infer.cxx

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    if (constant.get_value() == goal.get_value()) {
        result = true;
    }

    CYG_REPORT_RETVAL(result);
    return result;
}

//}}}
//{{{  infer_handle_integer_constant()          

// ----------------------------------------------------------------------------
// Integers are also fairly straightforward.
static bool
infer_handle_integer_constant_bool(CdlSimpleValue& constant, bool goal)
{
    CYG_REPORT_FUNCNAMETYPE("infer_handle_integer_constant_bool", "result %d");
    CYG_PRECONDITIONC(constant.has_integer_value());
    bool result = false;

    if (goal) {
        if (0 != constant.get_integer_value()) {
            result = true;
        }
    } else {
        if (0 == constant.get_integer_value()) {
            result = true;
        }
    }
    
    CYG_REPORT_RETVAL(result);
    return result;
}

static bool
infer_handle_integer_constant_value(CdlSimpleValue& constant, CdlSimpleValue& goal)
{
    CYG_REPORT_FUNCNAMETYPE("infer_handle_integer_constant_value", "result %d");
    CYG_PRECONDITIONC(constant.has_integer_value());
    bool result = false;

    if (goal.has_integer_value() && (constant.get_integer_value() == goal.get_integer_value())) {
        result = true;
    }

    CYG_REPORT_RETVAL(result);
    return result;
}

//}}}
//{{{  infer_handle_double_constant()           

// ----------------------------------------------------------------------------
// Doubles are also straightforward, except than an exact comparision may
// be too strict. There is not a lot that can be done about this right now.
// Future enhancements to CDL may support tolerances.
static bool
infer_handle_double_constant_bool(CdlSimpleValue& constant, bool goal)
{
    CYG_REPORT_FUNCNAMETYPE("infer_handle_double_constant_bool", "result %d");
    CYG_PRECONDITIONC(constant.has_double_value());
    bool result = false;

    if (goal) {
        if (0.0 != constant.get_double_value()) {
            result = true;
        }
    } else {
        if (0.0 == constant.get_double_value()) {
            result = true;
        }
    }

    CYG_REPORT_RETVAL(result);
    return result;
}

static bool
infer_handle_double_constant_value(CdlSimpleValue& constant, CdlSimpleValue& goal)
{
    CYG_REPORT_FUNCNAMETYPE("infer_handle_double_constant_value", "result %d");
    CYG_PRECONDITIONC(constant.has_double_value());
    bool result = false;

    if (goal.has_double_value() && (constant.get_double_value() == goal.get_double_value())) {
        result = true;
    }

    CYG_REPORT_RETVAL(result);
    return result;
}

//}}}
//{{{  infer_handle_logical_NOT()               

// ----------------------------------------------------------------------------
// Logical not simply involves inverting the goal and then trying to infer
// the rest of the sub-expression. There is little point in touching
// the other arguments.
static bool
infer_handle_logical_NOT_bool(CdlTransaction transaction, CdlExpression expr, unsigned int index, bool goal, int level)
{
    CYG_REPORT_FUNCNAMETYPE("infer_handle_logical_NOT_bool", "result %d");

    bool result = infer_subexpr_bool(transaction, expr, index, !goal, level);
    CYG_REPORT_RETVAL(result);
    return result;
}

static bool
infer_handle_logical_NOT_value(CdlTransaction transaction, CdlExpression expr, unsigned int index,
                               CdlSimpleValue& goal, int level)
{
    CYG_REPORT_FUNCNAMETYPE("infer_handle_logical_NOT_value", "result %d");

    bool new_goal = false;
    if (("0" == goal.get_value()) || ("" == goal.get_value())) {
        new_goal = true;
    }

    bool result = infer_subexpr_bool(transaction, expr, index, new_goal, level);
    CYG_REPORT_RETVAL(result);
    return result;
}

//}}}
//{{{  infer_handle_AND()                       

// ----------------------------------------------------------------------------
// Depending on the goal, we want either both sides of the AND to evaluate to
// true, or we want one of the sides to evaluate to false.

static bool
infer_handle_AND_bool(CdlTransaction transaction, CdlExpression expr, unsigned int lhs, unsigned int rhs,
                      bool goal, int level)
{
    CYG_REPORT_FUNCNAMETYPE("infer_handle_AND_bool", "result %d");
    CYG_REPORT_FUNCARG4XV(transaction, expr, lhs, rhs);
    CYG_PRECONDITION_CLASSC(transaction);
    CYG_PRECONDITION_CLASSC(expr);
    CYG_PRECONDITIONC(lhs != rhs);

    bool result = false;
    
    if (goal) {
        // Both sides must be true in the same transaction, in case
        // the solutions overlap in conflicting ways.
        // NOTE: this leaves the transaction argument in an indeterminate
        // state. Care has to be taken in the calling code.
        if (infer_subexpr_bool(transaction, expr, lhs, true, level) &&
            infer_subexpr_bool(transaction, expr, rhs, true, level)) {
            result = true;
        }
    } else {
        // We need to try out both sides of the OR and see which one is preferable.
        // An optimization would be to only try the LHS, but trying both allows
        // for a more informed choice.
        CdlTransaction lhs_transaction = transaction->make(transaction->get_conflict());
        CdlTransaction rhs_transaction = transaction->make(transaction->get_conflict());
        bool lhs_result = infer_subexpr_bool(lhs_transaction, expr, lhs, false, level);
        bool rhs_result = infer_subexpr_bool(rhs_transaction, expr, rhs, false, level);

