/**
\brief Increase the balance of the given variable.
*/
inline void kbo::inc(expr_offset v) {
SASSERT(is_var(v.get_expr()));
int val;
unsigned v_idx = to_var(v.get_expr())->get_idx();
unsigned offset = v.get_offset();
if (m_deltas.find(v_idx, offset, val)) {
if (val == -1)
m_num_neg--;
else if (val == 0)
m_num_pos++;
m_deltas.insert(v_idx, offset, val + 1);
}
else {
m_deltas.insert(v_idx, offset, 1);
m_num_pos ++;
}
}
bool kbo::VWBc(expr_offset t, expr_offset target_var) {
SASSERT(target_var.get_expr() == 0 || is_var(target_var.get_expr()));
svector<expr_offset> & todo = m_vwbc_todo;
expr_offset s;
bool found = false;
unsigned j;
SASSERT(todo.empty());
todo.push_back(t);
while (!todo.empty()) {
t = todo.back();
if (t == target_var)
found = true;
expr * n = t.get_expr();
unsigned offset = t.get_offset();
todo.pop_back();
switch (n->get_kind()) {
case AST_VAR:
if (m_subst && m_subst->find(to_var(n), offset, s))
todo.push_back(s);
else if (pos) {
inc(t);
m_weight_balance += var_weight();
}
else {
dec(t);
m_weight_balance -= var_weight();
}
break;
case AST_APP:
if (pos)
m_weight_balance += f_weight(to_app(n)->get_decl());
else
m_weight_balance -= f_weight(to_app(n)->get_decl());
j = to_app(n)->get_num_args();
while (j > 0) {
--j;
todo.push_back(expr_offset(to_app(n)->get_arg(j), offset));
}
break;
default:
UNREACHABLE();
break;
}
}
return found;
}
order::result lpo::lex_compare(expr_offset s, expr_offset t, unsigned depth) {
SASSERT(is_app(s.get_expr()));
SASSERT(is_app(t.get_expr()));
app * _s = to_app(s.get_expr());
app * _t = to_app(t.get_expr());
unsigned num_args1 = _s->get_num_args();
unsigned num_args2 = _t->get_num_args();
unsigned num_args = std::min(num_args1, num_args2);
unsigned off1 = s.get_offset();
unsigned off2 = t.get_offset();
result r = EQUAL;
for (unsigned i = 0; i < num_args; i++) {
r = compare(expr_offset(_s->get_arg(i), off1), expr_offset(_t->get_arg(i), off2), depth+1);
if (r != EQUAL)
break;
}
if (r == EQUAL) {
if (num_args1 > num_args2)
return GREATER;
if (num_args1 < num_args2)
return NOT_GTEQ;
}
return r;
}
else if (f != g)
return arg_dominates_expr(s, t, depth) ? GREATER : NOT_GTEQ;
else {
result r = lex_compare(s, t, depth);
if (r == GREATER) {
if (dominates_args(s, t, depth))
return GREATER;
}
else if (r == EQUAL)
return EQUAL;
return to_app(s.get_expr())->get_num_args() > 1 && arg_dominates_expr(s, t, depth) ? GREATER : NOT_GTEQ;
}
}
}
order::result lpo::compare(expr_offset s, expr_offset t, unsigned depth) {
TRACE("lpo", tout << "comparing:\n" << mk_pp(s.get_expr(), m_manager) << "\n" << mk_pp(t.get_expr(), m_manager) << "\n";);
result r = compare_core(s, t, depth);
TRACE("lpo", tout << "result of comparing:\n" << mk_pp(s.get_expr(), m_manager) << "\n" << mk_pp(t.get_expr(), m_manager) << "\nresult: " << r << "\n";);
return r;
}
bool lpo::greater(expr_offset const & t1, expr_offset const & t2, substitution * s) {
m_subst = s;
