mu/src/mu-query-xapian.cc

/* 
** Copyright (C) 2008 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.  
**  
*/

#include <stdlib.h>
#include <xapian.h>
#include <glib/gstdio.h>
#include <string.h>
#include <string>

#include "mu-query-xapian.h"

#include "mu-msg-xapian.h"
#include "mu-msg-xapian-priv.hh"

struct _MuQueryXapian {
	Xapian::Database    *_db;
	Xapian::QueryParser  _qparser;
	Xapian::Sorter*      _sorters[MU_MSG_FIELD_TYPE_NUM];
};

static void
add_prefix (const MuMsgField* field, Xapian::QueryParser* qparser)
{
	if (!mu_msg_field_is_xapian_enabled(field)) 
		return;

	const std::string prefix (mu_msg_field_xapian_prefix(field));

	qparser->add_boolean_prefix(std::string(mu_msg_field_name(field)),
				   prefix);
	qparser->add_boolean_prefix(std::string(mu_msg_field_shortcut(field)),
				   prefix);

	/* make the empty string match this field too*/
	qparser->add_prefix ("", prefix);
}

MuQueryXapian*
mu_query_xapian_new (const char* path, GError **err)
{
	MuQueryXapian *self;
	
	g_return_val_if_fail (path, NULL);

	if (!g_file_test (path, G_FILE_TEST_IS_DIR) ||
	    g_access(path, R_OK) != 0) { 
		g_set_error (err, 0, 0,"'%s' is not a readable xapian dir", path);
		return NULL;
	}

	try {
		self = new MuQueryXapian;
		
		self->_db      = new Xapian::Database(path);		
		self->_qparser.set_database(*self->_db);
		self->_qparser.set_default_op(Xapian::Query::OP_OR);
		self->_qparser.set_stemming_strategy 
			(Xapian::QueryParser::STEM_SOME);

		memset (self->_sorters, 0, sizeof(self->_sorters));
		
		mu_msg_field_foreach ((MuMsgFieldForEachFunc)add_prefix,
				      (gconstpointer)&self->_qparser);

		return self;
	
	} catch (const Xapian::Error &ex) {
		g_set_error (err, 0, 0,"%s: caught xapian exception '%s' (%s)", 
			     __FUNCTION__, ex.get_msg().c_str(), 
			     ex.get_error_string());
	} catch (...) {
		delete self->_db;
		g_set_error (err, 0, 0,"%s: caught exception", __FUNCTION__);
	}

	if (self) {
		delete self->_db;
		delete self;
	}

	return NULL;
}


void
mu_query_xapian_destroy (MuQueryXapian *self)
{
	if (!self)
		return;

	try {
		for (int i = 0; i != MU_MSG_FIELD_TYPE_NUM; ++i) {
			delete self->_sorters[i];
			self->_sorters[i] = 0;
		}
		
		delete self->_db;
		delete self;

	} catch (const Xapian::Error &err) {
		g_warning ("%s: caught xapian exception '%s' (%s)", 
			   __FUNCTION__, err.get_msg().c_str(), 
			   err.get_error_string());
	} catch (...) {
		g_warning ("%s: caught exception", __FUNCTION__);
	}
}



static Xapian::Query
get_query  (MuQueryXapian *self, const char* searchexpr) 
{	
	return (self->_qparser.parse_query 
		(searchexpr,
		 Xapian::QueryParser::FLAG_BOOLEAN          | 
		 Xapian::QueryParser::FLAG_PHRASE           |
		 Xapian::QueryParser::FLAG_LOVEHATE         |
		 Xapian::QueryParser::FLAG_BOOLEAN_ANY_CASE |
		 Xapian::QueryParser::FLAG_WILDCARD         |
		 Xapian::QueryParser::FLAG_PURE_NOT         |
		 Xapian::QueryParser::FLAG_PARTIAL));
}

MuMsgXapian*
mu_query_xapian_run (MuQueryXapian *self, const char* searchexpr,
		     const MuMsgField* sortfield, gboolean ascending)  
{
	g_return_val_if_fail (self, NULL);
	g_return_val_if_fail (searchexpr, NULL);
		
	try {
		Xapian::Query q(get_query(self, searchexpr));
		Xapian::Enquire enq (*self->_db);
		
		if (sortfield) 
			enq.set_sort_by_value (
				(Xapian::valueno)mu_msg_field_id(sortfield),
				ascending);

		enq.set_query  (q);
		enq.set_cutoff (0,0);

		return mu_msg_xapian_new (enq, 10000);
		
	} catch (const Xapian::Error &err) {
		g_warning ("%s: caught xapian exception '%s' for expr '%s' (%s)", 
			   __FUNCTION__, err.get_msg().c_str(),
			   searchexpr, err.get_error_string());
	} catch (...) {
		g_warning ("%s: caught exception", __FUNCTION__);
	}

	return NULL;

}

char*
mu_query_xapian_as_string  (MuQueryXapian *self, const char* searchexpr) 
{
	g_return_val_if_fail (self, NULL);
	g_return_val_if_fail (searchexpr, NULL);
		
	try {
		Xapian::Query q(get_query(self, searchexpr));
		return g_strdup(q.get_description().c_str());
		
	} catch (const Xapian::Error &err) {
		g_warning ("%s: caught xapian exception '%s' (%s)", 
			   __FUNCTION__, err.get_msg().c_str(), 
			   err.get_error_string());
	} catch (...) {
		g_warning ("%s: caught exception", __FUNCTION__);
	}

	return NULL;
}

char*
mu_query_xapian_combine (GSList *lst, gboolean connect_or)
{
	GString *str;

	g_return_val_if_fail (lst, NULL);
	
	str = g_string_sized_new (64); /* just a guess */
	while (lst) {
		const char* cnx = "";
		if (lst->next)
			cnx = connect_or ? " OR " : " AND ";
		
		g_string_append_printf (str, "%s%s", (gchar*)lst->data, cnx);
		lst = lst->next;
	}

	return g_string_free (str, FALSE);
}