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/*++
Copyright (c) 2020 Microsoft Corporation
Module Name:
dt_solver.h
Abstract:
Theory plugin for algebraic datatypes
Author:
Nikolaj Bjorner (nbjorner) 2020-09-08
--*/
#include "sat/smt/dt_solver.h"
#include "sat/smt/euf_solver.h"
#include "sat/smt/array_solver.h"
namespace euf {
class solver;
}
namespace dt {
solver::solver(euf::solver& ctx, theory_id id) :
th_euf_solver(ctx, ctx.get_manager().get_family_name(id), id),
dt(m),
m_autil(m),
m_sutil(m),
m_find(*this),
m_args(m)
{}
solver::~solver() {
std::for_each(m_var_data.begin(), m_var_data.end(), delete_proc());
m_var_data.reset();
}
void solver::clone_var(solver& src, theory_var v) {
enode* n = src.ctx.copy(ctx, src.var2enode(v));
VERIFY(v == th_euf_solver::mk_var(n));
m_var_data.push_back(alloc(var_data));
var_data* d_dst = m_var_data[v];
var_data* d_src = src.m_var_data[v];
ctx.attach_th_var(n, this, v);
if (d_src->m_constructor && !d_dst->m_constructor)
d_dst->m_constructor = src.ctx.copy(ctx, d_src->m_constructor);
for (auto* r : d_src->m_recognizers)
d_dst->m_recognizers.push_back(src.ctx.copy(ctx, r));
}
euf::th_solver* solver::clone(euf::solver& dst_ctx) {
auto* result = alloc(solver, dst_ctx, get_id());
for (unsigned v = 0; v < get_num_vars(); ++v)
result->clone_var(*this, v);
return result;
}
solver::final_check_st::final_check_st(solver& s) : s(s) {
SASSERT(s.m_to_unmark1.empty());
SASSERT(s.m_to_unmark2.empty());
s.m_used_eqs.reset();
s.m_dfs.reset();
s.m_parent.reset();
}
solver::final_check_st::~final_check_st() {
s.clear_mark();
}
void solver::clear_mark() {
for (enode* n : m_to_unmark1)
n->unmark1();
for (enode* n : m_to_unmark2)
n->unmark2();
m_to_unmark1.reset();
m_to_unmark2.reset();
}
void solver::oc_mark_on_stack(enode* n) {
n = n->get_root();
n->mark1();
m_to_unmark1.push_back(n);
}
void solver::oc_mark_cycle_free(enode* n) {
n = n->get_root();
n->mark2();
m_to_unmark2.push_back(n);
}
void solver::oc_push_stack(enode* n) {
m_dfs.push_back(std::make_pair(EXIT, n));
m_dfs.push_back(std::make_pair(ENTER, n));
}
/**
\brief Assert the axiom (antecedent => lhs = rhs)
antecedent may be null_literal
*/
void solver::assert_eq_axiom(enode* n1, expr* e2, literal antecedent) {
expr* e1 = n1->get_expr();
euf::th_proof_hint* ph = ctx.mk_smt_prop_hint(name(), antecedent, e1, e2);
if (antecedent == sat::null_literal)
add_unit(eq_internalize(e1, e2), ph);
else if (s().value(antecedent) == l_true) {
euf::enode* n2 = e_internalize(e2);
ctx.propagate(n1, n2, euf::th_explain::propagate(*this, antecedent, n1, n2, ph));
}
else
add_clause(~antecedent, eq_internalize(e1, e2), ph);
}
/**
\brief Assert the equality (= n (c (acc_1 n) ... (acc_m n))) where
where acc_i are the accessors of constructor c.
