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"

static void add_prefix (const MuMsgField* field, Xapian::QueryParser* qparser);

class _MuQueryXapian {
public:
	_MuQueryXapian (const char *path) : _db(Xapian::Database(path)) {

		_qparser.set_database(_db);
		_qparser.set_default_op(Xapian::Query::OP_OR);
		_qparser.set_stemming_strategy 
			(Xapian::QueryParser::STEM_SOME);

		memset (_sorters, 0, sizeof(_sorters));
		
		mu_msg_field_foreach ((MuMsgFieldForEachFunc)add_prefix,
				      (gconstpointer)&_qparser);
	}

	~_MuQueryXapian () {
		try {
			for (int i = 0; i != MU_MSG_FIELD_TYPE_NUM; ++i) 
				delete _sorters[i];
		} catch (...) {
			g_warning ("%s: caught exception", __FUNCTION__);
		}
	}
	
	Xapian::Query get_query  (const char* searchexpr) {
		return _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);
	}
	const Xapian::Database&    db() { return _db; }

private:
	const 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)
{
	char *xpath;
	
	g_return_val_if_fail (path, NULL);

	/* move this to common place? */
	xpath = g_strdup_printf ("%s%c%s", path, G_DIR_SEPARATOR, "xapian");
	if (!g_file_test (xpath, G_FILE_TEST_IS_DIR) ||
	    g_access(xpath, R_OK) != 0) { 
		g_warning ("'%s' is not a readable xapian dir", xpath);
		g_free (xpath);
		return NULL;
	}
	
	try {
		MuQueryXapian *qx (new MuQueryXapian (xpath));
		g_free (xpath);
		return qx;
		
	} catch (...) {
		g_free (xpath);
		g_warning ("%s: caught exception", __FUNCTION__);
		return NULL;
	}
}


void
mu_query_xapian_destroy (MuQueryXapian *self)
{
	try {
		delete self;
	} catch (...) {
		g_warning ("%s: caught exception", __FUNCTION__);
	}
}




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(self->get_query(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(self->get_query(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);
}