z3/lib/qe_bv_plugin.cpp

/*++
Copyright (c) 2010 Microsoft Corporation

Module Name:

    bv_plugin.cpp

Abstract:

    Eliminate Bit-vector variable from formula

Author:

    Nikolaj Bjorner (nbjorner) 2010-02-19

Revision History:

Notes:


--*/

#include "qe.h"
#include "expr_replacer.h"
#include "bv_decl_plugin.h"
#include "model_evaluator.h"

namespace qe {

    class bv_plugin : public qe_solver_plugin {
        scoped_ptr<expr_replacer> m_replace;
        bv_util      m_bv;
    public:
        bv_plugin(i_solver_context& ctx, ast_manager& m): 
            qe_solver_plugin(m, m.get_family_id("bv"), ctx),
            m_replace(mk_default_expr_replacer(m)),
            m_bv(m)
        {}

        virtual void assign(contains_app& x, expr* fml, rational const& vl) {
        }

        virtual bool get_num_branches(contains_app& x, expr* fml, rational& nb) {
            unsigned sz = m_bv.get_bv_size(x.x());
            nb = power(rational(2), sz);
            return true;
        }

        virtual void subst(contains_app& x, rational const& vl, expr_ref& fml, expr_ref* def) {
            app_ref c(m_bv.mk_numeral(vl, m_bv.get_bv_size(x.x())), m);
            m_replace->apply_substitution(x.x(), c, 0, fml);
            if (def) {
                *def = m_bv.mk_numeral(vl, m_bv.get_bv_size(x.x()));
            }
        }

        virtual bool project(contains_app& x, model_ref& model, expr_ref& fml) {
            model_evaluator model_eval(*model);
            expr_ref val_x(m);
            rational val(0);
            unsigned bv_size;
            model_eval(x.x(), val_x);
            m_bv.is_numeral(val_x, val, bv_size);
            subst(x, val, fml, 0);
            return true;
        }

        virtual unsigned get_weight(contains_app& contains_x, expr* fml) {
            return 2;
        }

        bool solve(conj_enum& conjs, expr* fml) { return false; }                   

        virtual bool is_uninterpreted(app* f) {
            switch(f->get_decl_kind()) {
            case OP_BSDIV0: 
            case OP_BUDIV0:
            case OP_BSREM0:
            case OP_BUREM0:
            case OP_BSMOD0:
            case OP_BSDIV_I:
            case OP_BUDIV_I:
            case OP_BSREM_I:
            case OP_BUREM_I:
            case OP_BSMOD_I:
                return true;
            default:
                return false;
            }
            return false;
        }
    };
    
    qe_solver_plugin* mk_bv_plugin(i_solver_context& ctx) {
        return alloc(bv_plugin, ctx, ctx.get_manager());
    }
}