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z3/src/sat/ba_solver.h
Nikolaj Bjorner 185b01dd35 fix #2416
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
2019-07-23 19:01:49 -07:00

621 lines
28 KiB
C++

/*++
Copyright (c) 2017 Microsoft Corporation
Module Name:
ba_solver.h
Abstract:
Cardinality extensions,
Pseudo Booleans,
Xors
Author:
Nikolaj Bjorner (nbjorner) 2017-01-30
Revision History:
--*/
#ifndef BA_SOLVER_H_
#define BA_SOLVER_H_
#include "sat/sat_extension.h"
#include "sat/sat_solver.h"
#include "sat/sat_lookahead.h"
#include "sat/sat_unit_walk.h"
#include "sat/sat_big.h"
#include "util/small_object_allocator.h"
#include "util/scoped_ptr_vector.h"
#include "util/sorting_network.h"
namespace sat {
class ba_solver : public extension {
friend class local_search;
struct stats {
unsigned m_num_propagations;
unsigned m_num_conflicts;
unsigned m_num_resolves;
unsigned m_num_bin_subsumes;
unsigned m_num_clause_subsumes;
unsigned m_num_pb_subsumes;
unsigned m_num_big_strengthenings;
unsigned m_num_cut;
unsigned m_num_gc;
unsigned m_num_overflow;
unsigned m_num_lemmas;
stats() { reset(); }
void reset() { memset(this, 0, sizeof(*this)); }
};
public:
enum tag_t {
card_t,
pb_t,
xr_t
};
class card;
class pb;
class xr;
class pb_base;
class constraint {
protected:
tag_t m_tag;
bool m_removed;
literal m_lit;
literal m_watch;
unsigned m_glue;
unsigned m_psm;
unsigned m_size;
size_t m_obj_size;
bool m_learned;
unsigned m_id;
bool m_pure; // is the constraint pure (only positive occurrences)
public:
constraint(tag_t t, unsigned id, literal l, unsigned sz, size_t osz):
m_tag(t), m_removed(false), m_lit(l), m_watch(null_literal), m_glue(0), m_psm(0), m_size(sz), m_obj_size(osz), m_learned(false), m_id(id), m_pure(false) {}
ext_constraint_idx index() const { return reinterpret_cast<ext_constraint_idx>(this); }
unsigned id() const { return m_id; }
tag_t tag() const { return m_tag; }
literal lit() const { return m_lit; }
unsigned size() const { return m_size; }
void set_size(unsigned sz) { SASSERT(sz <= m_size); m_size = sz; }
void update_literal(literal l) { m_lit = l; }
bool was_removed() const { return m_removed; }
void set_removed() { m_removed = true; }
void nullify_literal() { m_lit = null_literal; }
unsigned glue() const { return m_glue; }
void set_glue(unsigned g) { m_glue = g; }
unsigned psm() const { return m_psm; }
void set_psm(unsigned p) { m_psm = p; }
void set_learned(bool f) { m_learned = f; }
bool learned() const { return m_learned; }
bool is_watched() const { return m_watch == m_lit && m_lit != null_literal; }
void set_watch() { m_watch = m_lit; }
void clear_watch() { m_watch = null_literal; }
bool is_clear() const { return m_watch == null_literal && m_lit != null_literal; }
bool is_pure() const { return m_pure; }
void set_pure() { m_pure = true; }
unsigned fold_max_var(unsigned w) const;
size_t obj_size() const { return m_obj_size; }
card& to_card();
pb& to_pb();
xr& to_xr();
card const& to_card() const;
pb const& to_pb() const;
xr const& to_xr() const;
pb_base const& to_pb_base() const;
bool is_card() const { return m_tag == card_t; }
bool is_pb() const { return m_tag == pb_t; }
bool is_xr() const { return m_tag == xr_t; }
virtual bool is_watching(literal l) const { UNREACHABLE(); return false; };
virtual literal_vector literals() const { UNREACHABLE(); return literal_vector(); }
virtual void swap(unsigned i, unsigned j) { UNREACHABLE(); }
virtual literal get_lit(unsigned i) const { UNREACHABLE(); return null_literal; }
virtual void set_lit(unsigned i, literal l) { UNREACHABLE(); }
virtual bool well_formed() const { return true; }