*/
void solver::assert_is_constructor_axiom(enode* n, func_decl* c, literal antecedent) {
TRACE("dt", tout << mk_pp(c, m) << " " << ctx.bpp(n) << "\n";);
m_stats.m_assert_cnstr++;
expr* e = n->get_expr();
SASSERT(dt.is_constructor(c));
SASSERT(is_datatype(e));
SASSERT(c->get_range() == e->get_sort());
m_args.reset();
for (func_decl* d : *dt.get_constructor_accessors(c))
m_args.push_back(m.mk_app(d, e));
expr_ref con(m.mk_app(c, m_args), m);
assert_eq_axiom(n, con, antecedent);
}
/**
\brief Given a constructor n := (c a_1 ... a_m) assert the axioms
(= (acc_1 n) a_1)
...
(= (acc_m n) a_m)
*/
void solver::assert_accessor_axioms(enode* n) {
SASSERT(is_constructor(n));
expr* e = n->get_expr();
func_decl* d = n->get_decl();
unsigned i = 0;
for (func_decl* acc : *dt.get_constructor_accessors(d)) {
m_stats.m_assert_accessor++;
app_ref acc_app(m.mk_app(acc, e), m);
assert_eq_axiom(n->get_arg(i), acc_app);
++i;
}
}
/**
\brief Sign a conflict for r := is_mk(a), c := mk(...), not(r), and c == a.
*/
void solver::sign_recognizer_conflict(enode* c, enode* r) {
SASSERT(is_constructor(c));
SASSERT(is_recognizer(r));
SASSERT(dt.get_recognizer_constructor(r->get_decl()) == c->get_decl());
SASSERT(c->get_root() == r->get_arg(0)->get_root());
TRACE("dt", tout << ctx.bpp(c) << "\n" << ctx.bpp(r) << "\n";);
literal l = ctx.enode2literal(r);
SASSERT(s().value(l) == l_false);
clear_mark();
auto* ph = ctx.mk_smt_hint(name(), ~l, c, r->get_arg(0));
ctx.set_conflict(euf::th_explain::conflict(*this, ~l, c, r->get_arg(0), ph));
}
/**
\brief Given a field update n := { r with field := v } for constructor C, assert the axioms:
(=> (is-C r) (= (acc_j n) (acc_j r))) for acc_j != field
(=> (is-C r) (= (field n) v)) for acc_j != field
(=> (not (is-C r)) (= n r))
(=> (is-C r) (is-C n))
*/
void solver::assert_update_field_axioms(enode* n) {
m_stats.m_assert_update_field++;
SASSERT(is_update_field(n));
expr* own = n->get_expr();
expr* arg1 = n->get_arg(0)->get_expr();
func_decl* upd = n->get_decl();
func_decl* acc = to_func_decl(upd->get_parameter(0).get_ast());
func_decl* con = dt.get_accessor_constructor(acc);
func_decl* rec = dt.get_constructor_is(con);
ptr_vector const& accessors = *dt.get_constructor_accessors(con);
app_ref rec_app(m.mk_app(rec, arg1), m);
app_ref acc_app(m);
literal is_con = mk_literal(rec_app);
for (func_decl* acc1 : accessors) {
enode* arg;
if (acc1 == acc) {
arg = n->get_arg(1);
}
else {
acc_app = m.mk_app(acc1, arg1);
arg = e_internalize(acc_app);
}
app_ref acc_own(m.mk_app(acc1, own), m);
assert_eq_axiom(arg, acc_own, is_con);
}
// update_field is identity if 'n' is not created by a matching constructor.
assert_eq_axiom(n, arg1, ~is_con);
app_ref n_is_con(m.mk_app(rec, own), m);
literal _n_is_con = mk_literal(n_is_con);
auto* ph = ctx.mk_smt_hint(name(), is_con, ~_n_is_con);
add_clause(~is_con, _n_is_con, ph);
}
euf::theory_var solver::mk_var(enode* n) {
if (is_attached_to_var(n))
return n->get_th_var(get_id());
euf::theory_var r = th_euf_solver::mk_var(n);
VERIFY(r == static_cast(m_find.mk_var()));
SASSERT(r == static_cast(m_var_data.size()));
m_var_data.push_back(alloc(var_data));
var_data* d = m_var_data[r];
ctx.attach_th_var(n, this, r);
if (is_constructor(n)) {
d->m_constructor = n;
assert_accessor_axioms(n);
}
else if (is_update_field(n))
assert_update_field_axioms(n);
else if (!is_recognizer(n)) {
sort* s = n->get_sort();
if (dt.get_datatype_num_constructors(s) == 1)
assert_is_constructor_axiom(n, dt.get_datatype_constructors(s)->get(0));
else if (get_config().m_dt_lazy_splits == 0 || (get_config().m_dt_lazy_splits == 1 && !s->is_infinite()))
mk_split(r, false);
}
return r;
}
/**
\brief Create a new case split for v. That is, create the atom (is_mk v) and mark it as relevant.
