps track of the decision variable order.
  #endif

    vec<vec<Clause> >   watches;        // 'watches[index(lit)]' is a list of constraints watching 'lit' (will go there if literal becomes true).
    bool                watches_setup;  // Are the watcher lists set up yet? ('false' initially)
    vec<vec<Clause> >   occur;          // 'occur[index(lit)]' is a list of constraints containing 'lit'.
    OccurMode           occur_mode;     // What clauses to keep in the occur lists.
    vec<int>            n_occurs;       // Literal occurance count -- only for problem clauses. Used for pure-literal rule.
    Queue<Lit>          propQ;          // Propagation queue.

    vec<int>            assigns;        // The current assignments (lbool:s stored as char:s).
    vec<Lit>            units;          // ... the other solution to 'persistent'; re-propagate when reach toplevel.
    vec<Lit>            trail;          // List of assignments made.
    vec<int>            trail_lim;      // Separator indices for different decision levels in 'trail'.
    vec<Clause>         reason;         // 'reason[var]' is the clause that implied the variables current value, or 'NULL' if none.
    vec<int>            level;          // 'level[var]' is the decision level at which assignment was made.
    int                 root_level;     // Level of first proper decision.
    int                 last_simplify;  // Number of top-level assignments at last 'simplifyDB()'.

    vec<char>           touched;        // Is set to true when a variable is part of a removed clause. Also true initially (upon variable creation).
    vec<Var>            touched_list;   // A list of the true elements in 'touched'.
    CSet                cl_touched;     // Clauses strengthened.
    CSet                cl_added;       // Clauses created.
    bool                fwd_subsump;    // Forward subsumption activated?

    vec<char>           var_elimed;     // 'eliminated[var]' is TRUE if variable has been eliminated.
    vec<char>           frozen;         // Variables currently not to be subjected for elimination.

    int64               last_inspects;  // Number of inspects since last removal of satified clauses in 'simplifyDB()' -- to avoid doing it too often.

    // Temporaries (to reduce allocation overhead):
    //
    vec<char>           seen_tmp;       // (used in various places)
    vec<char>           touched_tmp;    // (used in 'simplifyBySubsumption()' to mark variables touched during elimination)
    vec<Lit>            unit_tmp;       // (used in 'addUnit()')
    vec<Lit>            io_tmp;         // (used for reading/writing clauses from/to disk)

    // Main internal methods:
    //
    void    analyze          (Clause confl, vec<Lit>& out_learnt, int& out_btlevel); // (bt = backtrack)
    bool    enqueue          (Lit fact, Clause from = NULL);
    Clause  propagate        (void);
    void    propagateToplevel(void);
    void    reduceDB         (void);
    void    compressDB       (void);
    Lit     pickBranchLit    (const SearchParams& params);
    lbool   search           (int nof_conflicts, int nof_learnts, const SearchParams& params);
    double  progressEstimate (void);
    void    extendModel      (void);

    // Clauses:
    //
    Clause  allocClause     (const vec<Lit>& ps, bool learnt, Clause overwrite = Clause_NULL);
    void    deallocClause   (Clause c, bool quick = false);
    void    unlinkClause    (Clause c, Var elim = var_Undef);
    bool    propagateClause (Clause c, Lit p, bool& keep_watch);
    void    calcReason      (Clause c, Lit p, vec<Lit>& out_reason);
    void    strengthenClause(Clause c, Lit p);

    // Other database management:
    //
    void    createTmpFiles(cchar* filename) {
        if (filename == NULL)
            elim_out = createTmpFile("/tmp/tmp_elims__", "w+b", elim_out_file);
        else
            elim_out = fopen(filename, "w+b"),
            elim_out_file = NULL; }
    void    deleteTmpFiles(void) { if (elim_out_file != NULL) deleteTmpFile(elim_out_file, true); }
    void    registerIteration  (vec<Clause>& iter_vec) { iter_vecs.push(&iter_vec); }
    void    unregisterIteration(vec<Clause>& iter_vec) { remove(iter_vecs, &iter_vec); }
    void    registerIteration  (CSet&        iter_set) { iter_sets.push(&iter_set); }
    void    unregisterIteration(CSet&        iter_set) { remove(iter_sets, &iter_set); }
    void    setOccurMode(OccurMode occur_mode);
    void    setupWatches(void);

    // Activity:
    //
    void    varBumpActivity(Lit p) {
        if (var_decay < 0) return;     // (negative decay means static variable order -- don't bump)
        if ( (activity[var(p)] += var_inc) > 1e100 ) varRescaleActivity();
      #ifdef VAR_ORDER_2
        lt_activity[var(p)] += 1.0;
      #endif
        order.update(var(p)); }
    void    varDecayActivity(void) { if (var_decay >= 0) var_inc *= var_decay; }
    void    varRescaleActivity(void);

    void    claBumpActivity(Clause c) { if ( (c.activity() += cla_inc) > 1e20 ) claRescaleActivity(); }
    void    claDecayActivity(void) { cla_inc *= cla_decay; }
    void    claRescaleActivity(void);

    // Helpers:
    //
    bool    assume       (Lit p);
    void    undoOne      (void);
    void    cancel       (void);
    void    cancelUntil  (int level);
    void    record       (const vec<Lit>& clause);
    bool    locked       (Clause c) { return reason[var(c[0])] == c; }
    int     decisionLevel(void) { return trail_lim.size(); }

    void    watch        (Clause c, Lit p) { watches[index(p)].push(c); }
    void    unwatch      (Clause c, Lit p) { remove(watches[index(p)], c); }

    int     allocClauseId(bool learnt);
    void    freeClauseId (int id, bool learnt);


