ToAutomatonTopDown.h

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#pragma once
 
#include <grammar/Grammar.h>
#include <grammar/ContextFree/CFG.h>
#include <grammar/ContextFree/EpsilonFreeCFG.h>
#include <grammar/RawRules.h>
 
#include <automaton/PDA/NPDA.h>
 
#include <label/InitialStateLabel.h>
 
namespace grammar {
 
namespace convert {
 
class ToAutomatonTopDown {
public:
    template < class T, class TerminalSymbolType = typename grammar::TerminalSymbolTypeOfGrammar < T >, class NonterminalSymbolType = typename grammar::NonterminalSymbolTypeOfGrammar < T > >
    static automaton::NPDA < TerminalSymbolType, ext::variant < TerminalSymbolType, NonterminalSymbolType >, unsigned > convert ( const T & grammar );
};
 
template < class T, class TerminalSymbolType, class NonterminalSymbolType >
automaton::NPDA < TerminalSymbolType, ext::variant < TerminalSymbolType, NonterminalSymbolType >, unsigned > ToAutomatonTopDown::convert ( const T & grammar ) {
    automaton::NPDA < TerminalSymbolType, ext::variant < TerminalSymbolType, NonterminalSymbolType >, unsigned > automaton ( label::InitialStateLabel::instance < unsigned > ( ), grammar.getInitialSymbol ( ) );
 
    automaton.setInputAlphabet ( grammar.getTerminalAlphabet ( ) );
 
    for ( const NonterminalSymbolType & nonterminal : grammar.getNonterminalAlphabet ( ) )
        automaton.addPushdownStoreSymbol ( nonterminal );
    for ( const TerminalSymbolType & terminal : grammar.getTerminalAlphabet ( ) )
        automaton.addPushdownStoreSymbol ( terminal );
 
    for ( const std::pair < const NonterminalSymbolType, ext::set < ext::vector < ext::variant < TerminalSymbolType, NonterminalSymbolType > > > > & kv : grammar.getRules ( ) )
        for ( const ext::vector < ext::variant < TerminalSymbolType, NonterminalSymbolType > > & rhs : kv.second )
            automaton.addTransition ( automaton.getInitialState ( ), ext::vector < ext::variant < TerminalSymbolType, NonterminalSymbolType > > { kv.first }, automaton.getInitialState ( ), rhs );
 
    for ( const TerminalSymbolType & symbol : grammar.getTerminalAlphabet ( ) )
        automaton.addTransition ( automaton.getInitialState ( ), symbol, ext::vector < ext::variant < TerminalSymbolType, NonterminalSymbolType > > { symbol }, automaton.getInitialState ( ), ext::vector < ext::variant < TerminalSymbolType, NonterminalSymbolType > > { } );
 
    return automaton;
}
 
} /* namespace convert */
 
} /* namespace grammar */