If first is true, it means that v does not have recognizer yet.
*/
void solver::mk_split(theory_var v, bool is_final) {
m_stats.m_splits++;
v = m_find.find(v);
enode* n = var2enode(v);
sort* srt = n->get_sort();
if (dt.is_enum_sort(srt)) {
mk_enum_split(v);
return;
}
func_decl* non_rec_c = dt.get_non_rec_constructor(srt);
unsigned non_rec_idx = dt.get_constructor_idx(non_rec_c);
var_data* d = m_var_data[v];
enode* recognizer = d->m_recognizers.get(non_rec_idx, nullptr);
SASSERT(!d->m_constructor);
SASSERT(!recognizer || ctx.value(recognizer) == l_false || !is_final);
TRACE("dt", tout << ctx.bpp(n) << " non_rec_c: " << non_rec_c->get_name() << " #rec: " << d->m_recognizers.size() << "\n";);
if (!recognizer && non_rec_c->get_arity() == 0) {
sat::literal eq = eq_internalize(n->get_expr(), m.mk_const(non_rec_c));
s().set_phase(eq);
if (s().value(eq) == l_false)
mk_enum_split(v);
}
else if (!recognizer)
mk_recognizer_constructor_literal(non_rec_c, n);
else if (ctx.value(recognizer) == l_false)
mk_enum_split(v);
}
sat::literal solver::mk_recognizer_constructor_literal(func_decl* c, euf::enode* n) {
func_decl* r = dt.get_constructor_is(c);
app_ref r_app(m.mk_app(r, n->get_expr()), m);
sat::literal lit = mk_literal(r_app);
s().set_phase(lit);
return lit;
}
void solver::mk_enum_split(theory_var v) {
enode* n = var2enode(v);
var_data* d = m_var_data[v];
sort* srt = n->get_sort();
auto const& constructors = *dt.get_datatype_constructors(srt);
unsigned sz = constructors.size();
int start = s().rand()();
m_lits.reset();
sat::literal lit;
for (unsigned i = 0; i < sz; ++i) {
unsigned j = (i + start) % sz;
func_decl* c = constructors[j];
if (c->get_arity() > 0) {
enode* curr = d->m_recognizers.get(j, nullptr);
if (curr && ctx.value(curr) != l_false)
return;
lit = mk_recognizer_constructor_literal(c, n);
if (!curr)
return;
if (s().value(lit) != l_false)
return;
m_lits.push_back(~lit);
}
else {
lit = eq_internalize(n->get_expr(), m.mk_const(c));
switch (s().value(lit)) {
case l_undef:
s().set_phase(lit);
return;
case l_true:
return;
case l_false:
m_lits.push_back(~lit);
break;
}
}
}
auto* ph = ctx.mk_smt_hint(name(), m_lits);
ctx.set_conflict(euf::th_explain::conflict(*this, m_lits, ph));
}
/**
* Remark: If s is an infinite sort, then it is not necessary to create
* a theory variable.
*
* Actually, when the logical context has quantifiers, it is better to
* disable this optimization.
* Example:
*
* (forall (l list) (a Int) (= (len (cons a l)) (+ (len l) 1)))
* (assert (> (len a) 1)
*
* If the theory variable is not created for 'a', then a wrong model will be generated.
