// If restricted is true, we don't use (e <-> true) rewrite
list<expr_pair> apply(expr const & e, expr const & H, bool restrited) {
expr c, Hdec, A, arg1, arg2;
if (is_relation(e)) {
return mk_singleton(e, H);
} else if (is_standard(m_env) && is_not(m_env, e, arg1)) {
expr new_e = mk_iff(arg1, mk_false());
expr new_H = mk_app(mk_constant(get_iff_false_intro_name()), arg1, H);
return mk_singleton(new_e, new_H);
} else if (is_standard(m_env) && is_and(e, arg1, arg2)) {
// TODO(Leo): we can extend this trick to any type that has only one constructor
expr H1 = mk_app(mk_constant(get_and_elim_left_name()), arg1, arg2, H);
expr H2 = mk_app(mk_constant(get_and_elim_right_name()), arg1, arg2, H);
auto r1 = apply(arg1, H1, restrited);
auto r2 = apply(arg2, H2, restrited);
return append(r1, r2);
} else if (is_pi(e)) {
// TODO(dhs): keep name?
expr local = m_tctx.mk_tmp_local(binding_domain(e), binding_info(e));
expr new_e = instantiate(binding_body(e), local);
expr new_H = mk_app(H, local);
auto r = apply(new_e, new_H, restrited);
unsigned len = length(r);
if (len == 0) {
return r;
} else if (len == 1 && head(r).first == new_e && head(r).second == new_H) {
return mk_singleton(e, H);
} else {
return lift(local, r);
}
} else if (is_standard(m_env) && is_ite(e, c, Hdec, A, arg1, arg2) && is_prop(e)) {
// TODO(Leo): support HoTT mode if users request
expr not_c = mk_app(mk_constant(get_not_name()), c);
expr Hc = m_tctx.mk_tmp_local(c);
expr Hnc = m_tctx.mk_tmp_local(not_c);
expr H1 = mk_app({mk_constant(get_implies_of_if_pos_name()),
c, arg1, arg2, Hdec, e, Hc});
expr H2 = mk_app({mk_constant(get_implies_of_if_neg_name()),
c, arg1, arg2, Hdec, e, Hnc});
auto r1 = lift(Hc, apply(arg1, H1, restrited));
auto r2 = lift(Hnc, apply(arg2, H2, restrited));
return append(r1, r2);
} else if (!restrited) {
expr new_e = m_tctx.whnf(e);
if (new_e != e) {
if (auto r = apply(new_e, H, true))
return r;
}
if (is_standard(m_env) && is_prop(e)) {
expr new_e = mk_iff(e, mk_true());
expr new_H = mk_app(mk_constant(get_iff_true_intro_name()), e, H);
return mk_singleton(new_e, new_H);
} else {
return list<expr_pair>();
}
} else {
return list<expr_pair>();
}
}
bool basic_simplifier_plugin::reduce(func_decl * f, unsigned num_args, expr * const * args, expr_ref & result) {
set_reduce_invoked();
SASSERT(f->get_family_id() == m_manager.get_basic_family_id());
basic_op_kind k = static_cast<basic_op_kind>(f->get_decl_kind());
switch (k) {
case OP_FALSE:
case OP_TRUE:
return false;
case OP_EQ:
SASSERT(num_args == 2);
mk_eq(args[0], args[1], result);
return true;
case OP_DISTINCT:
mk_distinct(num_args, args, result);
return true;
case OP_ITE:
SASSERT(num_args == 3);
mk_ite(args[0], args[1], args[2], result);
return true;
case OP_AND:
mk_and(num_args, args, result);
return true;
case OP_OR:
mk_or(num_args, args, result);
return true;
case OP_IMPLIES:
mk_implies(args[0], args[1], result);
return true;
case OP_IFF:
mk_iff(args[0], args[1], result);
return true;
case OP_XOR:
mk_xor(args[0], args[1], result);
return true;
case OP_NOT:
SASSERT(num_args == 1);
mk_not(args[0], result);
return true;
default:
UNREACHABLE();
return false;
}
}
