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

**

** Copyright (C) 2001-2004 Roberto Raggi

** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).

** All rights reserved.

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

**

** This file is part of the qt3to4 porting application 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.

**

**

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** $QT_END_LICENSE$

**

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

#ifndef SMALLOBJECT_H

#define SMALLOBJECT_H

#include <QList>

#include <assert.h>

#include <stdlib.h>

#include <string.h>

QT_BEGIN_NAMESPACE

struct block_t

{

    static int N;

    block_t *chain;

    char *data;

    char *ptr;

    char *end;

    inline void init(int block_size = 256)

    {

        ++N;

        chain = 0;

        data = (char*) malloc(block_size);

        ptr = data;

        end = data + block_size;

    }

    inline void init0(int block_size)

    {

        init();

        memset(data, '0', block_size);

    }

    inline void destroy()

    {

        --N;

        if (chain) {

            chain->destroy();

            free(chain);

        }

        free(data);

    }

    inline void *allocate(size_t size, block_t **right_most)

    {

        const unsigned int block_size = 1 << 16;

        if (end < ptr + size) {

            assert( size < block_size );

            if (!chain) {

                chain = (block_t*) malloc(sizeof(block_t));

                Q_ASSERT(chain);

                chain->init(block_size);

            }

            return chain->allocate(size, right_most);

        }

        char *r = ptr;

        ptr += size;

        if (right_most)

            *right_most = this;

        return r;

    }

};

// a stupid memory pool

struct pool

{

    block_t blk;

    block_t *right_most;

    inline pool() { blk.init(); right_most = &blk; }

    inline ~pool() { blk.destroy(); }

    inline void *allocate(size_t size)

    {

        void *ptr = right_most->allocate(size, &right_most);

        Q_ASSERT(ptr);

        return ptr;

    }

    inline void *reallocate(void *old, size_t old_size, size_t size)

    {

        void *alloc = right_most->allocate(size, &right_most);

        memcpy(alloc, old, old_size);

        return alloc;

    }

private:

   Q_DISABLE_COPY(pool)

};

/*

    A memory pool that calls the destructor for each stored item when memory is

    freed, at the expence storing one BaseType* per item.

    Note that allocations for types that does not inherit BaseType

    is not allowed and will result in a crash when the memory is freed.

*/

template <typename BaseType>

class TypedPool

{

public:

    inline TypedPool() { blk.init(); right_most = &blk; }

    inline ~TypedPool()

    {

        foreach(BaseType *item, allocated)

            item->~BaseType();

        blk.destroy();

    }

    inline void *allocate(size_t size)

    {

        void *memory = right_most->allocate(size, &right_most);

        allocated.append(reinterpret_cast<BaseType *>(memory));

        Q_ASSERT(memory);

        return memory;

    }

private:

    Q_DISABLE_COPY(TypedPool)

    block_t blk;

    block_t *right_most;

    QList<BaseType *> allocated;

};

struct SmallObject

{

    static void *operator new(size_t size);

    static void operator delete(void *p);

};

QT_END_NAMESPACE

#endif