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#include "qhash.h"

#ifdef truncate

#undef truncate

#endif

#include <qbitarray.h>

#include <qstring.h>

#include <stdlib.h>

#ifdef QT_QHASH_DEBUG

#include <qstring.h>

#endif

QT_BEGIN_NAMESPACE

/*

    These functions are based on Peter J. Weinberger's hash function

    (from the Dragon Book). The constant 24 in the original function

    was replaced with 23 to produce fewer collisions on input such as

    "a", "aa", "aaa", "aaaa", ...

*/

static uint hash(const uchar *p, int n)

{

    uint h = 0;

    uint g;

    while (n--) {

        h = (h << 4) + *p++;

        if ((g = (h & 0xf0000000)) != 0)

            h ^= g >> 23;

        h &= ~g;

    }

    return h;

}

static uint hash(const QChar *p, int n)

{

    uint h = 0;

    uint g;

    while (n--) {

        h = (h << 4) + (*p++).unicode();

        if ((g = (h & 0xf0000000)) != 0)

            h ^= g >> 23;

        h &= ~g;

    }

    return h;

}

uint qHash(const QByteArray &key)

{

    return hash(reinterpret_cast<const uchar *>(key.constData()), key.size());

}

uint qHash(const QString &key)

{

    return hash(key.unicode(), key.size());

}

uint qHash(const QStringRef &key)

{

    return hash(key.unicode(), key.size());

}

uint qHash(const QBitArray &bitArray)

{

    int m = bitArray.d.size() - 1;

    uint result = hash(reinterpret_cast<const uchar *>(bitArray.d.constData()), qMax(0, m));

    // deal with the last 0 to 7 bits manually, because we can't trust that

    // the padding is initialized to 0 in bitArray.d

    int n = bitArray.size();

    if (n & 0x7)

        result = ((result << 4) + bitArray.d.at(m)) & ((1 << n) - 1);

    return result;

}

/*

    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];

}

/*

    Returns the smallest integer n such that

    primeForNumBits(n) >= hint.

*/

static int countBits(int hint)

{

    int numBits = 0;

    int bits = hint;

    while (bits > 1) {

        bits >>= 1;

        numBits++;

    }

    if (numBits >= (int)sizeof(prime_deltas)) {

        numBits = sizeof(prime_deltas) - 1;

    } else if (primeForNumBits(numBits) < hint) {

        ++numBits;

    }

    return numBits;

}

/*

    A QHash has initially around pow(2, MinNumBits) buckets. For

    example, if MinNumBits is 4, it has 17 buckets.

*/

const int MinNumBits = 4;

QHashData QHashData::shared_null = {

    0, 0, Q_BASIC_ATOMIC_INITIALIZER(1), 0, 0, MinNumBits, 0, 0, true

};

void *QHashData::allocateNode()

{

    void *ptr = qMalloc(nodeSize);

    Q_CHECK_PTR(ptr);

    return ptr;

}

void QHashData::freeNode(void *node)

{

    qFree(node);

}

QHashData *QHashData::detach_helper(void (*node_duplicate)(Node *, void *), int nodeSize)

{

    return detach_helper( node_duplicate, 0, nodeSize );

}

QHashData *QHashData::detach_helper(void (*node_duplicate)(Node *, void *),

        void (*node_delete)(Node *),

        int nodeSize)

{

    union {

        QHashData *d;

        Node *e;

    };

    d = new QHashData;

    d->fakeNext = 0;

    d->buckets = 0;

    d->ref = 1;

    d->size = size;

    d->nodeSize = nodeSize;

    d->userNumBits = userNumBits;

    d->numBits = numBits;

    d->numBuckets = numBuckets;

    d->sharable = true;

    if (numBuckets) {

        QT_TRY {

            d->buckets = new Node *[numBuckets];

        } QT_CATCH(...) {

            // restore a consistent state for d

            d->numBuckets = 0;

