UsefulStates.h

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/*
 * This file is part of Algorithms library toolkit.
 * Copyright (C) 2017 Jan Travnicek (jan.travnicek@fit.cvut.cz)
 
 * Algorithms library toolkit 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 3 of the License, or
 * (at your option) any later version.
 
 * Algorithms library toolkit 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 Algorithms library toolkit.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#pragma once
 
#include <ext/algorithm>
 
#include <alib/deque>
#include <alib/set>
#include <alib/map>
 
#include <automaton/FSM/ExtendedNFA.h>
#include <automaton/FSM/CompactNFA.h>
#include <automaton/FSM/EpsilonNFA.h>
#include <automaton/FSM/NFA.h>
#include <automaton/FSM/DFA.h>
#include <automaton/TA/ArcFactoredDeterministicZAutomaton.h>
#include <automaton/TA/ArcFactoredNondeterministicZAutomaton.h>
#include <automaton/TA/DFTA.h>
#include <automaton/TA/NFTA.h>
 
namespace automaton {
 
namespace properties {
 
class UsefulStates {
public:
    template < class T >
    requires isDFA < T > || isNFA < T > || isEpsilonNFA < T > || isMultiInitialStateNFA < T > || isMultiInitialStateEpsilonNFA < T > || isCompactNFA < T > || isExtendedNFA < T >
    static ext::set < typename T::StateType > usefulStates ( const T & fsm );
 
    template < class T >
    requires isDFTA < T > || isNFTA < T >
    static ext::set < typename T::StateType > usefulStates ( const T & fta );
 
    template < class T >
    requires isAFDZA < T > || isAFNZA < T >
    static ext::set < typename T::StateType > usefulStates ( const T & afza );
};
 
template < class T >
requires isDFA < T > || isNFA < T > || isEpsilonNFA < T > || isMultiInitialStateNFA < T > || isMultiInitialStateEpsilonNFA < T > || isCompactNFA < T > || isExtendedNFA < T >
ext::set < typename T::StateType > UsefulStates::usefulStates ( const T & fsm ) {
    using StateType = typename T::StateType;
 
    // 1a
    ext::deque<ext::set<StateType>> Qi;
    Qi.push_back( ext::set<StateType>( ) );
    Qi.at( 0 ) = fsm.getFinalStates( );
 
    int i = 1;
 
    // 1bc
    while( true ) {
        Qi.push_back( Qi.at( i - 1 ) ); // copy Qi-1 into Qi
        for( const auto & p : Qi.at( i - 1 ) )
            for( const auto & t : fsm.getTransitionsToState( p ) )
                Qi.at( i ).insert( t.first.first );
 
        if( Qi.at( i ) == Qi.at( i - 1 ) )
            break;
 
        i = i + 1;
    }
    return Qi.at( i );
}
 
template < class T >
requires isDFTA < T > || isNFTA < T >
ext::set < typename T::StateType > UsefulStates::usefulStates ( const T & fta ) {
    using StateType = typename T::StateType;
 
    // 1a
    ext::deque<ext::set<StateType>> Qi;
    Qi.push_back( ext::set<StateType>( ) );
    Qi.at( 0 ) = fta.getFinalStates( );
 
    int i = 0;
 
    // 1bc
    do {
        i = i + 1;
 
        Qi.push_back( Qi.at( i - 1 ) ); // copy Qi-1 into Qi
        for( const auto & p : Qi.at( i - 1 ) )
            for( const auto & t : fta.getTransitionsToState ( p ) )
                Qi.at( i ).insert( t.first.second.begin ( ), t.first.second.end ( ) );
 
    } while ( Qi.at( i ) != Qi.at( i - 1 ) );
 
    return Qi.at( i );
}
 
template < class T >
requires isAFDZA < T > || isAFNZA < T >
ext::set < typename T::StateType > UsefulStates::usefulStates ( const T & afza ) {
    using StateType = typename T::StateType;
 
    // 1a
    ext::deque<ext::set<StateType>> Qi;
    Qi.push_back( ext::set<StateType>( ) );
    Qi.at( 0 ) = afza.getFinalStates( );
 
    int i = 0;
 
    // 1bc
    do {
        i = i + 1;
 
        Qi.push_back( Qi.at( i - 1 ) ); // copy Qi-1 into Qi
        for( const auto & p : Qi.at( i - 1 ) )
            for( const auto & t : afza.getTransitionsToState ( p ) ) {
                if ( t.first.template is < ext::pair < StateType, StateType > > ( ) ) {
                    const auto& lhs = t.first.template get < ext::pair < StateType, StateType > > ( );
                    Qi.at( i ).insert( lhs.first );
                    Qi.at( i ).insert( lhs.second );
                }
            }
 
    } while ( Qi.at( i ) != Qi.at( i - 1 ) );
 
    return Qi.at( i );
}
 
} /* namespace properties */
 
} /* namespace automaton */