get reader from R object

src/reco-read-data.cpp

@@ -2,6 +2,27 @@
 
 using namespace mf;
 
+// DataSource.R
+DataReader* get_reader(SEXP data_source)
+{
+    Rcpp::RObject ds(data_source);
+    std::string ds_class = ds.attr("class");
+    Rcpp::List ds_list(data_source);
+
+    DataReader* res = nullptr;
+
+    if(ds_class == "DataFile")
+    {
+        std::string path = Rcpp::as<std::string>(ds_list["path"]);
+        bool index1 = Rcpp::as<bool>(ds_list["index1"]);
+        res = new DataFileReader(path, index1);
+    } else {
+        Rcpp::stop("unsupported data source");
+    }
+
+    return res;
+}
+
 // An mf_problem stands for a data object
 mf_problem read_data(DataReader* reader)
 {

src/reco-read-data.h

@@ -45,10 +45,10 @@ class DataReader
 class DataFileReader: public DataReader
 {
 private:
-    std::string   path;
-    int           ind_offset;
-    std::ifstream in_file;
-    std::string   line;
+    const std::string path;
+    const int         ind_offset;
+    std::ifstream     in_file;
+    std::string       line;
 
 public:
     DataFileReader(const std::string& file_path, bool index1 = false) :
@@ -102,6 +102,8 @@ class DataFileReader: public DataReader
 };
 
 
+DataReader* get_reader(SEXP data_source);
+
 mf::mf_problem read_data(DataReader* reader);