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Diffstat (limited to 'src/corelib/tools/qhashfunctions.h')
-rw-r--r-- | src/corelib/tools/qhashfunctions.h | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/src/corelib/tools/qhashfunctions.h b/src/corelib/tools/qhashfunctions.h new file mode 100644 index 0000000000..e15fbb07ac --- /dev/null +++ b/src/corelib/tools/qhashfunctions.h @@ -0,0 +1,156 @@ +/**************************************************************************** +** +** Copyright (C) 2015 The Qt Company Ltd. +** Copyright (C) 2015 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Marc Mutz <marc.mutz@kdab.com> +** Contact: http://www.qt.io/licensing/ +** +** This file is part of the QtCore module of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL21$ +** 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 The Qt Company. For licensing terms +** and conditions see http://www.qt.io/terms-conditions. For further +** information use the contact form at http://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 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. +** +** As a special exception, The Qt Company gives you certain additional +** rights. These rights are described in The Qt Company LGPL Exception +** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#ifndef QHASHFUNCTIONS_H +#define QHASHFUNCTIONS_H + +#include <QtCore/qchar.h> +#include <QtCore/qpair.h> + +#include <numeric> // for std::accumulate + +#if 0 +#pragma qt_class(QHashFunctions) +#endif + +#if defined(Q_CC_MSVC) +#pragma warning( push ) +#pragma warning( disable : 4311 ) // disable pointer truncation warning +#pragma warning( disable : 4127 ) // conditional expression is constant +#endif + +QT_BEGIN_NAMESPACE + +class QBitArray; +class QByteArray; +class QString; +class QStringRef; +class QLatin1String; + +Q_CORE_EXPORT Q_DECL_PURE_FUNCTION uint qHashBits(const void *p, size_t size, uint seed = 0) Q_DECL_NOTHROW; + +Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline uint qHash(char key, uint seed = 0) Q_DECL_NOTHROW { return uint(key) ^ seed; } +Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline uint qHash(uchar key, uint seed = 0) Q_DECL_NOTHROW { return uint(key) ^ seed; } +Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline uint qHash(signed char key, uint seed = 0) Q_DECL_NOTHROW { return uint(key) ^ seed; } +Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline uint qHash(ushort key, uint seed = 0) Q_DECL_NOTHROW { return uint(key) ^ seed; } +Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline uint qHash(short key, uint seed = 0) Q_DECL_NOTHROW { return uint(key) ^ seed; } +Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline uint qHash(uint key, uint seed = 0) Q_DECL_NOTHROW { return key ^ seed; } +Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline uint qHash(int key, uint seed = 0) Q_DECL_NOTHROW { return uint(key) ^ seed; } +Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline uint qHash(ulong key, uint seed = 0) Q_DECL_NOTHROW +{ + return (sizeof(ulong) > sizeof(uint)) + ? (uint(((key >> (8 * sizeof(uint) - 1)) ^ key) & (~0U)) ^ seed) + : (uint(key & (~0U)) ^ seed); +} +Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline uint qHash(long key, uint seed = 0) Q_DECL_NOTHROW { return qHash(ulong(key), seed); } +Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline uint qHash(quint64 key, uint seed = 0) Q_DECL_NOTHROW +{ + return uint(((key >> (8 * sizeof(uint) - 1)) ^ key) & (~0U)) ^ seed; +} +Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline uint qHash(qint64 key, uint seed = 0) Q_DECL_NOTHROW { return qHash(quint64(key), seed); } +Q_CORE_EXPORT Q_DECL_CONST_FUNCTION uint qHash(float key, uint seed = 0) Q_DECL_NOTHROW; +Q_CORE_EXPORT Q_DECL_CONST_FUNCTION uint qHash(double key, uint seed = 0) Q_DECL_NOTHROW; +#ifndef Q_OS_DARWIN +Q_CORE_EXPORT Q_DECL_CONST_FUNCTION uint qHash(long double key, uint seed = 0) Q_DECL_NOTHROW; +#endif +Q_DECL_CONST_FUNCTION Q_DECL_CONSTEXPR inline uint qHash(const QChar key, uint seed = 0) Q_DECL_NOTHROW { return qHash(key.unicode(), seed); } +Q_CORE_EXPORT Q_DECL_PURE_FUNCTION uint qHash(const QByteArray &key, uint seed = 0) Q_DECL_NOTHROW; +Q_CORE_EXPORT Q_DECL_PURE_FUNCTION uint qHash(const QString &key, uint seed = 0) Q_DECL_NOTHROW; +Q_CORE_EXPORT Q_DECL_PURE_FUNCTION uint qHash(const QStringRef &key, uint seed = 0) Q_DECL_NOTHROW; +Q_CORE_EXPORT Q_DECL_PURE_FUNCTION uint qHash(const QBitArray &key, uint seed = 0) Q_DECL_NOTHROW; +Q_CORE_EXPORT Q_DECL_PURE_FUNCTION uint qHash(QLatin1String key, uint seed = 0) Q_DECL_NOTHROW; +Q_CORE_EXPORT Q_DECL_PURE_FUNCTION uint qt_hash(const QString &key) Q_DECL_NOTHROW; +Q_CORE_EXPORT Q_DECL_PURE_FUNCTION uint qt_hash(const QStringRef &key) Q_DECL_NOTHROW; + +template <class T> inline uint qHash(const T *key, uint seed = 0) Q_DECL_NOTHROW +{ + return qHash(reinterpret_cast<quintptr>(key), seed); +} +template<typename T> inline uint qHash(const T &t, uint seed) + Q_DECL_NOEXCEPT_EXPR(noexcept(qHash(t))) +{ return qHash(t) ^ seed; } + +namespace QtPrivate { + +struct QHashCombine { + typedef uint result_type; + template <typename T> + Q_DECL_CONSTEXPR result_type operator()(uint seed, const T &t) const Q_DECL_NOEXCEPT_EXPR(noexcept(qHash(t))) + // combiner taken from N3876 / boost::hash_combine + { return seed ^ (qHash(t) + 0x9e3779b9 + (seed << 6) + (seed >> 2)) ; } +}; + +struct QHashCombineCommutative { + // QHashCombine is a good hash combiner, but is not commutative, + // ie. it depends on the order of the input elements. That is + // usually what we want: {0,1,3} should hash differently than + // {1,3,0}. Except when it isn't (e.g. for QSet and + // QHash). Therefore, provide a commutative combiner, too. + typedef uint result_type; + template <typename T> + Q_DECL_CONSTEXPR result_type operator()(uint seed, const T &t) const Q_DECL_NOEXCEPT_EXPR(noexcept(qHash(t))) + { return seed + qHash(t); } // don't use xor! +}; + +} // namespace QtPrivate + +template <typename InputIterator> +inline uint qHashRange(InputIterator first, InputIterator last, uint seed = 0) + Q_DECL_NOEXCEPT_EXPR(noexcept(qHash(*first))) // assume iterator operations don't throw +{ + return std::accumulate(first, last, seed, QtPrivate::QHashCombine()); +} + +template <typename InputIterator> +inline uint qHashRangeCommutative(InputIterator first, InputIterator last, uint seed = 0) + Q_DECL_NOEXCEPT_EXPR(noexcept(qHash(*first))) // assume iterator operations don't throw +{ + return std::accumulate(first, last, seed, QtPrivate::QHashCombineCommutative()); +} + +template <typename T1, typename T2> inline uint qHash(const QPair<T1, T2> &key, uint seed = 0) + Q_DECL_NOEXCEPT_EXPR(noexcept(qHash(key.first, seed)) && noexcept(qHash(key.second, seed))) +{ + uint h1 = qHash(key.first, seed); + uint h2 = qHash(key.second, seed); + return ((h1 << 16) | (h1 >> 16)) ^ h2 ^ seed; +} + +QT_END_NAMESPACE + +#if defined(Q_CC_MSVC) +#pragma warning( pop ) +#endif + +#endif // QHASHFUNCTIONS_H |