*
*/
void solver::apply_sort_cnstr(enode* n, sort* s) {
TRACE("dt", tout << "apply_sort_cnstr: #" << ctx.bpp(n) << "\n";);
force_push();
if (!is_attached_to_var(n))
mk_var(n);
}
void solver::new_eq_eh(euf::th_eq const& eq) {
force_push();
m_find.merge(eq.v1(), eq.v2());
}
void solver::asserted(literal lit) {
force_push();
enode* n = bool_var2enode(lit.var());
if (!is_recognizer(n))
return;
TRACE("dt", tout << "assigning recognizer: #" << n->get_expr_id() << " " << ctx.bpp(n) << "\n";);
SASSERT(n->num_args() == 1);
enode* arg = n->get_arg(0);
theory_var tv = arg->get_th_var(get_id());
tv = m_find.find(tv);
var_data* d = m_var_data[tv];
func_decl* r = n->get_decl();
func_decl* c = dt.get_recognizer_constructor(r);
if (!lit.sign()) {
SASSERT(tv != euf::null_theory_var);
if (d->m_constructor && d->m_constructor->get_decl() == c)
return; // do nothing
assert_is_constructor_axiom(arg, c, lit);
}
else if (d->m_constructor == nullptr) // make sure a constructor is attached
propagate_recognizer(tv, n);
else if (d->m_constructor->get_decl() == c) // conflict
sign_recognizer_conflict(d->m_constructor, n);
}
void solver::add_recognizer(theory_var v, enode* recognizer) {
TRACE("dt", tout << "add recognizer " << v << " " << mk_pp(recognizer->get_expr(), m) << "\n";);
v = m_find.find(v);
var_data* d = m_var_data[v];
sort* s = recognizer->get_decl()->get_domain(0);
SASSERT(is_recognizer(recognizer));
SASSERT(dt.is_datatype(s));
if (d->m_recognizers.empty())
d->m_recognizers.resize(dt.get_datatype_num_constructors(s), nullptr);
SASSERT(d->m_recognizers.size() == dt.get_datatype_num_constructors(s));
unsigned c_idx = dt.get_recognizer_constructor_idx(recognizer->get_decl());
if (d->m_recognizers[c_idx])
return;
lbool val = ctx.value(recognizer);
TRACE("dt", tout << "adding recognizer to v" << v << " rec: #" << recognizer->get_expr_id() << " val: " << val << "\n";);
// do nothing...
// If recognizer assignment was already processed, then
// d->m_constructor is already set.
// Otherwise, it will be set when asserted is invoked.
if (val == l_true)
return;
if (val == l_false && d->m_constructor) {
// conflict
if (d->m_constructor->get_decl() == dt.get_recognizer_constructor(recognizer->get_decl()))
sign_recognizer_conflict(d->m_constructor, recognizer);
return;
}
SASSERT(val == l_undef || (val == l_false && !d->m_constructor));
ctx.push(set_vector_idx_trail(d->m_recognizers, c_idx));
d->m_recognizers[c_idx] = recognizer;
if (val == l_false)
propagate_recognizer(v, recognizer);
}
/**
\brief Propagate a recognizer assigned to false.
*/
void solver::propagate_recognizer(theory_var v, enode* recognizer) {
SASSERT(is_recognizer(recognizer));
SASSERT(static_cast(m_find.find(v)) == v);
SASSERT(ctx.value(recognizer) == l_false);
unsigned num_unassigned = 0;
unsigned unassigned_idx = UINT_MAX;
enode* n = var2enode(v);
sort* srt = n->get_sort();
var_data* d = m_var_data[v];
if (d->m_recognizers.empty()) {
add_recognizer(v, recognizer);
return;
}
CTRACE("dt", d->m_recognizers.empty(), ctx.display(tout););
SASSERT(!d->m_recognizers.empty());
m_lits.reset();
enode_pair_vector eqs;
unsigned idx = 0;
for (enode* r : d->m_recognizers) {
if (r && ctx.value(r) == l_true)
return; // nothing to be propagated
if (r && ctx.value(r) == l_false) {
SASSERT(r->num_args() == 1);
m_lits.push_back(~ctx.enode2literal(r));
if (n != r->get_arg(0)) {
// Argument of the current recognizer is not necessarily equal to n.
