AdventOfCode/src/common/lib/CyclicVector.h

#pragma once

#include <ostream>
#include <string>
#include <vector>

template <typename T>
struct CyclicVector
{
  std::vector<T> vector;
  size_t offset{0};

  CyclicVector(const std::initializer_list<T>& vector)
    : vector{vector}
  {
  }

  CyclicVector(const std::vector<T>& vector)
    : vector{vector}
  {
  }

  template <typename U = T, typename = std::enable_if_t<std::is_same_v<U, char>>>
  CyclicVector(const std::string& str)
    : vector{str.begin(), str.end()}
  {
  }

  template <std::size_t N, typename U = T, typename = std::enable_if_t<std::is_same_v<U, char>>>
  CyclicVector(const char (&str)[N])
  {
    vector.resize(N - 1);  // don't include \0 character
    for (size_t i = 0; i < N - 1; i++)
    {
      vector[i] = str[i];
    }
  }

  void Rotate(int i)
  {
    if (i < 0)
      RotateLeft(-i);
    else
      RotateRight(i);
  }

  void RotateRight(int i)
  {
    offset = (offset + vector.size() - (i % vector.size())) % vector.size();
  }

  void RotateLeft(size_t i)
  {
    offset = (offset + i) % vector.size();
  }

  T& operator[](size_t i)
  {
    return vector[(i + offset) % vector.size()];
  }

  const T& operator[](size_t i) const
  {
    return vector[(i + offset) % vector.size()];
  }

  size_t size() const
  {
    return vector.size();
  }

  bool empty() const
  {
    return vector.empty();
  }

  size_t Find(const T& t) const
  {
    return std::find(begin(), end(), t).GetPos();
  }

  struct iterator;
  struct const_iterator;

  iterator begin()
  {
    return iterator{*this, 0};
  }

  iterator end()
  {
    return iterator{*this, vector.size()};
  }

  const_iterator begin() const
  {
    return const_iterator{*this, 0};
  }

  const_iterator end() const
  {
    return const_iterator{*this, vector.size()};
  }

  const_iterator cbegin() const
  {
    return const_iterator{*this, 0};
  }

  const_iterator cend() const
  {
    return const_iterator{*this, vector.size()};
  }

  friend std::ostream& operator<<(std::ostream& os, const CyclicVector& vector)
  {
    os << "[";
    if (!vector.empty())
      os << vector[0];

    for (auto it = vector.cbegin() + 1; it != vector.cend(); it++)
    {
      os << ", " << *it;
    }
    os << "]";
    return os;
  }

  class iterator
  {
  private:
    CyclicVector<T>& data;
    size_t pos;

  public:
    using iterator_category = std::random_access_iterator_tag;
    using value_type = T;
    using difference_type = int;
    using pointer = T*;
    using reference = T&;

    iterator(CyclicVector<T>& data, size_t pos)
      : data{data},
        pos{pos}
    {
    }

    size_t GetPos() const
    {
      return pos;
    }

    reference operator*() const
    {
      return data[pos];
    }

    pointer operator->() const
    {
      return &data[pos];
    }

    iterator& operator++()
    {
      ++pos;
      return *this;
    }

    iterator operator++(int)
    {
      iterator ret = *this;
      ++(*this);
      return ret;
    }

    iterator& operator--()
    {
      --pos;
      return *this;
    }

    iterator operator--(int)
    {
      iterator ret = *this;
      --(*this);
      return ret;
    }

    iterator& operator+=(size_t advance)
    {
      if (std::numeric_limits<size_t>::max() - pos < advance)
      {
        pos = data.size();
      }
      else
      {
        pos += advance;
        if (pos >= data.size())
          pos = data.size();
      }
      return *this;
    }

    iterator& operator-=(size_t advance)
    {
      if (advance > pos)
      {
        pos = data.size();
      }
      else
      {
        pos -= advance;
      }
      return *this;
    }

    iterator operator+(size_t advance) const
    {
      iterator ret = *this;
      ret += advance;
      return ret;
    }

    iterator operator-(size_t advance) const
    {
      iterator ret = *this;
      ret -= advance;
      return ret;
    }

    bool operator==(const iterator& other) const
    {
      return pos == other.pos;
    }

    bool operator!=(const iterator& other) const
    {
      return !(*this == other);
    }
  };

  class const_iterator
  {
  private:
    const CyclicVector<T>& data;
    size_t pos;

  public:
    using iterator_category = std::random_access_iterator_tag;
    using value_type = T;
    using difference_type = int;
    using pointer = const T*;
    using reference = const T&;

    const_iterator(const CyclicVector<T>& data, size_t pos)
      : data{data},
        pos{pos}
    {
    }

    size_t GetPos() const
    {
      return pos;
    }

    reference operator*() const
    {
      return data[pos];
    }

    pointer operator->() const
    {
      return &data[pos];
    }

    const_iterator& operator++()
    {
      ++pos;
      return *this;
    }

    const_iterator operator++(int)
    {
      const_iterator ret = *this;
      ++(*this);
      return ret;
    }

    const_iterator& operator--()
    {
      --pos;
      return *this;
    }

    const_iterator operator--(int)
    {
      const_iterator ret = *this;
      --(*this);
      return ret;
    }

    const_iterator& operator+=(size_t advance)
    {
      if (std::numeric_limits<size_t>::max() - pos < advance)
      {
        pos = data.size();
      }
      else
      {
        pos += advance;
        if (pos >= data.size())
          pos = data.size();
      }
      return *this;
    }

    const_iterator& operator-=(size_t advance)
    {
      if (advance > pos)
      {
        pos = data.size();
      }
      else
      {
        pos -= advance;
      }
      return *this;
    }

    const_iterator operator+(size_t advance) const
    {
      const_iterator ret = *this;
      ret += advance;
      return ret;
    }

    const_iterator operator-(size_t advance) const
    {
      const_iterator ret = *this;
      ret -= advance;
      return ret;
    }

    bool operator==(const const_iterator& other) const
    {
      return pos == other.pos;
    }

    bool operator!=(const const_iterator& other) const
    {
      return !(*this == other);
    }
  };
};