--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/sql/kernel/qsqlcachedresult.cpp Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,313 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 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.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, 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.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#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 (!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