RangeIndexer.h

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// -*- mode: C++; c-indent-level: 4; c-basic-offset: 4; tab-width: 8 -*-
//
// RangeIndexer.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__vector__RangeIndexer_h
#define Rcpp__vector__RangeIndexer_h
       
#define UNROLL_LOOP(OP)                              \
    typedef typename ::Rcpp::traits::Extractor<RTYPE,NA,T>::type EXT ; \
    const EXT& input( x.get_ref() ) ;                   \
    int __trip_count = (size_) >> 2;                 \
    int i=0 ;                                        \
    for ( ; __trip_count > 0 ; --__trip_count) {     \
        start[i] OP input[i] ; i++ ;                 \
        start[i] OP input[i] ; i++ ;                 \
        start[i] OP input[i] ; i++ ;                 \
        start[i] OP input[i] ; i++ ;                 \
    }                                                \
    switch (size_ - i){                              \
      case 3:                                        \
          start[i] OP input[i] ; i++ ;               \
      case 2:                                        \
          start[i] OP input[i] ; i++ ;               \
      case 1:                                        \
          start[i] OP input[i] ; i++ ;               \
      case 0:                                        \
      default:                                       \
          return *this ;                             \
    }



namespace internal{

template <int RTYPE, typename VECTOR>
class RangeIndexer {
public:
        typedef typename VECTOR::Proxy Proxy ;
        typedef typename VECTOR::iterator iterator ;
        
        // TODO: check if the indexer is valid
        RangeIndexer( VECTOR& vec_, const Rcpp::Range& range_) : 
                start(vec_.begin() + range_.get_start() ), size_( range_.size() ) {}
        
                // TODO: size exceptions
        template <bool NA, typename T>  
        RangeIndexer& operator=( const Rcpp::VectorBase<RTYPE,NA,T>& x){
            UNROLL_LOOP(=)
        }
        
        template <bool NA, typename T>  
        RangeIndexer& operator+=( const Rcpp::VectorBase<RTYPE,NA,T>& x){
                 UNROLL_LOOP(+=)
        }
        
        template <bool NA, typename T>  
        RangeIndexer& operator*=( const Rcpp::VectorBase<RTYPE,NA,T>& x){
                UNROLL_LOOP(*=)
        }
        
        template <bool NA, typename T>  
        RangeIndexer& operator-=( const Rcpp::VectorBase<RTYPE,NA,T>& x){
                UNROLL_LOOP(-=)
        }
        
        template <bool NA, typename T>  
        RangeIndexer& operator/=( const Rcpp::VectorBase<RTYPE,NA,T>& x){
                UNROLL_LOOP(/=)
        }
        
        inline Proxy operator[]( int i ){
            return start[i] ;
        }
        
        inline int size(){
                return size_ ;
        }
        
private:
        iterator start ;
        int size_ ;
} ;
        
}

#undef UNROLL_LOOP

#endif