C++ XorClause::xorEqualFalse方法代码示例

/**
@brief Helper function for replace_set()
*/
bool VarReplacer::handleUpdatedClause(XorClause& c, const Var origVar1, const Var origVar2)
{
    uint32_t origSize = c.size();
    std::sort(c.getData(), c.getDataEnd());
    Lit p;
    uint32_t i, j;
    for (i = j = 0, p = lit_Undef; i != c.size(); i++) {
        if (c[i].var() == p.var()) {
            //added, but easily removed
            j--;
            p = lit_Undef;
            if (!solver.assigns[c[i].var()].isUndef())
                c.invert(solver.assigns[c[i].var()].getBool());
        } else if (solver.assigns[c[i].var()].isUndef()) //just add
            c[j++] = p = c[i];
        else c.invert(solver.assigns[c[i].var()].getBool()); //modify xorEqualFalse instead of adding
    }
    c.shrink(i - j);

    //Even if i==j, the clause *has* changed
    c.setChanged();

    #ifdef VERBOSE_DEBUG
    cout << "xor-clause after replacing: ";
    c.plainPrint();
    #endif

    switch (c.size()) {
    case 0:
        solver.detachModifiedClause(origVar1, origVar2, origSize, &c);
        if (!c.xorEqualFalse()) {
            solver.ok = false;
        }
        return true;
    case 1:
        solver.detachModifiedClause(origVar1, origVar2, origSize, &c);
        solver.uncheckedEnqueue(Lit(c[0].var(), c.xorEqualFalse()));
        solver.ok = (solver.propagate<false>().isNULL());
        return true;
    case 2: {
        solver.detachModifiedClause(origVar1, origVar2, origSize, &c);
        c[0] = c[0].unsign() ^ c.xorEqualFalse();
        c[1] = c[1].unsign();
        addBinaryXorClause(c[0], c[1]);
        return true;
    }
    default:
        solver.detachModifiedClause(origVar1, origVar2, origSize, &c);
        solver.attachClause(c);
        return false;
    }

    assert(false);
    return false;
}

/**
@brief Returns the 2-long xor clause that has been made of the longer xor-clause under current assignement

We KNOW that the xorclause "c" passed as a parameter must be 2-long. We just
need it so that we can work with it. We KNOW it's 2-long because of the
data structures and functions in place

@p[in] c MUST be a 2-long xor clause under current assignement
 */
FailedLitSearcher::TwoLongXor FailedLitSearcher::getTwoLongXor(const XorClause& c) {
    TwoLongXor tmp;
    uint32_t num = 0;
    tmp.inverted = c.xorEqualFalse();

    for (const Lit *l = c.getData(), *end = l + c.size(); l != end; l++) {
        if (solver.assigns[l->var()] == l_Undef) {
            assert(num < 2);
            tmp.var[num] = l->var();
            num++;
        } else {
            tmp.inverted ^= (solver.assigns[l->var()] == l_True);
        }
    }

#ifdef VERBOSE_DEUBUG
    if (num != 2) {
        std::cout << "Num:" << num << std::endl;
        c.plainPrint();
    }
#endif

    std::sort(&tmp.var[0], &tmp.var[0] + 2);
    assert(num == 2);
    return tmp;
}

// Will put NULL in 'cs' if clause removed.
void XorSubsumer::subsume0(XorClauseSimp ps)
{
#ifdef VERBOSE_DEBUGSUBSUME0
    cout << "subsume0 orig clause:";
    ps.clause->plainPrint();
#endif

    vec<Lit> unmatchedPart;
    vec<XorClauseSimp> subs;

