ListBuilder.h from Kevin Ushey

ListBuilder.h

//
// Based on code sent by Kevin Ushey
// to Rcpp-devel on Tue, 8 Jul 2014
//

#ifndef LIST_BUILDER_H
#define LIST_BUILDER_H

#include <Rcpp.h>
using namespace Rcpp;

class ListBuilder
{

public:

    ListBuilder() {};
    ~ListBuilder() {};

    inline ListBuilder& add(std::string name, SEXP x)
    {
        names.push_back(name);
        elements.push_back(x);
        return *this;
    }

    inline List get() const
    {
        return static_cast<List>(*this);
    }

    inline operator List() const
    {
        List result(elements.size());
        for (size_t i = 0; i < elements.size(); ++i)
        {
            result[i] = elements[i];
        }
        result.attr("names") = wrap(names);
        return result;
    }

    inline operator DataFrame() const
    {
        List result = static_cast<List>(*this);
        result.attr("class") = "data.frame";
        result.attr("row.names") = IntegerVector::create(NA_INTEGER, XLENGTH(elements[0]));
        return result;
    }

private:

    std::vector<std::string> names;
    std::vector<SEXP> elements;

    ListBuilder(ListBuilder const&) {};

};


#endif