src/system_wrappers/source/list_stl.cc

/*
 *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include "list_wrapper.h"

#include "trace.h"

namespace webrtc {
ListItem::ListItem(const void* item)
    : this_iter_(),
      item_ptr_(item),
      item_(0)
{
}

ListItem::ListItem(const unsigned int item)
    : this_iter_(),
      item_ptr_(0),
      item_(item)
{
}

ListItem::~ListItem()
{
}

void* ListItem::GetItem() const
{
    return const_cast<void*>(item_ptr_);
}

unsigned int ListItem::GetUnsignedItem() const
{
    return item_;
}

ListWrapper::ListWrapper() : list_()
{
}

ListWrapper::~ListWrapper()
{
    if (!Empty())
    {
        // TODO (hellner) I'm not sure this loggin is useful.
        WEBRTC_TRACE(kTraceMemory, kTraceUtility, -1,
                   "Potential memory leak in ListWrapper");
        // Remove all remaining list items.
        while (Erase(First()) == 0)
        {}
    }
}

bool ListWrapper::Empty() const
{
    return list_.empty();
}

unsigned int ListWrapper::GetSize() const
{
    return list_.size();
}

int ListWrapper::PushBack(const void* ptr)
{
    ListItem* item = new ListItem(ptr);
    list_.push_back(item);
    return 0;
}

int ListWrapper::PushBack(const unsigned int item_id)
{
    ListItem* item = new ListItem(item_id);
    list_.push_back(item);
    return 0;
}

int ListWrapper::PushFront(const unsigned int item_id)
{
    ListItem* item = new ListItem(item_id);
    list_.push_front(item);
    return 0;
}

int ListWrapper::PushFront(const void* ptr)
{
    ListItem* item = new ListItem(ptr);
    list_.push_front(item);
    return 0;
}

int ListWrapper::PopFront()
{
    if(list_.empty())
    {
        return -1;
    }
    list_.pop_front();
    return 0;
}

int ListWrapper::PopBack()
{
    if(list_.empty())
    {
        return -1;
    }
    list_.pop_back();
    return 0;
}

ListItem* ListWrapper::First() const
{
    if(list_.empty())
    {
        return NULL;
    }
    std::list<ListItem*>::iterator item_iter = list_.begin();
    ListItem* return_item = (*item_iter);
    return_item->this_iter_ = item_iter;
    return return_item;
}

ListItem* ListWrapper::Last() const
{
    if(list_.empty())
    {
        return NULL;
    }
    // std::list::end() addresses the last item + 1. Decrement so that the
    // actual last is accessed.
    std::list<ListItem*>::iterator item_iter = list_.end();
    --item_iter;
    ListItem* return_item = (*item_iter);
    return_item->this_iter_ = item_iter;
    return return_item;
}

ListItem* ListWrapper::Next(ListItem* item) const
{
    if(item == NULL)
    {
        return NULL;
    }
    std::list<ListItem*>::iterator item_iter = item->this_iter_;
    ++item_iter;
    if (item_iter == list_.end())
    {
        return NULL;
    }
    ListItem* return_item = (*item_iter);
    return_item->this_iter_ = item_iter;
    return return_item;
}

ListItem* ListWrapper::Previous(ListItem* item) const
{
    if(item == NULL)
    {
        return NULL;
    }
    std::list<ListItem*>::iterator item_iter = item->this_iter_;
    if (item_iter == list_.begin())
    {
      return NULL;
    }
    --item_iter;
    ListItem* return_item = (*item_iter);
    return_item->this_iter_ = item_iter;
    return return_item;
}

int ListWrapper::Insert(ListItem* existing_previous_item,
                        ListItem* new_item)
{
    // Allow existingPreviousItem to be NULL if the list is empty.
    // TODO (hellner) why allow this? Keep it as is for now to avoid
    // breaking API contract.
    if (!existing_previous_item && !Empty())
    {
        return -1;
    }

    if (!new_item)
    {
        return -1;
    }

    std::list<ListItem*>::iterator insert_location = list_.begin();
    if (!Empty())
    {
        insert_location = existing_previous_item->this_iter_;
        if(insert_location != list_.end())
        {
            ++insert_location;
        }
    }

    list_.insert(insert_location,new_item);
    return 0;
}

int ListWrapper::InsertBefore(ListItem* existing_next_item,
                           ListItem* new_item)
{
    // Allow existing_next_item to be NULL if the list is empty.
    // Todo: why allow this? Keep it as is for now to avoid breaking API
    // contract.
    if (!existing_next_item && !Empty())
    {
        return -1;
    }
    if (!new_item)
    {
        return -1;
    }

    std::list<ListItem*>::iterator insert_location = list_.begin();
    if (!Empty())
    {
        insert_location = existing_next_item->this_iter_;
    }

    list_.insert(insert_location,new_item);
    return 0;
}

int ListWrapper::Erase(ListItem* item)
{
    if(item == NULL)
    {
        return -1;
    }
    list_.erase(item->this_iter_);
    return 0;
}
} // namespace webrtc