Merge branch 'develop'

Author: devbean

sqlitecipher/sqlcachedresult.cpp

@@ -0,0 +1,314 @@
+/****************************************************************************
+**
+** 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.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "sqlcachedresult_p.h"
+
+QT_BEGIN_NAMESPACE
+
+/*
+   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.
+*/
+
+static const uint initial_cache_size = 128;
+
+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();
+
+    SqlCachedResult::ValueCache cache;
+    int rowCacheEnd;
+    int colCount;
+    bool forwardOnly;
+    bool atEnd;
+};
+
+SqlCachedResultPrivate::SqlCachedResultPrivate():
+    rowCacheEnd(0), colCount(0), forwardOnly(false), atEnd(false)
+{
+}
+
+void SqlCachedResultPrivate::cleanup()
+{
+    cache.clear();
+    forwardOnly = false;
+    atEnd = false;
+    colCount = 0;
+    rowCacheEnd = 0;
+}
+
+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);
+    }
+}
+
+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;
+
+    return newIdx;
+}
+
+bool SqlCachedResultPrivate::canSeek(int i) const
+{
+    if (forwardOnly || i < 0)
+        return false;
+    return rowCacheEnd >= (i + 1) * colCount;
+}
+
+void SqlCachedResultPrivate::revertLast()
+{
+    if (forwardOnly)
+        return;
+    rowCacheEnd -= colCount;
+}
+
+inline int SqlCachedResultPrivate::cacheCount() const
+{
+    Q_ASSERT(!forwardOnly);
+    Q_ASSERT(colCount);
+    return rowCacheEnd / colCount;
+}
+
+//////////////
+
+SqlCachedResult::SqlCachedResult(const QSqlDriver * db): QSqlResult (db)
+{
+    d = new SqlCachedResultPrivate();
+}
+
+SqlCachedResult::~SqlCachedResult()
+{
+    delete d;
+}
+
+void SqlCachedResult::init(int colCount)
+{
+    d->init(colCount, isForwardOnly());
+}
+
+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);
+
+    return true;
+}
+
+bool SqlCachedResult::fetchNext()
+{
+    if (d->canSeek(at() + 1)) {
+        setAt(at() + 1);
+        return true;
+    }
+    return cacheNext();
+}
+
+bool SqlCachedResult::fetchPrevious()
+{
+    return fetch(at() - 1);
+}
+
+bool SqlCachedResult::fetchFirst()
+{
+    if (d->forwardOnly && at() != QSql::BeforeFirstRow) {
+        return false;
+    }
+    if (d->canSeek(0)) {
+        setAt(0);
+        return true;
+    }
+    return cacheNext();
+}
+
+bool SqlCachedResult::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 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();
+
+    return d->cache.at(idx);
+}
+
+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;
+
+    return d->cache.at(idx).isNull();
+}
+
+void SqlCachedResult::cleanup()
+{
+    setAt(QSql::BeforeFirstRow);
+    setActive(false);
+    d->cleanup();
+}
+
+void SqlCachedResult::clearValues()
+{
+    setAt(QSql::BeforeFirstRow);
+    d->rowCacheEnd = 0;
+    d->atEnd = false;
+}
+
+bool SqlCachedResult::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 SqlCachedResult::colCount() const
+{
+    return d->colCount;
+}
+
+SqlCachedResult::ValueCache &SqlCachedResult::cache()
+{
+    return d->cache;
+}
+
+void SqlCachedResult::virtual_hook(int id, void *data)
+{
+    QSqlResult::virtual_hook(id, data);
+}
+
+void SqlCachedResult::detachFromResultSet()
+{
+    cleanup();
+}
+
+void SqlCachedResult::setNumericalPrecisionPolicy(QSql::NumericalPrecisionPolicy policy)
+{
+    QSqlResult::setNumericalPrecisionPolicy(policy);
+    cleanup();
+}
+
+QT_END_NAMESPACE