// This can happen when n and r->get_arg(0) are in the same equivalence class.
// We must add equality as an assumption to the conflict or propagation
SASSERT(n->get_root() == r->get_arg(0)->get_root());
eqs.push_back(euf::enode_pair(n, r->get_arg(0)));
}
}
else {
if (num_unassigned == 0)
unassigned_idx = idx;
++num_unassigned;
}
++idx;
}
TRACE("dt", tout << "propagate " << num_unassigned << " eqs: " << eqs.size() << "\n";);
if (num_unassigned == 0) {
auto* ph = ctx.mk_smt_hint(name(), m_lits, eqs);
ctx.set_conflict(euf::th_explain::conflict(*this, m_lits, eqs, ph));
}
else if (num_unassigned == 1) {
// propagate remaining recognizer
SASSERT(!m_lits.empty());
enode* r = d->m_recognizers[unassigned_idx];
literal consequent;
if (r)
consequent = ctx.enode2literal(r);
else {
func_decl* con = (*dt.get_datatype_constructors(srt))[unassigned_idx];
func_decl* rec = dt.get_constructor_is(con);
app_ref rec_app(m.mk_app(rec, n->get_expr()), m);
consequent = mk_literal(rec_app);
}
euf::th_proof_hint* ph = nullptr;
if (ctx.use_drat()) {
m_lits.push_back(~consequent);
ph = ctx.mk_smt_hint(name(), m_lits, eqs);
m_lits.pop_back();
}
ctx.propagate(consequent, euf::th_explain::propagate(*this, m_lits, eqs, consequent, ph));
}
else if (get_config().m_dt_lazy_splits == 0 || (!srt->is_infinite() && get_config().m_dt_lazy_splits == 1))
// there are more than 2 unassigned recognizers...
// if eager splits are enabled... create new case split
mk_split(v, false);
}
void solver::merge_eh(theory_var v1, theory_var v2, theory_var, theory_var) {
// v1 is the new root
SASSERT(v1 == static_cast(m_find.find(v1)));
var_data* d1 = m_var_data[v1];
var_data* d2 = m_var_data[v2];
auto* con1 = d1->m_constructor;
auto* con2 = d2->m_constructor;
TRACE("dt", tout << "merging v" << v1 << " v" << v2 << "\n" << ctx.bpp(var2enode(v1)) << " == " << ctx.bpp(var2enode(v2)) << " " << ctx.bpp(con1) << " " << ctx.bpp(con2) << "\n";);
if (con1 && con2 && con1->get_decl() != con2->get_decl())
ctx.set_conflict(euf::th_explain::conflict(*this, con1, con2, ctx.mk_smt_hint(name(), con1, con2)));
else if (con2 && !con1) {
ctx.push(set_ptr_trail(d1->m_constructor));
// check whether there is a recognizer in d1 that conflicts with con2;
if (!d1->m_recognizers.empty()) {
unsigned c_idx = dt.get_constructor_idx(con2->get_decl());
enode* recognizer = d1->m_recognizers[c_idx];
if (recognizer && ctx.value(recognizer) == l_false) {
sign_recognizer_conflict(con2, recognizer);
return;
}
}
d1->m_constructor = con2;
}
for (enode* e : d2->m_recognizers)
if (e)
add_recognizer(v1, e);
}
ptr_vector const& solver::get_array_args(enode* n) {
m_nodes.reset();
array::solver* th = dynamic_cast(ctx.fid2solver(m_autil.get_family_id()));
for (enode* p : th->parent_selects(n))
m_nodes.push_back(p);
app_ref def(m_autil.mk_default(n->get_expr()), m);
m_nodes.push_back(ctx.get_enode(def));
return m_nodes;
}
ptr_vector const& solver::get_seq_args(enode* n, enode*& sibling) {
m_nodes.reset();
m_todo.reset();
auto add_todo = [&](enode* n) {
if (!n->is_marked1()) {
n->mark1();
m_todo.push_back(n);
}
};
for (enode* sib : euf::enode_class(n)) {
if (m_sutil.str.is_concat_of_units(sib->get_expr())) {
add_todo(sib);
sibling = sib;
break;
}
}
for (unsigned i = 0; i < m_todo.size(); ++i) {
enode* n = m_todo[i];
expr* e = n->get_expr();
if (m_sutil.str.is_unit(e))
m_nodes.push_back(n->get_arg(0));
else if (m_sutil.str.is_concat(e))
for (expr* arg : *to_app(e))
add_todo(ctx.get_enode(arg));
}
for (enode* n : m_todo)
