77 lines
2.6 KiB
C++
77 lines
2.6 KiB
C++
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/*
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Copyright (c) 2014 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Leonardo de Moura
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*/
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#include "kernel/instantiate.h"
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#include "library/reducible.h"
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#include "library/tactic/tactic.h"
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namespace lean {
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/** \brief Return a "user" name that is not used by any local constant in the given goal */
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static name get_unused_name(goal const & g, name const & prefix, unsigned & idx) {
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buffer<expr> locals;
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get_app_rev_args(g.get_meta(), locals);
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while (true) {
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bool used = false;
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name curr = prefix.append_after(idx);
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idx++;
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for (expr const & local : locals) {
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if (is_local(local) && local_pp_name(local) == curr) {
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used = true;
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break;
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}
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}
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if (!used)
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return curr;
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}
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}
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tactic intros_tactic(list<name> _ns, bool relax_main_opaque) {
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auto fn = [=](environment const & env, io_state const &, proof_state const & s) {
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list<name> ns = _ns;
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goals const & gs = s.get_goals();
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if (empty(gs))
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return optional<proof_state>();
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goal const & g = head(gs);
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name_generator ngen = s.get_ngen();
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auto tc = mk_type_checker(env, ngen.mk_child(), relax_main_opaque);
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expr t = g.get_type();
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expr m = g.get_meta();
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bool gen_names = empty(ns);
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unsigned nidx = 1;
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try {
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while (true) {
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if (!gen_names && is_nil(ns))
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break;
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if (!is_pi(t)) {
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if (!is_nil(ns)) {
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t = tc->ensure_pi(t).first;
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} else {
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expr new_t = tc->whnf(t).first;
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if (!is_pi(new_t))
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break;
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}
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}
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name new_name;
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if (!is_nil(ns)) {
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new_name = head(ns);
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ns = tail(ns);
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} else {
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new_name = get_unused_name(g, name("H"), nidx);
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}
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expr new_local = mk_local(ngen.next(), new_name, binding_domain(t), binding_info(t));
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t = instantiate(binding_body(t), new_local);
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m = mk_app(m, new_local);
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}
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goal new_g(m, t);
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return some(proof_state(s, goals(new_g, tail(gs)), ngen));
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} catch (exception &) {
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return optional<proof_state>();
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}
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};
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return tactic01(fn);
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}
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}
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