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/* quartz_positionlist.cc
*
* ----START-LICENCE----
* Copyright 1999,2000,2001 BrightStation PLC
* Copyright 2002 Ananova Ltd
* Copyright 2002,2003,2004 Olly Betts
*
* 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 2 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307
* USA
* -----END-LICENCE-----
*/
#include <config.h>
#include "omdebug.h"
#include "quartz_positionlist.h"
#include "quartz_utils.h"
using std::string;
static inline void
make_key(Xapian::docid did, const string & tname, string & key)
{
key = pack_uint(did) + tname;
}
void
QuartzPositionList::read_data(const Btree * table,
Xapian::docid did,
const string & tname)
{
DEBUGCALL(DB, void, "QuartzPositionList::read_data",
table << ", " << did << ", " << tname);
string key;
string tag;
make_key(did, tname, key);
if (!table->get_exact_entry(key, tag)) {
// This isn't an error, since position list not be present simply
// implies that there is no positional information available.
data = "";
pos = data.data();
end = pos;
is_at_end = false;
have_started = false;
current_pos = 0;
number_of_entries = 0;
return;
}
// FIXME: Unwanted copy
data = tag;
pos = data.data();
end = pos + data.size();
is_at_end = false;
have_started = false;
current_pos = 0;
bool success = unpack_uint(&pos, end, &number_of_entries);
if (! success) {
if (pos == 0) {
// data ran out
throw Xapian::DatabaseCorruptError("Data ran out when reading position list length.");
} else {
// overflow
throw Xapian::RangeError("Position list length too large.");
}
}
}
void
QuartzPositionList::next_internal()
{
DEBUGCALL(DB, void, "QuartzPositionList::next_internal", "");
if (pos == end) {
is_at_end = true;
return;
}
Xapian::termpos pos_increment;
bool success = unpack_uint(&pos, end, &pos_increment);
if (! success) {
if (pos == 0) {
// data ran out
throw Xapian::DatabaseCorruptError("Data ran out when reading position list entry.");
} else {
// overflow
throw Xapian::RangeError("Position list length too large.");
}
}
Assert(pos != 0);
current_pos += pos_increment + 1;
}
void
QuartzPositionList::next()
{
DEBUGCALL(DB, void, "QuartzPositionList::next", "");
Assert(!is_at_end);
next_internal();
have_started = true;
DEBUGLINE(DB, string("QuartzPositionList - moved to ") <<
(is_at_end ? string("end.") : std::string("position = ") +
om_tostring(current_pos) + "."));
}
void
QuartzPositionList::skip_to(Xapian::termpos termpos)
{
DEBUGCALL(DB, void, "QuartzPositionList::skip_to", termpos);
if (!have_started) {
next_internal();
have_started = true;
}
while (!is_at_end && current_pos < termpos) next_internal();
DEBUGLINE(DB, string("QuartzPositionList - skipped to ") <<
(is_at_end ? string("end.") : std::string("position = ") +
om_tostring(current_pos) + "."));
}
// Methods modifying position lists
void
QuartzPositionListTable::set_positionlist(Xapian::docid did,
const string & tname,
Xapian::PositionIterator pos,
const Xapian::PositionIterator &pos_end)
{
DEBUGCALL(DB, void, "QuartzPositionList::set_positionlist", did << ", " << tname << ", " << pos << ", " << pos_end);
string key;
make_key(did, tname, key);
string tag;
Xapian::termpos prevpos = 0;
unsigned int size = 0;
for ( ; pos != pos_end; ++pos) {
tag += pack_uint(*pos - prevpos - 1);
prevpos = *pos;
size++;
}
tag = pack_uint(size) + tag;
add(key, tag);
}
void
QuartzPositionListTable::delete_positionlist(Xapian::docid did,
const string & tname)
{
DEBUGCALL(DB, void, "QuartzPositionList::delete_positionlist", did << ", " << tname);
string key;
make_key(did, tname, key);
del(key);
}
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