n->unmark1();
return m_nodes;
}
// Assuming `app` is equal to a constructor term, return the constructor enode
inline euf::enode* solver::oc_get_cstor(enode* app) const {
theory_var v = app->get_root()->get_th_var(get_id());
if (v == euf::null_theory_var)
return nullptr;
v = m_find.find(v);
var_data* d = m_var_data[v];
return d->m_constructor;
}
void solver::explain_is_child(enode* parent, enode* child) {
enode* parentc = oc_get_cstor(parent);
if (parent != parentc)
m_used_eqs.push_back(enode_pair(parent, parentc));
// collect equalities on all children that may have been used.
bool found = false;
auto add = [&](enode* seq_arg) {
if (seq_arg->get_root() == child->get_root()) {
if (seq_arg != child)
m_used_eqs.push_back(enode_pair(seq_arg, child));
found = true;
}
};
for (enode* arg : euf::enode_args(parentc)) {
add(arg);
sort* s = arg->get_sort();
if (m_autil.is_array(s) && dt.is_datatype(get_array_range(s)))
for (enode* aarg : get_array_args(arg))
add(aarg);
sort* se;
if (m_sutil.is_seq(arg->get_sort(), se) && dt.is_datatype(se)) {
enode* sibling = nullptr;
for (enode* seq_arg : get_seq_args(arg, sibling))
add(seq_arg);
if (sibling && sibling != arg)
m_used_eqs.push_back(enode_pair(arg, sibling));
}
}
VERIFY(found);
}
// explain the cycle root -> ... -> app -> root
void solver::occurs_check_explain(enode* app, enode* root) {
TRACE("dt", tout << "occurs_check_explain " << ctx.bpp(app) << " <-> " << ctx.bpp(root) << "\n";);
// first: explain that root=v, given that app=cstor(...,v,...)
explain_is_child(app, root);
// now explain app=cstor(..,v,..) where v=root, and recurse with parent of app
while (app->get_root() != root->get_root()) {
enode* parent_app = m_parent[app->get_root()];
explain_is_child(parent_app, app);
SASSERT(is_constructor(parent_app));
app = parent_app;
}
SASSERT(app->get_root() == root->get_root());
if (app != root)
m_used_eqs.push_back(enode_pair(app, root));
TRACE("dt",
tout << "occurs_check\n"; for (enode_pair const& p : m_used_eqs) tout << ctx.bpp(p.first) << " - " << ctx.bpp(p.second) << " ";);
}
// start exploring subgraph below `app`
bool solver::occurs_check_enter(enode* app) {
app = app->get_root();
theory_var v = app->get_th_var(get_id());
if (v == euf::null_theory_var)
return false;
v = m_find.find(v);
var_data* d = m_var_data[v];
if (!d->m_constructor)
return false;
enode* parent = d->m_constructor;
oc_mark_on_stack(parent);
auto process_arg = [&](enode* aarg) {
if (oc_cycle_free(aarg))
return false;
if (oc_on_stack(aarg)) {
occurs_check_explain(parent, aarg);
return true;
}
if (dt.is_datatype(aarg->get_sort())) {
m_parent.insert(aarg->get_root(), parent);
oc_push_stack(aarg);
}
return false;
};
for (enode* arg : euf::enode_args(parent)) {
if (oc_cycle_free(arg))
continue;
if (oc_on_stack(arg)) {
// arg was explored before app, and is still on the stack: cycle
occurs_check_explain(parent, arg);
return true;
}
// explore `arg` (with parent)
expr* earg = arg->get_expr();
sort* s = earg->get_sort(), *se;
enode* sibling;
if (dt.is_datatype(s)) {
m_parent.insert(arg->get_root(), parent);
oc_push_stack(arg);
}
else if (m_sutil.is_seq(s, se) && dt.is_datatype(se)) {
for (enode* sarg : get_seq_args(arg, sibling))
if (process_arg(sarg))
return true;
}
else if (m_autil.is_array(s) && dt.is_datatype(get_array_range(s))) {
for (enode* sarg : get_array_args(arg))
if (process_arg(sarg))
return true;
}
}
return false;
}
/**
\brief Check if n can be reached starting from n and following equalities and constructors.
