lean2/src/library/blast/simple_strategy.cpp

/*
Copyright (c) 2015 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.

Author: Leonardo de Moura
*/
#include "library/blast/blast.h"
#include "library/blast/options.h"
#include "library/blast/choice_point.h"
#include "library/blast/simple_actions.h"
#include "library/blast/proof_expr.h"
#include "library/blast/intros_action.h"
#include "library/blast/subst_action.h"
#include "library/blast/backward_action.h"
#include "library/blast/no_confusion_action.h"
#include "library/blast/simplify_actions.h"
#include "library/blast/recursor_action.h"
#include "library/blast/strategy.h"

namespace lean {
namespace blast {
/** \brief Implement a simple proof strategy for blast.
    We use it mainly for testing new actions and the whole blast infra-structure. */
class simple_strategy : public strategy {
    optional<hypothesis_idx> activate_hypothesis() {
        return curr_state().activate_hypothesis();
    }

    /* \brief Preprocess state
       It keeps applying intros, activating and finally simplify target.
       Return an expression if the goal has been proved during preprocessing step. */
    virtual optional<expr> preprocess() {
        display_msg("* Preprocess");
        while (true) {
            if (intros_action())
                continue;
            if (auto hidx = activate_hypothesis()) {
                if (auto pr = assumption_contradiction_actions(*hidx)) {
                    return pr;
                }
                if (subst_action(*hidx))
                    continue;
                action_result r = no_confusion_action(*hidx);
                if (solved(r))
                    return r.to_opt_expr();
                continue;
            }
            break;
        }
        if (auto pr = assumption_action())
            return pr;
        return simplify_target_action().to_opt_expr();
    }

    virtual action_result next_action() {
        if (intros_action()) {
            display_action("intros");
            return action_result::new_branch();
        }

        if (auto hidx = activate_hypothesis()) {
            display_action("activate");
            if (auto pr = assumption_contradiction_actions(*hidx)) {
                display_action("assumption-contradiction");
                return action_result::solved(*pr);
            }
            if (subst_action(*hidx)) {
                display_action("subst");
                return action_result::new_branch();
            }
            action_result r = no_confusion_action(*hidx);
            if (!failed(r)) {
                display_action("no_confusion");
                return r;
            }
            return action_result::new_branch();
        }

        if (auto pr = trivial_action()) {
            display_action("trivial");
            return action_result::solved(*pr);
        }

        if (auto pr = assumption_action()) {
            // Remark: this action is only relevant
            // when the target has been modified.
            display_action("assumption");
            return action_result::solved(*pr);
        }

        action_result r = constructor_action();
        if (!failed(r)) {
            display_action("constructor");
            return r;
        }

        // TODO(Leo): add more actions...

        display_msg(">>> FAILED <<<");
        return action_result::failed();
    }
};

optional<expr> apply_simple_strategy() {
    return simple_strategy()();
}
}}