/****************************************************************************

**

** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).

** All rights reserved.

** Contact: Nokia Corporation (qt-info@nokia.com)

**

** This file is part of the QtCore 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.

**

**

**

**

**

**

**

**

** $QT_END_LICENSE$

**

****************************************************************************/

#ifndef QCONTIGUOUSCACHE_H

#define QCONTIGUOUSCACHE_H

#include <QtCore/qatomic.h>

#include <limits.h>

#include <new>

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

#undef QT_QCONTIGUOUSCACHE_DEBUG

QT_MODULE(Core)

struct Q_CORE_EXPORT QContiguousCacheData

{

    QBasicAtomicInt ref;

    int alloc;

    int count;

    int start;

    int offset;

    uint sharable : 1;

    uint reserved : 31;

    // total is 24 bytes (HP-UX aCC: 40 bytes)

    // the next entry is already aligned to 8 bytes

    // there will be an 8 byte gap here if T requires 16-byte alignment

    //  (such as long double on 64-bit platforms, __int128, __float128)

    static QContiguousCacheData *allocate(int size, int alignment);

    static void free(QContiguousCacheData *data);

#ifdef QT_QCONTIGUOUSCACHE_DEBUG

    void dump() const;

#endif

};

template <typename T>

struct QContiguousCacheTypedData: private QContiguousCacheData

{

    // private inheritance to avoid aliasing warningss

    T array[1];

    static inline void free(QContiguousCacheTypedData *data) { QContiguousCacheData::free(data); }

};

template<typename T>

class QContiguousCache {

    typedef QContiguousCacheTypedData<T> Data;

    union { QContiguousCacheData *d; QContiguousCacheTypedData<T> *p; };

public:

    // STL compatibility

    typedef T value_type;

    typedef value_type* pointer;

    typedef const value_type* const_pointer;

    typedef value_type& reference;

    typedef const value_type& const_reference;

    typedef qptrdiff difference_type;

    typedef int size_type;

    explicit QContiguousCache(int capacity = 0);

    QContiguousCache(const QContiguousCache<T> &v) : d(v.d) { d->ref.ref(); if (!d->sharable) detach_helper(); }

    inline ~QContiguousCache() { if (!d) return; if (!d->ref.deref()) free(p); }

    inline void detach() { if (d->ref != 1) detach_helper(); }

    inline bool isDetached() const { return d->ref == 1; }

    inline void setSharable(bool sharable) { if (!sharable) detach(); d->sharable = sharable; }

    QContiguousCache<T> &operator=(const QContiguousCache<T> &other);

    bool operator==(const QContiguousCache<T> &other) const;

    inline bool operator!=(const QContiguousCache<T> &other) const { return !(*this == other); }

    inline int capacity() const {return d->alloc; }

    inline int count() const { return d->count; }

    inline int size() const { return d->count; }

    inline bool isEmpty() const { return d->count == 0; }

    inline bool isFull() const { return d->count == d->alloc; }

    inline int available() const { return d->alloc - d->count; }

    void clear();

    void setCapacity(int size);

    const T &at(int pos) const;

    T &operator[](int i);

    const T &operator[](int i) const;

    void append(const T &value);

    void prepend(const T &value);

    void insert(int pos, const T &value);

    inline bool containsIndex(int pos) const { return pos >= d->offset && pos - d->offset < d->count; }

    inline int firstIndex() const { return d->offset; }

    inline int lastIndex() const { return d->offset + d->count - 1; }

    inline const T &first() const { Q_ASSERT(!isEmpty()); return p->array[d->start]; }

    inline const T &last() const { Q_ASSERT(!isEmpty()); return p->array[(d->start + d->count -1) % d->alloc]; }

    inline T &first() { Q_ASSERT(!isEmpty()); detach(); return p->array[d->start]; }

    inline T &last() { Q_ASSERT(!isEmpty()); detach(); return p->array[(d->start + d->count -1) % d->alloc]; }

    void removeFirst();

    T takeFirst();

    void removeLast();

    T takeLast();

    inline bool areIndexesValid() const

    { return d->offset >= 0 && d->offset < INT_MAX - d->count && (d->offset % d->alloc) == d->start; }

    inline void normalizeIndexes() { d->offset = d->start; }

#ifdef QT_QCONTIGUOUSCACHE_DEBUG

    void dump() const { p->dump(); }

#endif

private:

    void detach_helper();

