added connection impl class

include/matador/sql/query_result.hpp

@@ -0,0 +1,95 @@
+#ifndef QUERY_QUERY_RESULT_HPP
+#define QUERY_QUERY_RESULT_HPP
+
+#include <memory>
+
+namespace matador::sql {
+
+template < typename Type >
+class query_result;
+
+template < typename Type >
+class query_result_iterator
+{
+public:
+  using iterator_category = std::forward_iterator_tag;
+  using value_type = Type;
+  using difference_type = std::ptrdiff_t;
+  using pointer = value_type*;               /**< Shortcut for the pointer type. */
+  using reference = value_type&;             /**< Shortcut for the reference type */
+
+public:
+  query_result_iterator() = default;
+  explicit query_result_iterator(query_result<Type> &res, Type *obj = nullptr)
+  : obj_(obj)
+  , result_(res)
+  {}
+  query_result_iterator(query_result_iterator&& x) noexcept
+  : obj_(std::move(x.obj_))
+  , result_(x.result_)
+  {}
+
+  query_result_iterator& operator=(query_result_iterator&& x) noexcept
+  {
+    result_ = x.result_;
+    obj_ = std::move(x.obj_);
+    return *this;
+  }
+
+  ~query_result_iterator() = default;
+
+  bool operator==(const query_result_iterator& rhs)
+  {
+    return obj_ == rhs.obj_;
+  }
+
+  bool operator!=(const query_result_iterator& rhs)
+  {
+    return obj_ != rhs.obj_;
+  }
+
+  pointer operator->()
+  {
+    return obj_.get();
+  }
+
+  reference operator&()
+  {
+    return &obj_.get();
+  }
+
+  std::unique_ptr<Type> operator*()
+  {
+    return std::move(obj_);
+  }
+
+  pointer get()
+  {
+    return obj_.get();
+  }
+
+  pointer release()
+  {
+    return obj_.release();
+  }
+
+protected:
+  std::unique_ptr<Type> obj_;
+  query_result<Type> &result_;
+};
+
+template < typename Type >
+class query_result
+{
+public:
+  query_result(std::string sql) : sql_(std::move(sql)) {}
+
+  [[nodiscard]] const std::string& str() const { return sql_; }
+
+  Type begin() { return {}; }
+private:
+  std::string sql_;
+};
+
+}
+#endif //QUERY_QUERY_RESULT_HPP