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Diffstat (limited to 'src/declarative/qml/v8/qhashedstring.cpp')
-rw-r--r-- | src/declarative/qml/v8/qhashedstring.cpp | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/src/declarative/qml/v8/qhashedstring.cpp b/src/declarative/qml/v8/qhashedstring.cpp new file mode 100644 index 0000000000..4a23e3b7dd --- /dev/null +++ b/src/declarative/qml/v8/qhashedstring.cpp @@ -0,0 +1,103 @@ +/**************************************************************************** +** +** 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 QtDeclarative module of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the Technology Preview License Agreement accompanying +** this package. +** +** 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. +** +** 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. +** +** If you have questions regarding the use of this file, please contact +** Nokia at qt-info@nokia.com. +** +** +** +** +** +** +** +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#include "qhashedstring_p.h" + +inline unsigned stringHash(const QChar* data, unsigned length) +{ + return v8::String::ComputeHash((uint16_t *)data, length); +} + +void QHashedString::computeHash() const +{ + m_hash = stringHash(constData(), length()); +} + +void QHashedStringRef::computeHash() const +{ + m_hash = stringHash(m_data, m_length); +} + +/* + A QHash has initially around pow(2, MinNumBits) buckets. For + example, if MinNumBits is 4, it has 17 buckets. +*/ +const int MinNumBits = 4; + +/* + The prime_deltas array is a table of selected prime values, even + though it doesn't look like one. The primes we are using are 1, + 2, 5, 11, 17, 37, 67, 131, 257, ..., i.e. primes in the immediate + surrounding of a power of two. + + The primeForNumBits() function returns the prime associated to a + power of two. For example, primeForNumBits(8) returns 257. +*/ + +static const uchar prime_deltas[] = { + 0, 0, 1, 3, 1, 5, 3, 3, 1, 9, 7, 5, 3, 9, 25, 3, + 1, 21, 3, 21, 7, 15, 9, 5, 3, 29, 15, 0, 0, 0, 0, 0 +}; + +static inline int primeForNumBits(int numBits) +{ + return (1 << numBits) + prime_deltas[numBits]; +} + +void QStringHashData::rehash() +{ + numBits = qMax(MinNumBits, numBits + 1); + numBuckets = primeForNumBits(numBits); + + delete [] buckets; + buckets = new QStringHashNode *[numBuckets]; + ::memset(buckets, 0, sizeof(QStringHashNode *) * numBuckets); + + QStringHashNode *nodeList = nodes; + while (nodeList) { + int bucket = nodeList->key.hash() % numBuckets; + nodeList->next = buckets[bucket]; + buckets[bucket] = nodeList; + + nodeList = nodeList->nlist; + } +} + |