etl/include/etl/queue.h

///\file

/******************************************************************************
The MIT License(MIT)

Embedded Template Library.
https://github.com/ETLCPP/etl
https://www.etlcpp.com

Copyright(c) 2014 John Wellbelove, Mark Kitson

Permission is hereby granted, free of charge, to any person obtaining a copy
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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******************************************************************************/

#ifndef ETL_QUEUE_INCLUDED
#define ETL_QUEUE_INCLUDED

#include "platform.h"
#include "iterator.h"
#include "alignment.h"
#include "array.h"
#include "exception.h"
#include "error_handler.h"
#include "debug_count.h"
#include "type_traits.h"
#include "parameter_type.h"
#include "memory_model.h"
#include "integral_limits.h"
#include "utility.h"
#include "placement_new.h"

#include <stddef.h>
#include <stdint.h>

//*****************************************************************************
///\defgroup queue queue
/// A First-in / first-out queue with the capacity defined at compile time,
/// written in the STL style.
///\ingroup containers
//*****************************************************************************

namespace etl
{
  //***************************************************************************
  /// The base class for queue exceptions.
  ///\ingroup queue
  //***************************************************************************
  class queue_exception : public exception
  {
  public:

    queue_exception(string_type reason_, string_type file_name_, numeric_type line_number_)
      : exception(reason_, file_name_, line_number_)
    {
    }
  };

  //***************************************************************************
  /// The exception thrown when the queue is full.
  ///\ingroup queue
  //***************************************************************************
  class queue_full : public queue_exception
  {
  public:

    queue_full(string_type file_name_, numeric_type line_number_)
      : queue_exception(ETL_ERROR_TEXT("queue:full", ETL_QUEUE_FILE_ID"A"), file_name_, line_number_)
    {
    }
  };

  //***************************************************************************
  /// The exception thrown when the queue is empty.
  ///\ingroup queue
  //***************************************************************************
  class queue_empty : public queue_exception
  {
  public:

    queue_empty(string_type file_name_, numeric_type line_number_)
      : queue_exception(ETL_ERROR_TEXT("queue:empty", ETL_QUEUE_FILE_ID"B"), file_name_, line_number_)
    {
    }
  };

  //***************************************************************************
  /// The base class for all queues.
  ///\ingroup queue
  //***************************************************************************
  template <size_t MEMORY_MODEL = etl::memory_model::MEMORY_MODEL_LARGE>
  class queue_base
  {
  public:

    /// The type used for determining the size of queue.
    typedef typename etl::size_type_lookup<MEMORY_MODEL>::type size_type;

    //*************************************************************************
    /// Returns the current number of items in the queue.
    //*************************************************************************
    size_type size() const
    {
      return current_size;
    }

    //*************************************************************************
    /// Returns the maximum number of items that can be queued.
    //*************************************************************************
    size_type max_size() const
    {
      return CAPACITY;
    }

    //*************************************************************************
    /// Returns the maximum number of items that can be queued.
    //*************************************************************************
    size_type capacity() const
    {
      return CAPACITY;
    }

    //*************************************************************************
    /// Checks to see if the queue is empty.
    /// \return <b>true</b> if the queue is empty, otherwise <b>false</b>
    //*************************************************************************
    bool empty() const
    {
      return current_size == 0;
    }

    //*************************************************************************
    /// Checks to see if the queue is full.
    /// \return <b>true</b> if the queue is full, otherwise <b>false</b>
    //*************************************************************************
    bool full() const
    {
      return current_size == CAPACITY;
    }

    //*************************************************************************
    /// Returns the remaining capacity.
    ///\return The remaining capacity.
    //*************************************************************************
    size_type available() const
    {
      return max_size() - size();
    }

  protected:

    //*************************************************************************
    /// The constructor that is called from derived classes.
    //*************************************************************************
    queue_base(size_type max_size_)
      : in(0),
        out(0),
        current_size(0),
        CAPACITY(max_size_)
    {
    }

    //*************************************************************************
    /// Destructor.
    //*************************************************************************
    ~queue_base()
    {
    }

    //*************************************************************************
    /// Increments (and wraps) the 'in' index value to record a queue addition.
    //*************************************************************************
    void add_in()
    {
      if (++in == CAPACITY) ETL_UNLIKELY
      {
        in = 0;
      }

      ++current_size;
      ETL_INCREMENT_DEBUG_COUNT;
    }

    //*************************************************************************
    /// Increments (and wraps) the 'out' index value to record a queue deletion.
    //*************************************************************************
    void del_out()
    {
      if (++out == CAPACITY) ETL_UNLIKELY
      {
        out = 0;
      }
      --current_size;
      ETL_DECREMENT_DEBUG_COUNT;
    }

    //*************************************************************************
    /// Clears the indexes.
    //*************************************************************************
    void index_clear()
    {
      in = 0;
      out = 0;
      current_size = 0;
      ETL_RESET_DEBUG_COUNT;
    }

    size_type in;            ///< Where to input new data.
    size_type out;           ///< Where to get the oldest data.
    size_type current_size;   ///< The number of items in the queue.
    const size_type CAPACITY; ///< The maximum number of items in the queue.
    ETL_DECLARE_DEBUG_COUNT;  ///< For internal debugging purposes.