    findSubsumed(*ps.clause, subs);
    for (uint32_t i = 0; i < subs.size(); i++) {
        XorClause* tmp = subs[i].clause;
        findUnMatched(*ps.clause, *tmp, unmatchedPart);
        if (unmatchedPart.size() == 0) {
#ifdef VERBOSE_DEBUGSUBSUME0
            cout << "subsume0 removing:";
            subs[i].clause->plainPrint();
#endif
            clauses_subsumed++;
            assert(tmp->size() == ps.clause->size());
            if (ps.clause->xorEqualFalse() == tmp->xorEqualFalse()) {
                unlinkClause(subs[i]);
            } else {
                solver.ok = false;
                return;
            }
        } else {
            assert(unmatchedPart.size() > 0);
            clauses_cut++;
#ifdef VERBOSE_DEBUG
            std::cout << "Cutting xor-clause:";
            subs[i].clause->plainPrint();
#endif //VERBOSE_DEBUG
            XorClause *c = solver.addXorClauseInt(unmatchedPart, tmp->xorEqualFalse() ^ !ps.clause->xorEqualFalse(), tmp->getGroup());
            if (c != NULL)
                linkInClause(*c);
            unlinkClause(subs[i]);
            if (!solver.ok) return;
        }
        unmatchedPart.clear();
    }
}

/**
@brief Utility function for addAllXorAsNorm() for converting 3-long xor clauses to normal clauses

\todo clean this up, it's ugly
*/
void XorFinder::addXorAsNormal3(XorClause& c)
{
    assert(c.size() == 3);
    Clause *tmp;
    vec<Var> vars;
    const bool inverted = c.xorEqualFalse();

    for (uint32_t i = 0; i < c.size(); i++) {
        vars.push(c[i].var());
    }

    vec<Lit> vars2;
    vars2.growTo(3);
    vars2[0] = Lit(vars[0], false ^ inverted);
    vars2[1] = Lit(vars[1], false ^ inverted);
    vars2[2] = Lit(vars[2], false ^ inverted);
    tmp = solver.addClauseInt(vars2);
    if (tmp) solver.clauses.push(tmp);

    vars2.growTo(3);
    vars2[0] = Lit(vars[0], true ^ inverted);
    vars2[1] = Lit(vars[1], true ^ inverted);
    vars2[2] = Lit(vars[2], false ^ inverted);
    tmp = solver.addClauseInt(vars2);
    if (tmp) solver.clauses.push(tmp);

    vars2.growTo(3);
    vars2[0] = Lit(vars[0], true ^ inverted);
    vars2[1] = Lit(vars[1], false ^ inverted);
    vars2[2] = Lit(vars[2], true ^ inverted);
    tmp = solver.addClauseInt(vars2);
    if (tmp) solver.clauses.push(tmp);

    vars2.growTo(3);
    vars2[0] = Lit(vars[0], false ^ inverted);
    vars2[1] = Lit(vars[1], true ^ inverted);
    vars2[2] = Lit(vars[2], true ^ inverted);
    tmp = solver.addClauseInt(vars2);
    if (tmp) solver.clauses.push(tmp);
}

inline bool ClauseCleaner::cleanClause(XorClause& c)
{
    Lit *i, *j, *end;
    Var origVar1 = c[0].var();
    Var origVar2 = c[1].var();
    uint32_t origSize = c.size();
    for (i = j = c.getData(), end = i + c.size();  i != end; i++) {
        const lbool& val = solver.assigns[i->var()];
        if (val.isUndef()) {
            *j = *i;
            j++;
        } else c.invert(val.getBool());
    }
    c.shrink(i-j);

    assert(c.size() != 1);
    switch (c.size()) {
        case 0: {
            solver.detachModifiedClause(origVar1, origVar2, origSize, &c);
            return true;
        }
        case 2: {
            c[0] = c[0].unsign();
            c[1] = c[1].unsign();
            solver.varReplacer->replace(c, c.xorEqualFalse());
            solver.detachModifiedClause(origVar1, origVar2, origSize, &c);
            return true;
        }
        default: {
            if (i-j > 0) {
                solver.clauses_literals -= i-j;
            }
            return false;
        }
    }

    assert(false);
    return false;
}