etl/src/intrusive_stack.h

///\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
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******************************************************************************/

#ifndef __ETL_INTRUSIVE_STACK__
#define __ETL_INTRUSIVE_STACK__

#include <stddef.h>

#include "type_traits.h"
#include "error_handler.h"
#include "intrusive_links.h"

#define ETL_FILE "28"

namespace etl
{
  //***************************************************************************
  /// Exception base for intrusive stack
  ///\ingroup intrusive_stack
  //***************************************************************************
  class intrusive_stack_exception : public etl::exception
  {
  public:

    intrusive_stack_exception(string_type what, string_type file_name, numeric_type line_number)
      : exception(what, file_name, line_number)
    {
    }
  };

  //***************************************************************************
  /// intrusive_stack empty exception.
  ///\ingroup intrusive_stack
  //***************************************************************************
  class intrusive_stack_empty : public intrusive_stack_exception
  {
  public:

    intrusive_stack_empty(string_type file_name, numeric_type line_number)
      : intrusive_stack_exception(ETL_ERROR_TEXT("intrusive_stack:empty", ETL_FILE"A"), file_name, line_number)
    {
    }
  };

  //***************************************************************************
  ///\ingroup stack
  /// An intrusive stack. Stores elements derived from etl::forward_link
  /// \warning This stack cannot be used for concurrent access from multiple threads.
  /// \tparam TValue The type of value that the stack holds.
  /// \tparam TLink  The link type that the value is derived from.
  //***************************************************************************
  template <typename TValue, typename TLink>
  class intrusive_stack
  {
  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;

    //*************************************************************************
    /// Constructor
    //*************************************************************************
    intrusive_stack()
    : p_top(nullptr),
      current_size(0)
    {
    }

    //*************************************************************************
    /// Gets a reference to the value at the top of the stack.
    /// Undefined behaviour if the stack is empty.
    /// \return A reference to the value at the top of the stack.
    //*************************************************************************
    reference top()
    {
      return *static_cast<TValue*>(p_top);
    }

    //*************************************************************************
    /// Gets a const reference to the value at the top of the stack.<br>
    /// \return A const reference to the value at the top of the stack.
    //*************************************************************************
    const_reference top() const
    {
      return *static_cast<const TValue*>(p_top);
    }

    //*************************************************************************
    /// Adds a value to the stack.
    ///\param value The value to push to the stack.
    //*************************************************************************
    void push(link_type& value)
    {
      value.clear();

      if (p_top != nullptr)
      {
        etl::link(value, p_top);
      }

      p_top = &value;

      ++current_size;
    }

    //*************************************************************************
    /// Removes the oldest item from the top of the stack.
    /// Undefined behaviour if the stack is already empty.
    //*************************************************************************
    void pop()
    {
#if defined(ETL_CHECK_PUSH_POP)
      ETL_ASSERT(!empty(), ETL_ERROR(intrusive_stack_empty));
#endif
      link_type* p_next = p_top->etl_next;
      p_top = p_next;
      --current_size;
    }

    //*************************************************************************
    /// Clears the stack to the empty state.
    //*************************************************************************
    void clear()
    {
      while (!empty())
      {
        pop();
      }

      current_size = 0;
    }

    //*************************************************************************
    /// Checks if the stack is in the empty state.
    //*************************************************************************
    bool empty() const
    {
      return current_size == 0;
    }

    //*************************************************************************
    /// Returns the number of elements.
    //*************************************************************************
    size_t size() const
    {
      return current_size;
    }

  private:

    // Disable copy construction and assignment.
    intrusive_stack(const intrusive_stack&);
    intrusive_stack& operator = (const intrusive_stack& rhs);

    link_type* p_top; // The current top of the stack.

    size_t current_size; ///< Counts the number of elements in the list.
  };
}

#undef ETL_FILE

#endif