added session context and implemented the executor interface for session

include/matador/sql/connection.hpp

@@ -16,7 +16,7 @@ class connection_impl;
 /**
  * @brief The connection class represents a connection to a database.
  */
-class connection final : public executor, public prepared_executor {
+class connection final : public executor {
 public:
   using logger_ptr = std::shared_ptr<abstract_sql_logger>;
   /**

include/matador/sql/executor.hpp

@@ -12,22 +12,13 @@ struct query_context;
 class query_result_impl;
 class statement;
 
-class dialect_executor_mixin {
+class executor {
 public:
-  virtual ~dialect_executor_mixin() = default;
+  virtual ~executor() = default;
   [[nodiscard]] virtual const class dialect& dialect() const = 0;
-};
-
-class prepared_executor : public dialect_executor_mixin {
-public:
-  [[nodiscard]] virtual utils::result<statement, utils::error> prepare(const query_context &ctx) = 0;
-};
-
-class executor : public dialect_executor_mixin {
-public:
   [[nodiscard]] virtual utils::result<size_t, utils::error> execute(const query_context &ctx) const = 0;
   [[nodiscard]] virtual utils::result<std::unique_ptr<query_result_impl>, utils::error> fetch(const query_context &ctx) const = 0;
-
+  [[nodiscard]] virtual utils::result<statement, utils::error> prepare(const query_context &ctx) = 0;
   [[nodiscard]] virtual std::string str(const query_context &ctx) const = 0;
 };
 

include/matador/sql/statement.hpp

@@ -123,6 +123,8 @@ public:
 
   [[nodiscard]] std::string sql() const;
 
+  [[nodiscard]] utils::result<std::unique_ptr<query_result_impl>, utils::error> fetch_internal() const;
+
 private:
   template<class Type>
   friend class detail::identifier_binder;

include/matador/sql/statement_cache.hpp

@@ -68,6 +68,7 @@ public:
     return bus_.subscribe<EventType>(handler);
   }
 
+  connection_pool& pool() const;
 
 private:
   size_t max_size_{};