    QContiguousCacheData *malloc(int aalloc);

    void free(Data *x);

    int sizeOfTypedData() {

        // this is more or less the same as sizeof(Data), except that it doesn't

        // count the padding at the end

        return reinterpret_cast<const char *>(&(reinterpret_cast<const Data *>(this))->array[1]) - reinterpret_cast<const char *>(this);

    }

    int alignOfTypedData() const

    {

#ifdef Q_ALIGNOF

        return qMax<int>(sizeof(void*), Q_ALIGNOF(Data));

#else

        return 0;

#endif

    }

};

template <typename T>

void QContiguousCache<T>::detach_helper()

{

    union { QContiguousCacheData *d; QContiguousCacheTypedData<T> *p; } x;

    x.d = malloc(d->alloc);

    x.d->ref = 1;

    x.d->count = d->count;

    x.d->start = d->start;

    x.d->offset = d->offset;

    x.d->alloc = d->alloc;

    x.d->sharable = true;

    x.d->reserved = 0;

    T *dest = x.p->array + x.d->start;

    T *src = p->array + d->start;

    int oldcount = x.d->count;

    while (oldcount--) {

        if (QTypeInfo<T>::isComplex) {

            new (dest) T(*src);

        } else {

            *dest = *src;

        }

        dest++;

        if (dest == x.p->array + x.d->alloc)

            dest = x.p->array;

        src++;

        if (src == p->array + d->alloc)

            src = p->array;

    }

    if (!d->ref.deref())

        free(p);

    d = x.d;

}

template <typename T>

void QContiguousCache<T>::setCapacity(int asize)

{

    if (asize == d->alloc)

        return;

    detach();

    union { QContiguousCacheData *d; QContiguousCacheTypedData<T> *p; } x;

    x.d = malloc(asize);

    x.d->alloc = asize;

    x.d->count = qMin(d->count, asize);

    x.d->offset = d->offset + d->count - x.d->count;

    if(asize)

        x.d->start = x.d->offset % x.d->alloc;

    else

        x.d->start = 0;

    int oldcount = x.d->count;

    if(oldcount)

    {

        T *dest = x.p->array + (x.d->start + x.d->count-1) % x.d->alloc;

        T *src = p->array + (d->start + d->count-1) % d->alloc;

        while (oldcount--) {

            if (QTypeInfo<T>::isComplex) {

                new (dest) T(*src);

            } else {

                *dest = *src;

            }

            if (dest == x.p->array)

                dest = x.p->array + x.d->alloc;

            dest--;

            if (src == p->array)

                src = p->array + d->alloc;

            src--;

        }

    }

    /* free old */

    free(p);

    d = x.d;

}

template <typename T>

void QContiguousCache<T>::clear()

{

    if (d->ref == 1) {

        if (QTypeInfo<T>::isComplex) {

            int oldcount = d->count;

            T * i = p->array + d->start;

            T * e = p->array + d->alloc;

            while (oldcount--) {

                i->~T();

                i++;

                if (i == e)

                    i = p->array;

            }

        }

        d->count = d->start = d->offset = 0;

    } else {

        union { QContiguousCacheData *d; QContiguousCacheTypedData<T> *p; } x;

        x.d = malloc(d->alloc);

        x.d->ref = 1;

        x.d->alloc = d->alloc;

        x.d->count = x.d->start = x.d->offset = 0;

        x.d->sharable = true;

        if (!d->ref.deref()) free(p);

        d = x.d;

    }

}

template <typename T>

inline QContiguousCacheData *QContiguousCache<T>::malloc(int aalloc)

{

    return QContiguousCacheData::allocate(sizeOfTypedData() + (aalloc - 1) * sizeof(T), alignOfTypedData());

}

template <typename T>

QContiguousCache<T>::QContiguousCache(int cap)

{

    d = malloc(cap);

    d->ref = 1;

    d->alloc = cap;

    d->count = d->start = d->offset = 0;

    d->sharable = true;

}

template <typename T>

QContiguousCache<T> &QContiguousCache<T>::operator=(const QContiguousCache<T> &other)

{

    other.d->ref.ref();

    if (!d->ref.deref())

        free(d);

    d = other.d;

    if (!d->sharable)

        detach_helper();

    return *this;

