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/**************************************************************************** | ||
** | ||
** Copyright (C) 2016 The Qt Company Ltd. | ||
** Contact: https://www.qt.io/licensing/ | ||
** | ||
** This file is part of the QtSql module of the Qt Toolkit. | ||
** | ||
** $QT_BEGIN_LICENSE:LGPL$ | ||
** Commercial License Usage | ||
** Licensees holding valid commercial Qt licenses may use this file in | ||
** accordance with the commercial license agreement provided with the | ||
** Software or, alternatively, in accordance with the terms contained in | ||
** a written agreement between you and The Qt Company. For licensing terms | ||
** and conditions see https://www.qt.io/terms-conditions. For further | ||
** information use the contact form at https://www.qt.io/contact-us. | ||
** | ||
** GNU Lesser General Public License Usage | ||
** Alternatively, this file may be used under the terms of the GNU Lesser | ||
** General Public License version 3 as published by the Free Software | ||
** Foundation and appearing in the file LICENSE.LGPL3 included in the | ||
** packaging of this file. Please review the following information to | ||
** ensure the GNU Lesser General Public License version 3 requirements | ||
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. | ||
** | ||
** GNU General Public License Usage | ||
** Alternatively, this file may be used under the terms of the GNU | ||
** General Public License version 2.0 or (at your option) the GNU General | ||
** Public license version 3 or any later version approved by the KDE Free | ||
** Qt Foundation. The licenses are as published by the Free Software | ||
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 | ||
** included in the packaging of this file. Please review the following | ||
** information to ensure the GNU General Public License requirements will | ||
** be met: https://www.gnu.org/licenses/gpl-2.0.html and | ||
** https://www.gnu.org/licenses/gpl-3.0.html. | ||
** | ||
** $QT_END_LICENSE$ | ||
** | ||
****************************************************************************/ | ||
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#include "sqlcachedresult_p.h" | ||
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QT_BEGIN_NAMESPACE | ||
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/* | ||
SqlCachedResult 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 SqlCachedResult 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. | ||
*/ | ||
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static const uint initial_cache_size = 128; | ||
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class SqlCachedResultPrivate | ||
{ | ||
public: | ||
SqlCachedResultPrivate(); | ||
bool canSeek(int i) const; | ||
inline int cacheCount() const; | ||
void init(int count, bool fo); | ||
void cleanup(); | ||
int nextIndex(); | ||
void revertLast(); | ||
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SqlCachedResult::ValueCache cache; | ||
int rowCacheEnd; | ||
int colCount; | ||
bool forwardOnly; | ||
bool atEnd; | ||
}; | ||
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SqlCachedResultPrivate::SqlCachedResultPrivate(): | ||
rowCacheEnd(0), colCount(0), forwardOnly(false), atEnd(false) | ||
{ | ||
} | ||
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void SqlCachedResultPrivate::cleanup() | ||
{ | ||
cache.clear(); | ||
forwardOnly = false; | ||
atEnd = false; | ||
colCount = 0; | ||
rowCacheEnd = 0; | ||
} | ||
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void SqlCachedResultPrivate::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); | ||
} | ||
} | ||
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int SqlCachedResultPrivate::nextIndex() | ||
{ | ||
if (forwardOnly) | ||
return 0; | ||
int newIdx = rowCacheEnd; | ||
if (newIdx + colCount > cache.size()) | ||
cache.resize(qMin(cache.size() * 2, cache.size() + 10000)); | ||
rowCacheEnd += colCount; | ||
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return newIdx; | ||
} | ||
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bool SqlCachedResultPrivate::canSeek(int i) const | ||
{ | ||
if (forwardOnly || i < 0) | ||
return false; | ||
return rowCacheEnd >= (i + 1) * colCount; | ||
} | ||
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void SqlCachedResultPrivate::revertLast() | ||
{ | ||
if (forwardOnly) | ||
