SingleLogicalResult.h

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// -*- mode: C++; c-indent-level: 4; c-basic-offset: 4; tab-width: 8 -*-
//
// SingleLogicalResult.h: Rcpp R/C++ interface class library -- 
//
// Copyright (C) 2010 - 2011 Dirk Eddelbuettel and Romain Francois
//
// This file is part of Rcpp.
//
// Rcpp 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 2 of the License, or
// (at your option) any later version.
//
// Rcpp 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 Rcpp.  If not, see <http://www.gnu.org/licenses/>.

#ifndef Rcpp__sugar__SingleLogicalResult_h
#define Rcpp__sugar__SingleLogicalResult_h

namespace Rcpp{
namespace sugar{  

template <bool> 
class forbidden_conversion ;

template <> 
class forbidden_conversion<true>{} ;

template <bool x>
class conversion_to_bool_is_forbidden : 
        conversion_to_bool_is_forbidden<x>{
        public:
                void touch(){}
}; 

template <bool NA,typename T>
class SingleLogicalResult {
public:
        const static int UNRESOLVED = -5 ;
        
        SingleLogicalResult() : result(UNRESOLVED) {} ;
        
        void apply(){
                if( result == UNRESOLVED ){
                        static_cast<T&>(*this).apply() ;
                }
        }
        
        inline bool is_true(){
                apply() ;
                return result == TRUE ;
        }
        
        inline bool is_false(){
                apply() ;
                return result == FALSE ;
        }
        
        inline bool is_na(){
                apply() ;
                return Rcpp::traits::is_na<LGLSXP>( result ) ;
        }
        
        operator SEXP(){
                apply() ;
                return Rf_ScalarLogical( result ) ;
        }
        
        operator bool(){
                conversion_to_bool_is_forbidden<!NA> x ;
                x.touch() ;
                return is_true() ;
        }
        
        inline int size(){ return 1 ; }
        
        inline int get(){
                apply();
                return result;
        }
        
protected:
        int result ;
        inline void set(int x){ result = x ;}
        inline void reset(){ set(UNRESOLVED) ; }
        inline void set_true(){ set(TRUE); }
        inline void set_false(){ set(FALSE); }
        inline void set_na(){ set(NA_LOGICAL); }
        inline bool is_unresolved(){ return result == UNRESOLVED ; }
} ;

}
}



#endif