| /**************************************************************************** |
| ** |
| ** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies). |
| ** All rights reserved. |
| ** Contact: Nokia Corporation (qt-info@nokia.com) |
| ** |
| ** This file is part of the QtSql module of the Qt Toolkit. |
| ** |
| ** $QT_BEGIN_LICENSE:LGPL$ |
| ** GNU Lesser General Public License Usage |
| ** This file may be used under the terms of the GNU Lesser General Public |
| ** License version 2.1 as published by the Free Software Foundation and |
| ** appearing in the file LICENSE.LGPL included in the packaging of this |
| ** file. Please review the following information to ensure the GNU Lesser |
| ** General Public License version 2.1 requirements will be met: |
| ** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. |
| ** |
| ** In addition, as a special exception, Nokia gives you certain additional |
| ** rights. These rights are described in the Nokia Qt LGPL Exception |
| ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. |
| ** |
| ** GNU General Public License Usage |
| ** Alternatively, this file may be used under the terms of the GNU General |
| ** Public License version 3.0 as published by the Free Software Foundation |
| ** and appearing in the file LICENSE.GPL included in the packaging of this |
| ** file. Please review the following information to ensure the GNU General |
| ** Public License version 3.0 requirements will be met: |
| ** http://www.gnu.org/copyleft/gpl.html. |
| ** |
| ** Other Usage |
| ** Alternatively, this file may be used in accordance with the terms and |
| ** conditions contained in a signed written agreement between you and Nokia. |
| ** |
| ** |
| ** |
| ** |
| ** |
| ** $QT_END_LICENSE$ |
| ** |
| ****************************************************************************/ |
| |
| #include "private/qsqlcachedresult_p.h" |
| |
| #include <qvariant.h> |
| #include <qdatetime.h> |
| #include <qvector.h> |
| |
| QT_BEGIN_NAMESPACE |
| |
| /* |
| QSqlCachedResult is a convenience class for databases that only allow |
| forward only fetching. It will cache all the results so we can iterate |
| backwards over the results again. |
| |
| All you need to do is to inherit from QSqlCachedResult and reimplement |
| gotoNext(). gotoNext() will have a reference to the internal cache and |
| will give you an index where you can start filling in your data. Special |
| case: If the user actually wants a forward-only query, idx will be -1 |
| to indicate that we are not interested in the actual values. |
| */ |
| |
| static const uint initial_cache_size = 128; |
| |
| class QSqlCachedResultPrivate |
| { |
| public: |
| QSqlCachedResultPrivate(); |
| bool canSeek(int i) const; |
| inline int cacheCount() const; |
| void init(int count, bool fo); |
| void cleanup(); |
| int nextIndex(); |
| void revertLast(); |
| |
| QSqlCachedResult::ValueCache cache; |
| int rowCacheEnd; |
| int colCount; |
| bool forwardOnly; |
| bool atEnd; |
| }; |
| |
| QSqlCachedResultPrivate::QSqlCachedResultPrivate(): |
| rowCacheEnd(0), colCount(0), forwardOnly(false), atEnd(false) |
| { |
| } |
| |
| void QSqlCachedResultPrivate::cleanup() |
| { |
| cache.clear(); |
| forwardOnly = false; |
| atEnd = false; |
| colCount = 0; |
| rowCacheEnd = 0; |
| } |
| |
| void QSqlCachedResultPrivate::init(int count, bool fo) |
| { |
| Q_ASSERT(count); |
| cleanup(); |
| forwardOnly = fo; |
| colCount = count; |
| if (fo) { |
| cache.resize(count); |
| rowCacheEnd = count; |
| } else { |
| cache.resize(initial_cache_size * count); |
| } |
| } |
| |
| int QSqlCachedResultPrivate::nextIndex() |
| { |
| if (forwardOnly) |
| return 0; |
| int newIdx = rowCacheEnd; |
| if (newIdx + colCount > cache.size()) |
| cache.resize(qMin(cache.size() * 2, cache.size() + 10000)); |
| rowCacheEnd += colCount; |
| |
| return newIdx; |
| } |
| |
