expr apply(expr const & a) {
check_system("max_sharing");
auto r = m_expr_cache.find(a);
if (r != m_expr_cache.end())
return *r;
expr res;
switch (a.kind()) {
case expr_kind::Var:
res = a;
break;
case expr_kind::Constant:
res = update_constant(a, map(const_levels(a), [&](level const & l) { return apply(l); }));
break;
case expr_kind::Sort:
res = update_sort(a, apply(sort_level(a)));
break;
case expr_kind::App:
res = update_app(a, apply(app_fn(a)), apply(app_arg(a)));
break;
case expr_kind::Lambda: case expr_kind::Pi:
res = update_binding(a, apply(binding_domain(a)), apply(binding_body(a)));
break;
case expr_kind::Meta: case expr_kind::Local:
res = update_mlocal(a, apply(mlocal_type(a)));
break;
case expr_kind::Macro: {
buffer<expr> new_args;
for (unsigned i = 0; i < macro_num_args(a); i++)
new_args.push_back(macro_arg(a, i));
res = update_macro(a, new_args.size(), new_args.data());
break;
}}
m_expr_cache.insert(res);
return res;
}
expr apply(expr const & a) {
auto r = m_cache.find(a);
if (r != m_cache.end()) {
lean_assert((*r).raw()->max_shared());
return *r;
}
if (a.raw()->max_shared()) {
m_cache.insert(a);
return a;
}
switch (a.kind()) {
case expr_kind::Var: case expr_kind::Constant: case expr_kind::Type: case expr_kind::Value:
cache(a);
return a;
case expr_kind::App: {
expr r = update_app(a, [=](expr const & c){ return apply(c); });
cache(r);
return r;
}
case expr_kind::Eq : {
expr r = update_eq(a, [=](expr const & l, expr const & r){ return std::make_pair(apply(l), apply(r)); });
cache(r);
return r;
}
case expr_kind::Lambda:
case expr_kind::Pi: {
expr r = update_abst(a, [=](expr const & t, expr const & b) { return std::make_pair(apply(t), apply(b)); });
cache(r);
return r;
}
case expr_kind::Let: {
expr r = update_let(a, [=](expr const & t, expr const & v, expr const & b) {
expr new_t = t ? apply(t) : expr();
return std::make_tuple(new_t, apply(v), apply(b));
});
cache(r);
return r;
}
case expr_kind::MetaVar: {
expr r = update_metavar(a, [=](meta_entry const & e) -> meta_entry {
if (e.is_inst())
return mk_inst(e.s(), apply(e.v()));
else
return e;
});
cache(r);
return r;
}}
lean_unreachable();
}
void cache(expr const & a) {
a.raw()->set_max_shared();
m_cache.insert(a);
}