~drizzle-trunk/drizzle/development

/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-

 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:

 *

 *  Copyright (C) 2010 Padraig O'Sullivan

 *

 *  Authors:

 *

 *    Padraig O'Sullivan <posullivan@akibainc.com>

 *

 *  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

 */

#pragma once

#include <drizzled/atomics.h>

#include <drizzled/plugin/plugin.h>

#include <drizzled/visibility.h>

/**

 * @file Defines the API for a QueryRewriter.  

 */

namespace drizzled

{

namespace plugin

{

/**

 * Class which rewrites queries

 */

class DRIZZLED_API QueryRewriter : public Plugin

{

public:

  explicit QueryRewriter(std::string name_arg)

    : 

      Plugin(name_arg, "QueryRewriter")

  {}

  /**

   * Rewrite a query in the form of a std::string

   *

   * @param[in] schema the schema the current session is in

   * @param[out] to_rewrite string representing the query to rewrite

   */

  virtual void rewrite(const std::string &schema, std::string &to_rewrite)= 0; 

  static bool addPlugin(QueryRewriter *in_rewriter);

  static void removePlugin(QueryRewriter *in_rewriter);

  /**

   * Take a query to be rewritten and go through all the rewriters that are registered as plugins

   * and let the enabled ones rewrite they query.

   * TODO: does it make sense to have multiple rewriters?

   *

   * @param[in] schema the schema the current session is

   * @param[out] to_rewrite the query to rewrite

   */

  static void rewriteQuery(const std::string &schema, std::string &to_rewrite);

};

} /* namespace plugin */

} /* namespace drizzled */