virtual void negate() { UNREACHABLE(); }
};
friend std::ostream& operator<<(std::ostream& out, constraint const& c);
// base class for pb and cardinality constraints
class pb_base : public constraint {
protected:
unsigned m_k;
public:
pb_base(tag_t t, unsigned id, literal l, unsigned sz, size_t osz, unsigned k): constraint(t, id, l, sz, osz), m_k(k) { VERIFY(k < 4000000000); }
virtual void set_k(unsigned k) { VERIFY(k < 4000000000); m_k = k; }
virtual unsigned get_coeff(unsigned i) const { UNREACHABLE(); return 0; }
unsigned k() const { return m_k; }
bool well_formed() const override;
};
class card : public pb_base {
literal m_lits[0];
public:
static size_t get_obj_size(unsigned num_lits) { return sizeof(card) + num_lits * sizeof(literal); }
card(unsigned id, literal lit, literal_vector const& lits, unsigned k);
literal operator[](unsigned i) const { return m_lits[i]; }
literal& operator[](unsigned i) { return m_lits[i]; }
literal const* begin() const { return m_lits; }
literal const* end() const { return static_cast<literal const*>(m_lits) + m_size; }
void negate() override;
void swap(unsigned i, unsigned j) override { std::swap(m_lits[i], m_lits[j]); }
literal_vector literals() const override { return literal_vector(m_size, m_lits); }
bool is_watching(literal l) const override;
literal get_lit(unsigned i) const override { return m_lits[i]; }
void set_lit(unsigned i, literal l) override { m_lits[i] = l; }
unsigned get_coeff(unsigned i) const override { return 1; }
};
typedef std::pair<unsigned, literal> wliteral;
class pb : public pb_base {
unsigned m_slack;
unsigned m_num_watch;
unsigned m_max_sum;
wliteral m_wlits[0];
public:
static size_t get_obj_size(unsigned num_lits) { return sizeof(pb) + num_lits * sizeof(wliteral); }
pb(unsigned id, literal lit, svector<wliteral> const& wlits, unsigned k);
literal lit() const { return m_lit; }
wliteral operator[](unsigned i) const { return m_wlits[i]; }
wliteral& operator[](unsigned i) { return m_wlits[i]; }
wliteral const* begin() const { return m_wlits; }
wliteral const* end() const { return begin() + m_size; }
unsigned slack() const { return m_slack; }
void set_slack(unsigned s) { m_slack = s; }
unsigned num_watch() const { return m_num_watch; }
unsigned max_sum() const { return m_max_sum; }
void update_max_sum();
void set_num_watch(unsigned s) { m_num_watch = s; }
bool is_cardinality() const;
void negate() override;
void set_k(unsigned k) override { m_k = k; VERIFY(k < 4000000000); update_max_sum(); }
void swap(unsigned i, unsigned j) override { std::swap(m_wlits[i], m_wlits[j]); }
literal_vector literals() const override { literal_vector lits; for (auto wl : *this) lits.push_back(wl.second); return lits; }
bool is_watching(literal l) const override;
literal get_lit(unsigned i) const override { return m_wlits[i].second; }
void set_lit(unsigned i, literal l) override { m_wlits[i].second = l; }
unsigned get_coeff(unsigned i) const override { return m_wlits[i].first; }
};
class xr : public constraint {
literal m_lits[0];
public:
static size_t get_obj_size(unsigned num_lits) { return sizeof(xr) + num_lits * sizeof(literal); }
xr(unsigned id, literal_vector const& lits);
literal operator[](unsigned i) const { return m_lits[i]; }
literal const* begin() const { return m_lits; }
literal const* end() const { return begin() + m_size; }
void negate() override { m_lits[0].neg(); }
void swap(unsigned i, unsigned j) override { std::swap(m_lits[i], m_lits[j]); }
bool is_watching(literal l) const override;
literal_vector literals() const override { return literal_vector(size(), begin()); }
literal get_lit(unsigned i) const override { return m_lits[i]; }
