infer.cxx

ecos实时嵌入式操作系统

//{{{  Banner                                   

//============================================================================
//
//      infer.cxx
//
//      Inference for common conflicts.
//
//============================================================================
//####COPYRIGHTBEGIN####
//                                                                          
// ----------------------------------------------------------------------------
// Copyright (C) 1999, 2000, 2001 Red Hat, Inc.
//
// This file is part of the eCos host tools.
//
// This program is free software; you can redistribute it and/or modify it 
// under the terms of the GNU General Public License as published by the Free 
// Software Foundation; either version 2 of the License, or (at your option) 
// any later version.
// 
// This program is distributed in the hope that it will be useful, but WITHOUT 
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for 
// more details.
// 
// You should have received a copy of the GNU General Public License along with
// this program; if not, write to the Free Software Foundation, Inc., 
// 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// ----------------------------------------------------------------------------
//                                                                          
//####COPYRIGHTEND####
//============================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):   bartv
// Contact(s):  bartv
// Date:        1999/11/1
// Version:     0.01
//
//####DESCRIPTIONEND####
//============================================================================

//}}}
//{{{  #include's                               

// ----------------------------------------------------------------------------
#include "cdlconfig.h"

// Get the infrastructure types, assertions, tracing and similar
// facilities.
#include <cyg/infra/cyg_ass.h>
#include <cyg/infra/cyg_trac.h>

// <cdlcore.hxx> defines everything implemented in this module.
// It implicitly supplies <string>, <vector> and <map> because
// the class definitions rely on these headers.
#include <cdlcore.hxx>

//}}}

//{{{  CdlInfer class                           

//{{{  Description                              

// ----------------------------------------------------------------------------
// The following functions provide the main entry points for inference.
//
// 1) bool CdlInfer::make_active(CdlTransaction, CdlValuable, level)
//    Do whatever it takes to make the valuable active in
//    a clean sub-transaction, if possible.
// 2) bool CdlInfer::make_inactive(CdlTransaction, CdlValuable, level)
//    Do whatever it takes to make the valuable inactive.
// 3) bool CdlInfer::set_valuable_value(CdlTransaction, CdlValuable, CdlSimpleValue&, level)
//    Try to set the valuable to the specified value, taking into
//    account the different flavors.
// 4) bool CdlInfer::set_valuable_bool(CdlTransaction, CdlValuable, bool, level)
//    Similar to (3) but deals with the boolean aspect of the valuable
//    rather than the data part.
// 5) bool CdlInfer::subexpr(CdlTransaction, CdlExpression, int index, CdlSimpleValue& goal, level)
//    Process a sub-expression and try to make it evaluate to the
//    goal.
// 6) bool CdlInfer::subexpr_bool(CdlTransaction, CdlExpression, int index, bool goal, level)
//    Ditto but only deal with boolean goals. If the expression starts to
//    involve arithmetic etc. then we need to move to CdlInfer::subexpr()
//
//    As might be expected, the sub-expression handlers contain a big
//    switch statement and calls into various auxiliary functions when
//    necessary.
//
// For convenience the various entry points check whether or not the
// desired condition is already satisfied.

//}}}
//{{{  Forward declarations                     

// ----------------------------------------------------------------------------

static bool infer_handle_interface_value(CdlTransaction, CdlInterface, CdlSimpleValue&, int);
static bool infer_handle_reference_bool(CdlTransaction, CdlValuable, bool, int);

//}}}
//{{{  CdlInfer::make_active()                  

// ----------------------------------------------------------------------------
// Making a node active. This requires the following conditions to be
// satisfied:
// 1) the parent must be made active
// 2) if the parent has flavor bool or booldata, it must be enabled
// 3) any active_if properties 

bool
CdlInfer::make_active(CdlTransaction transaction, CdlNode node, int level)
{
    CYG_REPORT_FUNCNAMETYPE("CdlInfer::make_active", "result %d");
    CYG_REPORT_FUNCARG3XV(transaction, node, level);
    CYG_PRECONDITION_CLASSC(transaction);
    CYG_PRECONDITION_CLASSC(node);

    bool result = false;
    if (transaction->is_active(node)) {
        result = true;
        CYG_REPORT_RETVAL(result);
        return result;
    }
    