            // roll back

            d->free_helper(node_delete);

            QT_RETHROW;

        }

        Node *this_e = reinterpret_cast<Node *>(this);

        for (int i = 0; i < numBuckets; ++i) {

            Node **nextNode = &d->buckets[i];

            Node *oldNode = buckets[i];

            while (oldNode != this_e) {

                QT_TRY {

                    Node *dup = static_cast<Node *>(allocateNode());

                    QT_TRY {

                        node_duplicate(oldNode, dup);

                    } QT_CATCH(...) {

                        freeNode( dup );

                        QT_RETHROW;

                    }

                    dup->h = oldNode->h;

                    *nextNode = dup;

                    nextNode = &dup->next;

                    oldNode = oldNode->next;

                } QT_CATCH(...) {

                    // restore a consistent state for d

                    *nextNode = e;

                    d->numBuckets = i+1;

                    // roll back

                    d->free_helper(node_delete);

                    QT_RETHROW;

                }

            }

            *nextNode = e;

        }

    }

    return d;

}

void QHashData::free_helper(void (*node_delete)(Node *))

{

    if (node_delete) {

        Node *this_e = reinterpret_cast<Node *>(this);

        Node **bucket = reinterpret_cast<Node **>(this->buckets);

        int n = numBuckets;

        while (n--) {

            Node *cur = *bucket++;

            while (cur != this_e) {

                Node *next = cur->next;

                node_delete(cur);

                cur = next;

            }

        }

    }

    delete [] buckets;

    delete this;

}

QHashData::Node *QHashData::nextNode(Node *node)

{

    union {

        Node *next;

        Node *e;

        QHashData *d;

    };

    next = node->next;

    Q_ASSERT_X(next, "QHash", "Iterating beyond end()");

    if (next->next)

        return next;

    int start = (node->h % d->numBuckets) + 1;

    Node **bucket = d->buckets + start;

    int n = d->numBuckets - start;

    while (n--) {

        if (*bucket != e)

            return *bucket;

        ++bucket;

    }

    return e;

}

QHashData::Node *QHashData::previousNode(Node *node)

{

    union {

        Node *e;

        QHashData *d;

    };

    e = node;

    while (e->next)

        e = e->next;

    int start;

    if (node == e)

        start = d->numBuckets - 1;

    else

        start = node->h % d->numBuckets;

    Node *sentinel = node;

    Node **bucket = d->buckets + start;

    while (start >= 0) {

        if (*bucket != sentinel) {

            Node *prev = *bucket;

            while (prev->next != sentinel)

                prev = prev->next;

            return prev;

        }

        sentinel = e;

        --bucket;

        --start;

    }

    Q_ASSERT_X(start >= 0, "QHash", "Iterating backward beyond begin()");

    return e;

}

/*

    If hint is negative, -hint gives the approximate number of

    buckets that should be used for the hash table. If hint is

    nonnegative, (1 << hint) gives the approximate number

    of buckets that should be used.

*/

void QHashData::rehash(int hint)

{

    if (hint < 0) {

        hint = countBits(-hint);

        if (hint < MinNumBits)

            hint = MinNumBits;

        userNumBits = hint;

        while (primeForNumBits(hint) < (size >> 1))

            ++hint;

    } else if (hint < MinNumBits) {

        hint = MinNumBits;

    }

    if (numBits != hint) {

        Node *e = reinterpret_cast<Node *>(this);

        Node **oldBuckets = buckets;

        int oldNumBuckets = numBuckets;

        int nb = primeForNumBits(hint);

        buckets = new Node *[nb];

        numBits = hint;

        numBuckets = nb;

        for (int i = 0; i < numBuckets; ++i)

            buckets[i] = e;

        for (int i = 0; i < oldNumBuckets; ++i) {

            Node *firstNode = oldBuckets[i];

            while (firstNode != e) {

                uint h = firstNode->h;

