* <many>: (WIP) use ~/mu/xapian as the database with an embedded version tag

- add checks in the code to make sure the database is up to date,
    if not, warn the user.

src/mu-util-xapian.h

@@ -0,0 +1,52 @@
+/*
+** Copyright (C) 2010 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+**
+** 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; either version 3 of the License, or
+** (at your option) any later version.
+**
+** 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 Street, Fifth Floor, Boston, MA 02110-1301, USA.
+**
+*/
+
+
+#ifndef __MU_UTIL_XAPIAN_H__
+#define __MU_UTIL_XAPIAN_H__
+
+#include <glib.h>
+
+G_BEGIN_DECLS
+
+/** 
+ * get the version of the xapian database (ie., the version of the
+ * 'schema' we are using). If this version != MU_XAPIAN_DB_VERSION,
+ * it's means we need to a full reindex.
+ * 
+ * @param xpath path to the xapian database
+ * 
+ * @return the version of the database as a newly allocated string
+ * (free with g_free); if there is no version yet, it will return NULL
+ */
+char* mu_util_xapian_db_version (const gchar *xpath);
+
+
+/** 
+ * check if the 'schema' of the current database is up-to-date
+ * 
+ * @param xpath path to the xapian database
+ * 
+ * @return TRUE if it's up-to-date, FALSE otherwise
+ */
+gboolean mu_util_xapian_db_version_up_to_date (const gchar *xpath);
+
+G_END_DECLS
+
+#endif /*__MU_UTIL_XAPIAN_H__*/