    CdlContainer parent = node->get_parent();
    CYG_ASSERT_CLASSC(parent);
    if (!transaction->is_active(parent)) {
        if (!CdlInfer::make_active(transaction, parent, level)) {
            CYG_REPORT_RETVAL(result);
            return result;
        }
    }
    // The parent is now active. Does it have to be enabled as well?
    CdlValuable parent_valuable = dynamic_cast<CdlValuable>(static_cast<CdlNode>(parent));
    if (0 != parent_valuable) {
        CdlValueFlavor flavor = parent_valuable->get_flavor();
        if (((CdlValueFlavor_Bool == flavor) || (CdlValueFlavor_BoolData == flavor)) &&
            !parent_valuable->is_enabled(transaction)) {
            if (!CdlInfer::set_valuable_bool(transaction, parent_valuable, true, level)) {
                CYG_REPORT_RETVAL(result);
                return result;
            }
        }
    }
    // The parent is now active and enabled. Are there any active_if properties to worry about?
    CdlValuable valuable = dynamic_cast<CdlValuable>(node);
    if (0 != valuable) {
        std::vector<CdlProperty_GoalExpression> active_if_goals;
        std::vector<CdlProperty_GoalExpression>::iterator goal_i;
        valuable->get_active_if_conditions(active_if_goals);
        for (goal_i = active_if_goals.begin(); goal_i != active_if_goals.end(); goal_i++) {
            
            CdlEvalContext context(transaction, valuable, *goal_i);
            try {
                if (!(*goal_i)->eval(context)) {
                    CdlExpression expr = (*goal_i)->get_expression();
                    if (!CdlInfer::subexpr_bool(transaction, expr, expr->first_subexpression, true, level)) {
                        CYG_REPORT_RETVAL(result);
                        return result;
                    }
                }
            } catch(...) {
                CYG_REPORT_RETVAL(result);
                return result;
            }
        }
        
    }
    
    result = transaction->is_active(node);
    CYG_REPORT_RETVAL(result);
    return result;
}

//}}}
//{{{  CdlInfer::make_inactive()                

// ----------------------------------------------------------------------------
// Making a node inactive can be done in three ways:
// 1) if the parent is boolean, try disabling it
// 2) otherwise if the parent can be made inactive, that will do
//    fine.
// 3) if there are any active_if properties, they could be considered
//    as well. For now this possibility is ignored.

bool
CdlInfer::make_inactive(CdlTransaction transaction, CdlNode node, int level)
{
    CYG_REPORT_FUNCNAMETYPE("CdlInfer::make_inactive", "result %d");
    CYG_REPORT_FUNCARG3XV(transaction, node, level);
    CYG_PRECONDITION_CLASSC(transaction);
    CYG_PRECONDITION_CLASSC(node);

    bool result = false;
    if (!transaction->is_active(node)) {
        result = true;
        CYG_REPORT_RETVAL(result);
        return result;
    }

    CdlContainer parent = node->get_parent();
    if (0 == parent) {
        // No point in trying to disable the entire configuration.
        CYG_REPORT_RETVAL(result);
        return result;
    }
    
    CdlValuable  parent_valuable = dynamic_cast<CdlValuable>(parent);
    if (0 != parent_valuable) {
        CdlValueFlavor flavor = parent_valuable->get_flavor();
        if ((CdlValueFlavor_Bool == flavor) || (CdlValueFlavor_BoolData == flavor)) {
            // Since the current node is active the parent must currently be enabled.
            // A sub-transaction is needed because an alternative approach is
            // possible later on.
            CdlTransaction subtransaction = transaction->make(transaction->get_conflict());
            if (CdlInfer::set_valuable_bool(subtransaction, parent_valuable, false, level)) {
                subtransaction->commit();
                delete subtransaction;
                result = true;
                CYG_REPORT_RETVAL(result);
                return result;
            } else {
                subtransaction->cancel();
                delete subtransaction;
            }
        }
    }

    // It is not possible to disable the parent. How about making it inactive?
    if (CdlInfer::make_inactive(transaction, parent, level)) {
        result = true;
        CYG_REPORT_RETVAL(result);
        return result;
    }

    // For now do not try to mess about with active_if conditions.
    
