65 lines
2.6 KiB
C++
65 lines
2.6 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 "library/constants.h"
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#include "kernel/abstract.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 clear_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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return none_proof_state();
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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 (depends_on(g.get_type(), h) || depends_on(i, hyps.end() - i, h))
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return none_proof_state(); // other hypotheses or result type depend on h
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name_generator ngen = s.get_ngen();
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expr new_type = 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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expr val = g.abstract(new_meta);
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substitution new_subst = s.get_subst();
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new_subst.assign(g.get_name(), val);
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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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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_clear_tactic() {
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register_tac(get_tactic_clear_name(),
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[](type_checker &, elaborate_fn const &, expr const & e, pos_info_provider const *) {
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name n = tactic_expr_to_id(app_arg(e), "invalid 'clear' tactic, argument must be an identifier");
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return clear_tactic(n);
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});
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register_tac(get_tactic_clear_lst_name(),
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[](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 'clears' tactic, list of identifiers expected");
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tactic r = clear_tactic(ns.back());
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ns.pop_back();
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while (!ns.empty()) {
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r = then(clear_tactic(ns.back()), r);
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ns.pop_back();
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}
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return r;
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});
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}
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void finalize_clear_tactic() {}
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}
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