                Node *lastNode = firstNode;

                while (lastNode->next != e && lastNode->next->h == h)

                    lastNode = lastNode->next;

                Node *afterLastNode = lastNode->next;

                Node **beforeFirstNode = &buckets[h % numBuckets];

                while (*beforeFirstNode != e)

                    beforeFirstNode = &(*beforeFirstNode)->next;

                lastNode->next = *beforeFirstNode;

                *beforeFirstNode = firstNode;

                firstNode = afterLastNode;

            }

        }

        delete [] oldBuckets;

    }

}

void QHashData::destroyAndFree()

{

    free_helper(0);

}

#ifdef QT_QHASH_DEBUG

void QHashData::dump()

{

    qDebug("Hash data (ref = %d, size = %d, nodeSize = %d, userNumBits = %d, numBits = %d, numBuckets = %d)",

            int(ref), size, nodeSize, userNumBits, numBits,

            numBuckets);

    qDebug("    %p (fakeNode = %p)", this, fakeNext);

    for (int i = 0; i < numBuckets; ++i) {

        QString line;

        Node *n = buckets[i];

        if (n != reinterpret_cast<Node *>(this)) {

            line.sprintf("%d:", i);

            while (n != reinterpret_cast<Node *>(this)) {

                line += QString().sprintf(" -> [%p]", n);

                if (!n) {

                    line += " (CORRUPT)";

                    break;

                }

                n = n->next;

            }

            qDebug(qPrintable(line));

        }

    }

}

void QHashData::checkSanity()

{

    if (fakeNext)

        qFatal("Fake next isn't 0");

    for (int i = 0; i < numBuckets; ++i) {

        Node *n = buckets[i];

        Node *p = n;

        if (!n)

            qFatal("%d: Bucket entry is 0", i);

        if (n != reinterpret_cast<Node *>(this)) {

            while (n != reinterpret_cast<Node *>(this)) {

                if (!n->next)

                    qFatal("%d: Next of %p is 0, should be %p", i, n, this);

                n = n->next;

            }

        }

    }

}

#endif

/*!

    \fn uint qHash(const QPair<T1, T2> &key)

    \since 4.3

    \relates QHash

    Returns the hash value for the \a key.

    Types \c T1 and \c T2 must be supported by qHash().

*/

/*! \fn uint qHash(char key)

    \relates QHash

    Returns the hash value for the \a key.

*/

/*! \fn uint qHash(uchar key)

    \relates QHash

    Returns the hash value for the \a key.

*/

/*! \fn uint qHash(signed char key)

    \relates QHash

    Returns the hash value for the \a key.

*/

/*! \fn uint qHash(ushort key)

    \relates QHash

    Returns the hash value for the \a key.

*/

/*! \fn uint qHash(short key)

    \relates QHash

    Returns the hash value for the \a key.

*/

/*! \fn uint qHash(uint key)

    \relates QHash

    Returns the hash value for the \a key.

*/

/*! \fn uint qHash(int key)

    \relates QHash

    Returns the hash value for the \a key.

*/

/*! \fn uint qHash(ulong key)

    \relates QHash

    Returns the hash value for the \a key.

*/

/*! \fn uint qHash(long key)

    \relates QHash

    Returns the hash value for the \a key.

*/

/*! \fn uint qHash(quint64 key)

    \relates QHash

    Returns the hash value for the \a key.

*/

/*! \fn uint qHash(qint64 key)

    \relates QHash

    Returns the hash value for the \a key.

*/

/*! \fn uint qHash(QChar key)

    \relates QHash

    Returns the hash value for the \a key.

*/

/*! \fn uint qHash(const QByteArray &key)

    \fn uint qHash(const QBitArray &key)

    \relates QHash

    Returns the hash value for the \a key.

*/

/*! \fn uint qHash(const QString &key)

    \relates QHash

    Returns the hash value for the \a key.

*/