/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
 *
 *  Copyright (C) 2008 Sun Microsystems, Inc.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; version 2 of the License.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */


#ifndef DRIZZLED_INTERNAL_ERROR_HANDLER_H
#define DRIZZLED_INTERNAL_ERROR_HANDLER_H

#include <drizzled/sql_error.h>

namespace drizzled
{

/**
  This class represents the interface for internal error handlers.
  Internal error handlers are exception handlers used by the server
  implementation.
*/
class Internal_error_handler
{
protected:
  Internal_error_handler() {}
  virtual ~Internal_error_handler() {}

public:
  /**
    Handle an error condition.
    This method can be implemented by a subclass to achieve any of the
    following:
    - mask an error internally, prevent exposing it to the user,
    - mask an error and throw another one instead.
    When this method returns true, the error condition is considered
    'handled', and will not be propagated to upper layers.
    It is the responsability of the code installing an internal handler
    to then check for trapped conditions, and implement logic to recover
    from the anticipated conditions trapped during runtime.

    This mechanism is similar to C++ try/throw/catch:
    - 'try' correspond to <code>Session::push_internal_handler()</code>,
    - 'throw' correspond to <code>my_error()</code>,
    which invokes <code>my_message_sql()</code>,
    - 'catch' correspond to checking how/if an internal handler was invoked,
    before removing it from the exception stack with
    <code>Session::pop_internal_handler()</code>.

    @param sql_errno the error number
    @param level the error level
    @param session the calling thread
    @return true if the error is handled
  */
  virtual bool handle_error(drizzled::error_t sql_errno,
                            const char *message,
                            DRIZZLE_ERROR::enum_warning_level level,
                            Session *session) = 0;
};

} /* namespace drizzled */

#endif /* DRIZZLED_INTERNAL_ERROR_HANDLER_H */
