etl/istack.h

///\file

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

Embedded Template Library.

Copyright(c) 2014 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
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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SOFTWARE.
******************************************************************************/

#ifndef __ETL_ISTACK__
#define __ETL_ISTACK__
#define __ETL_IN_ISTACK_H__

#include <stddef.h>

#include "stack_base.h"
#include "type_traits.h"
#include "parameter_type.h"

#ifndef ETL_THROW_EXCEPTIONS
#include "error_handler.h"
#endif

namespace etl
{
  //***************************************************************************
  ///\ingroup stack
  ///\brief This is the base for all stacks that contain a particular type.
  ///\details Normally a reference to this type will be taken from a derived stack.
  ///\code
  /// etl::stack<int, 10> myQueue;
  /// etl::istack<int>& iQueue = myQueue;
  ///\endcode
  /// \warning This stack cannot be used for concurrent access from multiple threads.
  /// \tparam T The type of item that the stack holds.
  //***************************************************************************
  template <typename T>
  class istack : public stack_base
  {
  public:

    typedef T                     value_type;      ///< The type stored in the stack.
    typedef T&                    reference;       ///< A reference to the type used in the stack.
    typedef const T&              const_reference; ///< A const reference to the type used in the stack.
    typedef T*                    pointer;         ///< A pointer to the type used in the stack.
    typedef const T*              const_pointer;   ///< A const pointer to the type used in the stack.
    typedef stack_base::size_type size_type;       ///< The type used for determining the size of the stack.

  private:

    typedef typename parameter_type<T>::type parameter_t;

  public:

    //*************************************************************************
    /// Gets a reference to the item at the top of the stack.<br>
    /// \return A reference to the item at the top of the stack.
    //*************************************************************************
    reference top()
    {
      return buffer[top_index];
    }

    //*************************************************************************
    /// Adds an item to the stack.
    /// If ETL_THROW_EXCEPTIONS is defined, throws an etl::stack_full is the stack is already full,
    /// otherwise does nothing if full.
    ///\param item The item to push to the stack.
    //*************************************************************************
    void push(parameter_t item)
    {
      if (!full())
      {
        top_index = current_size++;
        buffer[top_index] = item;
      }
      else
#ifdef ETL_THROW_EXCEPTIONS     
      {
        throw stack_full();
      }
#else
      {
        error_handler::error(stack_full());
      }
#endif
    }

    //*************************************************************************
    /// Allows a possibly more efficient 'push' by moving to the next input item
    /// and returning a reference to it.
    /// This may eliminate a copy by allowing direct construction in-place.<br>
    /// If ETL_THROW_EXCEPTIONS is defined, throws an etl::stack_full is the stack is already full,
    /// otherwise does nothing if full.
    /// \return A reference to the position to 'push' to.
    //*************************************************************************
    reference push()
    {
      if (!full())
      {
        top_index = current_size++;
      }
      else
#ifdef ETL_THROW_EXCEPTIONS     
      {
        throw stack_full();
      }
#else
      {
        error_handler::error(stack_full());
      }
#endif

      return buffer[top_index];
    }

    //*************************************************************************
    /// Gets a const reference to the item at the top of the stack.<br>
    /// \return A const reference to the item at the top of the stack.
    //*************************************************************************
    const_reference top() const
    {
      return buffer[top_index];
    }

  protected:

    //*************************************************************************
    /// The constructor that is called from derived classes.
    //*************************************************************************
    istack(T* buffer, size_type max_size)
      : stack_base(max_size),
        buffer(buffer)
    {
    }

  private:

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

#undef __ETL_IN_ISTACK_H__
#endif