// PUBLIC INTERFACE

    Solver(OccurMode mode = occ_Permanent, cchar* elimed_filename = NULL)
                 : ok               (true)
                 , cla_inc          (1)
                 , cla_decay        (1)
                 , n_literals       (0)
                 , var_inc          (1)
                 , var_decay        (1)
               #ifdef VAR_ORDER_2
                 , order            (assigns, activity, lt_activity, var_inc)
               #else
                 , order            (assigns, activity)
               #endif
                 , watches_setup    (false)
                 , occur_mode       (mode)
                 , root_level       (0)
                 , last_simplify    (-1)
                 , fwd_subsump      (false)
                 , last_inspects    (0)
                 , unit_tmp         (1, lit_Undef)
                 , progress_estimate(0)
                 , verbosity(0)
                 { createTmpFiles(elimed_filename);
                #ifndef WATCH_OPTIMIZATION
                   watches_setup = true;
                #endif
                 }
   ~Solver(void);

    // Helpers: (semi-internal)
    //
    lbool   value(Var x) { return toLbool(assigns[x]); }
    lbool   value(Lit p) { return sign(p) ? ~toLbool(assigns[var(p)]) : toLbool(assigns[var(p)]); }

    int     nAssigns (void) { return trail.size(); }
    int     nLiterals(void) { return n_literals; }
    int     nClauses (void) { return constrs.size() - constrs_free.size(); }
    int     nLearnts (void) { return learnts.size() - learnts_free.size(); }

    // Statistics: (read-only member variable)
    //
    SolverStats stats;

    // Problem specification:
    //
    Var     newVar (bool decision_var = true);
    int     nVars  (void)  { return assigns.size(); }
    void    addUnit(Lit p) { assert(unit_tmp.size() == 1); unit_tmp[0] = p; addClause(unit_tmp); }

    // -- constraints:
    Clause  addClause(const vec<Lit>& ps, bool learnt = false, Clause overwrite = Clause_NULL);
    void    removeClause(Clause c, Var elim = var_Undef) { if (ok) { unlinkClause(c, elim); deallocClause(c); } }

    void    freeze(Var x) { frozen[x] = 1; }
    void    thaw  (Var x) { frozen[x] = 0; }

    // Solving:
    //
    bool    okay(void) { return ok; }
    void    simplifyDB(bool subsume = false);
    bool    solve(const vec<Lit>& assumps);
    bool    solve(void) { vec<Lit> empty; return solve(empty); }

    double      progress_estimate;  // Set by 'search()'.
    vec<lbool>  model;              // If problem is solved, this vector contains the model (if any).
    int         verbosity;          // Verbosity level. 0=silent, 1=some progress report, 2=everything

    // Subsumption:
    //
    void touch(Var x) { if (!touched[x]) touched[x] = 1, touched_list.push(x); }
    void touch(Lit p) { touch(var(p)); }
    bool updateOccur(Clause c) { return occur_mode == occ_All || (occur_mode == occ_Permanent && !c.learnt()); }

    int  literalCount(void);        // (just progress measure)
    void findSubsumed(Clause ps, vec<Clause>& out_subsumed);
    bool isSubsumed(Clause ps);
    bool hasClause(Clause ps);
    void subsume0(Clause ps, int& counter = *(int*)NULL);
    void subsume1(Clause ps, int& counter = *(int*)NULL);
    void simplifyBySubsumption(bool with_var_elim = true);

    void orderVarsForElim(vec<Var>& order);
    int  substitute(Lit x, Clause def, vec<Clause>& poss, vec<Clause>& negs, vec<Clause>& new_clauses);
    Lit  findUnitDef(Var x, vec<Clause>& poss, vec<Clause>& negs);
    bool findDef(Lit x, vec<Clause>& poss, vec<Clause>& negs, Clause out_def);
    bool maybeEliminate(Var x);

    void checkConsistency(void);

    void clauseReduction(void);
    void asymmetricBranching(Lit p);

};


//=================================================================================================
// Debug:


// For derivation output (verbosity level 2)
#define L_IND    "%-*d"
#define L_ind    decisionLevel()*3+3,decisionLevel()
#define L_LIT    "%sx%d"
#define L_lit(p) sign(p)?"~":"", var(p)

// Just like 'assert()' but expression will be evaluated in the release version as well.
#ifdef NDEBUG
  inline void SECheck(bool expr) { assert(expr); }
#else
  #define SECheck assert
#endif

macro void dump(Clause c, bool newline = true, FILE* out = stdout) {
    fprintf(out, "{");
    for (int i = 0; i < c.size(); i++) fprintf(out, " "L_LIT, L_lit(c[i]));
    fprintf(out, " }%s", newline ? "\n" : "");
    fflush(out);
}
macro void dump(Solver& S, Clause c, bool newline = true, FILE* out = stdout) {
    fprintf(out, "{");
    for (int i = 0; i < c.size(); i++) fprintf(out, " "L_LIT":%c", L_lit(c[i]), name(S.value(c[i])));
    fprintf(out, " }%s", newline ? "\n" : "");
    fflush(out);
}

macro void dump(const vec<Lit>& c, bool newline = true, FILE* out = stdout) {
    fprintf(out, "{");
    for (int i = 0; i < c.size(); i++) fprintf(out, " "L_LIT, L_lit(c[i]));
    fprintf(out, " }%s", newline ? "\n" : "");
    fflush(out);
}
macro void dump(Solver& S, vec<Lit>& c, bool newline = true, FILE* out = stdout) {
    fprintf(out, "{");
    for (int i = 0; i < c.size(); i++) fprintf(out, " "L_LIT":%c", L_lit(c[i]), name(S.value(c[i])));
    fprintf(out, " }%s", newline ? "\n" : "");
    fflush(out);
}


//=================================================================================================
}
#endif