}

template <typename T>

bool QContiguousCache<T>::operator==(const QContiguousCache<T> &other) const

{

    if (other.d == d)

        return true;

    if (other.d->start != d->start

            || other.d->count != d->count

            || other.d->offset != d->offset

            || other.d->alloc != d->alloc)

        return false;

    for (int i = firstIndex(); i <= lastIndex(); ++i)

        if (!(at(i) == other.at(i)))

            return false;

    return true;

}

template <typename T>

void QContiguousCache<T>::free(Data *x)

{

    if (QTypeInfo<T>::isComplex) {

        int oldcount = d->count;

        T * i = p->array + d->start;

        T * e = p->array + d->alloc;

        while (oldcount--) {

            i->~T();

            i++;

            if (i == e)

                i = p->array;

        }

    }

    x->free(x);

}

template <typename T>

void QContiguousCache<T>::append(const T &value)

{

    detach();

    if (QTypeInfo<T>::isComplex) {

        if (d->count == d->alloc)

            (p->array + (d->start+d->count) % d->alloc)->~T();

        new (p->array + (d->start+d->count) % d->alloc) T(value);

    } else {

        p->array[(d->start+d->count) % d->alloc] = value;

    }

    if (d->count == d->alloc) {

        d->start++;

        d->start %= d->alloc;

        d->offset++;

    } else {

        d->count++;

    }

}

template<typename T>

void QContiguousCache<T>::prepend(const T &value)

{

    detach();

    if (d->start)

        d->start--;

    else

        d->start = d->alloc-1;

    d->offset--;

    if (d->count != d->alloc)

        d->count++;

    else

        if (d->count == d->alloc)

            (p->array + d->start)->~T();

    if (QTypeInfo<T>::isComplex)

        new (p->array + d->start) T(value);

    else

        p->array[d->start] = value;

}

template<typename T>

void QContiguousCache<T>::insert(int pos, const T &value)

{

    Q_ASSERT_X(pos >= 0 && pos < INT_MAX, "QContiguousCache<T>::insert", "index out of range");

    detach();

    if (containsIndex(pos)) {

        if(QTypeInfo<T>::isComplex)

            new (p->array + pos % d->alloc) T(value);

        else

            p->array[pos % d->alloc] = value;

    } else if (pos == d->offset-1)

        prepend(value);

    else if (pos == d->offset+d->count)

        append(value);

    else {

        // we don't leave gaps.

        clear();

        d->offset = pos;

        d->start = pos % d->alloc;

        d->count = 1;

        if (QTypeInfo<T>::isComplex)

            new (p->array + d->start) T(value);

        else

            p->array[d->start] = value;

    }

}

template <typename T>

inline const T &QContiguousCache<T>::at(int pos) const

{ Q_ASSERT_X(pos >= d->offset && pos - d->offset < d->count, "QContiguousCache<T>::at", "index out of range"); return p->array[pos % d->alloc]; }

template <typename T>

inline const T &QContiguousCache<T>::operator[](int pos) const

{ Q_ASSERT_X(pos >= d->offset && pos - d->offset < d->count, "QContiguousCache<T>::at", "index out of range"); return p->array[pos % d->alloc]; }

template <typename T>

inline T &QContiguousCache<T>::operator[](int pos)

{

    detach();

    if (!containsIndex(pos))

        insert(pos, T());

    return p->array[pos % d->alloc];

}

template <typename T>

inline void QContiguousCache<T>::removeFirst()

{

    Q_ASSERT(d->count > 0);

    detach();

    d->count--;

    if (QTypeInfo<T>::isComplex)

        (p->array + d->start)->~T();

    d->start = (d->start + 1) % d->alloc;

    d->offset++;

}

template <typename T>

inline void QContiguousCache<T>::removeLast()

{

    Q_ASSERT(d->count > 0);

    detach();

    d->count--;

    if (QTypeInfo<T>::isComplex)

        (p->array + (d->start + d->count) % d->alloc)->~T();

}

template <typename T>

inline T QContiguousCache<T>::takeFirst()

{ T t = first(); removeFirst(); return t; }

template <typename T>

inline T QContiguousCache<T>::takeLast()

{ T t = last(); removeLast(); return t; }

QT_END_NAMESPACE

QT_END_HEADER

#endif