xref: /dports/math/z3/z3-z3-4.8.13/src/sat/smt/user_solver.cpp

/*++
Copyright (c) 2020 Microsoft Corporation

Module Name:

    user_solver.cpp

Abstract:

    User propagator plugin.

Author:

    Nikolaj Bjorner (nbjorner) 2020-09-23

--*/

#include "sat/smt/user_solver.h"
#include "sat/smt/euf_solver.h"

namespace user_solver {

    solver::solver(euf::solver& ctx) :
        th_euf_solver(ctx, symbol("user"), ctx.get_manager().mk_family_id("user"))
    {}

    solver::~solver() {
        dealloc(m_api_context);
    }

    unsigned solver::add_expr(expr* e) {
        force_push();
        ctx.internalize(e, false);
        euf::enode* n = expr2enode(e);
        if (is_attached_to_var(n))
            return n->get_th_var(get_id());
        euf::theory_var v = mk_var(n);
        ctx.attach_th_var(n, this, v);
        return v;
    }

    void solver::propagate_cb(
        unsigned num_fixed, unsigned const* fixed_ids,
        unsigned num_eqs, unsigned const* eq_lhs, unsigned const* eq_rhs,
        expr* conseq) {
        m_prop.push_back(prop_info(num_fixed, fixed_ids, num_eqs, eq_lhs, eq_rhs, expr_ref(conseq, m)));
        DEBUG_CODE(validate_propagation(););
    }

    sat::check_result solver::check() {
        if (!(bool)m_final_eh)
            return  sat::check_result::CR_DONE;
        unsigned sz = m_prop.size();
        m_final_eh(m_user_context, this);
        return sz == m_prop.size() ? sat::check_result::CR_DONE : sat::check_result::CR_CONTINUE;
    }

    void solver::new_fixed_eh(euf::theory_var v, expr* value, unsigned num_lits, sat::literal const* jlits) {
        if (!m_fixed_eh)
            return;
        force_push();
        m_id2justification.setx(v, sat::literal_vector(num_lits, jlits), sat::literal_vector());
        m_fixed_eh(m_user_context, this, v, value);
    }

    void solver::asserted(sat::literal lit) {
        if (!m_fixed_eh)
            return;
        force_push();
        auto* n = bool_var2enode(lit.var());
        euf::theory_var v = n->get_th_var(get_id());
        sat::literal_vector lits;
        lits.push_back(lit);
        m_id2justification.setx(v, lits, sat::literal_vector());
        m_fixed_eh(m_user_context, this, v, lit.sign() ? m.mk_false() : m.mk_true());
    }

    void solver::push_core() {
        th_euf_solver::push_core();
        m_prop_lim.push_back(m_prop.size());
        m_push_eh(m_user_context);
    }

    void solver::pop_core(unsigned num_scopes) {
        th_euf_solver::pop_core(num_scopes);
        unsigned old_sz = m_prop_lim.size() - num_scopes;
        m_prop.shrink(m_prop_lim[old_sz]);
        m_prop_lim.shrink(old_sz);
        m_pop_eh(m_user_context, num_scopes);
    }

    bool solver::unit_propagate() {
        if (m_qhead == m_prop.size())
            return false;
        force_push();
        ctx.push(value_trail<unsigned>(m_qhead));
        unsigned np = m_stats.m_num_propagations;
        for (; m_qhead < m_prop.size() && !s().inconsistent(); ++m_qhead) {
            auto const& prop = m_prop[m_qhead];
            sat::literal lit = ctx.internalize(prop.m_conseq, false, false, true);
            if (s().value(lit) != l_true) {
                s().assign(lit, mk_justification(m_qhead));
                ++m_stats.m_num_propagations;
            }
        }
        return np < m_stats.m_num_propagations;
    }

    void solver::collect_statistics(::statistics& st) const {
        st.update("user-propagations", m_stats.m_num_propagations);
        st.update("user-watched", get_num_vars());
    }

    sat::justification solver::mk_justification(unsigned prop_idx) {
        void* mem = get_region().allocate(justification::get_obj_size());
        sat::constraint_base::initialize(mem, this);
        auto* constraint = new (sat::constraint_base::ptr2mem(mem)) justification(prop_idx);
        return sat::justification::mk_ext_justification(s().scope_lvl(), constraint->to_index());
    }

    void solver::get_antecedents(sat::literal l, sat::ext_justification_idx idx, sat::literal_vector & r, bool probing) {
        auto& j = justification::from_index(idx);
        auto const& prop = m_prop[j.m_propagation_index];
        for (unsigned id : prop.m_ids)
            r.append(m_id2justification[id]);
        for (auto const& p : prop.m_eqs)
            ctx.add_antecedent(var2enode(p.first), var2enode(p.second));
    }

    /*
     * All assumptions and equalities have to be true in the current scope.
     * A caller could mistakingly supply some assumption that isn't set.
     */
    void solver::validate_propagation() {
        auto const& prop = m_prop.back();
        for (unsigned id : prop.m_ids)
            for (auto lit: m_id2justification[id])
                VERIFY(s().value(lit) == l_true);
        for (auto const& p : prop.m_eqs)
            VERIFY(var2enode(p.first)->get_root() == var2enode(p.second)->get_root());
    }

    std::ostream& solver::display(std::ostream& out) const {
        for (unsigned i = 0; i < get_num_vars(); ++i)
            out << i << ": " << mk_pp(var2expr(i), m) << "\n";
        return out;
    }

    std::ostream& solver::display_justification(std::ostream& out, sat::ext_justification_idx idx) const {
        auto& j = justification::from_index(idx);
        auto const& prop = m_prop[j.m_propagation_index];
        for (unsigned id : prop.m_ids)
            out << id << ": " << m_id2justification[id];
        for (auto const& p : prop.m_eqs)
            out << "v" << p.first << " == v" << p.second << " ";
        return out;
    }

    std::ostream& solver::display_constraint(std::ostream& out, sat::ext_constraint_idx idx) const {
        return display_justification(out, idx);
    }

    euf::th_solver* solver::clone(euf::solver& dst_ctx) {
        auto* result = alloc(solver, dst_ctx);
        for (unsigned i = 0; i < get_num_vars(); ++i)
            result->add_expr(ctx.copy(dst_ctx, var2enode(i))->get_expr());
        return result;
    }

}