    CYG_REPORT_RETVAL(result);
    return result;
}

//}}}
//{{{  CdlInfer::set_valuable_value()           

// ----------------------------------------------------------------------------
// Deal with the value part of a valuable. The valuable is known to exist
// and be active, so this code only deals with the actual value part.

bool
CdlInfer::set_valuable_value(CdlTransaction transaction, CdlValuable valuable, CdlSimpleValue& goal, int level)
{
    CYG_REPORT_FUNCNAMETYPE("CdlInfer::set_valuable_value", "result %d");
    CYG_REPORT_FUNCARG3XV(transaction, valuable, level);
    CYG_PRECONDITION_CLASSC(transaction);
    CYG_PRECONDITION_CLASSC(valuable);
    CYG_PRECONDITIONC(transaction->is_active(valuable));

    bool result = false;

    const CdlValue& current_value = transaction->get_whole_value(valuable);
    CdlValueFlavor  flavor        = current_value.get_flavor();
    bool bool_goal                = goal.get_bool_value();

    switch(flavor) {
      default                  :
      case CdlValueFlavor_None :
          break;

      case CdlValueFlavor_Bool :
          if (bool_goal == current_value.is_enabled()) {
              result = true;
          } else {
              if (valuable->is_modifiable() &&
                  (0 == dynamic_cast<CdlLoadable>(valuable)) &&
                  !transaction->changed_by_user(valuable)) {

                  valuable->set_enabled(transaction, bool_goal, CdlValueSource_Inferred);
                  valuable->set_source(transaction, CdlValueSource_Inferred);
                  result = transaction->resolve_recursion(level);
              }

          }
          break;

      case CdlValueFlavor_BoolData :
          if (!bool_goal && !current_value.is_enabled()) {
              result = true;
          } else if (bool_goal && current_value.is_enabled() && (goal == current_value.get_simple_value())) {
              result = true;
          } else {
              if (valuable->is_modifiable() &&
                  (0 == dynamic_cast<CdlLoadable>(valuable)) &&
                  !transaction->changed_by_user(valuable)) {
                  
                  if (!bool_goal) {
                      valuable->disable(transaction, CdlValueSource_Inferred);
                  } else {
                      valuable->enable_and_set_value(transaction, goal, CdlValueSource_Inferred);
                  }
                  valuable->set_source(transaction, CdlValueSource_Inferred);
                  result = transaction->resolve_recursion(level);
              } else if (0 != dynamic_cast<CdlInterface>(valuable)) {
                  // Interfaces are not directly modifiable, but their implementors are.
                  result = infer_handle_interface_value(transaction, dynamic_cast<CdlInterface>(valuable), goal, level);
              }
          }
          break;

      case CdlValueFlavor_Data:
        // Now check whether or not the valuable already has the desired value
        if (goal == current_value.get_simple_value()) {
            result = true;
        } else {
            if (valuable->is_modifiable() &&
                (0 == dynamic_cast<CdlLoadable>(valuable)) &&
                !transaction->changed_by_user(valuable)) {
    
                // Make the change, propagate, and perform further resolution.
                valuable->set_value(transaction, goal, CdlValueSource_Inferred);
                valuable->set_source(transaction, CdlValueSource_Inferred);
                result = transaction->resolve_recursion(level);
            } else if (0 != dynamic_cast<CdlInterface>(valuable)) {
                // Interfaces are not directly modifiable, but their implementors are.
                result = infer_handle_interface_value(transaction, dynamic_cast<CdlInterface>(valuable), goal, level);
            }
        }
        break;
    }