63 lines
2.5 KiB
C++
63 lines
2.5 KiB
C++
/*
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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/abstract.h"
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#include "library/constants.h"
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#include "library/locals.h"
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#include "library/tactic/tactic.h"
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#include "library/tactic/expr_to_tactic.h"
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namespace lean {
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tactic revert_tactic(name const & n) {
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auto fn = [=](environment const &, io_state const &, proof_state const & s) -> optional<proof_state> {
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goals const & gs = s.get_goals();
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if (empty(gs)) {
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throw_no_goal_if_enabled(s);
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return none_proof_state();
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}
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goal g = head(gs);
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goals tail_gs = tail(gs);
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if (auto p = g.find_hyp(n)) {
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expr const & h = p->first;
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unsigned i = p->second;
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buffer<expr> hyps;
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g.get_hyps(hyps);
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hyps.erase(hyps.size() - i - 1);
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if (optional<expr> other_h = depends_on(i, hyps.end() - i, h)) {
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throw_tactic_exception_if_enabled(s, sstream() << "invalid 'revert' tactic, hypothesis '" << local_pp_name(*other_h)
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<< "' depends on '" << local_pp_name(h) << "'");
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return none_proof_state(); // other hypotheses depend on h
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}
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name_generator ngen = s.get_ngen();
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expr new_type = Pi(h, g.get_type());
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expr new_meta = mk_app(mk_metavar(ngen.next(), Pi(hyps, new_type)), hyps);
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goal new_g(new_meta, new_type);
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substitution new_subst = s.get_subst();
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assign(new_subst, g, mk_app(new_meta, h));
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proof_state new_s(s, goals(new_g, tail_gs), new_subst, ngen);
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return some_proof_state(new_s);
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} else {
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throw_tactic_exception_if_enabled(s, sstream() << "invalid 'revert' tactic, unknown hypothesis '" << n << "'");
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return none_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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void initialize_revert_tactic() {
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auto fn = [](type_checker &, elaborate_fn const &, expr const & e, pos_info_provider const *) {
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buffer<name> ns;
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get_tactic_id_list_elements(app_arg(e), ns, "invalid 'reverts' tactic, list of identifiers expected");
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tactic r = revert_tactic(ns[0]);
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for (unsigned i = 1; i < ns.size(); i++)
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r = then(revert_tactic(ns[i]), r);
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return r;
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};
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register_tac(get_tactic_revert_name(), fn);
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register_tac(get_tactic_reverts_name(), fn);
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}
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void finalize_revert_tactic() {}
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}
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