| bool QSqlCachedResultPrivate::canSeek(int i) const |
| { |
| if (forwardOnly || i < 0) |
| return false; |
| return rowCacheEnd >= (i + 1) * colCount; |
| } |
| |
| void QSqlCachedResultPrivate::revertLast() |
| { |
| if (forwardOnly) |
| return; |
| rowCacheEnd -= colCount; |
| } |
| |
| inline int QSqlCachedResultPrivate::cacheCount() const |
| { |
| Q_ASSERT(!forwardOnly); |
| Q_ASSERT(colCount); |
| return rowCacheEnd / colCount; |
| } |
| |
| ////////////// |
| |
| QSqlCachedResult::QSqlCachedResult(const QSqlDriver * db): QSqlResult (db) |
| { |
| d = new QSqlCachedResultPrivate(); |
| } |
| |
| QSqlCachedResult::~QSqlCachedResult() |
| { |
| delete d; |
| } |
| |
| void QSqlCachedResult::init(int colCount) |
| { |
| d->init(colCount, isForwardOnly()); |
| } |
| |
| bool QSqlCachedResult::fetch(int i) |
| { |
| if ((!isActive()) || (i < 0)) |
| return false; |
| if (at() == i) |
| return true; |
| if (d->forwardOnly) { |
| // speed hack - do not copy values if not needed |
| if (at() > i || at() == QSql::AfterLastRow) |
| return false; |
| while(at() < i - 1) { |
| if (!gotoNext(d->cache, -1)) |
| return false; |
| setAt(at() + 1); |
| } |
| if (!gotoNext(d->cache, 0)) |
| return false; |
| setAt(at() + 1); |
| return true; |
| } |
| if (d->canSeek(i)) { |
| setAt(i); |
| return true; |
| } |
| if (d->rowCacheEnd > 0) |
| setAt(d->cacheCount()); |
| while (at() < i + 1) { |
| if (!cacheNext()) { |
| if (d->canSeek(i)) |
| break; |
| return false; |
| } |
| } |
| setAt(i); |
| |
| return true; |
| } |
| |
| bool QSqlCachedResult::fetchNext() |
| { |
| if (d->canSeek(at() + 1)) { |
| setAt(at() + 1); |
| return true; |
| } |
| return cacheNext(); |
| } |
| |
| bool QSqlCachedResult::fetchPrevious() |
| { |
| return fetch(at() - 1); |
| } |
| |
| bool QSqlCachedResult::fetchFirst() |
| { |
| if (d->forwardOnly && at() != QSql::BeforeFirstRow) { |
| return false; |
| } |
| if (d->canSeek(0)) { |
| setAt(0); |
| return true; |
| } |
| return cacheNext(); |
| } |
| |
| bool QSqlCachedResult::fetchLast() |
| { |
| if (d->atEnd) { |
| if (d->forwardOnly) |
| return false; |
| else |
| return fetch(d->cacheCount() - 1); |
| } |
| |
| int i = at(); |
| while (fetchNext()) |
| ++i; /* brute force */ |
| if (d->forwardOnly && at() == QSql::AfterLastRow) { |
| setAt(i); |
| return true; |
| } else { |
| return fetch(i); |
| } |
| } |
| |
| QVariant QSqlCachedResult::data(int i) |
| { |
| int idx = d->forwardOnly ? i : at() * d->colCount + i; |
| if (i >= d->colCount || i < 0 || at() < 0 || idx >= d->rowCacheEnd) |
| return QVariant(); |
| |
| return d->cache.at(idx); |
| } |
| |
| bool QSqlCachedResult::isNull(int i) |
| { |
| int idx = d->forwardOnly ? i : at() * d->colCount + i; |
| if (i > d->colCount || i < 0 || at() < 0 || idx >= d->rowCacheEnd) |
| return true; |
| |
| return d->cache.at(idx).isNull(); |
| } |
| |
| void QSqlCachedResult::cleanup() |
| { |
| setAt(QSql::BeforeFirstRow); |
| setActive(false); |
| d->cleanup(); |
| } |
| |
| void QSqlCachedResult::clearValues() |
| { |
| setAt(QSql::BeforeFirstRow); |
| d->rowCacheEnd = 0; |
| d->atEnd = false; |
| } |
| |
| bool QSqlCachedResult::cacheNext() |
| { |
| if (d->atEnd) |
| return false; |
| |
| if(isForwardOnly()) { |
| d->cache.clear(); |
| d->cache.resize(d->colCount); |
| } |
| |
| if (!gotoNext(d->cache, d->nextIndex())) { |
| d->revertLast(); |
| d->atEnd = true; |
| return false; |
| } |
| setAt(at() + 1); |
| return true; |
| } |
| |
| int QSqlCachedResult::colCount() const |
| { |
| return d->colCount; |
| } |
| |
| QSqlCachedResult::ValueCache &QSqlCachedResult::cache() |
| { |
| return d->cache; |
| } |
| |
| void QSqlCachedResult::virtual_hook(int id, void *data) |
| { |
| switch (id) { |
| case QSqlResult::DetachFromResultSet: |
| case QSqlResult::SetNumericalPrecision: |
| cleanup(); |
| break; |
| default: |
| QSqlResult::virtual_hook(id, data); |
| } |
| } |
| |
| |
| QT_END_NAMESPACE |