Reference.cpp

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// -*- mode: C++; c-indent-level: 4; c-basic-offset: 4; indent-tabs-mode: nil; -*-
//
// S4.cpp: Rcpp R/C++ interface class library -- S4 objects
//
// 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/>.

#include <Rcpp/Reference.h>
#include <Rcpp/exceptions.h>
#include <Rcpp/Vector.h>

namespace Rcpp {

    Reference::Reference() : S4(){}
    
    Reference::Reference(SEXP x) : S4(){
        set( x) ;
    }
    
    Reference::Reference( const Reference& other) : S4(){
        setSEXP( other.asSexp() ) ; 
    }
    
    Reference::Reference( const RObject::SlotProxy& proxy ) : S4() {
        set( proxy ) ;
    }
    Reference::Reference( const RObject::AttributeProxy& proxy ) : S4() {
        set( proxy ) ;
    }
    
    Reference& Reference::operator=( const Reference& other){
        setSEXP( other.asSexp() ) ;
        return *this ;
    }
    
    Reference& Reference::operator=( SEXP other ) {
        set( other ) ;
        return *this ;
    }
    
    Reference::Reference( const std::string& klass ) : S4(){
        // using callback to R as apparently R_do_new_object always makes the same environment
        SEXP newSym = Rf_install("new");
        SEXP call = PROTECT( Rf_lang2( newSym, Rf_mkString( klass.c_str() ) ) ) ;
        setSEXP( Rcpp::internal::try_catch( call ) ) ;
        UNPROTECT(1) ; // call
    }
    
    void Reference::set( SEXP x) {
        // TODO: check that x is of a reference class
        if( ! ::Rf_isS4(x) ){
            throw not_reference() ;
        } else{
            setSEXP( x) ;
        }
    }
    
    Reference::FieldProxy::FieldProxy( const Reference& v, const std::string& name) : 
        parent(v), field_name(name) {}

    Reference::FieldProxy& Reference::FieldProxy::operator=(const FieldProxy& rhs){
        set( rhs.get() ) ;
        return *this ;
    }
    
    
    SEXP Reference::FieldProxy::get() const {
        // TODO: get the field  
        
        SEXP call = PROTECT( Rf_lang3( 
                                                                          R_DollarSymbol, 
                                                                          const_cast<Reference&>(parent).asSexp(), 
                                                                          Rf_mkString( field_name.c_str() )
                                                                           ) ) ;
        return Rcpp::internal::try_catch( call ) ;
        UNPROTECT(1) ;
    }
    
    void Reference::FieldProxy::set( SEXP x) const {
        PROTECT(x);
        SEXP dollarGetsSym = Rf_install( "$<-");
        SEXP call = PROTECT( Rf_lang4( 
                                                                          dollarGetsSym,
                                                                          const_cast<Reference&>(parent).asSexp(), 
                                                                          Rf_mkString( field_name.c_str() ), 
                                                                          x
                                                                           ) ) ;
        const_cast<Reference&>(parent).setSEXP( Rf_eval( call, R_GlobalEnv ) ); 
        UNPROTECT(2) ;
    }

    Reference::FieldProxy Reference::field( const std::string& name) const {
        return FieldProxy( *this, name );
    }
    
} // namespace Rcpp