return greater(t1, t2, static_cast<unsigned>(0));
}
order::result lpo::compare(expr_offset const & t1, expr_offset const & t2, substitution * s) {
m_subst = s;
result r = compare(t1, t2, static_cast<unsigned>(0));
if (r != NOT_GTEQ)
order::result kbo::compare(expr_offset const & t1, expr_offset const & t2, substitution * s) {
reset();
m_subst = s;
if (t1 == t2)
return EQUAL;
expr * n1 = t1.get_expr();
expr * n2 = t2.get_expr();
// f(s) >_{kbo} f(t) iff s >_{kbo} t
while (is_unary_app(n1) && is_unary_app(n2) && to_app(n1)->get_decl() == to_app(n2)->get_decl()) {
n1 = to_app(n1)->get_arg(0);
n2 = to_app(n2)->get_arg(0);
}
svector<entry> & todo = m_compare_todo;
SASSERT(todo.empty());
todo.push_back(entry(find(expr_offset(n1, t1.get_offset())),
find(expr_offset(n2, t2.get_offset())),
0));
result res = UNKNOWN;
while (!todo.empty()) {
entry & e = todo.back();
expr_offset t1 = e.m_t1;
expr_offset t2 = e.m_t2;
expr * n1 = t1.get_expr();
expr * n2 = t2.get_expr();
TRACE("kbo", tout << "processing with idx: " << e.m_idx << "\n" <<
mk_pp(n1, m_manager) << "\n" << mk_pp(n2, m_manager) << "\n";
tout << "wb : " << m_weight_balance << "\n";);
SASSERT(!is_quantifier(n1) && !is_quantifier(n2));
bool v1 = is_var(n1);
bool v2 = is_var(n2);
if (v1 && v2) {
todo.pop_back();
inc(t1);
dec(t2);
res = t1 == t2 ? EQUAL : UNCOMPARABLE;
}
else if (v1) {
todo.pop_back();
res = VWBc<false>(t2, t1) ? LESSER : UNCOMPARABLE;
inc(t1);
m_weight_balance += var_weight();
}
else if (v2) {
todo.pop_back();
res = VWBc<true>(t1, t2) ? GREATER : UNCOMPARABLE;
dec(t2);
m_weight_balance -= var_weight();
}
else {
func_decl * f = to_app(n1)->get_decl();
func_decl * g = to_app(n2)->get_decl();
result lex;
if (f != g || to_app(n1)->get_num_args() != to_app(n2)->get_num_args()) {
VWB<true>(t1, 0);
VWB<false>(t2, 0);
lex = UNCOMPARABLE;
}
else {
unsigned & idx = e.m_idx;
// when idx > 0, res contains the result for child (idx - 1)
if (idx > 0 && res != EQUAL) {
VWB<true>(t1, idx);
VWB<false>(t2, idx);
lex = res;
}
else if (idx == to_app(n1)->get_num_args()) {
// all children were visited
lex = EQUAL;
}
else if (idx < to_app(n1)->get_num_args()) {
expr_offset c1 = find(expr_offset(to_app(n1)->get_arg(idx), t1.get_offset()));
expr_offset c2 = find(expr_offset(to_app(n2)->get_arg(idx), t2.get_offset()));
idx++; // move curr entry child idx
entry new_entry(c1, c2, 0);
todo.push_back(new_entry);
continue; // process child before continuing
}
}
todo.pop_back();
m_weight_balance += f_weight(f);
m_weight_balance -= f_weight(g);
if (m_weight_balance > 0)
res = no_neg();
else if (m_weight_balance < 0)
res = no_pos();
else if (f_greater(f, g))
res = no_neg();
else if (f_greater(g, f))
res = no_pos();
else if (f != g)
res = UNCOMPARABLE;
else if (lex == EQUAL)
res = EQUAL;
else if (lex == GREATER)
res = no_neg();
else if (lex == LESSER)
res = no_pos();
else
res = UNCOMPARABLE;
}
TRACE("kbo", tout << "result: " << res << "\n";);