  };

  //***************************************************************************
  ///\ingroup queue
  ///\brief This is the base for all queues that contain a particular type.
  ///\details Normally a reference to this type will be taken from a derived queue.
  ///\code
  /// etl::queue<int, 10> myQueue;
  /// etl::iqueue<int>& iQueue = myQueue;
  ///\endcode
  /// \warning This queue cannot be used for concurrent access from multiple threads.
  /// \tparam T The type of value that the queue holds.
  //***************************************************************************
  template <typename T, const size_t MEMORY_MODEL = etl::memory_model::MEMORY_MODEL_LARGE>
  class iqueue : public etl::queue_base<MEMORY_MODEL>
  {
  private:

    typedef typename etl::queue_base<MEMORY_MODEL> base_t;

  public:

    typedef T                          value_type;      ///< The type stored in the queue.
    typedef T&                         reference;       ///< A reference to the type used in the queue.
    typedef const T&                   const_reference; ///< A const reference to the type used in the queue.
#if ETL_USING_CPP11
    typedef T&&                        rvalue_reference;///< An rvalue reference to the type used in the queue.
#endif
    typedef T*                         pointer;         ///< A pointer to the type used in the queue.
    typedef const T*                   const_pointer;   ///< A const pointer to the type used in the queue.
    typedef typename base_t::size_type size_type;       ///< The type used for determining the size of the queue.

    using base_t::in;
    using base_t::out;
    using base_t::CAPACITY;
    using base_t::current_size;
    using base_t::full;
    using base_t::empty;
    using base_t::add_in;
    using base_t::del_out;

    //*************************************************************************
    /// Gets a reference to the value at the front of the queue.<br>
    /// \return A reference to the value at the front of the queue.
    //*************************************************************************
    reference front()
    {
      return p_buffer[out];
    }

    //*************************************************************************
    /// Gets a const reference to the value at the front of the queue.<br>
    /// \return A const reference to the value at the front of the queue.
    //*************************************************************************
    const_reference front() const
    {
      return p_buffer[out];
    }

    //*************************************************************************
    /// Gets a reference to the value at the back of the queue.<br>
    /// \return A reference to the value at the back of the queue.
    //*************************************************************************
    reference back()
    {
      return p_buffer[in == 0 ? CAPACITY - 1 : in - 1];
    }

    //*************************************************************************
    /// Gets a const reference to the value at the back of the queue.<br>
    /// \return A const reference to the value at the back of the queue.
    //*************************************************************************
    const_reference back() const
    {
      return p_buffer[in == 0 ? CAPACITY - 1 : in - 1];
    }

    //*************************************************************************
    /// Adds a value to the queue.
    /// If asserts or exceptions are enabled, throws an etl::queue_full if the queue if already full.
    ///\param value The value to push to the queue.
    //*************************************************************************
    void push(const_reference value)
    {
#if defined(ETL_CHECK_PUSH_POP)
      ETL_ASSERT(!full(), ETL_ERROR(queue_full));
#endif
      ::new (&p_buffer[in]) T(value);
      add_in();
    }

#if ETL_USING_CPP11
    //*************************************************************************
    /// Adds a value to the queue.
    /// If asserts or exceptions are enabled, throws an etl::queue_full if the queue if already full.
    ///\param value The value to push to the queue.
    //*************************************************************************
    void push(rvalue_reference value)
    {
#if defined(ETL_CHECK_PUSH_POP)
      ETL_ASSERT(!full(), ETL_ERROR(queue_full));
#endif
      ::new (&p_buffer[in]) T(etl::move(value));
      add_in();
    }
#endif

