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add code review to constraint

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-08-30 11:11:55 -07:00
parent ef297ced13
commit 7ea1bf12b6
4 changed files with 32 additions and 16 deletions
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33
src/math/polysat/constraint.h
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@ -24,7 +24,6 @@ Author:
namespace polysat {
enum ckind_t { eq_t, ule_t };
enum csign_t : bool { neg_t = false, pos_t = true };
class constraint;
class eq_constraint;
@ -55,9 +54,19 @@ namespace polysat {
constraint_table m_constraint_table;
// Constraint storage per level
vector<scoped_ptr_vector<constraint>> m_constraints;
vector<vector<clause_ref>> m_clauses;
// NB code review: Elsewhere we use flat arrays for m_constraints, m_clauses and then
// unsigned_vector m_constraints_lim;
// unsigned m_clauses_lim;
// The code for 'release_level' would require rewriting and the assumptions about how many
// scopes are released have to be revisited then. ~constraint_manager calls release_level
// to gc remaining constraints and ensure destruction. It's possible this call is not
// needed since memory management is scoped.
// Association to external dependency values (i.e., external names for constraints)
u_map<constraint*> m_external_constraints;
@ -126,6 +135,8 @@ namespace polysat {
* If this is not null_bool_var, then the constraint corresponds to a literal on the assignment stack.
* Convention: the plain constraint corresponds the positive sat::literal.
*/
// NB code review: the convention would make sense. Unfortunately, elsewhere in z3 we use "true" for negative literals
// and "false" for positive literals. It is called the "sign" bit.
sat::bool_var m_bvar = sat::null_bool_var;
constraint(constraint_manager& m, unsigned lvl, ckind_t k):
@ -137,8 +148,8 @@ namespace polysat {
public:
virtual ~constraint() {}
virtual unsigned hash() const = 0;
virtual bool operator==(constraint const& other) const = 0;
virtual unsigned hash() const = 0;
virtual bool operator==(constraint const& other) const = 0;
bool is_eq() const { return m_kind == ckind_t::eq_t; }
bool is_ule() const { return m_kind == ckind_t::ule_t; }
@ -296,7 +307,9 @@ namespace polysat {
};
template <bool is_owned>
inline std::ostream& operator<<(std::ostream& out, signed_constraint_base<is_owned> const& c) { return c.display(out); }
inline std::ostream& operator<<(std::ostream& out, signed_constraint_base<is_owned> const& c) {
return c.display(out);
}
inline signed_constraint operator~(signed_constraint const& c) {
return {c.get(), !c.is_positive()};
@ -306,8 +319,12 @@ namespace polysat {
return {c.detach(), !c.is_positive()};
}
/// Disjunction of constraints represented by boolean literals
// NB code review:
// right, ref-count is unlikely the right mechanism.
// In the SAT solver all clauses are managed in one arena (auxiliarary and redundant)
// and deleted when they exist the arena.
//
class clause {
friend class constraint_manager;
@ -327,8 +344,7 @@ namespace polysat {
*/
clause(unsigned lvl, p_dependency_ref d, sat::literal_vector literals):
m_level(lvl), m_dep(std::move(d)), m_literals(std::move(literals))
{
m_level(lvl), m_dep(std::move(d)), m_literals(std::move(literals)) {
SASSERT(std::count(m_literals.begin(), m_literals.end(), sat::null_literal) == 0);
}
@ -342,7 +358,6 @@ namespace polysat {
// Resolve with 'other' upon 'var'.
bool resolve(sat::bool_var var, clause const& other);
sat::literal_vector const& literals() const { return m_literals; }
p_dependency* dep() const { return m_dep; }
unsigned level() const { return m_level; }
@ -358,7 +373,7 @@ namespace polysat {
bool is_currently_false(solver& s) const;
unsigned next_guess() {
SASSERT(m_next_guess < m_literals.size());
SASSERT(m_next_guess < size());
return m_next_guess++;
}