initial matador ng commit

include/matador/sql/abstract_sql_logger.hpp

@@ -0,0 +1,86 @@
+#ifndef MATADOR_BASIC_SQL_LOGGER_HPP
+#define MATADOR_BASIC_SQL_LOGGER_HPP
+
+#include <string>
+
+namespace matador::sql {
+
+/**
+ * @brief Base class for sql logging
+ *
+ * This class acts as a base class to
+ * implement a concrete logger for sql
+ * statements.
+ *
+ * It provides interfaces to handle
+ * the establishing and closing of
+ * a database connection as well as
+ * when a sql statement is about to
+ * execute or going to be prepared.
+ */
+class abstract_sql_logger
+{
+public:
+
+  virtual ~abstract_sql_logger() = default;
+  /**
+   * Is called when a connection to a database is
+   * going to be established
+   */
+  virtual void on_connect() = 0;
+
+  /**
+   * Is called when a connection is going to be closed
+   */
+  virtual void on_close() = 0;
+
+  /**
+   * Is called when a sql statement is going to
+   * be executed
+   *
+   * @param stmt SQL statement to be executed
+   */
+  virtual void on_execute(const std::string &stmt) = 0;
+
+  /**
+   * Is called when a sql statement is going to
+   * be prepared
+   *
+   * @param stmt SQL statement to be prepared
+   */
+  virtual void on_prepare(const std::string &stmt) = 0;
+};
+
+/**
+ * Implements the basic_sql_logger to do no
+ * logging at all.
+ * This is used as the default logger for all
+ * connections and statements.
+ */
+class null_sql_logger final : public abstract_sql_logger
+{
+public:
+  /**
+   * No logging on establishing a connection.
+   */
+  void on_connect() override { }
+
+  /**
+   * No logging on closing a connection.
+   */
+  void on_close() override { }
+
+  /**
+   * No logging on executing a statement.
+   */
+  void on_execute(const std::string &) override { }
+
+  /**
+   * No logging on preparing a statement.
+   */
+  void on_prepare(const std::string &) override { }
+};
+
+}
+
+#endif //MATADOR_BASIC_SQL_LOGGER_HPP