Line data    Source code

       1             : // Author(s): Muck van Weerdenburg, Jan Friso Groote
       2             : // Copyright: see the accompanying file COPYING or copy at
       3             : // https://github.com/mCRL2org/mCRL2/blob/master/COPYING
       4             : //
       5             : // Distributed under the Boost Software License, Version 1.0.
       6             : // (See accompanying file LICENSE_1_0.txt or copy at
       7             : // http://www.boost.org/LICENSE_1_0.txt)
       8             : //
       9             : 
      10             : // This file contains the merge algorithm that merges two lts's.
      11             : // Merges an LTS L with this LTS (say K) and stores the resulting LTS
      12             : // (say M) in this LTS datastructure, effectively replacing K.
      13             : // Conceptually, we just take the union of the sets of states and the
      14             : // sets of transitions of K and L:
      15             : //   States_M      = States_K + States_L
      16             : //   Transitions_M = Transitions_K + Transitions_L
      17             : // where + denotes set union.
      18             : // However, this assumes that States_K and States_L are disjoint,
      19             : // which is generally not the case. More specifically we have:
      20             : //   States_K = { 0, ..., N_K - 1 }   and
      21             : //   States_L = { 0, ..., N_L - 1 }
      22             : // for some N_K, N_L > 0.
      23             : // Therefore, state i of L will be numbered |N_K| + i in the resulting
      24             : // LTS M and state i of K will be numbered i in M. This yields:
      25             : //   States_M = { 0, ..., N_K + N_L - 1 }.
      26             : 
      27             : 
      28             : #ifndef MCRL2_LTS_LIBLTS_MERGE_H
      29             : #define MCRL2_LTS_LIBLTS_MERGE_H
      30             : 
      31             : #include <map>
      32             : #include "mcrl2/utilities/exception.h"
      33             : #include "mcrl2/lts/lts.h"
      34             : 
      35             : namespace mcrl2
      36             : {
      37             : namespace lts
      38             : {
      39             : namespace detail
      40             : {
      41             : 
      42             : template <class LTS_TYPE>
      43         143 : void merge(LTS_TYPE& l1, const LTS_TYPE& l2)
      44             : {
      45         143 :   const std::size_t old_nstates=l1.num_states();
      46         143 :   l1.set_num_states(l1.num_states() + l2.num_states());
      47             : 
      48             :   // The resulting LTS will have state information only if BOTH LTSs
      49             :   // currently have state information.
      50         143 :   if (l1.has_state_info() && l2.has_state_info())
      51             :   {
      52          61 :     for (std::size_t i=0; i<l2.num_states(); ++i)
      53             :     {
      54          46 :       l1.add_state(l2.state_label(i));
      55             :     }
      56             :   }
      57             :   else
      58             :   {
      59             :     // remove state information from this LTS, if any
      60         128 :     l1.clear_state_labels();
      61             :   }
      62             : 
      63             :   // Before we can set the label data in a new transitions
      64             :   // array, we first have to collect the labels of both LTSs in a
      65             :   // map, of which the second element indicates the new index of each action label.
      66             : 
      67             :   typedef typename LTS_TYPE::action_label_t action_label_type;
      68             :   typedef typename LTS_TYPE::labels_size_type label_index;
      69             :   typedef typename std::pair< typename std::map < action_label_type,label_index >::const_iterator, bool > insert_type;
      70         143 :   std::map < action_label_type,label_index > labs;
      71             : 
      72             :   // Put the labels of the LTS l1 in a map.
      73         726 :   for (std::size_t i = 0; i < l1.num_action_labels(); ++i)
      74             :   {
      75         583 :     labs.insert(std::pair <typename LTS_TYPE::action_label_t,typename LTS_TYPE::labels_size_type>
      76             :                 (l1.action_label(i),i));
      77             :   }
      78             :   // Add the labels for the LTS l2, and put them there with a new index if it was
      79             :   // not added yet.
      80             :   // Furthermore, update the hidden_label_set. 
      81             :   // If label a1 is mapped to a2 in l2, then this must be the same
      82             :   // in l1. It may be that label a1 did not exist yet in which case it needs
      83             :   // to be added too.
      84             : 
      85         725 :   for (std::size_t i=0; i<l2.num_action_labels(); ++i)
      86             :   {
      87             :     typename LTS_TYPE::labels_size_type new_index;
      88         582 :     const insert_type it=labs.insert(std::pair < action_label_type,label_index >
      89         582 :                                (l2.action_label(i),l1.num_action_labels()));
      90         582 :     if (it.second) 
      91             :     {
      92             :       // New element has been inserted.
      93           8 :       new_index=l1.add_action(l2.action_label(i));
      94           8 :       if (l2.is_tau(l2.apply_hidden_label_map(i)))
      95             :       {
      96           0 :         l1.hidden_label_set().insert(new_index);
      97             :       }
      98             : 
      99             :     }
     100             :     else 
     101             :     {
     102         574 :       new_index=it.first->second; // Old index to which i is mapped.
     103             : 
     104             :       // If label i occurred in l1 and both were not mapped to the hidden label, raise an exception.
     105         574 :       if (l1.is_tau(l1.apply_hidden_label_map(new_index)) != l2.is_tau(l2.apply_hidden_label_map(i)))
     106             :       {
     107           0 :         throw mcrl2::runtime_error("The action " + pp(l2.action_label(i)) + " has incompatible hidden actions " +
     108             :                                        pp(l1.action_label(l1.apply_hidden_label_map(new_index))) + " and " + 
     109             :                                        pp(l2.action_label(l2.apply_hidden_label_map(i))) + ".");
     110             :       }
     111             :     }
     112         582 :     assert(new_index==it.first->second);
     113             :   }
     114             : 
     115             :   // Update the label numbers of all transitions of the LTS l1 to reflect
     116             :   // the new indices as given by labs.
     117         143 :   std::vector<transition>& trans1=l1.get_transitions();
     118         768 :   for (std::vector<transition>::iterator r=trans1.begin(); r!=trans1.end(); ++r)
     119             :   {
     120         625 :     r->set_label(labs[l1.action_label(r->label())]);
     121             :   }
     122             : 
     123             :   // Now add the transition labels of LTS l2
     124             :   // Now add the source and target states of the transitions of LTS l2.
     125             :   // The labels will be added below, depending on whether there is label
     126             :   // information in both LTSs.
     127         143 :   const std::vector<transition>& trans2=l2.get_transitions();
     128         754 :   for (std::vector<transition>::const_iterator r=trans2.begin(); r!=trans2.end(); ++r)
     129             :   {
     130         611 :     const transition transition_to_add=*r;
     131         611 :     l1.add_transition(transition(transition_to_add.from()+old_nstates,
     132        1222 :                                  labs[l2.action_label(transition_to_add.label())],
     133         611 :                                  transition_to_add.to()+old_nstates));
     134             :   }
     135             : 
     136         143 : }
     137             : } // namespace detail
     138             : } // namespace lts
     139             : } // namespace mcrl2
     140             : 
     141             : 
     142             : #endif