slowvaluelist.cc

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/* Copyright (C) 2008,2011,2013,2014,2018 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 "slowvaluelist.h"

#include "document.h"
#include "str.h"
#include "unicode/description_append.h"

#include "xapian/error.h"

#include "autoptr.h"

using namespace std;

Xapian::docid
SlowValueList::get_docid() const
{
    return current_did;
}

string
SlowValueList::get_value() const
{
    return current_value;
}

Xapian::valueno
SlowValueList::get_valueno() const
{
    return slot;
}

bool
SlowValueList::at_end() const
{
    return last_docid == 0;
}

void
SlowValueList::next()
{
    // Compare before incrementing, since last_docid could be the largest
    // representable value in which case current_did will wrap to zero before
    // exceeding it.
    while (current_did++ < last_docid) {
        try {
            // Open document lazily so that we don't waste time checking for
            // its existence.
            void * d = db->open_document(current_did, true);
            if (!d)
                continue;
            AutoPtr<Xapian::Document::Internal>
                doc(static_cast<Xapian::Document::Internal*>(d));
            string value = doc->get_value(slot);
            if (!value.empty()) {
                swap(current_value, value);
                return;
            }
        } catch (const Xapian::DocNotFoundError &) {
        }
    }

    // Indicate that we're at_end().
    last_docid = 0;
}

void
SlowValueList::skip_to(Xapian::docid did)
{
    if (did <= current_did) return;
    current_did = did - 1;
    next();
}

bool
SlowValueList::check(Xapian::docid did)
{
    if (did <= current_did) {
        return !current_value.empty();
    }

    if (did > last_docid) {
        // Indicate that we're at_end().
        last_docid = 0;
        return true;
    }

    current_did = did;
    try {
        void * d = db->open_document(current_did, true);
        if (d) {
            AutoPtr<Xapian::Document::Internal>
                doc(static_cast<Xapian::Document::Internal*>(d));
            current_value = doc->get_value(slot);
            if (!current_value.empty()) return true;
        }
    } catch (const Xapian::DocNotFoundError &) {
    }
    current_value = string();
    return false;
}

string
SlowValueList::get_description() const
{
    string desc = "SlowValueList(slot=";
    desc += str(slot);
    if (last_docid != 0) {
        desc += ", docid=";
        desc += str(current_did);
        desc += ", value=\"";
        description_append(desc, current_value);
        desc += "\")";
    } else {
        desc += ", atend)";
    }
    return desc;
}