EpsilonRemoverIncoming.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 <automaton/FSM/EpsilonNFA.h>
#include <automaton/FSM/MultiInitialStateNFA.h>
#include <automaton/FSM/NFA.h>
#include <automaton/FSM/DFA.h>
 
#include <automaton/properties/EpsilonClosure.h>
 
namespace automaton {
 
namespace simplify {
 
class EpsilonRemoverIncoming {
public:
    template < class SymbolType, class StateType >
    static automaton::NFA < SymbolType, StateType > remove( const automaton::EpsilonNFA < SymbolType, StateType > & fsm );
 
    template < class SymbolType, class StateType >
    static automaton::MultiInitialStateNFA < SymbolType, StateType > remove( const automaton::MultiInitialStateNFA < SymbolType, StateType > & fsm );
 
    template < class SymbolType, class StateType >
    static automaton::NFA < SymbolType, StateType > remove( const automaton::NFA < SymbolType, StateType > & fsm );
 
    template < class SymbolType, class StateType >
    static automaton::DFA < SymbolType, StateType > remove( const automaton::DFA < SymbolType, StateType > & fsm );
 
};
 
template < class SymbolType, class StateType >
automaton::DFA < SymbolType, StateType > EpsilonRemoverIncoming::remove(const automaton::DFA < SymbolType, StateType > & fsm) {
    return fsm;
}
 
template < class SymbolType, class StateType >
automaton::MultiInitialStateNFA < SymbolType, StateType > EpsilonRemoverIncoming::remove(const automaton::MultiInitialStateNFA < SymbolType, StateType > & fsm) {
    return fsm;
}
 
template < class SymbolType, class StateType >
automaton::NFA < SymbolType, StateType > EpsilonRemoverIncoming::remove(const automaton::NFA < SymbolType, StateType > & fsm) {
    return fsm;
}
 
template < class SymbolType, class StateType >
automaton::NFA < SymbolType, StateType > EpsilonRemoverIncoming::remove( const automaton::EpsilonNFA < SymbolType, StateType > & fsm ) {
    automaton::NFA < SymbolType, StateType > res(fsm.getInitialState());
 
    res.setStates( fsm.getStates() );
    res.setInputAlphabet( fsm.getInputAlphabet() );
 
    ext::multimap < ext::pair < StateType, SymbolType >, StateType > origTransitions = fsm.getSymbolTransitions();
 
    for( const auto & from : fsm.getStates( ) )
        for( const auto & fromClosure : automaton::properties::EpsilonClosure::epsilonClosure( fsm, from ) )
            for( const auto & symbol : fsm.getInputAlphabet() )
                for( const auto & transition : origTransitions.equal_range(ext::make_pair(fromClosure, symbol)) )
                    res.addTransition( from, symbol, transition.second );
 
    const ext::set<StateType> & F = fsm.getFinalStates( );
    for( const auto & q : res.getStates( ) ) {
        const ext::set<StateType> & cl = automaton::properties::EpsilonClosure::epsilonClosure( fsm, q );
 
        if ( ! ext::excludes ( cl.begin(), cl.end(), F.begin(), F.end() ) )
            res.addFinalState( q );
    }
 
    return res;
}
 
} /* namespace simplify */
 
} /* namespace automaton */