#if ETL_USING_CPP11 && ETL_NOT_USING_STLPORT && !defined(ETL_QUEUE_FORCE_CPP03_IMPLEMENTATION)
    //*************************************************************************
    /// Constructs a value in the queue 'in place'.
    /// If asserts or exceptions are enabled, throws an etl::queue_full if the queue if already full.
    ///\param value The value to use to construct the item to push to the queue.
    //*************************************************************************
    template <typename ... Args>
    void emplace(Args && ... args)
    {
#if defined(ETL_CHECK_PUSH_POP)
      ETL_ASSERT(!full(), ETL_ERROR(queue_full));
#endif
      ::new (&p_buffer[in]) T(etl::forward<Args>(args)...);
      add_in();
    }
#else
    //*************************************************************************
    /// Constructs a value in the queue 'in place'.
    /// If asserts or exceptions are enabled, throws an etl::queue_full if the queue if already full.
    ///\param value The value to use to construct the item to push to the queue.
    //*************************************************************************
    void emplace()
    {
#if defined(ETL_CHECK_PUSH_POP)
      ETL_ASSERT(!full(), ETL_ERROR(queue_full));
#endif
      ::new (&p_buffer[in]) T();
      add_in();
    }

    //*************************************************************************
    /// Constructs a value in the queue 'in place'.
    /// If asserts or exceptions are enabled, throws an etl::queue_full if the queue if already full.
    ///\param value The value to use to construct the item to push to the queue.
    //*************************************************************************
    template <typename T1>
    void emplace(const T1& value1)
    {
#if defined(ETL_CHECK_PUSH_POP)
      ETL_ASSERT(!full(), ETL_ERROR(queue_full));
#endif
      ::new (&p_buffer[in]) T(value1);
      add_in();
    }

    //*************************************************************************
    /// Constructs a value in the queue 'in place'.
    /// If asserts or exceptions are enabled, throws an etl::queue_full if the queue if already full.
    ///\param value The value to use to construct the item to push to the queue.
    //*************************************************************************
    template <typename T1, typename T2>
    void emplace(const T1& value1, const T2& value2)
    {
#if defined(ETL_CHECK_PUSH_POP)
      ETL_ASSERT(!full(), ETL_ERROR(queue_full));
#endif
      ::new (&p_buffer[in]) T(value1, value2);
      add_in();
    }

    //*************************************************************************
    /// Constructs a value in the queue 'in place'.
    /// If asserts or exceptions are enabled, throws an etl::queue_full if the queue if already full.
    ///\param value The value to use to construct the item to push to the queue.
    //*************************************************************************
    template <typename T1, typename T2, typename T3>
    void emplace(const T1& value1, const T2& value2, const T3& value3)
    {
#if defined(ETL_CHECK_PUSH_POP)
      ETL_ASSERT(!full(), ETL_ERROR(queue_full));
#endif
      ::new (&p_buffer[in]) T(value1, value2, value3);
      add_in();
    }

    //*************************************************************************
    /// Constructs a value in the queue 'in place'.
    /// If asserts or exceptions are enabled, throws an etl::queue_full if the queue if already full.
    ///\param value The value to use to construct the item to push to the queue.
    //*************************************************************************
    template <typename T1, typename T2, typename T3, typename T4>
    void emplace(const T1& value1, const T2& value2, const T3& value3, const T4& value4)
    {
#if defined(ETL_CHECK_PUSH_POP)
      ETL_ASSERT(!full(), ETL_ERROR(queue_full));
#endif
      ::new (&p_buffer[in]) T(value1, value2, value3, value4);
      add_in();
    }
#endif

    //*************************************************************************
    /// Clears the queue to the empty state.
    //*************************************************************************
    void clear()
    {
      if ETL_IF_CONSTEXPR(etl::is_trivially_destructible<T>::value)
      {
        base_t::index_clear();
      }
      else
      {
        while (current_size > 0)
        {
          p_buffer[out].~T();
          del_out();
        }

        in = 0;
        out = 0;
      }
    }

    //*************************************************************************
    /// Removes the oldest value from the back of the queue.
    /// Does nothing if the queue is already empty.
    /// If asserts or exceptions are enabled, throws an etl::queue_empty if the queue is empty.
    //*************************************************************************
    void pop()
    {
#if defined(ETL_CHECK_PUSH_POP)
      ETL_ASSERT(!empty(), ETL_ERROR(queue_empty));
#endif
      p_buffer[out].~T();
      del_out();
    }

    //*************************************************************************
    /// Gets the oldest value and removes it from the front of the queue.
    /// If asserts or exceptions are enabled, throws an etl::queue_empty if the queue is empty.
    //*************************************************************************
    void pop_into(reference destination)
    {
      destination = ETL_MOVE(front());
      pop();
    }

    //*************************************************************************
    /// Gets the oldest value and removes it from the front of the queue and
    /// pushes it to the destination container.
    /// If asserts or exceptions are enabled, throws an etl::queue_empty if the queue is empty.
    /// NOTE: The destination must support a push(T) member function.
    //*************************************************************************
    template <typename TContainer>
    void pop_into(TContainer& destination)
    {
      destination.push(ETL_MOVE(front()));
      pop();
    }