        if (lhs_result && !rhs_result) {
            // Only the lhs succeeded.
            rhs_transaction->cancel();
            lhs_transaction->commit();
            result = true;
        } else if (!lhs_result && rhs_result) {
            // Only the rhs succeeded.
            lhs_transaction->cancel();
            rhs_transaction->commit();
            result = true;
        } else if (lhs_result && rhs_result) {
            // Both sides succeeded. Next check for user_confirmation.
            bool lhs_confirm_needed = lhs_transaction->user_confirmation_required();
            bool rhs_confirm_needed = rhs_transaction->user_confirmation_required();
            if (lhs_confirm_needed && !rhs_confirm_needed) {
                lhs_transaction->cancel();
                rhs_transaction->commit();
                result = true;
            } else if (!lhs_confirm_needed && rhs_confirm_needed) {
                rhs_transaction->cancel();
                lhs_transaction->commit();
                result = true;
            } else {
                // Neither or both of the two sides need user confirmation, so they
                // are equal in that respect
                if (lhs_transaction->is_preferable_to(rhs_transaction)) {
                    rhs_transaction->cancel();
                    lhs_transaction->commit();
                    result = true;
                } else {
                    lhs_transaction->cancel();
                    rhs_transaction->commit();
                    result = true;
                }
            }
        } else {
            // Neither side succeeded.
            lhs_transaction->cancel();
            rhs_transaction->cancel();
        }

        // Zero or one of these transactions will have been committed,
        // neither is still necessary.
        delete lhs_transaction;
        delete rhs_transaction;
    }

    CYG_REPORT_RETVAL(result);
    return result;
}

static bool
infer_handle_AND_value(CdlTransaction transaction, CdlExpression expr, unsigned int lhs, unsigned int rhs,
                       CdlSimpleValue& goal, int level)
{
    CYG_REPORT_FUNCNAMETYPE("infer_handle_AND_value", "result %d");

    bool new_goal = true;
    if (("0" == goal.get_value()) || ("" == goal.get_value())) {
        new_goal = false;
    }
    bool result = infer_handle_AND_bool(transaction, expr, lhs, rhs, new_goal, level);
    CYG_REPORT_RETVAL(result);
    return result;
}

//}}}
//{{{  infer_handle_OR()                        

// ----------------------------------------------------------------------------
// The support for OR logic is much the same as for AND

static bool
infer_handle_OR_bool(CdlTransaction transaction, CdlExpression expr, unsigned int lhs, unsigned int rhs,
                     bool goal, int level)
{
    CYG_REPORT_FUNCNAMETYPE("infer_handle_OR_bool", "result %d");
    CYG_REPORT_FUNCARG4XV(transaction, expr, lhs, rhs);
    CYG_PRECONDITION_CLASSC(transaction);
    CYG_PRECONDITION_CLASSC(expr);
    CYG_PRECONDITIONC(lhs != rhs);


    bool result = false;
    
    if (goal) {
        // We need to try out both sides of the OR and see which one is preferable.
        // An optimization would be to only try the LHS, but trying both allows
        // for a more informed choice.
        CdlTransaction lhs_transaction = transaction->make(transaction->get_conflict());
        CdlTransaction rhs_transaction = transaction->make(transaction->get_conflict());
        bool lhs_result = infer_subexpr_bool(lhs_transaction, expr, lhs, true, level);
        bool rhs_result = infer_subexpr_bool(rhs_transaction, expr, rhs, true, level);

        if (lhs_result && !rhs_result) {
            // Only the lhs succeeded.
            rhs_transaction->cancel();
            lhs_transaction->commit();
            result = true;
        } else if (!lhs_result && rhs_result) {
            // Only the rhs succeeded.
            lhs_transaction->cancel();
            rhs_transaction->commit();
            result = true;
        } else if (lhs_result && rhs_result) {
            // Both sides succeeded. Next check for user_confirmation.
            bool lhs_confirm_needed = lhs_transaction->user_confirmation_required();
            bool rhs_confirm_needed = rhs_transaction->user_confirmation_required();
            if (lhs_confirm_needed && !rhs_confirm_needed) {
                lhs_transaction->cancel();
                rhs_transaction->commit();
                result = true;
            } else if (!lhs_confirm_needed && rhs_confirm_needed) {
                rhs_transaction->cancel();
                lhs_transaction->commit();
                result = true;
            } else {
                // Neither or both of the two sides need user confirmation, so they
                // are equal in that respect
                if (lhs_transaction->is_preferable_to(rhs_transaction)) {
                    rhs_transaction->cancel();
                    lhs_transaction->commit();
                    result = true;
                } else {
                    lhs_transaction->cancel();
                    rhs_transaction->commit();
                    result = true;
                }
            }
        } else {
            // Neither side succeeded
            lhs_transaction->cancel();
            rhs_transaction->cancel();
        }
        
        // Zero or one of these transactions will have been committed,
        // neither is still necessary.
        delete lhs_transaction;
        delete rhs_transaction;
    } else {
        
        // !(A || B) -> !A && !B
        if (infer_subexpr_bool(transaction, expr, lhs, false, level) &&
            infer_subexpr_bool(transaction, expr, rhs, false, level)) {
            result = true;
        }
    }
    
    CYG_REPORT_RETVAL(result);
    return result;
}

static bool
infer_handle_OR_value(CdlTransaction transaction, CdlExpression expr, unsigned int lhs, unsigned int rhs,
                CdlSimpleValue& goal, int level)
{
    CYG_REPORT_FUNCNAMETYPE("infer_handle_OR_value", "result %d");

    bool new_goal = true;
    if (("0" == goal.get_value()) || ("" == goal.get_value())) {
        new_goal = false;
    }
    bool result = infer_handle_OR_bool(transaction, expr, lhs, rhs, new_goal, level);
    CYG_REPORT_RETVAL(result);
    return result;
}

//}}}
//{{{  infer_handle_Equal()