optional<constraints> try_instance(expr const & inst, expr const & inst_type) {
type_checker & tc = m_C->tc();
name_generator & ngen = m_C->m_ngen;
tag g = inst.get_tag();
try {
flet<local_context> scope(m_ctx, m_ctx);
buffer<expr> locals;
expr meta_type = m_meta_type;
while (true) {
meta_type = tc.whnf(meta_type).first;
if (!is_pi(meta_type))
break;
expr local = mk_local(ngen.next(), binding_name(meta_type),
binding_domain(meta_type), binding_info(meta_type));
m_ctx.add_local(local);
locals.push_back(local);
meta_type = instantiate(binding_body(meta_type), local);
}
expr type = inst_type;
expr r = inst;
buffer<constraint> cs;
while (true) {
type = tc.whnf(type).first;
if (!is_pi(type))
break;
expr arg;
if (binding_info(type).is_inst_implicit()) {
pair<expr, constraint> ac = mk_class_instance_elaborator(m_C, m_ctx, some_expr(binding_domain(type)),
g, m_depth+1);
arg = ac.first;
cs.push_back(ac.second);
} else {
arg = m_ctx.mk_meta(m_C->m_ngen, some_expr(binding_domain(type)), g);
}
r = mk_app(r, arg, g);
type = instantiate(binding_body(type), arg);
}
r = Fun(locals, r);
trace(meta_type, r);
bool relax = m_C->m_relax;
constraint c = mk_eq_cnstr(m_meta, r, m_jst, relax);
return optional<constraints>(mk_constraints(c, cs));
} catch (exception &) {
return optional<constraints>();
}
}
static proof_state_seq apply_tactic_core(environment const & env, io_state const & ios, proof_state const & s,
expr const & _e, buffer<constraint> & cs,
add_meta_kind add_meta, subgoals_action_kind subgoals_action,
optional<unifier_kind> const & uk = optional<unifier_kind>()) {
goals const & gs = s.get_goals();
if (empty(gs)) {
throw_no_goal_if_enabled(s);
return proof_state_seq();
}
bool class_inst = get_apply_class_instance(ios.get_options());
name_generator ngen = s.get_ngen();
std::shared_ptr<type_checker> tc(mk_type_checker(env, ngen.mk_child()));
goal g = head(gs);
goals tail_gs = tail(gs);
expr t = g.get_type();
expr e = _e;
auto e_t_cs = tc->infer(e);
e_t_cs.second.linearize(cs);
expr e_t = e_t_cs.first;
buffer<expr> metas;
local_context ctx;
bool initialized_ctx = false;
unifier_config cfg(ios.get_options());
if (uk)
cfg.m_kind = *uk;
if (add_meta != DoNotAdd) {
unsigned num_e_t = get_expect_num_args(*tc, e_t);
if (add_meta == AddDiff) {
unsigned num_t = get_expect_num_args(*tc, t);
if (num_t <= num_e_t)
num_e_t -= num_t;
else
num_e_t = 0;
} else {
lean_assert(add_meta == AddAll);
}
for (unsigned i = 0; i < num_e_t; i++) {
auto e_t_cs = tc->whnf(e_t);
e_t_cs.second.linearize(cs);
e_t = e_t_cs.first;
expr meta;
if (class_inst && binding_info(e_t).is_inst_implicit()) {
if (!initialized_ctx) {
ctx = g.to_local_context();
initialized_ctx = true;
}
bool use_local_insts = true;
bool is_strict = false;
auto mc = mk_class_instance_elaborator(
env, ios, ctx, ngen.next(), optional<name>(),
use_local_insts, is_strict,
some_expr(head_beta_reduce(binding_domain(e_t))), e.get_tag(), cfg, nullptr);
meta = mc.first;
cs.push_back(mc.second);
} else {
meta = g.mk_meta(ngen.next(), head_beta_reduce(binding_domain(e_t)));
}
e = mk_app(e, meta);
e_t = instantiate(binding_body(e_t), meta);
metas.push_back(meta);
}
}
metavar_closure cls(t);
cls.mk_constraints(s.get_subst(), justification());
pair<bool, constraint_seq> dcs = tc->is_def_eq(t, e_t);
if (!dcs.first) {
throw_tactic_exception_if_enabled(s, [=](formatter const & fmt) {
format r = format("invalid 'apply' tactic, failed to unify");
r += pp_indent_expr(fmt, t);
r += compose(line(), format("with"));
r += pp_indent_expr(fmt, e_t);
return r;
});
return proof_state_seq();
}
dcs.second.linearize(cs);
unify_result_seq rseq = unify(env, cs.size(), cs.data(), ngen.mk_child(), s.get_subst(), cfg);
list<expr> meta_lst = to_list(metas.begin(), metas.end());
return map2<proof_state>(rseq, [=](pair<substitution, constraints> const & p) -> proof_state {
substitution const & subst = p.first;
constraints const & postponed = p.second;
name_generator new_ngen(ngen);
substitution new_subst = subst;
expr new_e = new_subst.instantiate_all(e);
assign(new_subst, g, new_e);
goals new_gs = tail_gs;
if (subgoals_action != IgnoreSubgoals) {
buffer<expr> metas;
for (auto m : meta_lst) {
if (!new_subst.is_assigned(get_app_fn(m)))
metas.push_back(m);
}
if (subgoals_action == AddRevSubgoals) {
for (unsigned i = 0; i < metas.size(); i++)
new_gs = cons(goal(metas[i], new_subst.instantiate_all(tc->infer(metas[i]).first)), new_gs);
} else {
lean_assert(subgoals_action == AddSubgoals || subgoals_action == AddAllSubgoals);
if (subgoals_action == AddSubgoals)
remove_redundant_metas(metas);
unsigned i = metas.size();
while (i > 0) {
--i;
new_gs = cons(goal(metas[i], new_subst.instantiate_all(tc->infer(metas[i]).first)), new_gs);
}
}
}
return proof_state(s, new_gs, new_subst, new_ngen, postponed);
});
}
