diag.h

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// -*- mode: C++; c-indent-level: 4; c-basic-offset: 4; tab-width: 8 -*-
//
// diag.h: Rcpp R/C++ interface class library -- diag
//
// 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__diag_h
#define Rcpp__sugar__diag_h

namespace Rcpp{ 
namespace sugar{
        
template <int RTYPE, bool NA, typename T>
class Diag_Extractor : public Rcpp::VectorBase< RTYPE ,NA, Diag_Extractor<RTYPE,NA,T> > {
public:
        typedef typename Rcpp::MatrixBase<RTYPE,NA,T> MAT_TYPE ;
        typedef typename Rcpp::traits::storage_type<RTYPE>::type STORAGE ;
        
        Diag_Extractor( const MAT_TYPE& object_ ) : object(object_), n(0) {
                int nr = object.nrow() ;
                int nc = object.ncol() ;
                n = (nc < nr ) ? nc : nr ;
        }
        
        inline STORAGE operator[]( int i ) const {
                return object( i, i ) ;
        }
        inline int size() const { return n; }
                 
private:
        const MAT_TYPE& object ;
        int n ;
} ;
        

template <int RTYPE, bool NA, typename T>
class Diag_Maker : public Rcpp::MatrixBase< RTYPE ,NA, Diag_Maker<RTYPE,NA,T> > {
public:
        typedef typename Rcpp::VectorBase<RTYPE,NA,T> VEC_TYPE ;
        typedef typename Rcpp::traits::storage_type<RTYPE>::type STORAGE ;
        
        Diag_Maker( const VEC_TYPE& object_ ) : object(object_), n(object_.size()) {}
        
        inline STORAGE operator()( int i, int j ) const {
                return (i==j) ? object[i] : 0 ;
        }
        inline int size() const { return n * n; }
        inline int ncol() const { return n; }
        inline int nrow() const { return n; }
                 
private:
        const VEC_TYPE& object ;
        int n ;
} ;

template <typename T> struct diag_result_type_trait{
        typedef typename Rcpp::traits::if_<
                Rcpp::traits::matrix_interface<T>::value, 
                Diag_Extractor< T::r_type::value , T::can_have_na::value , T >, 
                Diag_Maker< T::r_type::value , T::can_have_na::value , T > 
        >::type type ;
} ;

} // sugar

template <typename T>
inline typename sugar::diag_result_type_trait<T>::type 
diag( const T& t ){
        return typename sugar::diag_result_type_trait<T>::type( t ) ;
}


} // Rcpp
#endif