QArrayDataOps: generic array operations

This class, the selector and underlying implementations provide
specialized operations on QArrayData, while allowing for optimized
implementations that benefit from type-specific information.

Currently, offering a generic implementation and specializations for
PODs (trivial ctor, dtor and move operations) and movable types (can be
trivially moved in memory).

Change-Id: I2c5829b66c2aea79f12f21debe5c01f7104c7ea3
Reviewed-by: Bradley T. Hughes <bradley.hughes@nokia.com>

2 files changed, 183 insertions, 0 deletions

diff --git a/src/corelib/tools/qarraydataops.h b/src/corelib/tools/qarraydataops.h
new file mode 100644
index 0000000000..d62c411511
--- /dev/null
+++ b/src/corelib/tools/qarraydataops.h
@@ -0,0 +1,182 @@
+/****************************************************************************
+**
+** 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 QtCore 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.
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QARRAYDATAOPS_H
+#define QARRAYDATAOPS_H
+
+#include <QtCore/qarraydata.h>
+
+#include <new>
+#include <string.h>
+
+QT_BEGIN_HEADER
+
+QT_BEGIN_NAMESPACE
+
+QT_MODULE(Core)
+
+namespace QtPrivate {
+
+template <class T>
+struct QPodArrayOps
+    : QTypedArrayData<T>
+{
+    void copyAppend(const T *b, const T *e)
+    {
+        Q_ASSERT(this->ref == 1);
+        Q_ASSERT(b < e);
+        Q_ASSERT(size_t(e - b) <= this->alloc - uint(this->size));
+
+        ::memcpy(this->end(), b, (e - b) * sizeof(T));
+        this->size += e - b;
+    }
+
+    void copyAppend(size_t n, const T &t)
+    {
+        Q_ASSERT(this->ref == 1);
+        Q_ASSERT(n <= this->alloc - uint(this->size));
+
+        T *iter = this->end();
+        const T *const end = iter + n;
+        for (; iter != end; ++iter)
+            ::memcpy(iter, &t, sizeof(T));
+        this->size += n;
+    }
+
+    void destroyAll() // Call from destructors, ONLY!
+    {
+        Q_ASSERT(this->ref == 0);
+
+        // As this is to be called only from destructor, it doesn't need to be
+        // exception safe; size not updated.
+    }
+};
+
+template <class T>
+struct QGenericArrayOps
+    : QTypedArrayData<T>
+{
+    void copyAppend(const T *b, const T *e)
+    {
+        Q_ASSERT(this->ref == 1);
+        Q_ASSERT(b < e);
+        Q_ASSERT(size_t(e - b) <= this->alloc - uint(this->size));
+
+        T *iter = this->end();
+        for (; b != e; ++iter, ++b) {
+            new (iter) T(*b);
+            ++this->size;
+        }
+    }
+
+    void copyAppend(size_t n, const T &t)
+    {
+        Q_ASSERT(this->ref == 1);
+        Q_ASSERT(n <= this->alloc - uint(this->size));
+
+        T *iter = this->end();
+        const T *const end = iter + n;
+        for (; iter != end; ++iter) {
+            new (iter) T(t);
+            ++this->size;
+        }
+    }
+
+    void destroyAll() // Call from destructors, ONLY
+    {
+        // As this is to be called only from destructor, it doesn't need to be
+        // exception safe; size not updated.
+
+        Q_ASSERT(this->ref == 0);
+
+        const T *const b = this->begin();
+        const T *i = this->end();
+
+        while (i != b)
+            (--i)->~T();
+    }
+};
+
+template <class T>
+struct QMovableArrayOps
+    : QGenericArrayOps<T>
+{
+    // using QGenericArrayOps<T>::copyAppend;
+    // using QGenericArrayOps<T>::destroyAll;
+};
+
+template <class T, class = void>
+struct QArrayOpsSelector
+{
+    typedef QGenericArrayOps<T> Type;
+};
+
+template <class T>
+struct QArrayOpsSelector<T,
+    typename QEnableIf<
+        !QTypeInfo<T>::isComplex && !QTypeInfo<T>::isStatic
+    >::Type>
+{
+    typedef QPodArrayOps<T> Type;
+};
+
+template <class T>
+struct QArrayOpsSelector<T,
+    typename QEnableIf<
+        QTypeInfo<T>::isComplex && !QTypeInfo<T>::isStatic
+    >::Type>
+{
+    typedef QMovableArrayOps<T> Type;
+};
+
+} // namespace QtPrivate
+
+template <class T>
+struct QArrayDataOps
+    : QtPrivate::QArrayOpsSelector<T>::Type
+{
+};
+
+QT_END_NAMESPACE
+
+QT_END_HEADER
+
+#endif // include guard
diff --git a/src/corelib/tools/tools.pri b/src/corelib/tools/tools.pri
index 199dd85354..2ec32fd9e9 100644
--- a/src/corelib/tools/tools.pri
+++ b/src/corelib/tools/tools.pri
@@ -3,6 +3,7 @@
 HEADERS +=  \
         tools/qalgorithms.h \
         tools/qarraydata.h \
+        tools/qarraydataops.h \
         tools/qbitarray.h \
         tools/qbytearray.h \
         tools/qbytearraymatcher.h \