satcheck_lingeling.cpp

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/*******************************************************************\
 
Module:
 
Author: Michael Tautschnig, michael.tautschnig@cs.ox.ac.uk
 
\*******************************************************************/
 
#include "satcheck_lingeling.h"
 
#include <algorithm>
 
#include <util/invariant.h>
#include <util/threeval.h>
 
extern "C"
{
#include <lglib.h>
}
 
#ifndef HAVE_LINGELING
#error "Expected HAVE_LINGELING"
#endif
 
tvt satcheck_lingelingt::l_get(literalt a) const
{
  if(a.is_constant())
    return tvt(a.sign());
 
  tvt result;
 
  if(a.var_no()>lglmaxvar(solver))
    return tvt(tvt::tv_enumt::TV_UNKNOWN);
 
  const int val=lglderef(solver, a.dimacs());
  if(val>0)
    result=tvt(true);
  else if(val<0)
    result=tvt(false);
  else
    return tvt(tvt::tv_enumt::TV_UNKNOWN);
 
  return result;
}
 
std::string satcheck_lingelingt::solver_text() const
{
  return "Lingeling";
}
 
void satcheck_lingelingt::lcnf(const bvt &bv)
{
  bvt new_bv;
 
  if(process_clause(bv, new_bv))
    return;
 
  for(const auto &literal : new_bv)
    lgladd(solver, literal.dimacs());
 
  lgladd(solver, 0);
 
  clause_counter++;
}
 
propt::resultt satcheck_lingelingt::do_prop_solve(const bvt &assumptions)
{
  PRECONDITION(status != ERROR);
 
  // We start counting at 1, thus there is one variable fewer.
  {
    std::string msg=
      std::to_string(no_variables()-1)+" variables, "+
      std::to_string(clause_counter)+" clauses";
    log.statistics() << msg << messaget::eom;
  }
 
  std::string msg;
 
  for(const auto &literal : assumptions)
    if(!literal.is_true())
      lglassume(solver, literal.dimacs());
 
  const int res=lglsat(solver);
  CHECK_RETURN(res == 10 || res == 20);
 
  if(res==10)
  {
    msg="SAT checker: instance is SATISFIABLE";
    log.status() << msg << messaget::eom;
    status=SAT;
    return P_SATISFIABLE;
  }
  else
  {
    INVARIANT(res == 20, "result value is either 10 or 20");
    msg="SAT checker: instance is UNSATISFIABLE";
    log.status() << msg << messaget::eom;
  }
 
  status=UNSAT;
  return P_UNSATISFIABLE;
}
 
void satcheck_lingelingt::set_assignment(literalt a, bool value)
{
  UNREACHABLE;
}
 
satcheck_lingelingt::satcheck_lingelingt() :
  solver(lglinit())
{
}
 
satcheck_lingelingt::~satcheck_lingelingt()
{
  lglrelease(solver);
  solver=0;
}
 
void satcheck_lingelingt::set_frozen(literalt a)
{
  if(!a.is_constant())
    lglfreeze(solver, a.dimacs());
}

bool satcheck_lingelingt::is_in_conflict(literalt a) const
{
  PRECONDITION(!a.is_constant());
  return lglfailed(solver, a.dimacs())!=0;
}