    //*************************************************************************
    /// Assignment operator.
    //*************************************************************************
    iqueue& operator = (const iqueue& rhs)
    {
      if (&rhs != this)
      {
        clear();
        clone(rhs);
      }

      return *this;
    }

#if ETL_USING_CPP11
    //*************************************************************************
    /// Assignment operator.
    //*************************************************************************
    iqueue& operator = (iqueue&& rhs)
    {
      if (&rhs != this)
      {
        clear();
        move_clone(rhs);
      }

      return *this;
    }
#endif

  protected:

    //*************************************************************************
    /// Make this a clone of the supplied queue
    //*************************************************************************
    void clone(const iqueue& other)
    {
      clear();

      size_type index = other.out;

      for (size_type i = 0; i < other.size(); ++i)
      {
        push(other.p_buffer[index]);
        index = (index == (CAPACITY - 1)) ? 0 : index + 1;
      }
    }

#if ETL_USING_CPP11
    //*************************************************************************
    /// Make this a moved clone of the supplied queue
    //*************************************************************************
    void move_clone(iqueue&& other)
    {
      clear();

      size_type index = other.out;

      for (size_type i = 0; i < other.size(); ++i)
      {
        push(etl::move(other.p_buffer[index]));
        index = (index == (CAPACITY - 1)) ? 0 : index + 1;
      }
    }
#endif

    //*************************************************************************
    /// The constructor that is called from derived classes.
    //*************************************************************************
    iqueue(T* p_buffer_, size_type max_size_)
      : base_t(max_size_),
        p_buffer(p_buffer_)
    {
    }

  private:

    // Disable copy construction.
    iqueue(const iqueue&);

    T* p_buffer; ///< The internal buffer.

    //*************************************************************************
    /// Destructor.
    //*************************************************************************
#if defined(ETL_POLYMORPHIC_QUEUE) || defined(ETL_POLYMORPHIC_CONTAINERS)
  public:
    virtual ~iqueue()
    {
    }
#else
  protected:
    ~iqueue()
    {
    }
#endif
  };

  //***************************************************************************
  ///\ingroup queue
  /// A fixed capacity queue.
  /// This queue does not support concurrent access by different threads.
  /// \tparam T            The type this queue should support.
  /// \tparam SIZE         The maximum capacity of the queue.
  /// \tparam MEMORY_MODEL The memory model for the queue. Determines the type of the internal counter variables.
  //***************************************************************************
  template <typename T, const size_t SIZE, const size_t MEMORY_MODEL = etl::memory_model::MEMORY_MODEL_LARGE>
  class queue : public etl::iqueue<T, MEMORY_MODEL>
  {
  private:

    typedef etl::iqueue<T, MEMORY_MODEL> base_t;

  public:

    typedef typename base_t::size_type                                                  size_type;
    typedef typename etl::aligned_storage<sizeof(T), etl::alignment_of<T>::value>::type container_type;

    ETL_STATIC_ASSERT((SIZE <= etl::integral_limits<size_type>::max), "Size too large for memory model");

    static ETL_CONSTANT size_type MAX_SIZE = size_type(SIZE);

    //*************************************************************************
    /// Default constructor.
    //*************************************************************************
    queue()
      : base_t(reinterpret_cast<T*>(&buffer[0]), SIZE)
    {
    }

    //*************************************************************************
    /// Copy constructor
    //*************************************************************************
    queue(const queue& rhs)
      : base_t(reinterpret_cast<T*>(&buffer[0]), SIZE)
    {
      base_t::clone(rhs);
    }

#if ETL_USING_CPP11
    //*************************************************************************
    /// Copy constructor
    //*************************************************************************
    queue(queue&& rhs)
      : base_t(reinterpret_cast<T*>(&buffer[0]), SIZE)
    {
      base_t::move_clone(etl::move(rhs));
    }
#endif

    //*************************************************************************
    /// Destructor.
    //*************************************************************************
    ~queue()
    {
      base_t::clear();
    }

    //*************************************************************************
    /// Assignment operator.
    //*************************************************************************
    queue& operator = (const queue& rhs)
    {
      if (&rhs != this)
      {
        base_t::clone(rhs);
      }

      return *this;
    }

#if ETL_USING_CPP11
    //*************************************************************************
    /// Move assignment operator.
    //*************************************************************************
    queue& operator = (queue&& rhs)
    {
      if (&rhs != this)
      {
        base_t::move_clone(rhs);
      }

      return *this;
    }
#endif

  private:

    /// The uninitialised buffer of T used in the queue.
    container_type buffer[SIZE];
  };

  template <typename T, const size_t SIZE, const size_t MEMORY_MODEL>
  ETL_CONSTANT typename queue<T, SIZE, MEMORY_MODEL>::size_type queue<T, SIZE, MEMORY_MODEL>::MAX_SIZE;
}

#endif