return; | ||
rowCacheEnd -= colCount; | ||
} | ||
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inline int SqlCachedResultPrivate::cacheCount() const | ||
{ | ||
Q_ASSERT(!forwardOnly); | ||
Q_ASSERT(colCount); | ||
return rowCacheEnd / colCount; | ||
} | ||
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////////////// | ||
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SqlCachedResult::SqlCachedResult(const QSqlDriver * db): QSqlResult (db) | ||
{ | ||
d = new SqlCachedResultPrivate(); | ||
} | ||
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SqlCachedResult::~SqlCachedResult() | ||
{ | ||
delete d; | ||
} | ||
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void SqlCachedResult::init(int colCount) | ||
{ | ||
d->init(colCount, isForwardOnly()); | ||
} | ||
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bool SqlCachedResult::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); | ||
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return true; | ||
} | ||
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bool SqlCachedResult::fetchNext() | ||
{ | ||
if (d->canSeek(at() + 1)) { | ||
setAt(at() + 1); | ||
return true; | ||
} | ||
return cacheNext(); | ||
} | ||
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bool SqlCachedResult::fetchPrevious() | ||
{ | ||
return fetch(at() - 1); | ||
} | ||
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bool SqlCachedResult::fetchFirst() | ||
{ | ||
if (d->forwardOnly && at() != QSql::BeforeFirstRow) { | ||
return false; | ||
} | ||
if (d->canSeek(0)) { | ||
setAt(0); | ||
return true; | ||
} | ||
return cacheNext(); | ||
} | ||
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bool SqlCachedResult::fetchLast() | ||
{ | ||
if (d->atEnd) { | ||
if (d->forwardOnly) | ||
return false; | ||
else | ||
return fetch(d->cacheCount() - 1); | ||
} | ||
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int i = at(); | ||
while (fetchNext()) | ||
++i; /* brute force */ | ||
if (d->forwardOnly && at() == QSql::AfterLastRow) { | ||
setAt(i); | ||
return true; | ||
} else { | ||
return fetch(i); | ||
} | ||
} | ||
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QVariant SqlCachedResult::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(); | ||
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return d->cache.at(idx); | ||
} | ||
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bool SqlCachedResult::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; | ||
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return d->cache.at(idx).isNull(); | ||
} | ||
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void SqlCachedResult::cleanup() | ||
{ | ||
setAt(QSql::BeforeFirstRow); | ||
setActive(false); | ||
d->cleanup(); | ||
} | ||
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void SqlCachedResult::clearValues() | ||
{ | ||
setAt(QSql::BeforeFirstRow); | ||
d->rowCacheEnd = 0; | ||
d->atEnd = false; | ||
} | ||
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bool SqlCachedResult::cacheNext() | ||
{ | ||
if (d->atEnd) | ||
return false; | ||
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if(isForwardOnly()) { | ||
d->cache.clear(); | ||
d->cache.resize(d->colCount); | ||
} | ||
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if (!gotoNext(d->cache, d->nextIndex())) { | ||
d->revertLast(); | ||
d->atEnd = true; | ||
return false; | ||
} | ||
setAt(at() + 1); | ||
return true; | ||
} | ||
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int SqlCachedResult::colCount() const | ||
{ | ||
return d->colCount; | ||
} | ||
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SqlCachedResult::ValueCache &SqlCachedResult::cache() | ||
{ | ||
return d->cache; | ||
} | ||
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void SqlCachedResult::virtual_hook(int id, void *data) | ||
{ | ||
QSqlResult::virtual_hook(id, data); | ||
} | ||
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void SqlCachedResult::detachFromResultSet() | ||
{ | ||
cleanup(); | ||
} | ||
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void SqlCachedResult::setNumericalPrecisionPolicy(QSql::NumericalPrecisionPolicy policy) | ||
{ | ||
QSqlResult::setNumericalPrecisionPolicy(policy); | ||
cleanup(); | ||
} | ||
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QT_END_NAMESPACE |
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