void set_lit(unsigned i, literal l) override { m_lits[i] = l; }
bool well_formed() const override;
};
protected:
struct ineq {
svector<wliteral> m_wlits;
uint64_t m_k;
ineq(): m_k(0) {}
unsigned size() const { return m_wlits.size(); }
literal lit(unsigned i) const { return m_wlits[i].second; }
unsigned coeff(unsigned i) const { return m_wlits[i].first; }
void reset(uint64_t k) { m_wlits.reset(); m_k = k; }
void push(literal l, unsigned c) { m_wlits.push_back(wliteral(c,l)); }
unsigned bv_coeff(bool_var v) const;
void divide(unsigned c);
void weaken(unsigned i);
bool contains(literal l) const { for (auto wl : m_wlits) if (wl.second == l) return true; return false; }
};
solver* m_solver;
lookahead* m_lookahead;
unit_walk* m_unit_walk;
stats m_stats;
small_object_allocator m_allocator;
ptr_vector<constraint> m_constraints;
ptr_vector<constraint> m_learned;
ptr_vector<constraint> m_constraint_to_reinit;
unsigned_vector m_constraint_to_reinit_lim;
unsigned m_constraint_to_reinit_last_sz;
unsigned m_constraint_id;
// conflict resolution
unsigned m_num_marks;
unsigned m_conflict_lvl;
svector<int64_t> m_coeffs;
svector<bool_var> m_active_vars;
unsigned m_bound;
tracked_uint_set m_active_var_set;
literal_vector m_lemma;
literal_vector m_skipped;
unsigned m_num_propagations_since_pop;
unsigned_vector m_parity_marks;
literal_vector m_parity_trail;
unsigned_vector m_pb_undef;
struct ba_sort {
typedef sat::literal pliteral;
typedef sat::literal_vector pliteral_vector;
ba_solver& s;
pliteral m_true;
pliteral_vector m_lits;
ba_sort(ba_solver& s): s(s), m_true(null_literal) {}
pliteral mk_false();
pliteral mk_true();
pliteral mk_not(pliteral l);
pliteral fresh(char const*);
pliteral mk_min(unsigned, pliteral const* lits);
pliteral mk_max(unsigned, pliteral const* lits);
void mk_clause(unsigned n, literal const* lits);
std::ostream& pp(std::ostream& out, pliteral l) const;
};
ba_sort m_ba;
psort_nw<ba_sort> m_sort;
void ensure_parity_size(bool_var v);
unsigned get_parity(bool_var v);
void inc_parity(bool_var v);
void reset_parity(bool_var v);
solver& s() const { return *m_solver; }
// simplification routines
svector<unsigned> m_visited;
unsigned m_visited_ts;
vector<svector<constraint*>> m_cnstr_use_list;
use_list m_clause_use_list;
bool m_simplify_change;
bool m_clause_removed;
bool m_constraint_removed;
literal_vector m_roots;
svector<bool> m_root_vars;
unsigned_vector m_weights;
svector<wliteral> m_wlits;
bool subsumes(card& c1, card& c2, literal_vector& comp);
bool subsumes(card& c1, clause& c2, bool& self);
bool subsumed(card& c1, literal l1, literal l2);
bool subsumes(pb const& p1, pb_base const& p2);
void subsumes(pb& p1, literal lit);
void subsumption(pb& p1);
void binary_subsumption(card& c1, literal lit);
void clause_subsumption(card& c1, literal lit, clause_vector& removed_clauses);
void card_subsumption(card& c1, literal lit);
void init_visited();
void mark_visited(literal l) { m_visited[l.index()] = m_visited_ts; }
void mark_visited(bool_var v) { mark_visited(literal(v, false)); }
bool is_visited(bool_var v) const { return is_visited(literal(v, false)); }
bool is_visited(literal l) const { return m_visited[l.index()] == m_visited_ts; }
unsigned get_num_unblocked_bin(literal l);
literal get_min_occurrence_literal(card const& c);
void init_use_lists();
void remove_unused_defs();
unsigned set_non_external();
unsigned elim_pure();
bool elim_pure(literal lit);
void unit_strengthen();
void unit_strengthen(big& big, constraint& cs);
void unit_strengthen(big& big, pb_base& p);
void subsumption(constraint& c1);
void subsumption(card& c1);
