unary_minus.h

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// -*- mode: C++; c-indent-level: 4; c-basic-offset: 4; tab-width: 8 -*-
//
// unary_minus.h: Rcpp R/C++ interface class library -- unary operator-
//                                                                      
// 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__unary_minus_h
#define Rcpp__sugar__unary_minus_h

namespace Rcpp{
namespace sugar{

        template <int RTYPE>
        struct unary_minus_result_type{
                typedef typename traits::storage_type<RTYPE>::type type ;
                enum{ value = RTYPE } ;
        } ;
        template <>
        struct unary_minus_result_type<LGLSXP>{
                typedef traits::storage_type<INTSXP>::type type ;
                enum{ value = INTSXP } ;
        } ;
        
        
        template <int RTYPE,bool NA> 
        class unary_minus {
        public:
                typedef typename traits::storage_type<RTYPE>::type STORAGE ;
                typedef typename unary_minus_result_type<RTYPE>::type RESULT ;
                inline RESULT apply( STORAGE x ) const {
                        return Rcpp::traits::is_na<RTYPE>(x) ? x : ( -x ) ;
                }
        } ;
        template <int RTYPE>
        class unary_minus<RTYPE,false> {
        public:
                typedef typename Rcpp::traits::storage_type<RTYPE>::type STORAGE ;
                typedef typename unary_minus_result_type<RTYPE>::type RESULT ;
                inline RESULT apply( STORAGE x ) const {
                        return -x ;
                }
        } ;
        template <bool NA>
        class unary_minus<CPLXSXP,NA>{
        public:
                inline Rcomplex apply( Rcomplex x ) const {
                        if (Rcpp::traits::is_na<CPLXSXP>( x ) ) return x; 
                        
                        Rcomplex cx ;
                        cx.r = -x.r; 
                        cx.i = -x.i ;
                        return cx ;
                }
        } ;
        template <>
        class unary_minus<CPLXSXP,false>{
        public:
                inline Rcomplex apply( Rcomplex x ) const {
                        Rcomplex cx ;
                        cx.r = -x.r; 
                        cx.i = -x.i ;
                        return cx ;
                }
        } ;
        

        template <int RTYPE, bool NA, typename T>
        class UnaryMinus_Vector : public Rcpp::VectorBase< 
                unary_minus_result_type<RTYPE>::value ,
                NA, 
                UnaryMinus_Vector< unary_minus_result_type<RTYPE>::value ,NA,T> 
                > {
        public:
                typedef typename Rcpp::VectorBase<RTYPE,NA,T> VEC_TYPE ;
                typedef typename traits::storage_type<RTYPE>::type STORAGE ;
                typedef typename unary_minus_result_type<RTYPE>::type RESULT ;
                typedef unary_minus<RTYPE,NA> OPERATOR ;
                
                UnaryMinus_Vector( const VEC_TYPE& lhs_ ) : 
                        lhs(lhs_), op() {}
                
                inline RESULT operator[]( int i ) const {
                        return op.apply( lhs[i] ) ;
                }
                
                inline int size() const { return lhs.size() ; }
                
        private:
                const VEC_TYPE& lhs ;
                OPERATOR op ; 
        } ;
        
}
}

template <int RTYPE,bool NA, typename T>
inline Rcpp::sugar::UnaryMinus_Vector< RTYPE , NA , T >
operator-( 
        const Rcpp::VectorBase<RTYPE,NA,T>& x
) {
        return Rcpp::sugar::UnaryMinus_Vector<RTYPE,NA, T >( x ) ;
}


#endif