mirror of
https://github.com/clementine-player/Clementine
synced 2024-12-23 08:20:01 +01:00
323 lines
7.9 KiB
C++
323 lines
7.9 KiB
C++
/****************************************************************************
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**
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** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
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** Contact: http://www.qt-project.org/legal
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**
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** This file is part of the QtSql module of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and Digia. For licensing terms and
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** conditions see http://qt.digia.com/licensing. For further information
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** use the contact form at http://qt.digia.com/contact-us.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 2.1 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU Lesser General Public License version 2.1 requirements
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** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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**
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** In addition, as a special exception, Digia gives you certain additional
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** rights. These rights are described in the Digia Qt LGPL Exception
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 3.0 as published by the Free Software
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** Foundation and appearing in the file LICENSE.GPL included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU General Public License version 3.0 requirements will be
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** met: http://www.gnu.org/copyleft/gpl.html.
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**
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#include <qvariant.h>
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#include <qdatetime.h>
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#include <qvector.h>
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#include "clementinesqlcachedresult.h"
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QT_BEGIN_NAMESPACE
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/*
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ClementineSqlCachedResult is a convenience class for databases that only allow
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forward only fetching. It will cache all the results so we can iterate
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backwards over the results again.
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All you need to do is to inherit from ClementineSqlCachedResult and reimplement
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gotoNext(). gotoNext() will have a reference to the internal cache and
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will give you an index where you can start filling in your data. Special
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case: If the user actually wants a forward-only query, idx will be -1
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to indicate that we are not interested in the actual values.
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*/
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static const uint initial_cache_size = 128;
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class ClementineSqlCachedResultPrivate
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{
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public:
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ClementineSqlCachedResultPrivate();
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bool canSeek(int i) const;
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inline int cacheCount() const;
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void init(int count, bool fo);
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void cleanup();
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int nextIndex();
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void revertLast();
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ClementineSqlCachedResult::ValueCache cache;
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int rowCacheEnd;
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int colCount;
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bool forwardOnly;
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bool atEnd;
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};
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ClementineSqlCachedResultPrivate::ClementineSqlCachedResultPrivate():
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rowCacheEnd(0), colCount(0), forwardOnly(false), atEnd(false)
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{
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}
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void ClementineSqlCachedResultPrivate::cleanup()
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{
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cache.clear();
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forwardOnly = false;
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atEnd = false;
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colCount = 0;
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rowCacheEnd = 0;
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}
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void ClementineSqlCachedResultPrivate::init(int count, bool fo)
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{
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Q_ASSERT(count);
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cleanup();
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forwardOnly = fo;
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colCount = count;
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if (fo) {
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cache.resize(count);
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rowCacheEnd = count;
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} else {
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cache.resize(initial_cache_size * count);
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}
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}
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int ClementineSqlCachedResultPrivate::nextIndex()
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{
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if (forwardOnly)
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return 0;
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int newIdx = rowCacheEnd;
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if (newIdx + colCount > cache.size())
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cache.resize(qMin(cache.size() * 2, cache.size() + 10000));
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rowCacheEnd += colCount;
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return newIdx;
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}
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bool ClementineSqlCachedResultPrivate::canSeek(int i) const
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{
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if (forwardOnly || i < 0)
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return false;
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return rowCacheEnd >= (i + 1) * colCount;
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}
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void ClementineSqlCachedResultPrivate::revertLast()
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{
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if (forwardOnly)
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return;
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rowCacheEnd -= colCount;
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}
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inline int ClementineSqlCachedResultPrivate::cacheCount() const
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{
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Q_ASSERT(!forwardOnly);
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Q_ASSERT(colCount);
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return rowCacheEnd / colCount;
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}
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//////////////
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ClementineSqlCachedResult::ClementineSqlCachedResult(const QSqlDriver * db): QSqlResult (db)
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{
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d = new ClementineSqlCachedResultPrivate();
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}
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ClementineSqlCachedResult::~ClementineSqlCachedResult()
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{
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delete d;
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}
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void ClementineSqlCachedResult::init(int colCount)
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{
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d->init(colCount, isForwardOnly());
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}
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bool ClementineSqlCachedResult::fetch(int i)
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{
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if ((!isActive()) || (i < 0))
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return false;