void gc_half(char const* _method);
void update_psm(constraint& c) const;
void mutex_reduction();
void update_pure();
unsigned use_count(literal lit) const { return m_cnstr_use_list[lit.index()].size() + m_clause_use_list.get(lit).size(); }
void cleanup_clauses();
void cleanup_clauses(clause_vector& clauses);
void cleanup_constraints();
void cleanup_constraints(ptr_vector<constraint>& cs, bool learned);
void remove_constraint(constraint& c, char const* reason);
// constraints
constraint& index2constraint(size_t idx) const { return *reinterpret_cast<constraint*>(idx); }
void pop_constraint();
void unwatch_literal(literal w, constraint& c);
void watch_literal(literal w, constraint& c);
void watch_literal(wliteral w, pb& p);
bool is_watched(literal l, constraint const& c) const;
void add_constraint(constraint* c);
bool init_watch(constraint& c);
void init_watch(bool_var v);
void clear_watch(constraint& c);
lbool add_assign(constraint& c, literal l);
bool incremental_mode() const;
void simplify(constraint& c);
void pre_simplify(constraint& c);
void nullify_tracking_literal(constraint& c);
void set_conflict(constraint& c, literal lit);
void assign(constraint& c, literal lit);
bool assigned_above(literal above, literal below);
void get_antecedents(literal l, constraint const& c, literal_vector & r);
bool validate_conflict(constraint const& c) const;
bool validate_unit_propagation(constraint const& c, literal alit) const;
void validate_eliminated();
void validate_eliminated(ptr_vector<constraint> const& cs);
void attach_constraint(constraint const& c);
void detach_constraint(constraint const& c);
lbool eval(constraint const& c) const;
lbool eval(model const& m, constraint const& c) const;
lbool eval(lbool a, lbool b) const;
void assert_unconstrained(literal lit, literal_vector const& lits);
void flush_roots(constraint& c);
void recompile(constraint& c);
void split_root(constraint& c);
unsigned next_id() { return m_constraint_id++; }
void set_non_learned(constraint& c);
// cardinality
bool init_watch(card& c);
lbool add_assign(card& c, literal lit);
void clear_watch(card& c);
void reset_coeffs();
void reset_marked_literals();
void get_antecedents(literal l, card const& c, literal_vector & r);
void flush_roots(card& c);
void recompile(card& c);
bool clausify(card& c);
bool clausify(literal lit, unsigned n, literal const* lits, unsigned k);
lbool eval(card const& c) const;
lbool eval(model const& m, card const& c) const;
double get_reward(card const& c, literal_occs_fun& occs) const;
// xr specific functionality
void clear_watch(xr& x);
bool init_watch(xr& x);
bool parity(xr const& x, unsigned offset) const;
lbool add_assign(xr& x, literal alit);
void get_xr_antecedents(literal l, unsigned index, justification js, literal_vector& r);
void get_antecedents(literal l, xr const& x, literal_vector & r);
void simplify(xr& x);
void extract_xor();
void merge_xor();
struct clause_filter {
unsigned m_filter;
clause* m_clause;
clause_filter(unsigned f, clause* cp):
m_filter(f), m_clause(cp) {}
};
typedef svector<bool> bool_vector;
unsigned m_max_xor_size;
vector<svector<clause_filter>> m_clause_filters; // index of clauses.
unsigned m_barbet_combination; // bit-mask of parities that have been found
vector<bool_vector> m_barbet_parity; // lookup parity for clauses
clause_vector m_barbet_clauses_to_remove; // remove clauses that become xors
unsigned_vector m_barbet_var_position; // position of var in main clause
literal_vector m_barbet_clause; // reference clause with literals sorted according to main clause
unsigned_vector m_barbet_missing; // set of indices not occurring in clause.
