backends/flint/flint_modifiedpostlist.cc

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/* Copyright (C) 2006,2007 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 */

#include <config.h>

#include "flint_database.h"
#include "flint_modifiedpostlist.h"

FlintModifiedPostList::~FlintModifiedPostList()
{
    delete poslist;
}

void
FlintModifiedPostList::skip_deletes(Xapian::weight w_min)
{
    while (!FlintPostList::at_end()) {
        while (it != mods.end() && it->second.first == 'D' &&
               it->first < FlintPostList::get_docid())
            ++it;
        if (it == mods.end()) return;
        if (it->first != FlintPostList::get_docid()) return;
        if (it->second.first != 'D') return;
        ++it;
        FlintPostList::next(w_min);
    }
    while (it != mods.end() && it->second.first == 'D') ++it;
}

Xapian::doccount
FlintModifiedPostList::get_termfreq() const
{
    return this_db->get_termfreq(term);
}

Xapian::docid
FlintModifiedPostList::get_docid() const
{
    if (it == mods.end()) return FlintPostList::get_docid();
    if (FlintPostList::at_end()) return it->first;
    Assert(it->second.first != 'D');
    return min(it->first, FlintPostList::get_docid());
}

Xapian::doclength
FlintModifiedPostList::get_doclength() const
{
    DEBUGCALL(DB, Xapian::doclength, "FlintModifiedPostList::get_doclength", "");
    if (it != mods.end() && (FlintPostList::at_end() || it->first <= FlintPostList::get_docid()))
        RETURN(this_db->get_doclength(it->first));
    RETURN(FlintPostList::get_doclength());
}

Xapian::termcount
FlintModifiedPostList::get_wdf() const
{
    if (FlintPostList::at_end()) return it->second.second;
    Xapian::docid unmod_did = FlintPostList::get_docid();
    if (it != mods.end() && it->first <= unmod_did) {
        if (it->first < unmod_did) return it->second.second;
        return it->second.second;
    }
    return FlintPostList::get_wdf();
}

PositionList *
FlintModifiedPostList::read_position_list()
{
    if (it != mods.end() && (FlintPostList::at_end() || it->first <= FlintPostList::get_docid())) {
        if (poslist) {
            delete poslist;
            poslist = NULL;
        }
        poslist = this_db->open_position_list(it->first, term);
        return poslist;
    }
    return FlintPostList::read_position_list();
}

PositionList *
FlintModifiedPostList::open_position_list() const
{
    if (it != mods.end() && (FlintPostList::at_end() || it->first <= FlintPostList::get_docid())) {
        return this_db->open_position_list(it->first, term);
    }
    return FlintPostList::open_position_list();
}

PostList *
FlintModifiedPostList::next(Xapian::weight w_min)
{
    if (have_started) {
        if (FlintPostList::at_end()) {
            ++it;
            skip_deletes(w_min);
            return NULL;
        }
        Xapian::docid unmod_did = FlintPostList::get_docid();
        if (it != mods.end() && it->first <= unmod_did) {
            if (it->first < unmod_did && it->second.first != 'D') {
                ++it;
                skip_deletes(w_min);
                return NULL;
            }
            ++it;
        }
    }
    FlintPostList::next(w_min);
    skip_deletes(w_min);
    return NULL;
}

PostList *
FlintModifiedPostList::skip_to(Xapian::docid desired_did, Xapian::weight w_min)
{
    if (!FlintPostList::at_end()) FlintPostList::skip_to(desired_did, w_min);
    /* FIXME: should we use lower_bound() on the map? */
    while (it != mods.end() && it->first < desired_did) ++it;
    skip_deletes(w_min);
    return NULL;
}

bool
FlintModifiedPostList::at_end() const {
    return it == mods.end() && FlintPostList::at_end();
}

std::string
FlintModifiedPostList::get_description() const
{
    std::string desc = "FlintModifiedPostList(";
    desc += FlintPostList::get_description();
    desc += ')';
    return desc;
}

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