added sqlite query result and enhanced column generator and value extractor

include/matador/utils/access.hpp

@@ -1,12 +1,12 @@
 #ifndef QUERY_ACCESS_HPP
 #define QUERY_ACCESS_HPP
 
+#include "matador/utils/cascade_type.hpp"
+
 #include <string>
 
 namespace matador::utils {
 
-enum class cascade_type;
-
 template < class Type, template < class ... > class ContainerType >
 class container;
 

include/matador/utils/string.hpp

@@ -15,5 +15,35 @@ namespace matador::utils {
  */
 void replace_all(std::string &in, const std::string &from, const std::string &to);
 
+const std::string& to_string(const std::string &str);
+
+/**
+ * Joins a range of elements as string within a list
+ * with a given delimiter and writes it to the
+ * given stream
+ *
+ * @tparam R Type og the range (e.g. map, list, vector, etc)
+ * @param range The range with the elements to join
+ * @param delim The delimiter for the elements
+ * @return The ostream reference
+ */
+template < class R >
+std::string join(R &range, const std::string &delim)
+{
+  std::string result {};
+  if (range.size() < 2) {
+    for (const auto &i : range) {
+      result += to_string(i);
+    }
+  } else {
+    auto it = range.begin();
+    result += to_string(*it++);
+    for (;it != range.end(); ++it) {
+      result += delim + to_string(*it);
+    }
+  }
+  return result;
+}
+
 }
 #endif //QUERY_STRING_HPP