// ==========================================================================
//                 SeqAn - The Library for Sequence Analysis
// ==========================================================================
// Copyright (c) 2006-2018, Knut Reinert, FU Berlin
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above copyright
//       notice, this list of conditions and the following disclaimer in the
//       documentation and/or other materials provided with the distribution.
//     * Neither the name of Knut Reinert or the FU Berlin nor the names of
//       its contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
// DAMAGE.
//
// ==========================================================================
// Author: Andreas Gogol-Doering <andreas.doering@mdc-berlin.de>
// ==========================================================================
// General purpose allocator.
// ==========================================================================

#ifndef SEQAN_INCLUDE_SEQAN_BASIC_ALLOCATOR_SIMPLE_H_
#define SEQAN_INCLUDE_SEQAN_BASIC_ALLOCATOR_SIMPLE_H_

#include <seqan/basic/allocator_interface.h>

namespace seqan {

// ============================================================================
// Forwards
// ============================================================================

// ============================================================================
// Tags, Classes, Enums
// ============================================================================

/*!
 * @class SimpleAllocator
 * @extends Allocator
 * @headerfile <seqan/basic.h>
 * @brief General purpose allocator.
 *
 * @signature template <typename TParentAllocator>
 *            class Allocator<SimpleAlloc<TParentAllocator> >;
 *
 * @tparam TParentAllocator An allocator that is used by the simple allocator to allocate memory.
 *
 * The tag Default used as TparentAllocator means that the default implementations of <tt>allocate</tt> and
 * <tt>deallocate</tt> are used.
 */

template <typename TParentAllocator = Default>
struct SimpleAlloc;

typedef Allocator<SimpleAlloc<Default> > SimpleAllocator;

template <typename TParentAllocator>
struct Allocator<SimpleAlloc<TParentAllocator> >
{
    struct Header
    {
        Header * left;
        Header * right;
        size_t size;
    };

    Header * data_storages;
    Holder<TParentAllocator, Tristate> data_parent_allocator;

    Allocator()
        : data_storages(0)
    {
    }

    Allocator(TParentAllocator & parent_alloc)
        : data_storages(0)
    {
        setValue(data_parent_allocator, parent_alloc);
    }

    //Dummy copy
    Allocator(Allocator const &)
        : data_storages(0)
    {
    }

    inline Allocator &
    operator = (Allocator const &)
    {
        clear(*this);
        return *this;
    }

    ~Allocator()
    {
        clear(*this);
    }
};

// ============================================================================
// Metafunctions
// ============================================================================

// ============================================================================
// Functions
// ============================================================================

// ----------------------------------------------------------------------------
// Function parentAllocator()
// ----------------------------------------------------------------------------

template <typename TParentAllocator>
inline TParentAllocator &
parentAllocator(Allocator<SimpleAlloc<TParentAllocator> > & me)
{
    return value(me.data_parent_allocator);
}

// ----------------------------------------------------------------------------
// Function clear()
// ----------------------------------------------------------------------------

/*!
 * @fn Allocator#clear
 * @brief Deallocates all memory blocks.
 *
 * @signature void clear(allocator);
 *
 * @param[in,out] The allocator to clear.
 *
 * @section Remarks
 *
 * This function deallocates all memory block sthat were allocated using <tt>allocate()</tt> for <tt>allocator</tt>.
 * The memory is not pooled but directly passed back to the heap manager.
 */

// TODO(holtgrew): Using #-functions messes up search results.
template <typename TParentAllocator>
void
clear(Allocator<SimpleAlloc<TParentAllocator> > & me)
{
    typedef Allocator<SimpleAlloc<TParentAllocator> > TAllocator;

    while (me.data_storages)
    {
        typename TAllocator::Header * next_storage = me.data_storages->right;
        deallocate(parentAllocator(me), reinterpret_cast<char *>(me.data_storages), me.data_storages->size);
        me.data_storages = next_storage;
    }
}

// ----------------------------------------------------------------------------
// Function allocate()
// ----------------------------------------------------------------------------

template <typename TParentAllocator, typename TValue, typename TSize, typename TUsage>
inline void
allocate(Allocator<SimpleAlloc<TParentAllocator> > & me,
         TValue * & data,
         TSize count,
         Tag<TUsage> const &)
{
    typedef Allocator<SimpleAlloc<TParentAllocator> > TAllocator;
    typedef typename TAllocator::Header THeader;

    //compute needed bytes
    size_t bytes_needed = count * sizeof(TValue) + sizeof(THeader);

    //allocate storage from parent
    char * ptr;
    allocate(parentAllocator(me), ptr, bytes_needed, TagAllocateStorage());

    THeader * new_block = reinterpret_cast<THeader *>(ptr);
    new_block->left = 0;
    new_block->right = me.data_storages;
    new_block->size = bytes_needed;

    if (me.data_storages)
    {
        me.data_storages->left = new_block;
    }
    me.data_storages = new_block;

    //return data
    data = reinterpret_cast<TValue *>(ptr + sizeof(THeader));
}

// ----------------------------------------------------------------------------
// Function deallocate()
// ----------------------------------------------------------------------------

template <typename TParentAllocator, typename TValue, typename TSize, typename TUsage>
inline void
deallocate(Allocator<SimpleAlloc<TParentAllocator> > & me,
           TValue * data,
           TSize,
           Tag<TUsage> const &)
{
    typedef Allocator<SimpleAlloc<TParentAllocator> > TAllocator;
    typedef typename TAllocator::Header THeader;

    //update links
    THeader & header = *(reinterpret_cast<THeader *>(data) - 1);
    if (header.left)
    {
        header.left->right = header.right;
    }
    else
    {
        me.data_storages = header.right;
    }
    if (header.right)
    {
        header.right->left = header.left;
    }

    //deallocate storage using parent
    char * ptr = reinterpret_cast<char *>(& header);
    deallocate(parentAllocator(me), ptr, header.size);
}

}  // namespace seqan

#endif  // #ifndef SEQAN_INCLUDE_SEQAN_BASIC_ALLOCATOR_SIMPLE_H_
