Split qHash()-related code into separate header

The reduces the amount of code the compiler has to parse when all
the header does is implement its own qHash().

I left the implementation in qhash.cpp, as it doesn't influence
qHash*() users.

Change-Id: Id320d690a33769bae78b03ccc3b08f7124123459
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>

3 files changed, 158 insertions, 97 deletions

diff --git a/src/corelib/tools/qhash.h b/src/corelib/tools/qhash.h
index a9ece12670..c4c8c8f3cc 100644
--- a/src/corelib/tools/qhash.h
+++ b/src/corelib/tools/qhash.h
@@ -38,10 +38,9 @@
 #include <QtCore/qchar.h>
 #include <QtCore/qiterator.h>
 #include <QtCore/qlist.h>
-#include <QtCore/qpair.h>
 #include <QtCore/qrefcount.h>
+#include <QtCore/qhashfunctions.h>
 
-#include <numeric> // for std::accumulate
 #ifdef Q_COMPILER_INITIALIZER_LISTS
 #include <initializer_list>
 #endif
@@ -54,101 +53,6 @@
 
 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;
-}
-
 struct Q_CORE_EXPORT QHashData
 {
     struct Node {
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
diff --git a/src/corelib/tools/tools.pri b/src/corelib/tools/tools.pri
index 5de0c09a4d..5e4a22e283 100644
--- a/src/corelib/tools/tools.pri
+++ b/src/corelib/tools/tools.pri
@@ -26,6 +26,7 @@ HEADERS +=  \
         tools/qeasingcurve.h \
         tools/qfreelist_p.h \
         tools/qhash.h \
+        tools/qhashfunctions.h \
         tools/qiterator.h \
         tools/qline.h \
         tools/qlinkedlist.h \