For example, occur_check(a1) returns true in the following set of equalities:
a1 = cons(v1, a2)
a2 = cons(v2, a3)
a3 = cons(v3, a1)
*/
bool solver::occurs_check(enode* n) {
TRACE("dt_verbose", tout << "occurs check: " << ctx.bpp(n) << "\n";);
m_stats.m_occurs_check++;
bool res = false;
oc_push_stack(n);
// DFS traversal from `n`. Look at top element and explore it.
while (!res && !m_dfs.empty()) {
stack_op op = m_dfs.back().first;
enode* app = m_dfs.back().second;
m_dfs.pop_back();
if (oc_cycle_free(app))
continue;
TRACE("dt_verbose", tout << "occurs check loop: " << ctx.bpp(app) << (op == ENTER ? " enter" : " exit") << "\n";);
switch (op) {
case ENTER:
res = occurs_check_enter(app);
break;
case EXIT:
oc_mark_cycle_free(app);
break;
}
}
if (res) {
clear_mark();
ctx.set_conflict(euf::th_explain::conflict(*this, m_used_eqs, ctx.mk_smt_hint(name(), m_used_eqs)));
TRACE("dt", tout << "occurs check conflict: " << ctx.bpp(n) << "\n";);
}
return res;
}
sat::check_result solver::check() {
force_push();
int num_vars = get_num_vars();
sat::check_result r = sat::check_result::CR_DONE;
final_check_st _guard(*this);
int start = s().rand()();
for (int i = 0; i < num_vars; i++) {
theory_var v = (i + start) % num_vars;
if (v != static_cast(m_find.find(v)))
continue;
enode* node = var2enode(v);
if (!is_datatype(node))
continue;
if (dt.is_recursive(node->get_sort()) && !oc_cycle_free(node) && occurs_check(node))
return sat::check_result::CR_CONTINUE;
if (get_config().m_dt_lazy_splits == 0)
continue;
if (m_var_data[v]->m_constructor)
continue;
clear_mark();
mk_split(v, true);
r = sat::check_result::CR_CONTINUE;
}
return r;
}
void solver::pop_core(unsigned num_scopes) {
th_euf_solver::pop_core(num_scopes);
std::for_each(m_var_data.begin() + get_num_vars(), m_var_data.end(), delete_proc());
m_var_data.shrink(get_num_vars());
SASSERT(m_find.get_num_vars() == m_var_data.size());
SASSERT(m_find.get_num_vars() == get_num_vars());
}
void solver::get_antecedents(literal l, sat::ext_justification_idx idx, literal_vector& r, bool probing) {
auto& jst = euf::th_explain::from_index(idx);
ctx.get_th_antecedents(l, jst, r, probing);
}
void solver::add_value(euf::enode* n, model& mdl, expr_ref_vector& values) {
theory_var v = n->get_th_var(get_id());
if (v == euf::null_theory_var) {
values.set(n->get_root_id(), mdl.get_fresh_value(n->get_sort()));
return;
}
v = m_find.find(v);
SASSERT(v != euf::null_theory_var);
enode* con = m_var_data[v]->m_constructor;
func_decl* c_decl = con->get_decl();
m_args.reset();
for (enode* arg : euf::enode_args(con))
m_args.push_back(values.get(arg->get_root_id()));
values.set(n->get_root_id(), m.mk_app(c_decl, m_args));
}
bool solver::add_dep(euf::enode* n, top_sort& dep) {
if (!is_datatype(n->get_expr()))
return false;
theory_var v = n->get_th_var(get_id());
if (v == euf::null_theory_var)
return false;
