/// @file dpf/subinterval_iterable.hpp
/// @author Ryan Henry <ryan.henry@ucalgary.ca>
/// @brief defines `dpf::subinterval_iterable` and associated helpers
/// @copyright Copyright (c) 2019-2024 Ryan Henry and [others](@ref authors)
/// @license Released under a GNU General Public v2.0 (GPLv2) license;
///          see [LICENSE.md](@ref license) for details.

#ifndef LIBDPF_INCLUDE_DPF_SUBINTERVAL_ITERABLE_HPP__
#define LIBDPF_INCLUDE_DPF_SUBINTERVAL_ITERABLE_HPP__

#include <cstddef>

#include "hedley/hedley.h"

namespace dpf
{

template <typename ChildT,
          typename WordT>
class setbit_index_iterable;  // forward declaration

template <typename IteratorT>
class subinterval_iterable
{
  public:
    using iterator = IteratorT;
    using size_type = std::size_t;

    HEDLEY_NO_THROW
    HEDLEY_ALWAYS_INLINE
    explicit subinterval_iterable(iterator it, size_type buf_size, size_type from, size_type to, size_type preclip, size_type outputs_per_leaf, bool nonempty = true) noexcept
      : it_{it}, buf_size_{buf_size}, from_{from}, to_{to},
        length_{nonempty ? to_ - from_ : 0}, preclip_{preclip},
        outputs_{outputs_per_leaf}, nonempty_{nonempty}
    { }

    HEDLEY_NO_THROW
    HEDLEY_ALWAYS_INLINE
    iterator begin() const noexcept
    {
        return it_ + preclip_;
    }
    HEDLEY_NO_THROW
    HEDLEY_ALWAYS_INLINE
    iterator cbegin() const noexcept
    {
        return it_ + preclip_;
    }
    HEDLEY_NO_THROW
    HEDLEY_ALWAYS_INLINE
    iterator end() const noexcept
    {
        if (!nonempty_)
            return it_ + preclip_;
        return it_ + preclip_ + length_ + 1;
    }
    HEDLEY_NO_THROW
    HEDLEY_ALWAYS_INLINE
    iterator cend() const noexcept
    {
        return end();
    }

  private:
    iterator it_;
    size_type buf_size_;
    size_type from_;
    size_type to_;
    size_type length_;
    size_type preclip_;
    size_type outputs_;
    bool nonempty_;

    template <typename ChildT,
              typename WordT>
    friend class setbit_index_iterable;
};  // class dpf::subinterval_iterable

}  // namespace dpf

#endif  // LIBDPF_INCLUDE_DPF_SUBINTERVAL_ITERABLE_HPP__