diff options
Diffstat (limited to 'src/corelib/tools/qhash.cpp')
| -rw-r--r-- | src/corelib/tools/qhash.cpp | 69 |
1 files changed, 43 insertions, 26 deletions
diff --git a/src/corelib/tools/qhash.cpp b/src/corelib/tools/qhash.cpp index 7200ea7993..fe8c52d103 100644 --- a/src/corelib/tools/qhash.cpp +++ b/src/corelib/tools/qhash.cpp @@ -1,42 +1,34 @@ /**************************************************************************** ** -** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies). +** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies). ** Copyright (C) 2012 Giuseppe D'Angelo <dangelog@gmail.com>. ** Contact: http://www.qt-project.org/legal ** ** This file is part of the QtCore module of the Qt Toolkit. ** -** $QT_BEGIN_LICENSE:LGPL$ +** $QT_BEGIN_LICENSE:LGPL21$ ** 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 Digia. For licensing terms and -** conditions see http://qt.digia.com/licensing. For further information +** a written agreement between you and Digia. For licensing terms and +** conditions see http://qt.digia.com/licensing. For further information ** use the contact form at http://qt.digia.com/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 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. +** General Public License version 2.1 or version 3 as published by the Free +** Software Foundation and appearing in the file LICENSE.LGPLv21 and +** LICENSE.LGPLv3 included in the packaging of this file. Please review the +** following information to ensure the GNU Lesser General Public License +** requirements will be met: https://www.gnu.org/licenses/lgpl.html and +** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. ** ** In addition, as a special exception, Digia gives you certain additional -** rights. These rights are described in the Digia Qt LGPL Exception +** rights. These rights are described in the Digia 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. -** -** ** $QT_END_LICENSE$ ** ****************************************************************************/ @@ -94,13 +86,14 @@ QT_BEGIN_NAMESPACE (for instance, gcc 4.4 does that even at -O0). */ -#ifdef __SSE4_2__ +#if QT_COMPILER_SUPPORTS_HERE(SSE4_2) static inline bool hasFastCrc32() { - return true; + return qCpuHasFeature(SSE4_2); } template <typename Char> +QT_FUNCTION_TARGET(SSE4_2) static uint crc32(const Char *ptr, size_t len, uint h) { // The CRC32 instructions from Nehalem calculate a 32-bit CRC32 checksum @@ -163,6 +156,11 @@ static inline uint hash(const uchar *p, int len, uint seed) Q_DECL_NOTHROW return h; } +uint qHashBits(const void *p, size_t len, uint seed) Q_DECL_NOTHROW +{ + return hash(static_cast<const uchar*>(p), int(len), seed); +} + static inline uint hash(const QChar *p, int len, uint seed) Q_DECL_NOTHROW { uint h = seed; @@ -669,6 +667,25 @@ void QHashData::checkSanity() Types \c T1 and \c T2 must be supported by qHash(). */ +/*! \fn uint qHashBits(const void *p, size_t len, uint seed = 0) + \relates QHash + \since 5.4 + + Returns the hash value for the memory block of size \a len pointed + to by \a p, using \a seed to seed the calculation. + + Use this function only to implement qHash() for your own custom + types. E.g., here's how you could implement a qHash() overload for + std::vector<int>: + + \snippet code/src_corelib_tools_qhash.cpp qhashbits + + It bears repeating that the implementation of qHashBits() - like + the qHash() overloads offered by Qt - may change at any time. You + \b{must not} rely on the fact that qHashBits() will give the same + results (for the same inputs) across different Qt versions. +*/ + /*! \fn uint qHash(char key, uint seed = 0) \relates QHash \since 5.0 @@ -778,7 +795,7 @@ uint qHash(long double key, uint seed) Q_DECL_NOTHROW } #endif -/*! \fn uint qHash(QChar key, uint seed = 0) +/*! \fn uint qHash(const QChar key, uint seed = 0) \relates QHash \since 5.0 @@ -961,8 +978,8 @@ uint qHash(long double key, uint seed) Q_DECL_NOTHROW A QHash's key type has additional requirements other than being an assignable data type: it must provide operator==(), and there must also be - a global qHash() function that returns a hash value for an argument of the - key's type. + a qHash() function in the type's namespace that returns a hash value for an + argument of the key's type. The qHash() function computes a numeric value based on a key. It can use any algorithm imaginable, as long as it always returns @@ -2127,8 +2144,8 @@ uint qHash(long double key, uint seed) Q_DECL_NOTHROW QMultiHash's key and value data types must be \l{assignable data types}. You cannot, for example, store a QWidget as a value; instead, store a QWidget *. In addition, QMultiHash's key type - must provide operator==(), and there must also be a global - qHash() function that returns a hash value for an argument of the + must provide operator==(), and there must also be a qHash() function + in the type's namespace that returns a hash value for an argument of the key's type. See the QHash documentation for details. \sa QHash, QHashIterator, QMutableHashIterator, QMultiMap |