void init_clause_filter();
void init_clause_filter(clause_vector& clauses);
inline void barbet_set_combination(unsigned mask) { m_barbet_combination |= (1 << mask); }
inline bool barbet_get_combination(unsigned mask) const { return (m_barbet_combination & (1 << mask)) != 0; }
void barbet_extract_xor();
void barbet_init_parity();
void barbet_extract_xor(clause& c);
bool barbet_extract_xor(bool parity, clause& c, clause& c2);
bool barbet_extract_xor(bool parity, clause& c, literal l1, literal l2);
bool barbet_update_combinations(clause& c, bool parity, unsigned mask);
void barbet_add_xor(bool parity, clause& c);
unsigned get_clause_filter(clause& c);
vector<ptr_vector<clause>> m_ternary;
void extract_ternary(clause_vector const& clauses);
bool extract_xor(clause& c, literal l);
bool extract_xor(clause& c1, clause& c2);
bool clausify(xr& x);
void flush_roots(xr& x);
lbool eval(xr const& x) const;
lbool eval(model const& m, xr const& x) const;
// pb functionality
unsigned m_a_max;
bool init_watch(pb& p);
lbool add_assign(pb& p, literal alit);
void add_index(pb& p, unsigned index, literal lit);
void clear_watch(pb& p);
void get_antecedents(literal l, pb const& p, literal_vector & r);
void split_root(pb_base& p);
void simplify(pb_base& p);
void simplify2(pb& p);
bool is_cardinality(pb const& p);
void flush_roots(pb& p);
void recompile(pb& p);
bool clausify(pb& p);
bool is_cardinality(pb const& p, literal_vector& lits);
lbool eval(pb const& p) const;
lbool eval(model const& m, pb const& p) const;
double get_reward(pb const& p, literal_occs_fun& occs) const;
// RoundingPb conflict resolution
lbool resolve_conflict_rs();
void round_to_one(ineq& ineq, bool_var v);
void round_to_one(bool_var v);
void divide(unsigned c);
void resolve_on(literal lit);
void resolve_with(ineq const& ineq);
void reset_marks(unsigned idx);
void mark_variables(ineq const& ineq);
void bail_resolve_conflict(unsigned idx);
// access solver
inline lbool value(bool_var v) const { return value(literal(v, false)); }
inline lbool value(literal lit) const { return m_lookahead ? m_lookahead->value(lit) : m_solver->value(lit); }
inline lbool value(model const& m, literal l) const { return l.sign() ? ~m[l.var()] : m[l.var()]; }
inline bool is_false(literal lit) const { return l_false == value(lit); }
inline unsigned lvl(literal lit) const { return m_lookahead || m_unit_walk ? 0 : m_solver->lvl(lit); }
inline unsigned lvl(bool_var v) const { return m_lookahead || m_unit_walk ? 0 : m_solver->lvl(v); }
inline bool inconsistent() const {
if (m_lookahead) return m_lookahead->inconsistent();
if (m_unit_walk) return m_unit_walk->inconsistent();
return m_solver->inconsistent();
}
inline watch_list& get_wlist(literal l) { return m_lookahead ? m_lookahead->get_wlist(l) : m_solver->get_wlist(l); }
inline watch_list const& get_wlist(literal l) const { return m_lookahead ? m_lookahead->get_wlist(l) : m_solver->get_wlist(l); }
inline void assign(literal l, justification j) {
if (m_lookahead) m_lookahead->assign(l);
else if (m_unit_walk) m_unit_walk->assign(l);
else m_solver->assign(l, j);
}
inline void set_conflict(justification j, literal l) {
if (m_lookahead) m_lookahead->set_conflict();
else if (m_unit_walk) m_unit_walk->set_conflict();
else m_solver->set_conflict(j, l);
}
inline config const& get_config() const { return m_lookahead ? m_lookahead->get_config() : m_solver->get_config(); }
inline void drat_add(literal_vector const& c, svector<drat::premise> const& premises) { if (m_solver) m_solver->m_drat.add(c, premises); }
mutable bool m_overflow;
void reset_active_var_set();
bool test_and_set_active(bool_var v);
void inc_coeff(literal l, unsigned offset);
int64_t get_coeff(bool_var v) const;
uint64_t get_coeff(literal lit) const;
wliteral get_wliteral(bool_var v);
unsigned get_abs_coeff(bool_var v) const;
int get_int_coeff(bool_var v) const;
unsigned get_bound() const;
void inc_bound(int64_t i);
literal get_asserting_literal(literal conseq);
void process_antecedent(literal l, unsigned offset);
void process_antecedent(literal l) { process_antecedent(l, 1); }
void process_card(card& c, unsigned offset);
void cut();
bool create_asserting_lemma();
// validation utilities
bool validate_conflict(card const& c) const;
bool validate_conflict(xr const& x) const;
bool validate_conflict(pb const& p) const;
bool validate_assign(literal_vector const& lits, literal lit);
