cpp-lazy-stream/test/stream_helpers.h

//
//  stream_helpers.h
//  stream
//
//  Created by Sam Jaffe on 4/4/23.
//

#pragma once

#include <iterator/end_aware_iterator.h>
#include <iterator/proxy.h>
#include <stream/detail/traits.h>

namespace ranges = stream::ranges;
namespace views = stream::ranges::views;

#include <iterator/detail/macro.h>

#define SELF() (*static_cast<CRTP const *>(this))

/**
 * There are the following types of iterators/containers that we are interested
 * in:
 * - Does the object use common iterators or sentinel iterators
 * - Does the object have a size/empty
 */

template <typename It>
class remaining_iterator : public iterator::end_aware_iterator<It> {
public:
  using super_t = iterator::end_aware_iterator<It>;

public:
  using super_t::super_t;

  friend auto operator-(remaining_iterator const & it, iterator::sentinel_t) {
    return std::distance(super_t::impl(), super_t::end());
  }
};

MAKE_ITERATOR_FACADE_TYPEDEFS_T(remaining_iterator);

template <typename CRTP> struct Sized {
  size_t size() const { return SELF().impl().size(); }
  bool empty() const { return SELF().impl().size() == 0; }
};

template <typename CRTP> struct Common {
  auto begin() const { return SELF().impl().begin(); }
  auto end() const { return SELF().impl().end(); }
};

template <typename CRTP> struct Sentinel {
  auto begin() const { return iterator::end_aware_iterator(SELF().impl()); }
  auto end() const { return iterator::sentinel; }
};

template <typename CRTP> struct SizedSentinel {
  auto begin() const { return remaining_iterator(SELF().impl()); }
  auto end() const { return iterator::sentinel; }
};

template <typename C, template <typename> class... Traits>
class Range : public Traits<Range<C, Traits...>>... {
private:
  C impl_;

public:
  Range() = default;
  Range(C impl) : impl_(std::move(impl)) {}
  template <typename T> Range(std::initializer_list<T> init) : impl_(init) {}

  auto & impl() const { return impl_; }
};

#include <iterator/detail/undef.h>