euf::enode* con = m_var_data[m_find.find(v)]->m_constructor;
TRACE("dt", display(tout) << ctx.bpp(n) << " con: " << ctx.bpp(con) << "\n";);
if (con->num_args() == 0)
dep.insert(n, nullptr);
for (enode* arg : euf::enode_args(con))
dep.add(n, arg->get_root());
return true;
}
bool solver::include_func_interp(func_decl* f) const {
if (!dt.is_accessor(f))
return false;
func_decl* con_decl = dt.get_accessor_constructor(f);
for (enode* app : ctx.get_egraph().enodes_of(f)) {
enode* con = oc_get_cstor(app->get_arg(0));
if (con && is_constructor(con) && con->get_decl() != con_decl)
return true;
}
return false;
}
sat::literal solver::internalize(expr* e, bool sign, bool root) {
if (!visit_rec(m, e, sign, root))
return sat::null_literal;
auto lit = ctx.expr2literal(e);
if (sign)
lit.neg();
return lit;
}
void solver::internalize(expr* e) {
visit_rec(m, e, false, false);
}
bool solver::visit(expr* e) {
if (visited(e))
return true;
if (!is_app(e) || to_app(e)->get_family_id() != get_id()) {
ctx.internalize(e);
if (is_datatype(e))
mk_var(expr2enode(e));
return true;
}
m_stack.push_back(sat::eframe(e));
return false;
}
bool solver::visited(expr* e) {
euf::enode* n = expr2enode(e);
return n && n->is_attached_to(get_id());
}
bool solver::post_visit(expr* term, bool sign, bool root) {
euf::enode* n = expr2enode(term);
SASSERT(!n || !n->is_attached_to(get_id()));
if (!n)
n = mk_enode(term);
SASSERT(!n->is_attached_to(get_id()));
if (is_constructor(term) || is_update_field(term)) {
for (enode* arg : euf::enode_args(n)) {
sort* s = arg->get_sort();
if (dt.is_datatype(s))
mk_var(arg);
else if (m_autil.is_array(s) && dt.is_datatype(get_array_range(s))) {
app_ref def(m_autil.mk_default(arg->get_expr()), m);
mk_var(e_internalize(def));
}
}
mk_var(n);
}
else if (is_recognizer(term)) {
mk_var(n);
enode* arg = n->get_arg(0);
theory_var v = mk_var(arg);
add_recognizer(v, n);
}
else {
SASSERT(is_accessor(term));
SASSERT(n->num_args() == 1);
mk_var(n->get_arg(0));
if (is_datatype(n))
mk_var(n);
}
return true;
}
void solver::collect_statistics(::statistics& st) const {
st.update("datatype occurs check", m_stats.m_occurs_check);
st.update("datatype splits", m_stats.m_splits);
st.update("datatype constructor ax", m_stats.m_assert_cnstr);
st.update("datatype accessor ax", m_stats.m_assert_accessor);
st.update("datatype update ax", m_stats.m_assert_update_field);
}
std::ostream& solver::display(std::ostream& out) const {
unsigned num_vars = get_num_vars();
if (num_vars > 0)
out << "Theory datatype:\n";
for (unsigned v = 0; v < num_vars; v++)
display_var(out, v);
return out;
}
void solver::display_var(std::ostream& out, theory_var v) const {
var_data* d = m_var_data[v];
out << "v" << v << " #" << var2expr(v)->get_id() << " -> v" << m_find.find(v) << " ";
if (d->m_constructor)
out << ctx.bpp(d->m_constructor);
else
out << "(null)";
out << "\n";
}
}