| /**************************************************************************** |
| ** |
| ** Copyright (C) 2016 The Qt Company Ltd. |
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| ** |
| ** This file is part of the QtSql module of the Qt Toolkit. |
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| ** $QT_BEGIN_LICENSE:LGPL$ |
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| ****************************************************************************/ |
| |
| #include "private/qsqlcachedresult_p.h" |
| |
| #include <qvariant.h> |
| #include <qdatetime.h> |
| #include <qvector.h> |
| #include <QtSql/private/qsqldriver_p.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; |
| |
| QSqlCachedResultPrivate::QSqlCachedResultPrivate(QSqlCachedResult *q, const QSqlDriver *drv) |
| : QSqlResultPrivate(q, drv), |
| rowCacheEnd(0), |
| colCount(0), |
| atEnd(false) |
| { |
| } |
| |
| void QSqlCachedResultPrivate::cleanup() |
| { |
| cache.clear(); |
| 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(QSqlCachedResultPrivate &d) |
| : QSqlResult(d) |
| { |
| } |
| |
| void QSqlCachedResult::init(int colCount) |
| { |
| Q_D(QSqlCachedResult); |
| d->init(colCount, isForwardOnly()); |
| } |
| |
| bool QSqlCachedResult::fetch(int i) |
| { |
| Q_D(QSqlCachedResult); |
| 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() |
| { |
| Q_D(QSqlCachedResult); |
| if (d->canSeek(at() + 1)) { |
| setAt(at() + 1); |
| return true; |
| } |
| return cacheNext(); |
| } |
| |
| bool QSqlCachedResult::fetchPrevious() |
| { |
| return fetch(at() - 1); |
| } |
| |
| bool QSqlCachedResult::fetchFirst() |
| { |
| Q_D(QSqlCachedResult); |
| if (d->forwardOnly && at() != QSql::BeforeFirstRow) { |
| return false; |
| } |
| if (d->canSeek(0)) { |
| setAt(0); |
| return true; |
| } |
| return cacheNext(); |
| } |
| |
| bool QSqlCachedResult::fetchLast() |
| { |
| Q_D(QSqlCachedResult); |
| 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) |
| { |
| Q_D(const QSqlCachedResult); |
| 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) |
| { |
| Q_D(const QSqlCachedResult); |
| 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() |
| { |
| Q_D(QSqlCachedResult); |
| setAt(QSql::BeforeFirstRow); |
| setActive(false); |
| d->cleanup(); |
| } |
| |
| void QSqlCachedResult::clearValues() |
| { |
| Q_D(QSqlCachedResult); |
| setAt(QSql::BeforeFirstRow); |
| d->rowCacheEnd = 0; |
| d->atEnd = false; |
| } |
| |
| bool QSqlCachedResult::cacheNext() |
| { |
| Q_D(QSqlCachedResult); |
| if (d->atEnd) |
| return false; |
| |
| if(isForwardOnly()) { |
| 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 |
| { |
| Q_D(const QSqlCachedResult); |
| return d->colCount; |
| } |
| |
| QSqlCachedResult::ValueCache &QSqlCachedResult::cache() |
| { |
| Q_D(QSqlCachedResult); |
| return d->cache; |
| } |
| |
| void QSqlCachedResult::virtual_hook(int id, void *data) |
| { |
| QSqlResult::virtual_hook(id, data); |
| } |
| |
| void QSqlCachedResult::detachFromResultSet() |
| { |
| cleanup(); |
| } |
| |
| void QSqlCachedResult::setNumericalPrecisionPolicy(QSql::NumericalPrecisionPolicy policy) |
| { |
| QSqlResult::setNumericalPrecisionPolicy(policy); |
| cleanup(); |
| } |
| |
| |
| QT_END_NAMESPACE |