multi_range.h

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/******************************************************************************
The MIT License(MIT)
 
Embedded Template Library.
https://github.com/ETLCPP/etl
https://www.etlcpp.com
 
Copyright(c) 2020 John Wellbelove
 
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
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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,
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SOFTWARE.
******************************************************************************/
 
#ifndef ETL_MULTI_LOOP_INCLUDED
#define ETL_MULTI_LOOP_INCLUDED
 
#include "platform.h"
#include "error_handler.h"
#include "exception.h"
#include "functional.h"
#include "nullptr.h"
 
namespace etl
{
  //***************************************************************************
  //***************************************************************************
  class multi_range_exception : public etl::exception
  {
  public:
 
    multi_range_exception(string_type reason_, string_type file_name_, numeric_type line_number_)
      : exception(reason_, file_name_, line_number_)
    {
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  class multi_range_circular_reference : public etl::multi_range_exception
  {
  public:
 
    multi_range_circular_reference(string_type file_name_, numeric_type line_number_)
      : etl::multi_range_exception(ETL_ERROR_TEXT("multi_range:circular reference", ETL_MULTI_LOOP_FILE_ID"A"), file_name_, line_number_)
    {
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  class imulti_range
  {
  public:
 
    //***************************************************************************
    //***************************************************************************
    imulti_range& insert(imulti_range& inner_range)
    {
      ETL_ASSERT(is_valid(inner_range), ETL_ERROR(multi_range_circular_reference));
 
      // Remember what the next range was.
      imulti_range* next = inner;
 
      // Append the new range
      inner = &inner_range;
 
      // Link to the original next range.
      inner_range.set_last(next);
 
      return *this;
    }
 
    //***************************************************************************
    //***************************************************************************
    imulti_range& append(imulti_range& inner_range)
    {
      ETL_ASSERT(is_valid(inner_range), ETL_ERROR(multi_range_circular_reference));
 
      if (inner != ETL_NULLPTR)
      {
        inner->append(inner_range);
      }
      else
      {
        inner = &inner_range;
      }
 
      return *this;
    }
 
    //***************************************************************************
    //***************************************************************************
    void detach()
    {
      inner = ETL_NULLPTR;
    }
 
    //***************************************************************************
    //***************************************************************************
    void detach_all()
    {
      if (inner != ETL_NULLPTR)
      {
        inner->detach_all();
      }
 
      detach();
    }
 
    //***************************************************************************
    //***************************************************************************
    bool completed() const
    {
      return has_completed;
    }
 
    //***************************************************************************
    //***************************************************************************
    size_t number_of_ranges() const
    {
      size_t count = 1UL;
 
      imulti_range* p_range = inner;
 
      while (p_range != ETL_NULLPTR)
      {
        ++count;
        p_range = p_range->inner;
      }
 
      return count;
    }
 
    //***************************************************************************
    //***************************************************************************
    size_t number_of_iterations()
    {
      size_t count = 0UL;
 
      for (start(); !completed(); next())
      {
        ++count;
      }
 
      return count;
    }
 
    //***************************************************************************
    //***************************************************************************
    virtual void next()  = 0;
    virtual void start() = 0;
 
  protected:
 
    //***************************************************************************
    //***************************************************************************
    imulti_range()
      : has_completed(true)
      , inner(ETL_NULLPTR)
    {
    }
 
    //***************************************************************************
    //***************************************************************************
    bool is_valid(imulti_range& inner_range)
    {
      imulti_range* range = &inner_range;
 
      while (range != ETL_NULLPTR)
      {
        if (range == this)
        {
          return false;
        }
 
        range = range->inner;
      }
 
      return true;
    }
 
    //***************************************************************************
    //***************************************************************************
    void set_last(imulti_range* next)
    {
      // Find the last range.
      imulti_range* range = this;
 
      while (range->inner != ETL_NULLPTR)
      {
        range = range->inner;
      }
 
      range->inner = next;
    }
 
    bool          has_completed;
    imulti_range* inner;
  };
 
  //***************************************************************************
  //***************************************************************************
  template <typename T>
  class multi_range : public imulti_range
  {
  public:
 
    typedef T        value_type;
    typedef const T& const_reference;
 
    //***************************************************************************
    //***************************************************************************
    struct step_type
    {
      typedef T value_type;
 
      virtual void operator()(value_type& value) = 0;
    };
 
    //***************************************************************************
    //***************************************************************************
    struct forward_step : public step_type
    {
      typedef T value_type;
 
      virtual void operator()(value_type& value)
      {
        ++value;
      }
    };
 
