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Creating an automaton in C++

This example demonstrates how to create an automaton in C++, and then print it. The interface

#include <iostream>
#include "twaalgos/hoa.hh"
#include "twa/twagraph.hh"

int main(void)
{
  // The dict is used to maintain the correspondence between the
  // atomic propositions and the BDD variables to label the edges of
  // the automaton.
  spot::bdd_dict_ptr dict = spot::make_bdd_dict();
  // This creates an empty automaton that we have yet to fill.
  spot::twa_graph_ptr aut = make_twa_graph(dict);

  // The current way to associate a BDD to an atomic proposition is
  // not really nice, and should be improved in the future.  Currently
  // the string first have to be converted into (LTL) formulas...
  spot::ltl::environment& e = spot::ltl::default_environment::instance();
  const spot::ltl::formula* f1 = e.require("p1");
  const spot::ltl::formula* f2 = e.require("p2");
  // ...and then those formula can be registered to the BDD dict.  The
  // BDD dict wants to keep track of which automaton uses which BDD
  // variable, so we supply that pointer to aut.  The
  // register_proposition() function returns a BDD variable number
  // that can be converted into a BDD using bdd_ithvar().
  bdd p1 = bdd_ithvar(dict->register_proposition(f1, aut));
  bdd p2 = bdd_ithvar(dict->register_proposition(f2, aut));

  // Set the acceptance condition of the automaton to Inf(0)&Inf(1)
  aut->set_generalized_buchi(2);

  // States are numbered from 0.
  aut->new_states(3);

  // new_edge() takes 3 mandatory parameters:
  // source state, destination state, label
  // and a last optional parameter can be used
  // to specify membership to acceptance sets.
  aut->new_edge(0, 1, p1);
  aut->new_edge(1, 1, p1 & p2, {0});
  aut->new_edge(1, 2, p2, {1});
  aut->new_edge(2, 1, p1 | p2, {0, 1});

  // Print the resulting automaton.
  print_hoa(std::cout, aut);
  return 0;
}
HOA: v1
States: 3
Start: 0
AP: 2 "p1" "p2"
acc-name: generalized-Buchi 2
Acceptance: 2 Inf(0)&Inf(1)
properties: trans-labels explicit-labels trans-acc
--BODY--
State: 0
[0] 1
State: 1
[0&1] 1 {0}
[1] 2 {1}
State: 2
[0 | 1] 1 {0 1}
--END--

Author: root

Created: 2015-08-26 Wed 08:42

Emacs 24.4.1 (Org mode 8.2.10)

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