IteratorWrapper.hpp

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/*
 * Copyright 2025 Håvard Krogstie <krogstie.havard@gmail.com>
 * See COPYING for terms of redistribution.
 */
 
#ifndef JLM_UTIL_ITERATORWRAPPER_HPP
#define JLM_UTIL_ITERATORWRAPPER_HPP
 
#include <jlm/util/common.hpp>
 
#include <iterator>
 
namespace jlm::util
{
 
template<typename T, typename BaseIterator>
struct PtrDereferenceFunc
{
  [[nodiscard]] T &
  operator()(const BaseIterator & it) const
  {
    JLM_ASSERT(*it != nullptr);
    return *(*it);
  }
};
 
template<typename T, typename BaseIterator>
struct MapValuePtrDereferenceFunc
{
  [[nodiscard]] T &
  operator()(const BaseIterator & it) const
  {
    JLM_ASSERT(it->second != nullptr);
    return *(it->second);
  }
};
 
template<typename T, typename BaseIterator>
struct MapValueFunc
{
  [[nodiscard]] T &
  operator()(const BaseIterator & it) const
  {
    return it->second;
  }
};
 
template<typename T, typename BaseIterator, typename DereferenceFunc>
class IteratorWrapper final
{
public:
  using difference_type = std::ptrdiff_t;
  using value_type = T;
  using pointer = T *;
  using reference = T &;
  using iterator_category = std::forward_iterator_tag;
 
  explicit IteratorWrapper(BaseIterator it)
      : Iterator_(it)
  {}
 
  IteratorWrapper &
  operator++() noexcept
  {
    ++Iterator_;
    return *this;
  }
 
  IteratorWrapper
  operator++(int) noexcept
  {
    auto tmp = *this;
    ++*this;
    return tmp;
  }
 
  [[nodiscard]] bool
  operator==(const IteratorWrapper & other) const noexcept
  {
    return Iterator_ == other.Iterator_;
  }
 
  [[nodiscard]] bool
  operator!=(const IteratorWrapper & other) const noexcept
  {
    return !(other == *this);
  }
 
  [[nodiscard]] reference
  operator*() const noexcept
  {
    return DereferenceFunc{}(Iterator_);
  }
 
  [[nodiscard]] pointer
  operator->() const noexcept
  {
    return &operator*();
  }
 
private:
  BaseIterator Iterator_;
};
 
template<typename T, typename BaseIterator>
using PtrIterator = IteratorWrapper<T, BaseIterator, PtrDereferenceFunc<T, BaseIterator>>;
 
template<typename T, typename BaseIterator>
using MapValuePtrIterator =
    IteratorWrapper<T, BaseIterator, MapValuePtrDereferenceFunc<T, BaseIterator>>;
 
template<typename T, typename BaseIterator>
using MapValueIterator = IteratorWrapper<T, BaseIterator, MapValueFunc<T, BaseIterator>>;
 
}
 
#endif // JLM_UTIL_ITERATORWRAPPER_HPP