RemoveUnused.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 <ext/iostream>
 
#include <alib/map>
#include <alib/vector>
 
#include <automaton/PDA/RealTimeHeightDeterministicDPDA.h>
 
namespace automaton {
 
namespace simplify {
 
class RemoveUnused {
public:
    template < class InputSymbolType, class PushdownStoreSymbolType, class StateType >
    static automaton::RealTimeHeightDeterministicDPDA < InputSymbolType, PushdownStoreSymbolType, StateType > removeUnused ( const automaton::RealTimeHeightDeterministicDPDA < InputSymbolType, PushdownStoreSymbolType, StateType > & pda );
};
 
template < class InputSymbolType, class PushdownStoreSymbolType, class StateType >
automaton::RealTimeHeightDeterministicDPDA < InputSymbolType, PushdownStoreSymbolType, StateType > RemoveUnused::removeUnused ( const automaton::RealTimeHeightDeterministicDPDA < InputSymbolType, PushdownStoreSymbolType, StateType > & pda ) {
    ext::set < InputSymbolType > alphabet;
    ext::set < PushdownStoreSymbolType > pushdownAlphabet;
    ext::set < StateType > states;
 
    states.insert ( pda.getInitialState ( ) );
    pushdownAlphabet.insert ( pda.getBottomOfTheStackSymbol ( ) );
 
    for ( const auto & transition : pda.getCallTransitions ( ) ) {
        if ( ! transition.first.second.is_epsilon ( ) )
            alphabet.insert ( transition.first.second.getSymbol ( ) );
        pushdownAlphabet.insert ( transition.second.second );
        states.insert ( transition.first.first );
        states.insert ( transition.second.first );
    }
 
    for ( const auto & transition : pda.getLocalTransitions ( ) ) {
        if ( ! transition.first.second.is_epsilon ( ) )
            alphabet.insert ( transition.first.second.getSymbol ( ) );
        states.insert ( transition.first.first );
        states.insert ( transition.second );
    }
 
    for ( const auto & transition : pda.getReturnTransitions ( ) ) {
        if ( ! std::get < 1 > ( transition.first ).is_epsilon ( ) )
            alphabet.insert ( std::get < 1 > ( transition.first ).getSymbol ( ) );
        pushdownAlphabet.insert ( std::get < 2 > ( transition.first ) );
        states.insert ( std::get < 0 > ( transition.first ) );
        states.insert ( transition.second );
    }
 
    automaton::RealTimeHeightDeterministicDPDA < InputSymbolType, PushdownStoreSymbolType, StateType > result ( pda.getInitialState ( ), pda.getBottomOfTheStackSymbol ( ) );
 
    result.setInputAlphabet ( alphabet );
    result.setPushdownStoreAlphabet ( pushdownAlphabet );
    result.setStates ( states );
 
    for ( const StateType & state : pda.getFinalStates ( ) )
        if ( states.contains ( state ) )
            result.addFinalState ( state );
 
    for ( const auto & transition : pda.getCallTransitions ( ) )
        result.addCallTransition ( transition.first.first, transition.first.second, transition.second.first, transition.second.second );
 
    for ( const auto & transition : pda.getLocalTransitions ( ) )
        result.addLocalTransition ( transition.first.first, transition.first.second, transition.second );
 
    for ( const auto & transition : pda.getReturnTransitions ( ) )
        result.addReturnTransition ( std::get < 0 > ( transition.first ), std::get < 1 > ( transition.first ), std::get < 2 > ( transition.first ), transition.second );
 
    return result;
}
 
} /* namespace simplify */
 
} /* namespace automaton */