    //***************************************************************************
    //***************************************************************************
    struct forward_step_by : public step_type
    {
      typedef T value_type;
 
      explicit forward_step_by(const value_type& step_value_)
        : step_value(step_value_)
      {
      }
 
      virtual void operator()(value_type& value)
      {
        value += step_value;
      }
 
      const value_type step_value;
    };
 
    //***************************************************************************
    //***************************************************************************
    struct reverse_step : public step_type
    {
      typedef T value_type;
 
      virtual void operator()(value_type& value)
      {
        --value;
      }
    };
 
    //***************************************************************************
    //***************************************************************************
    struct reverse_step_by : public step_type
    {
      typedef T value_type;
 
      explicit reverse_step_by(const value_type& step_value_)
        : step_value(step_value_)
      {
      }
 
      virtual void operator()(value_type& value)
      {
        value -= step_value;
      }
 
      const value_type step_value;
    };
 
    //***************************************************************************
    //***************************************************************************
    struct compare_type
    {
      typedef T value_type;
 
      virtual bool operator()(const value_type& lhs, const value_type& rhs) const = 0;
    };
 
    //***************************************************************************
    //***************************************************************************
    struct not_equal_compare : public compare_type
    {
      typedef T value_type;
 
      virtual bool operator()(const value_type& lhs, const value_type& rhs) const ETL_OVERRIDE
      {
        return etl::not_equal_to<value_type>()(lhs, rhs);
      }
    };
 
    //***************************************************************************
    //***************************************************************************
    struct less_than_compare : public compare_type
    {
      typedef T value_type;
 
      virtual bool operator()(const value_type& lhs, const value_type& rhs) const ETL_OVERRIDE
      {
        return etl::less<value_type>()(lhs, rhs);
      }
    };
 
    //***************************************************************************
    //***************************************************************************
    struct greater_than_compare : public compare_type
    {
      typedef T value_type;
 
      virtual bool operator()(const value_type& lhs, const value_type& rhs) const ETL_OVERRIDE
      {
        return etl::greater<value_type>()(lhs, rhs);
      }
    };
 
    //***************************************************************************
    //***************************************************************************
    multi_range(value_type first_, value_type last_)
      : first(first_)
      , last(last_)
      , current(first_)
      , p_stepper(&default_stepper)
      , p_compare(&default_compare)
    {
    }
 
    //***************************************************************************
    //***************************************************************************
    multi_range(value_type first_, value_type last_, step_type& stepper_)
      : first(first_)
      , last(last_)
      , current(first_)
      , p_stepper(&stepper_)
      , p_compare(&default_compare)
    {
    }
 
    //***************************************************************************
    //***************************************************************************
    multi_range(value_type first_, value_type last_, compare_type& compare_)
      : first(first_)
      , last(last_)
      , current(first_)
      , p_stepper(&default_stepper)
      , p_compare(&compare_)
    {
    }
 
    //***************************************************************************
    //***************************************************************************
    multi_range(value_type first_, value_type last_, step_type& stepper_, compare_type& compare_)
      : first(first_)
      , last(last_)
      , current(first_)
      , p_stepper(&stepper_)
      , p_compare(&compare_)
    {
    }
 
    //***************************************************************************
    //***************************************************************************
    const_reference begin()
    {
      return first;
    }
 
    //***************************************************************************
    //***************************************************************************
    const_reference end()
    {
      return last;
    }
 
    //***************************************************************************
    //***************************************************************************
    void start() ETL_OVERRIDE
    {
      if (inner != ETL_NULLPTR)
      {
        inner->start();
      }
 
      current       = first;
      has_completed = !(*p_compare)(current, last); // Check for null range.
    }
 
    //***************************************************************************
    //***************************************************************************
    void next() ETL_OVERRIDE
    {
      has_completed = false;
 
      if (inner != ETL_NULLPTR)
      {
        inner->next();
 
        if (inner->completed())
        {
          has_completed = step();
        }
      }
      else
      {
        has_completed = step();
      }
    }
 
    //***************************************************************************
    //***************************************************************************
    const_reference value() const
    {
      return current;
    }
 
  private:
 
    //***************************************************************************
    //***************************************************************************
    bool step()
    {
      (*p_stepper)(current);
 
      const bool has_rolled_over = !(*p_compare)(current, last);
 
      if (has_rolled_over)
      {
        current = first;
      }
 
      return has_rolled_over;
    }
 
    multi_range() ETL_DELETE;
    multi_range(const multi_range&) ETL_DELETE;
    multi_range& operator=(const multi_range&) ETL_DELETE;
 
    value_type first;   
    value_type last;    
    value_type current; 
 
    step_type*   p_stepper;
    forward_step default_stepper;
 
    compare_type*     p_compare;
    not_equal_compare default_compare;
  };
} // namespace etl
 
#endif