bool validate_lemma();
bool validate_ineq(ineq const& ineq) const;
bool validate_unit_propagation(card const& c, literal alit) const;
bool validate_unit_propagation(pb const& p, literal alit) const;
bool validate_unit_propagation(pb const& p, literal_vector const& r, literal alit) const;
bool validate_unit_propagation(xr const& x, literal alit) const;
bool validate_conflict(literal_vector const& lits, ineq& p);
bool validate_watch_literals() const;
bool validate_watch_literal(literal lit) const;
bool validate_watched_constraint(constraint const& c) const;
bool validate_watch(pb const& p, literal alit) const;
bool is_watching(literal lit, constraint const& c) const;
literal translate_to_sat(solver& s, u_map<bool_var>& translation, ineq const& pb);
literal translate_to_sat(solver& s, u_map<bool_var>& translation, ineq& a, ineq& b);
literal translate_to_sat(solver& s, u_map<bool_var>& translation, literal lit);
ineq negate(ineq const& a) const;
void push_lit(literal_vector& lits, literal lit);
ineq m_A, m_B, m_C;
void active2pb(ineq& p);
constraint* active2lemma();
constraint* active2constraint();
constraint* active2card();
void active2wlits();
void active2wlits(svector<wliteral>& wlits);
void justification2pb(justification const& j, literal lit, unsigned offset, ineq& p);
void constraint2pb(constraint& cnstr, literal lit, unsigned offset, ineq& p);
bool validate_resolvent();
unsigned get_coeff(ineq const& pb, literal lit);
void display(std::ostream& out, ineq const& p, bool values = false) const;
void display(std::ostream& out, card const& c, bool values) const;
void display(std::ostream& out, pb const& p, bool values) const;
void display(std::ostream& out, xr const& c, bool values) const;
void display_lit(std::ostream& out, literal l, unsigned sz, bool values) const;
constraint* add_at_least(literal l, literal_vector const& lits, unsigned k, bool learned);
constraint* add_pb_ge(literal l, svector<wliteral> const& wlits, unsigned k, bool learned);
constraint* add_xr(literal_vector const& lits, bool learned);
literal add_xor_def(literal_vector& lits, bool learned = false);
bool all_distinct(literal_vector const& lits);
bool all_distinct(xr const& x);
bool all_distinct(clause const& cl);
void copy_core(ba_solver* result, bool learned);
void copy_constraints(ba_solver* result, ptr_vector<constraint> const& constraints);
public:
ba_solver();
~ba_solver() override;
void set_solver(solver* s) override { m_solver = s; }
void set_lookahead(lookahead* l) override { m_lookahead = l; }
void set_unit_walk(unit_walk* u) override { m_unit_walk = u; }
void add_at_least(bool_var v, literal_vector const& lits, unsigned k);
void add_pb_ge(bool_var v, svector<wliteral> const& wlits, unsigned k);
void add_xr(literal_vector const& lits);
bool propagate(literal l, ext_constraint_idx idx) override;
lbool resolve_conflict() override;
void get_antecedents(literal l, ext_justification_idx idx, literal_vector & r) override;
void asserted(literal l) override;
check_result check() override;
void push() override;
void pop(unsigned n) override;
void pre_simplify() override;
void simplify() override;
void clauses_modifed() override;
lbool get_phase(bool_var v) override;
bool set_root(literal l, literal r) override;
void flush_roots() override;
std::ostream& display(std::ostream& out) const override;
std::ostream& display_justification(std::ostream& out, ext_justification_idx idx) const override;
std::ostream& display_constraint(std::ostream& out, ext_constraint_idx idx) const override;
void collect_statistics(statistics& st) const override;
extension* copy(solver* s) override;
extension* copy(lookahead* s, bool learned) override;
void find_mutexes(literal_vector& lits, vector<literal_vector> & mutexes) override;
void pop_reinit() override;
void gc() override;
unsigned max_var(unsigned w) const override;
double get_reward(literal l, ext_justification_idx idx, literal_occs_fun& occs) const override;
bool is_extended_binary(ext_justification_idx idx, literal_vector & r) override;
void init_use_list(ext_use_list& ul) override;
bool is_blocked(literal l, ext_constraint_idx idx) override;
bool check_model(model const& m) const override;
ptr_vector<constraint> const & constraints() const { return m_constraints; }
std::ostream& display(std::ostream& out, constraint const& c, bool values) const;
bool validate() override;
};
};
#endif