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Initial code for intrusive_queue.

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jwellbelove 2016-12-14 11:25:33 +00:00
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///\file
/******************************************************************************
The MIT License(MIT)
Embedded Template Library.
https://github.com/ETLCPP/etl
http://www.etlcpp.com
Copyright(c) 2016 jwellbelove
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files(the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions :
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
******************************************************************************/
#ifndef __ETL_INTRUSIVE_QUEUE__
#define __ETL_INTRUSIVE_QUEUE__
#error In Development. Do not use.
#include <stddef.h>
#include "type_traits.h"
#include "error_handler.h"
#include "intrusive_links.h"
#include "private/counter_type.h"
namespace etl
{
//***************************************************************************
/// Exception base for intrusive queue
///\ingroup intrusive_queue
//***************************************************************************
class intrusive_queue_exception : public etl::exception
{
public:
intrusive_queue_exception(string_type what, string_type file_name, numeric_type line_number)
: exception(what, file_name, line_number)
{
}
};
//***************************************************************************
/// intrusive_queue empty exception.
///\ingroup intrusive_queue
//***************************************************************************
class intrusive_queue_empty : public intrusive_queue_exception
{
public:
intrusive_queue_empty(string_type file_name, numeric_type line_number)
: intrusive_queue_exception(ETL_ERROR_TEXT("intrusive_queue:empty", ETL_FILE"A"), file_name, line_number)
{
}
};
//***************************************************************************
///\ingroup queue
/// An intrusive queue. Stores elements derived from etl::forward_link
/// \warning This queue cannot be used for concurrent access from multiple threads.
/// \tparam TValue The type of value that the queue holds.
/// \tparam TLink The link type that the value is derived from.
//***************************************************************************
template <typename TValue, typename TLink>
class intrusive_queue
{
public:
// Node typedef.
typedef TLink link_type;
// STL style typedefs.
typedef TValue value_type;
typedef value_type* pointer;
typedef const value_type* const_pointer;
typedef value_type& reference;
typedef const value_type& const_reference;
typedef size_t size_type;
enum
{
// The count option is based on the type of link.
COUNT_OPTION = ((TLink::OPTION == etl::link_option::AUTO) || (TLink::OPTION == etl::link_option::CHECKED)) ?
etl::count_option::SLOW_COUNT :
etl::count_option::FAST_COUNT
};
//*************************************************************************
/// Constructor
//*************************************************************************
intrusive_queue()
: p_front(nullptr),
p_back(nullptr)
{
}
//*************************************************************************
/// Gets a reference to the value at the front of the queue.
/// Undefined behaviour if the queue is empty.
/// \return A reference to the value at the front of the queue.
//*************************************************************************
reference front()
{
return *static_cast<TValue*>(p_front);
}
//*************************************************************************
/// Gets a reference to the value at the back of the queue.
/// Undefined behaviour if the queue is empty.
/// \return A reference to the value at the back of the queue.
//*************************************************************************
reference back()
{
return *static_cast<TValue*>(p_back);
}
//*************************************************************************
/// Gets a const reference to the value at the front of the queue.
/// Undefined behaviour if the queue is empty.
/// \return A const reference to the value at the front of the queue.
//*************************************************************************
const_reference front() const
{
return *static_cast<const TValue*>(p_front);
}
//*************************************************************************
/// Gets a reference to the value at the back of the queue.
/// Undefined behaviour if the queue is empty.
/// \return A reference to the value at the back of the queue.
//*************************************************************************
const_reference back() const
{
return *static_cast<const TValue*>(p_back);
}
//*************************************************************************
/// Adds a value to the queue.
///\param value The value to push to the queue.
//*************************************************************************
void push(link_type& value)
{
if (p_back != nullptr)
{
etl::link(p_front, value);
}
else
{
p_front = &value;
}
p_back = &value;
++current_size;
}
//*************************************************************************
/// Removes the oldest item from the queue.
/// Undefined behaviour if the queue is already empty.
//*************************************************************************
void pop()
{
#if defined(ETL_CHECK_PUSH_POP)
ETL_ASSERT(!empty(), ETL_ERROR(intrusive_queue_empty));
#endif
link_type* p_next = p_front->etl_next;
p_front->clear();
p_front = p_next;
// Now empty?
if (p_front == nullptr)
{
p_back == nullptr;
}
--current_size;
}
//*************************************************************************
/// Clears the queue to the empty state.
//*************************************************************************
void clear()
{
while (!empty())
{
pop();
}
current_size = 0;
}
//*************************************************************************
/// Checks if the queue is in the empty state.
//*************************************************************************
bool empty() const
{
return p_front == nullptr;
}
//*************************************************************************
/// Returns the number of elements.
//*************************************************************************
size_t size() const
{
if (COUNT_OPTION == etl::count_option::SLOW_COUNT)
{
size_t count = 0;
if (p_front != nullptr)
{
link_type* p_link = p_front;
while (p_link != nullptr)
{
++count;
p_link = p_link->etl_next;
}
}
return count;
}
else
{
return current_size.get_count();
}
}
private:
// Disable copy construction and assignment.
intrusive_queue(const intrusive_queue&);
intrusive_queue& operator = (const intrusive_queue& rhs);
link_type* p_front; // The current front of the queue.
link_type* p_back; // The current back of the queue.
etl::counter_type<COUNT_OPTION> current_size; ///< Counts the number of elements in the list.
};
}
#endif