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if (at() == i)
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return true;
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if (d->forwardOnly) {
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// speed hack - do not copy values if not needed
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if (at() > i || at() == QSql::AfterLastRow)
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return false;
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while(at() < i - 1) {
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if (!gotoNext(d->cache, -1))
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return false;
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setAt(at() + 1);
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}
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if (!gotoNext(d->cache, 0))
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return false;
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setAt(at() + 1);
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return true;
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}
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if (d->canSeek(i)) {
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setAt(i);
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return true;
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}
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if (d->rowCacheEnd > 0)
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setAt(d->cacheCount());
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while (at() < i + 1) {
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if (!cacheNext()) {
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if (d->canSeek(i))
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break;
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return false;
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}
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}
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setAt(i);
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return true;
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}
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bool ClementineSqlCachedResult::fetchNext()
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{
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if (d->canSeek(at() + 1)) {
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setAt(at() + 1);
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return true;
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}
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return cacheNext();
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}
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bool ClementineSqlCachedResult::fetchPrevious()
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{
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return fetch(at() - 1);
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}
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bool ClementineSqlCachedResult::fetchFirst()
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{
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if (d->forwardOnly && at() != QSql::BeforeFirstRow) {
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return false;
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}
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if (d->canSeek(0)) {
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setAt(0);
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return true;
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}
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return cacheNext();
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}
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bool ClementineSqlCachedResult::fetchLast()
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{
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if (d->atEnd) {
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if (d->forwardOnly)
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return false;
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else
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return fetch(d->cacheCount() - 1);
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}
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int i = at();
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while (fetchNext())
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++i; /* brute force */
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if (d->forwardOnly && at() == QSql::AfterLastRow) {
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setAt(i);
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return true;
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} else {
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return fetch(i);
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}
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}
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QVariant ClementineSqlCachedResult::data(int i)
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{
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int idx = d->forwardOnly ? i : at() * d->colCount + i;
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if (i >= d->colCount || i < 0 || at() < 0 || idx >= d->rowCacheEnd)
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return QVariant();
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return d->cache.at(idx);
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}
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bool ClementineSqlCachedResult::isNull(int i)
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{
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int idx = d->forwardOnly ? i : at() * d->colCount + i;
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if (i > d->colCount || i < 0 || at() < 0 || idx >= d->rowCacheEnd)
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return true;
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return d->cache.at(idx).isNull();
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}
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void ClementineSqlCachedResult::cleanup()
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{
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setAt(QSql::BeforeFirstRow);
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setActive(false);
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d->cleanup();
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}
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void ClementineSqlCachedResult::clearValues()
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{
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setAt(QSql::BeforeFirstRow);
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d->rowCacheEnd = 0;
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d->atEnd = false;
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}
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bool ClementineSqlCachedResult::cacheNext()
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{
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if (d->atEnd)
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return false;
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if(isForwardOnly()) {
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d->cache.clear();
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d->cache.resize(d->colCount);
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}
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if (!gotoNext(d->cache, d->nextIndex())) {
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d->revertLast();
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d->atEnd = true;
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return false;
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}
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setAt(at() + 1);
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return true;
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}
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int ClementineSqlCachedResult::colCount() const
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{
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return d->colCount;
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}
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ClementineSqlCachedResult::ValueCache &ClementineSqlCachedResult::cache()
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{
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return d->cache;
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}
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void ClementineSqlCachedResult::virtual_hook(int id, void *data)
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{
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QSqlResult::virtual_hook(id, data);
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}
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void ClementineSqlCachedResult::detachFromResultSet()
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{
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cleanup();
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}
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void ClementineSqlCachedResult::setNumericalPrecisionPolicy(QSql::NumericalPrecisionPolicy policy)
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{
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QSqlResult::setNumericalPrecisionPolicy(policy);
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cleanup();
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}
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QT_END_NAMESPACE
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